Diff Rebuild - Reassembly (Open or LSD)

OK kids,heres part 2 to go along with the LSD rebuild I outlined a couple weeks ago.Sorry about the delay,its been busy lately and the weather has been bad too.

So,assuming you have the 3rd member out of the car already and have rebuilt your LSD,are adding an LSD to an open diff unit,or are changing gear ratios,here are the steps for rebuilding the entire unit.You WILL need a few special tools,a vice and a clean work space.You do not have to own a press,although one will make things easier.Also,nearly all the special tools needed can be bought on a child's allowance from Harbor Freight......not that I advocate shopping there,but some items they sell do work fine and are dirt cheap.Heres a list of tools needed.

Micrometer and magnetic stand. (cheaper than you might think)
Vernier calipers. (digitals are great and are getting cheaper)
Inch lb torque wrench. (must be dial or beam "bendy" type)
Foot lb torque wrench. (I preffer "clickers" for the bigger stuff).
Gear puller. (2 jaw,or bearing splitter type....or a small grinder and a steady hand)

First off,get the entire unit stripped down and clean.Lay out all the parts on a clean table and keep left and right stuff in place.The bearing caps for the differential MUST be kept in order,so mark or stamp them "R" and "L".Strip off all the old bearings using a puller,press or demolish them with a screwdriver and CAREFULLY grind a slit in the inner race until you can pop a crack in it with a hammer and chisel.They will pull right off after that,but I dont recommend this method because of the potential for damage and the grinding grit is thrown everywhere.....but it does work.

Here is the bare housing.A vice works well for holding it,just slip the fat rib at the bottom into the jaws and tighten.Be sure EVERYTHING is clean,especially where the bearings slip in.


Here are the 4 bearings youll need for the rebuild.They are NAPA parts and they are the same numbers as the stock Japanese bearings.These are German made,but Timkins will also work and are the same number.Much cheaper than the dealer or Mazdatrix,especially with my discount!


First,drive in the new pinion outer races with a hammer and punch.Be careful not to slip and gouge the running surface,but be sure to seat them well.Youll hear and feel the difference when they seat.


Next,we have the depth shim for the pinion,mine measured 3.11 MM.
These place the gears at the right position dependant on the housing you are using.Getting the right shim for a given housing requires a lot of special factory tools and measuring.If you use the shim that goes with the 3rd member housing you are using,then it should be close, regardless of what gears you install.If your just adding an LSD carrier or replacing bearings,then the original shim will definately be the right one.14 different shims are availible in varying thickness',but repeated installs and teardowns are needed to get the right one if you dont have all the special tools needed......so if you have mulitple 3rd members lying around,be sure to keep the pinion shims together with the housings they came out of.


Place the shim on the pinion with the beveled end down and slide on a new big bearing.Youll need a piece of pipe to drive the bearing on.Be sure its clean inside before starting.A hammer will do it,or use a press.


Now we have the crush sleeve.It helps you to get the pinion bearing preload correct by crushing down as you tighten the nut.
This makes things a lot easier since you dont have to install shims,measure and then install/replace shims again and again.Its a one-shot deal with these.
The FSM does not say you HAVE to use a new sleeve everytime,but its not a garuantee that the old one will work,so its best to use a new sleeve with a rebuild.Slide that onto the pinion after the bearing is pressed on,then slide the whole thing into the 3rd member.


Next, from the front of the 3rd member,install the small pinion bearing and tap it down into contact with the crush sleeve.


Install a new pinion oil seal and slide the companion flange into place.Dont worry that my seal and flange look different,Im running a modified TII flange with a special seal since I have a large custom driveline.Install the washer and nut on a pinion threads and dab a little locktite on the threads,especially if you reuse an old nut.Tighten the nut just snug.....Just until it bottoms on the washer,but dont torque it yet.





Now,we need to determine the oil seal drag so we can deduct that from the total bearing preload torque.Lightly oil both bearings first,then use an inch lb torque wrench and rotate the pinion,noting at what amount the pointer holds steady when turning.Do not take the reading that shows when the wrench starts to turn,it will be higher than the actual reading while in motion.This is the torque needed to overcome the drag of the oil seal,mine was between 1-2 inch/lbs.



Now,we need to lock the pinion in place and torque the nut down to either crush the sleeve (if its new) or get some bearing preload into the pinions(if a used sleeve is installed).This is where you can get into trouble with an old sleeve,because you might bottom out the bearings before the races both contact the old,crushed sleeve.I used a couple short bolts and a long bar to hold the pinion.Dont be tempted to just jam a screw driver in the flange hole,it takes several hundred lbs of force to crush a new sleeve and you will distort the flange,trust me.


If you use an old sleeve,the pinion preload of 7.8-12.2 in/lbs....after deducting the oil seal drag..... must be reached before the nut reaches 130 lb/ft of torque.Also,if your preload exceeds 7.8-12.2 in/lbs BEFORE the nut reaches 94lb/ft,then you need a new sleeve.Its best to just get a new sleeve,its cheap.
Run the nut down until the "in-out" slop of the pinion starts to get down to zero.Once it gets down to nothing,limit your tightening to little tiny increments.....maybe 1/8" at a time.The bearing preload will increase exponentially once the bearings make contact with their races,and you dont want to over-do it.Take your inch-lb torque wrench and keep checking the rotating preload of the pinion.It will take several nudges,but once it starts to get past 5 in/lbs,things will go fast so only tighten in SMALL amounts.You want a pinion preload of between 7.8 and 12.2, not including the tiny amount you determined was the oil seal drag.I stopped right about 12in/lbs,minus the 1-2 in/lbs of oil seal drag I got,and Im sitting pretty at 10 in/lbs of bearing preload.It feels tight,but its correct and will accomidate bearing wear as the diff gets used.


Now the pinion is fully installed,you can see why its not wise to change companion flanges or oil seals with the diff installed in the car.Its impossible to do all this setting up when the differential is fully assembled and its also pretty much a death sentence for the unit if the bearing preload is too tight/loose.
Now we need to install the carrier/lsd.First,make ABSOLUTELY sure the carrier is clean and flat where the ring gear slips on.Any dirt or dings in the carrier will mess things up and youll be pulling your hair out later when the backlash settings will not pan out.File any burrs and clean both surfaces well.Be sure to tap the gear on with the holes lined up.If you have to wrench the first few bolts into place,then start over,they should go in with your fingers.Pushing them in to align the gear and carrier will cause the threads of the bolt to peel and the shavings will get under the gear and mess everything up.Once the holes are perfectly aligned,dab some locktite on all the bolts and run them down in a criss-cross pattern,stopping at 51-61 lb/ft or torque.


Now,install the new carrier bearings onto the carrier.You can press them or hammer them on,but dont use a socket to do it.I know,it seems like the perfect tool for it,but in addition to messing up your tools,you can contaminate the new bearings with chrome flakes from the socket.Use a piece of pipe or at least a plain steel impact socket.No shims are needed,so pre-clearanced "setup" bearings are not needed.....thank God!








Also,I forgot to mention that once you get the pinion preload set,give both sides of the pinion a couple good taps with a hammer,then recheck the preload.The taps will ensure the bearings/races are fully seated and not cocked.I usually will have to go back and give her a little more torque after tapping the pinion and this time was no exception.....lost about 3-4 in/lbs on my preload setting after the first round of taps,after that she held steady.


Now,set the carrier with its new bearings and outer races into the 3rd member and lightly oil the bearings.....were almost done!


Slip the adjuster nuts into their grooves and spin them in against the bearing races until the bearing slop is gone.Youll want there to be a little tiny bit of gear backlash for now,but just do it by feel to get things close.Run the left adjuster out and the right adjuster in equal amounts to obtain more gear lash, and vise-versa to obtain less gear lash.


Now,install the bearing caps onto their saddles (you did mark them left and right earlier,correct?) and tighten the bolts just till they bottom,very loose for now.


Set up your mag stand and dial indicator so that the pointer is touching the ring gear tooth at its very edge and so the pointer is in-line with the ring gear.Mark the ring gear at 4 points,at roughly 90* spaces around the gear.These are your measuring points.Rock the ring gear back and forth and measure the lash.Your final setting is going to be .0035in - .0043in.....very tight lash compared to the big 4x4 stuff Im used to,so be precise and certain as you check this setting.Turn the adjusters in or out in equal amounts until you get this reading at all 4 points along the ring gear.There can be variations,but the lowest reading must never be below .002in and the spread between the highest and lowest reading must not exceed .0028in......so theres very little room for error.This is why the ring gear MUST sit flat on the carrier when you install it. There are proponents for going higher or lower within the allowable backlash settings.Some say a tighter backlash will compensate for deflection when the pinion pushes ring gear away under power.Some say a looser backlash will allow more oil to find its way between the gear teeth,better protecting them.Both camps are correct,so its up to you to decide which end of the range to set things.I got a nice .004in setting all around the ring gear,so I left things at that,right in the middle of the allowable tolerances.


Now,tighten the two adjusters equally to set the carrier preload.Be sure to rotate each adjuster equally so the lash doesnt change.Its impossible to actually measure the carrier preload the way you check the pinion bearing preload since the diff unit is now assembled and the gear and pinion drag would mess things up.Yukon's gear guy says he's never had a failure due to excessive carrier bearing preload and it makes sense.The carrier bearings are turning at a leisurely pace,only 1/4 the speed of the pinion and they dont have to support any of the cars weight.Mazda has a spec for checking the value and it requires a large micrometer you use to take measurements at the little "nubs" on the bearings caps.Measure diagonally across the diff to those 4 points and tighten the adjusters until both measurements are between 7.3004in - 7.30033in.I took Yukons advice and tightened the adjusters with a 12" tool I made.Its pretty easy to put together,I welded 2 small bolts to a bar,but you could easily drill and fasten the bolts if you dont have a welder.Center spacing for the bolts is 57MM and they will fit into the adjuster slots perfectly.


"Tight as you can resonably get them with a 12" tool" is Yukon's recommendation.Be sure the last adjustment you make is to tighten the left side adjuster in.This will insure that there is no slack between the left bearing and the left adjuster.The left bearing takes ALL the load of the pinion when the power is on,so you dont want to have it loose.Once the carrier preload is set,tighten the bearing cap bolt to 27-38lb/ft of torque.


Install the locking tabs.You might have to alter the adjusters positions a tiny bit to get the slots lined up for the locks.The diff should feel pretty tight,but you should be able to turn it fairly easily with your hands.



Once the caps are tight,go back and re-check the backlash one last time to be sure you didnt alter it when running the carrier bearing adjusters down.
Now its time to check the pattern,which should be dead on if you kept the right pinion shim for your housing.This part normally sucks,because you have to do it several times when selecting pinion shims for Dana and other style diffs.This type of system makes pattern setup a one-shot deal most of the time,if you keep the parts together from a given housing.
This is the only stuff to use.Forget about white grease,red lead or prussian blue.......GM gear marking compound is THE BEST for setting gears and a $5 tube will last you a lifetime.


Coat a few teeth on both sides and repeat this at 3 or 4 points along the ring gear.I use a 3" bolt, tightened up in the companion flange to use as a crank to spin the pinion.


Use you right hand to crank the pinion and drag your left palm along the backside of the ring gear to provide some drag.Spin the pinion both directions many times to get a good pattern built up on the drive and coast sides of the teeth.You want the sliding action of the hypoid gears to rub away the compound where they mesh,allowing you to see where along the tooth the contact is being made.The bare spot should always be in the middle of the tooth,relative to the base(flank) and tip (face) of the tooth.There should always be some yellow left down at the bottom of each tooth and there should be at least a small line of yellow at the top.The pattern should be centered front to back(heal and toe) on the tooth as well,but this is not always possible, and not 100% required.I took several pics,but its a tough shot to get,so Ill only post the best ones.It was dead on perfect the first time,on both the drive and coast sides of the teeth.Sometimes its easier to see the pattern on the ring teeth you didnt coat with compound,since the stuff tends to get distributed on everything as the compound transfers to the pinion teeth and makes its way around the rest of the ring gear.



Its OK to leave the compound on the teeth,it will dissolve in the gear oil.Some say to wipe it off,but Id rather not risk getting towel or rag lint into my fresh rebuilt differential while trying to pick all the goop out of the teeth.....plus it gets everywhere,its like ultra-high pigment oilpaint.

Well,thats it!!!!
If you are done,you can officially call yourself a gear head!
Just install and enjoy.My new 3.90 gears dont feel much different than the old 4.07 gears,but its hard to tell when the redline buzzer is screeching and the tires are breaking loose.I'd hoped the taller gears would help quell the traction loss issues,but it didnt.At least my MPG on the highway might go up 1/2 of a percent!And I have the piece of mind knowing that all my bearings are fresh and the LSD is working the best it possibly can.If anyone has any questions or comments regarding this job,feel free to ask.
For quick refference,additional info and good pattern setting knowledge,heres the link to Yukon's install guide,which I always carry with me when doing gears.Theres no shame in using the manual,setting gears is a precise and critical job and only one who has been doing it a very long time, can say they can do it by "feel" or without instructuons.

Yukons Rebuild info




Reposted from RX7 CLub written by steve84GS TII

RX-7 Yearly Model Differences

SCHWARCZ_LARRY/...
Tue, 4 Aug 92 17:48:33 EDT

From: SCHWARCZ_LARRY/...
Subject: RX-7 Yearly Model Differences

Hey, y'all,

Well, there had been some discussion on the list about the differences between the different years of RX-7's.

Well, I've compiled the following which lists a good deal of the changes from year to year. It also lists some info about reading the VIN, performance, prices, etc.

I compiled this document from many different sources and I've already corrected some of the errors in it. There are a few spots where I have "?" indicating that I'm not sure of a figure. If anyone can add to this or correct any errors, please e-mail me (and the list). Maybe we can get a decent document.

The bulk of this came from a book called, "Mazda RX-7: The First Generation" by John Ball and from the Mazda RX-7 Parts Catalog.

Later...
Larry Schwarcz

Adjusting the Steering Box

Make sure that before you attempt this ;
First replace all steering components. 
tie rod ends, and idler arm. and pitman arm. 
Lots of play is from these components.

What you will need

Very important! 
Grind the beveled edge off of the large socket that you are going to use. 40mm or 1-9/16"

 It is almost impossible to get that one loose without rounding the corners off even without the bevel on the socket.
Use vice grips to pull the stupid round plug off the freeplay adjuster.

Okay, once that is done then get that large nut broken loose. If you manage to do that then you are home free. Once it is loose, then hold it while you turn the next largest nut (mine has a series of holes drilled into it). I used a hammer and cold punch to turn it. Tighten it about 1/8 of a turn, then retighten the large nut and take it for a drive.

This will be a trial and error type of thing. If its still too loose, then tighten that inner nut (the one with the holes in it) another 1/8 turn. If you end up getting it too tight then your steering will loose its self-centering properties and will quickly wear out completely.

Really, its easy, even without pictures. there's only 6 things that move.

1. the locking ring on the column where it enters the box

2. the shaft where it enters the box

3. the freeplay adjuster and 

4.locking nut

5. the preload adjuster

6. the locking ring.

Here's abreviated instructions that may make it easier to understand.

Note: I cheated and didn't disconnect my pitman arm, so this is my version.

1. adjust the column where it enters the box until there is a tiny bit of resistance.

2. loosen freeplay locknut and back off the adjustment a little

3. loosen preload locking ring with a huge socket or cold chisel

4. put a punch in one of the holes in the preload adjuster

5. tighten the preload by tapping the punch until there is a little resistance

6. wiggle steering wheel back and forth while tightening freeplay with screwdriver until there is no more.

7. tighten all locking rings/bolts

___________________________________________________________________________

Here is an alternate version of the adjustment writeup

1) The yellow circles - (A) The one on the left is the locking nut that must be cracked loose to adjust it. Use a hammer and a chisel. You can't see it very well, but there are little dips at each corner. To crack it loose, you'll need a long chisel to get at it, and a hammer. You want it to go counter-clockwise to loosen it, which means the chisel will be at the BOTTOM in relation to the picture. I used a sharp chisel, and as you can see it's a pretty dirty box - while the chisel started cutting at first, it eventually cracked loose, although I had to use some Liquid Wrench first. (B) The one on the right is the actual adjuster. You will need a somewhat large crescent wrench to get at it, and the angle is less-than pleasant because of the brake lines being in the way (I had to get at it diagonally). Don't touch it until you've cracked the adjustments loose for the other parts, but for now keep in mind you will be turning it CLOCKWISE.

2) The dark purple cirlces - (A) The outer locking nut. Gotta crack this one loose too. This uses a 40mm socket (or optionally a 1 9/16" should work). Because the nut is super thin, you'll have to grind the socket down to remove the light bevel around the rim - otherwise it won't grab properly. If for the life of you you can't get it to come and it starts stripping, you can take the entire top plate off after removing the nut for #3, as well as the 3 bolts you see in the image - with those removed, you should be able to keep the screw from moving with a flat screwdriver, and "unscrew" the entire plate from it. Careful if removing it because it's easy to break that threaded screw - hopefully you don't have to remove it but if the nut strips (which happened to me), that's your only option, in which case once you have it off, a vice, a bunch of liquid wrench, a massive pair of vicegrips, and possibly some heat is what you're likely to need to get that nut to come off. (B) The middle dark purple circle with the 4 little dimples on it is the adjustment itself. If things are well lubed, you should be able to stick the edge of a screwdriver in at an angle and turn it with arm force - otherwise you may need to use a punch and LIGHTLY tap it with a hammer to get it to move. Dont adjust it until you've cracked all the other adjustments loose.

3) The light purple circles - (A) The locking nut. I believe it's a 14mm wrench that you'll use if I'm remembering correctly. Use a flat screwdriver to hold the screw in place while you crack the nut loose. (B) The adjusting screw in the very center. Turning this does a fairly significant bit of adjusting that you feel in the steering wheel - which way you have to turn it seems to vary - having someone wiggle the steering wheel from inside helps it to turn more easily (and they can also start to feel when it tightens up).

Alright, on to the method of adjustment. Make sure you've loosened all the locking nuts before proceeding.

First, the crescent wrench on the #1 section. Turn it clockwise (or moving "up" in the picture) to tighten it slowly. Have someone inside the car wiggling the wheel until they start to feel it getting a little more tight/snug/harder-to-wiggle. This shouldn't have to be adjusted much at all - in fact, sometimes it doesn't even need to be adjusted. I turned it probably 1/8-1/6 of a turn - not much at all. Again, a helper works great. Too much probably breaks something, so if you're going to make an error, make it on the side of adjusting not-quite-enough instead of too-much.

Second, the circle thing with the 4 dimples (#2). I read that turning it clockwise half a turn or so can help as a starting point. I ended up needing to go counter-clockwise though a fair bit. You have to push quite hard with a screwdriver, or do the punch/hammer light-tap - always at an angle to the side. Which way you need to go may vary, but again, don't force it too much whichever way you decide to go. If it's not moving, you may want to pull the whole top plate off and clean it up so it moves more easily. Again, have someone inside the car wiggling the steering wheel so they can feel when it starts to actually tighten up a bit.

Third, the screw in the middle. Again, this may need to go clockwise or counterclockwise. Have someone wiggling the steering wheel from inside. This should be the final adjustment that has to be made. For me, I needed it unscrewed as far as it went to be tight regardless of where the other adjustments were (probably because one of the issues with my box was the assembly not being tight in the cap or other bearings that should center it being worn). This meant the #2 adjustment was doing the most "real" adjusting for me and #3 was just keeping it tight in the cap.

With all the adjustments done, assuming it's nice and tight, re-tighten all 3 locking nuts (being sure that they don't turn the adjustors while being tightened) and you should be good to go!

NOTE: What you're doing is basically taking the free play out of the steering box. If your front-end parts aren't tight though (tie rods, etc), this won't help you a lot and you'll probalby end up accidently OVERTIGHTENING things which will wear out the box faster. When tightening things / making adjustment and having someone inside wiggle the steering wheel slightly, a nice trick is to watch the pitman arm coming from the bottom of the steering box. If each wiggle of the steering wheel moves that arm, things are probably in pretty good shape. If on the other hand they're wiggling the wheel back and forth, and there's no movement at all in the pitman arm, adjustments probably need to be made.

Also note that it will never be perfectly tight. You'll never get it to the point where a 1mm movement in the steering wheel moves the pitman arm. The idea is to get it tight *enough* so that you don't have an inch or more of play. Get it reasonable and don't go overboard.

Finally, don't overtighten - not only does it wear things out faster (in which case you'll be back to square 1 in no time anyway), but the car will lose the self-centering characteristics which isn't exactly safe.

If all else fails, or if something goes wrong/breaks, you'll need to get a new box. Don't adjust unless you're comfortable doing so. If your steering isn't that bad, don't bother taking the risks of adjusting. On the other hand, if you're at the point where you're about to buy a new box anyway because it's so terrible, definitely give adjustment a try first. Best case scenerio it works great again for years, and worst-case scenerio you end up buying the new box you were going to buy anyway. There are also other guides out there - feel free to look at them - they may mention better details than I have here.

SA / FB RX7 Drift Tune Index

Photo Credit : Shutter Andi or ShutterAndi.com

For Starters

Basic Mods for the beginner to start with

SA/FB Rx7s responds well to left foot braking, high entry speeds and fients. Power, angle, and hydro for beginners is a crutch. It's a huge crutch that will make you suck later on.

Imho if you weld the diff, and remove steering locks, add some air pressure in rear, PB&J mod the watts and just run it. You will have a solid start that will allow you to learn how to drive. As you progress you can start to add these mods as you grasp your technique and improve to the point you can utilize everything that the car already had.

Brakes

If You Go Fast you need to be able to stop

1. FC brakes - See FC Front Suspension on FB with 626 Ball Joint (S5 T2 suspension/brakes on an S1/2/3) and FC Subframe Swap
2. FC - Bolt on kit 
3. S13 Brakes - See S13 Suspension Stock Arms or S13 Suspension Adjustable Arms
4. Brakes Upgrades
5. Brake Cooling
6. 4 Piston Brake Conversion
7. Put 81-85 rear disc brakes and limited slip in a 79-80

Steering

Why is my steering wheel so wobbly?

1. Adjusting the Steering Box
2. Rack conversion - Blacktie has a nice kit put together (currently Preorders only)
3. Steering Gear Restoration
4. Steering Wheel Lock Removal
5. FC subframe
   
   
   
   Suspension
   How to get low and handle good

1. S13 Suspension Stock Arms 
2. S13 Suspension Adjustable Arms 
3. S13 Suspension Rear 
4. FC Front Suspension on FB with 626 Ball Joint (S5 T2 suspension/brakes on an S1/2/3) 
5. FC Subframe Swap 
6. FB weld on Coils - T3 has a weld on set available as well as completed struts 
7. Mustang Rear Coilovers 
8. AE86 Rear Coilovers 
9. GSL-SE Suspension upgrade 
10. Ball Joint Replacement FB Mazda RX-7 
11. Front Suspension Refresh in FB Mazda RX7 


Rear Axle
How to fix our Cars weakest link

Basic overview of your factory RX-7 Suspension:
Lowered car, factory 4 link suspension with a watts link.

The lower trailing arms are straight, but the uppers angle inwards from the rear end, and are much shorter than the lowers. This causes a few problems. When you lower the car, the axle will pivot and cause extreme wear to the axle pinion and trans tail shaft. Also, when you enter a corner the axle will pivot at an awkward rate and finally hit a point where it will bind up, normally causing snap oversteer. The Watts link is not centered on the diff and the bars are unequal length. This causes the rear end to act slightly differently on either a left or right turn.

1. PB&J Mod - how to help fix your watts link binding and axle wrap 
2. LSD Shimming 
3. Welding your LSD 
4. Welding your Open Diff 
5. Diff Rebuild - Reassembly (Open or LSD) 
6. Miata Torsion Diff 
7. 4 Link and Watts Link DIY adjustable links
8. 8.8 swap 
9. 9" swap 
10. 
    
11. Torque arm Granny's Speedshop has a torque arm option (though only for the Ford 8.8 retro, I don't see why something like this couldn't be made for the stock RX7 rearend. 
12. Grannys Torque Arm 8.8
13. 3 (tri) Link - kcraceware does make a nice trilink for the rx7 
14. Pan Hard Bar
15. T3 makes a bolt in option
16. Rear Gearing Options -Kia Gears, and other stock replacement gears -Aftermarket gears 
17. Axle Interchange/Upgrades

Engine

You're ready to go FAST

1. 12a Rats Nest Delete
2. Nikki Carb Rebuilding
3. Modding the Nikki
4. Mod Vacuum Secondaries (non mechanical)
5. Carb Facts
6. Mechanical secondaries
7. Teeter Totter syndrome
8. ATF Treatment
9. Cold Air Intake Set up
10. Cooling System
11. Diagnosing Drivability Problems
12. Electrical Upgrades Part One
13. Electrical Upgrades Part Two
14. Upgrading to the 81-85 Electronic Ignition
15. Electronic Ignition Swap
16. MSD Install
17. Oil Metering Pump Overhaul
18. Side Fire Spark Plug Conversion
19. Taurus Electric Fan Installation in FB Mazda RX-7
20. Wiring in a Fuel Pump Relay in a FB Mazda RX-7
21. Autopower Bolt-In Roll Cage Mock Up FB Mazda RX7 RXSE7EN
22. FB TII Swap

Transmission
Get that Power Down

1. Mazdatrix Flywheel Holding Tool Review
2. Rotary Engine Pilot Bearing Removal Explanation
3. Running a Turbo Transmission Behind an N/A Rotary Engine

Wheels

What the hell will fit.

1. Wheel Sizing

Aero

What to buy, What can you make? How wide do you want it?

1. Where To Start

Interior

1. How to add relays to your FB power windows
2. Put an 81-83 guage cluster in a 79-80
3. 81-85 Power mirror upgrade (for 79-85)
4. Upgrading a 79-80 to with an 81-83 steering column
5. Corbeau Forza Wide Install
6. Simple Sound System Installation in FB Mazda RX-7

Generic SA /FB Information - Manuals

1. Rx-7 Yearly Model Differences
2. http://www.worleys.com/rx-7/12a.index.html

This is currently under construction and in the layout phase, looking for feed back to help build this to a nice index of information for everyone. please let me know what you would like to see, or if you have information to share!

Shimming your LSD

PDF Write up how to shim diff (it is for FC but will work same for FB)

Step 1:

Jack the rear of the ol' beasty up nice and high so you have plenty of room to move around. Make sure you put some Metallica on to get you in the right mood for it - none of this Reload crap, some Master of Puppets or Ride the Lightning!

Step 2:

Drain Diff oil. There is a plug on the bottom of the diff housing that you can use to drain it into a suitable container. Make sure you do the drain plug back up tight so you don't forget about it later. It's a good idea to wipe the metallic sludge off the magnet with a rag (you'll see what I mean). Also, if you want to re-use the oil, drain it into a clean container. It is a good idea to change it though. I'm not sure on how much oil it takes exactly but you just have to refill it until it starts comming back out of the checker plug, located about halfway up the diff housing.

Step 3:

Make sure handbrake is on firmly. Loosen the 4 bolts holding the driveshaft to the diff flange. If you can't reach them all put the gearbox in neutral, remove the handbrake and rotate driveshaft to suit then repeat.

Step 4:

Once you have loosened the 4 driveshaft bolts, its time to tackle the half shaft flanges. on either side of the diff there will be a flange bolted to the housing, assuming you removed all the brakes, you should be able to pop the axle out of the tubes, you may need a slide hammer to affix to the axle flanges, pop both axles out until you feel them disengage the diff splines

Step 5:

Now we're ready to remove everything. Before you do this make sure all the little housing bolts are removed that you're cracked off.Then it just takes a bit of dicking around to get it out.

Now, with a bit of luck (and maybe a jack too) you have the diff infront of you. It's quite a heavy f**ker yea?

Step 6:

there are 2 bolts either side, undo these and remove the bearing caps (again remember which way around and what side these go on). You will then see some bearings and spacers and things beside the diff head on either side. Lever the crownwheel out with a big bar and make sure u keep all the bearings etc in the correct order and sides (a vivid is handy for marking everything with terms like "inside, outside, left, right etc).

Step 7:

Now you have an oily diff head funky lookin' thing sittin there. There are several (about 10?) large bolts holding the crown wheel on. They are FUCKING tight!!!!! I'd recommend a decent vice and large powerbar or something - alternatively a pneumatic gun will work. Once the crownwheel's off, you'l see 2 large phillips screws. Remove these and off comes the viscous center. You'll see once u pull it off a washer sitting on a flat surface. That's your original preload shim - See below for a rough indication of what it looks like in new form.

lay everything out in order.Here is the entire differential assembely in the order its assembled.You can see the spider at the center,spider gears,the side gears,thrust blocks and case halves.The LSD discs go between the thrust blocks and case halves.

Here are the drive portions of the diff within the carrier unit.The outer case,thrust blocks and drive discs all have corresponding tabs that lock together and rotate them as a unit.

Here are the driven portions that are part of each axle shaft.The side gear is splined to the axle and the driven LSD discs have tabs that engage the side gear which makes them all spin as a unit.

Here you can see the ramps on the thrust blocks and the spider.If you look close,youll see that one side of the spider has heavier wear and the other has lighter wear.This is also visible on the bottom ramp of the thrust block.The heavy side wear is input torque from the engine and the light wear side is caused by coasting torque from the wheels.The wear marks can help you to determine which side is which should you misplace the thrust blocks or get the spider flipped over backwards.

Step 1 is to determine the clearance you have inside the case for the LSD core. It can be anywhere from 0 to .20MM standard clearance with a maximum gap of 1.0MM.

First measure the thickness(not the height) of each cone spring and record it.Then measure the width of the LSD unit with all the discs installed...measure to the outer side of each end disc and be sure to hold everything tightly together.I took 4 measurements from all around the discs and averaged them.Heres what I got.....

The carrier case inside width will not change or wear because the point where the factory measures it is behind the cone springs,and they do not move relative to the carrier,so no wear is possible.The carrier width is 84.0MM, so you take your LSD core width,add the width of the cone springs and them subtract that number from 84.0MM.......I got .11MM total clearance,which means that each cone spring is within .055MM of being totally crushed flat when the LSD is assembled.....that about as much preload as can be obtained provided that the cone springs are in new condition.

involves measuring the LSD core with the copper thrust washers installed.Too much clearance will induce slop in the spider gears since they are beveled and gain lash as they spread apart from each other.The thrust washers bear against the side gears and put them into contact with the spider gears.

They do no affect the LSD preload tension as I incorrectly stated when REVHEAD mentioned machining the cases.Thicker LSD drive discs are availible for taking up excess play in the previous proceedure.For this part of the assembely,if the tolerances are outside of spec,you can get thicker thrust washers to close up the slop in the spiders/side gears.

First measure the width of the LSD unit including the thrust washers.I took several measurements and backed them up by measuring the LSD assembely and the washers seperately and then adding the 3 values.I averaged them all for a width of 87.81MM.

The factory spec is 88.2MM. You then subtract your measurment from that number and get your clearance.....mine was .39MM of clearance.The factory spec range is .16 to .42MM so Im within spec,although a tad loose.No biggie, since the max allowable clearance is .80MM which I am far from.Oversize thrust washers can be used to take up the wear or you can install better or buy new spider gears to get rid of the slop without the thicker washers.

Now for assembely.........

First lay the right side thrust washer and cone spring inside the carrier case.Then stack the 4 LSD discs starting with an outside spline disc and ending with an inside spline disc.This will give you the maximum friction surfaces allowable with 4 LSD discs on each side.

Then install the thrust block over the discs.I found it easier to first alighn the driven discs with a side gear before installing the thrust block.

Then,install the side gear into the block,engaging the gear's splines with the driven discs.Then you can drop the spider and spider gears into the block and engage all the gears together.

Your now halfway there.Just install the other side gear,thrust block and 4 LSD plates,starting with an inside spline disc and ending with an outside spline disc.

Now install the other cone spring and thrust washer on the pack.

Once the end cap is in place,line up the ID marks on the circumference of each and loosely screw in the 4 little phillips screw that hold the case together.Before tightening,check that the thrust washers and cone springs are centered and alighned with everything.They can move around a little,but its unlikely they will gwet out of place.But still,better to be sure.

Then snug up the screws and you are done!

Now the original plan was to double that thickness and put more load on the viscous center, somewhat 'reviving' it to how a LSD should be. If you're me however (you wish!), 1 extra shim just isn't enough for drifting (it is great for everyday driving however). So go on, be a devil and chuck 2 extra ones in there if its mainly for the dr- ifting.

This is what I posted about them on another thread, be your own judge about how many extra to put in:

Add 1 new one to the existing one (total of 2) if you want a decent predictable lsd for driving that spins up 2 wheels with ease. Comparable say to a BRAND NEW viscous diff (i.e. not worn out, you've probably never driven on one).

Add 2 extra preload shims to the existing one (total of 3) if you want a very solid diff that's very tight but not quite locked (comparable to say a kaaz 1.5 way mechanical).

Add 4 extra preload shims to the existing one (total of 5) if you're a crazy c*** and see if it actually works.

Step 8:

Do everything in reverse, make sure you listen to Metallica again!

**VERY IMPORTANT NOTE:**

some high temp silicone to seal it before u bolt it up so it doesn't leak everywhere.

Just a little more info on the shim - It costs aroundabout $17ish including freight from japan. Usually about a 10 working day wait, usually less. You'll need to order this from your local mazda Authorised Dealer. You could also rob one from another lsd but not worth the hassle of pulling 1 apart.

i Personally like to take an extra worn friction plate and install it into the diff as a super thick shim. or you can make shims by taking the friction plate and tracing it on sheet metal and installing. old brake clean cans work great for this.



Content is not my information, and i do not have the original source, if this is yours please contact me so i can cite you and give you credit.

PB & J Mod - how to fix your Watts link Bind

This Information is Reposted from

RetroTuned.com

JUNE 30, 2017 BY GEOFF JENSEN
Watts link & trailing arm modification

The watts-link and trailing arm rear suspension in the first-gen SA (78-80) and FB (81-85) Mazda RX-7 is notorious for”binding” at the extremes – full extension and compression of the rear solid axle. In these situations the watts link and trailing arm bushings will be compressed and torqued to their limit, as they are solidly clamped to their mounting points.

By securely de-tensioning these mounting points, we can allow the bushings to act as a pivot joint, with significantly smoother operation throughout their range of motion. This creates a flatter suspension curve, rather than it ramping up as soon as the bushings engage.

Regardless of your application, casual driving, aggressive road, or especially track and racing, you can gain significantly increased articulation from your rear suspension from this inexpensive, at-home tuning technique.

Thanks go to Carl Perez (Rx7Carl) for his PBandJ Racing write-up for the source material – you’re a legend my friend, brap on.

Required materials

• Jack 
• Jack stands (2) 
• Bearing/axle grease 
• Nylock nuts, M14x1.5 qty 9, M12x1.5 qty 4 
• Loctite 
• Remove watts link

Raise the car by jacking up from the differential. Put jack stands under the forward mount of the rear trailing arms. Leave the jack stand supporting the differential, this will make removing and installing rear suspension components much easier. (See Factory service manual section 13-15 – Watts link and 13-17 – Upper & lower links)


Remove the watts link. Check and clean the bolts, bolt holes and bushings. Mazda was kind enough to weld tabs on the body mounts to prevent bolt rotation. Verify these are intact and functional.


Lubricate the shanks on the axle stub and center section.
Free-pivoting watts link


Put the rods back on and use the nylock nuts to secure it. Carefully tighten the nuts until all side play is removed, but still allowing the rod to pivot freely on the studs. THIS more than anything is the key to this mod.
How this works


The original design by Mazda had the center sleeve of the bushings firmly clamped, and any movement of the rod/link had to come from the rubber bushing twisting. By using nylock nuts to create a secure fitment but not clamping down on the rubber bushing the sleeve/bolt combo now acts as if it were a bearing.


This is why it is critical to get the nuts correctly tightened. Too tight and your back to where you started. Too loose and you’ll know it when you drive the car for the first time. The slop will cause the car to be uncontrollable. It needs to be snug enough to remove all end clearance, but free enough to pivot.

Re-install watts link


The anti-rotation tabs for the watts link bolts need to be functional, otherwise the nuts can work their way loose and the bolts WILL start to saw through the bracket, ovaling out the holes. If you are unsure about their integrity then you’ll need to secure the bolts from rotating. (Suggestion: A tack weld or 2 on the bolt head to the bracket should work, although this makes disassembly tough in the future.)


As an added safety, there’s enough threads left to put the old nuts back on with some loctite and snug them against the nylocks to lock them in place.
Upper & lower links / trailing arms


Repeat this same nylock procedure for the upper and lower links (aka trailing arms). In similar fashion, this allows them to rotate freely rather than flexing the bushing.


However, there is still a flaw in the OEM trailing arm design that causes binding at the extreme: they are not parallel, so when flexed they will want to twist laterally. We can address this issue by softening the upper link bushings.
Modifying upper link bushings


Since the upper links will still want to twist when the suspension rolls (because they are not parallel), we need to soften the rubber bushings so they can deflect and twist easier, reducing binding. This is accomplished by drilling holes around the periphery.


It’s important to modify the bushing equally so you don’t have an asymmetrical resistance to roll. You can make a template or measure and mark an identical pattern directly onto the bushings.


Using a 1/8 (approx) drill bit, drill the holes through the bushings. A drill press is preferred as it’s easier to get the holes straight, although if you are very careful with a hand drill it should be ok. Use a slow drill speed and a sharp bit, as you want to cut through the rubber, not burn through it.


Re-install and enjoy your new suspension. It will feel different now. You may want to work at rebalancing the front and rear roll rates depending on your spring/shock package.


Cheers!

This article is a resurrection/adaptation of PBandJ Racing’s“Rear suspension mod.”

the idea on the PB&J mod is a inexpensive solution to the suspension issues, now why is it called the pb and j mod, well because PB an J Racing came up with it. But their site is no more, but the information lives on. So sorry about the one shitty pic, but this will get the point across, this information is almost lost.




The purpose of the mod is to make the bushing softer and more flexible. If using a newer rubber bushing, it is going to be much more pliable and you may have to use a larger drill bit to get the same effects. the control arm bushings and center watts link bushing need to be drilled out. An 8 hole pattern as proven to work best. This is a control link bushing that has been piloted out with 1/8th drill, you will need to step up slowly removing the rubber and not burning it. finished hole size will be 3/16. This will allow the control links to act more like spherical bearings and reduce binding




AS i said this information is incomplete i am reaching out into the community to help make this whole again. What is here is to the best of my knowledge and memory as i can get.

New Drifters... so you want to drift a SA/FB Rx7

I seen this post and it struck a cord, so maybe i can share some advice as well. 

If you want hydros for entries, more power, more angle, more low, and you want to drive like a hero....

Few things

1. Your driving too slow, 

2. You don't need a hydro one, you'll be a better driver learning without. and you will need to learn to use the hydro to correct understeer before you can really use it for good entries

3. 12a has enough power to slide fine.

4. You don't need more angle the FB has plenty stock

5. You don't need more low, you need to learn to feel the way the car moves with stock gear under it, and learn how it transfers weight.

6. Fb is not an easy chassis to learn on its like an AE86 , it trains the driver.

7. If any of this offends you, you need to be humbled and listen and learn.

SA/FB rx7s responds well to left foot braking, high entry speeds and fients. Power, Angle, and hydro for  beginners is a crutch. Its a huge crutch that will make you suck later on. 

Imho if weld diff , remove steering locks, add some air pressure in rear, PB&J mod the watts And run it. You will have a solid start that will allow you to learn how to drive. As you progress you can start to add these as you grasp yet technique and improve to the point you can utilize everything that the car already had. 

I have more respect for a driver that can do more with less, than a driver with every option at their fingertips.

And if your looking for a place to start modding head over and check out the
SA /FB Drift Tune Index