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Discussion Starter #1 (Edited)
Alternately titled..."Pain, Suffering and just for good measure...Anguish"

This was not easy.

A little while ago I got this little item. The last of the first(only?) run of Guru torque biasing differentials.






Quick story. A while back a group of annoyed Australians decided that all torque and no go was slow. There had to be a better way. After an aborted attempt to get Kaaz to build a clutch pack diff for the "4 cyl MX6" (they did apparently...the 2nd gen 4cyl MX6) they turned to in country manufacturers.

Gurumotorsports is a speciality shop that deals primarily with RX7s and Miatas. All sorts of trick items from straight cut dog boxes to custom eccentric shafts. They also have the ability to fabricate their own torque biasing differentials(AKA Torsen style diff).

Now I had been keeping an eye on the movements of the Australians because I felt that something was going to come of this and I wanted a piece of the action. Sure enough it did. Half of the money up front to cover the cost of tooling/manufacturing the initial run of units and a guarantee of one of the final products. Unfortunately when that time came I became unemployed. CRAP! :(

I had to hope that there would be some items left to be purchaced or perhaps a second run one day. For over a year and a half I kept in touch with Guru expressing my interest and keeping tabs on how things were going. Persistence and a bit of luck helps. I had just gotten employed this past December when I got word that "a few" items were left. I was told By Guru that after those items were sold no more would be made (citing lack of consumer interest). The heads up was much appreciated and I tried to save as much as I can as quickly as I could.....Now, unbeknowst to me There was actually only ONE item left. Moreover, someone else had made inquiries about buying one. CRAP!

Now Heres the cool/strange part....It turns out that through some spying and well placed questions my significant other got the full grasp of the scenario I was in. Furthermore she had been secretly corresponding to Gurumotorsports for weeks at the point where there was only one item left. Her plan was to get that item for me as a gift without me knowing, but upon getting the news that someone else had made motions on the last item, she broker her silence and sprung into action purchacing the diff I have here now.

Women are amazing...and treacharous. Never turn your back on them (or else they may buy you performance parts for your car? )

Naturally I was flabbergasted that i had been duped, but very pleased with the outcome. This is an integral part to the buildup of my car and honestly, If I didnt get it. This whole escapade would be pointless. No amount of shock and suspension tuning will be enough. If I cant get power to the ground I go nowhere.

A torque biasing diff does just that. Through a set of set of precicely machined gears the diff will sense the slippage of one wheel and automatically adjust the remainder of torque to the wheel that has the most traction.

This is exactly what I need for an autocrossing application where the car is in transitional moves many times. It will give me grip in corners where before when the car shifted torque to the wheel with less grip.

So I have the Guru TBD......what do I do with it now? :confused:
 

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Discussion Starter #2
You know how its easy to say things like...."one of these days Ill...........", but somehow that mythical day never comes? Its easy to put things off into the future so you escape reality and hold out the possibility that "one day ill do....." . Well here was my reality. Now what?

I also noticed something interesting on this thread regarding a second run of the diffs. Save for one person, no one even mentioned how the diff is to be installed. After all, it doesnt install itself. Its 1200$ but the truth is, thats not the final price. Theres machining, parts, labor, tools, etc. It was surprising that no one considered bringing this up. I actually wanted to say something, but out of deference to Chunchoy14, I didnt want to derail the thread and have people fall out of the group buy. (Im not entirely sure this was the best decision) In any case I waited until I had something else to offer, and this is it.

Hang on kids...Its going to get a bit bumpy
 

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Discussion Starter #3 (Edited)
You have a Gurumotorsport differential. how do you install it?

My advice after installing mine?...get a shop to do it for you. Seriously There are a couple reasons for this and Ill go through them as best as I can.

"But Gavin, I like doing things myself"....control is an illusion, get a shop to do it for you
"but itll be an experience"....so's passing a kidney stone, get a shop to do it
"I dont trust the shops here to do the work"...Get over your paranoia and then find a reputable shop to do it.

If I havent convinced you that finding a shop is the best option follow along.

Now I dont necessarily offer these techinques as the final word on the installation because I made them up as I went along. Follow them at your own risk. Adjust and adapt as you see fit. Your experiences and success will depend on the level of your proficiency. Basically if you dont have the skills you are better off leaving this to a shop(Wait, did I mention that?) .

Your milage may vary, batteries not included, much assembly will be required.


Schedule a good amount of time for this project. If all you have like me is a driveway, check the weather reports and schedule accordingly (buy a tarp). Hows your clutch? Your starter? the small coolant lines on the backside of the engine that tend to corrode from age/infrequent coolant flushes? This would be a good time to do changes here as everything will be out. Look at all the things that can be changed while the car is up in the air and the transmission is out of the car and realistically set a timeframe that you can work with to get all of the jobs done....and then add a week to that estimate. Things happen and probably will, so take that into account.

I scheduled 8 days(2 weekends) to do this(the amount of time I would have my housemates car at my disposal while my car was being worked on) to do this project which included a new clutch, flywheel and some other odds and ends to be installed. It wasnt enough time.

-Speaking of which...have a 2nd vehicle available to you for the duration of the project. (Dont ask)

-Get a factory service manual

-Tools..youll need plenty. Standard assortment of spanners, ratchets, breaker bars, pry bars, hydrolic jacks etc. Youll need something to help take the transmission out of the car. If you have a lift and a transmission jack, all the better.

-Youll also need some speciality tools. Like gear pullers, a torque wrench that goes from 0-60 INCH/lbs, a variety of feeler guages, roll pin punches, wood(ill explain later). If you are fancy a bearing press is a nice thing to have

-Get a friend to help you (no seriously)

-There will be a lot of parts to disassemble and lots of small doo-dads. Zip-loc bags and a sharpie maker marker will be your friend in categorizing what bolts go with what widget. I had a variety of sized bags from bags as large as the starter to as small as a single bolt. Label everything.

-Air tools. Thats all I need to say about this.

Get all of the parts that you need to install/change/update/whatever, before you start working on the car. (This will prove difficult because itll be hard to tell which parts may need replacing until after the transmission is opened and you have a chance to inspect them)

-Get some mechanical skillz. Dont have any? Get a shop to do this for you then.


Ok then, here we go.
 

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Discussion Starter #4 (Edited)



If anyone is keeping score the differential is BOTH shiny and comes with stickers ;)

The parts are: differential bearings, speedo gear, output shaft seal, axle seals, roll pins, nuts, 1st and 2nd gear synchro rings.

A couple of notes. The differential bearings wont survive an extraction, so its best to get a new set(these are VERY important to this buildup, Ill elaborate in a bit). The speedo gear may/may not survive as well, best to get another just in case. The 1st and 2nd gear reputedly wear over time so I got another set to replace mine. It turned out that my synchros were in immaculate condition(this was a good thing for a few reasons..Ill cover this in a bit also).


Support the engine so that it will remain in place with only one mount(passenger side engine mount). Get the transmission out of the car. Use the tools available to you to remove the intake piping, battery/tray, intermediate shaft, drivers side subframe, driver side axle, etc. Im not getting into the finer details of this process becuase between the FSM and instructionals like this one from our very own sicksix6(regarding replacing the clutch)

http://www.mx6.com/forums/showthread.php?t=99032

and others, this should be pretty well covered already. Use those zip-loc bags.

By now the transmission should be out of the car and youll have this to look at.




The oil is from a failed valve cover gasket that was replaced at the same time as this project was going on.

Now to crack the transmission open and get to the diff.

Remove the 5th gear inspection cover. Be careful not to strip the 10mm bolts. Youll be faced with this.


26mm and 38mm. Youll need an impact gun to take these nuts off as theres no locking mechanism to stop the shafts from spinning.

remove primary/secondary reverse synchronizer gears


remove roll pin from 5th/rev shift fork


remove 5th/rev shift fork and clutch hub assembly as a unit


remove primary 5th gear(and synchro ring if it plops out of the clutch hub assembly like it did mine)


remove secondary 5th gear.

Youll probably need the gear puller for this. I found I had to lever the gear up with a thin prybar to get the jaws of the gear puller under it sufficiently. Be careful not to damage the gear while prying it up.

At this point the first set of gears are off and the next thing will be to separate the transmission case halves. However some other items have to come off for this to happen.

remove the 4 (14mm) nuts you see in this picture

(3 radially located on the case and the one to the right and below the reverse switch) and the springs and balls that are recessed insde the cases.(told you those small zip-loc bags were going to come in handy)

a magnetic probe is helpful for the very stubborn balls.


There is another 12mm bolt opposite the 4 14mm nuts to be removed
(didnt get a picture of it) This holds the reverse idler shaft in place.

remove the interlock plate(12mm bolts)


Unbolt all of the 14mm blots surrounding the transmission case and use thin prybars to crack the case halves.

(note: 3 of the 14mm bolts are longer that the rest. take notes of the orientation)

youll be faced with this


...............getting there.
 

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Discussion Starter #5 (Edited)
At this point you may want to get some feeler guages and check the clearances of the shifter gate, shift forks synchro rings and the like(check the service manual for tollerances). The clearances in my transmission were well within spec.

Now, back to buisiness.

remove the base plate(shift gate)

(10mm bolts, these have an order to them, take notes on their orientation)

remove the reverse shift lever
(10mm bolts)


remove the roll pin from the 3rd/4th shift fork


remove roll pin from the 1st/2nd shift fork


remove 1st/2nd shift rod


remove 1st/2nd shift fork


youll have enough clearance to remove the 5th/reverse shift rod


pull up on the 3rd/4th shift rod and remove it and the 3rd/4th shift fork together



almost there....

remove the primany gear shaft assembly.


This will take a bit of careful wiggling and muscle as its a fairly beefy piece

remove reverse idler gear and shaft



remove the secontary gear shaft assembly
.

This will also take some delicate muscling to get out as its slightly trapped by the differential.

finally!!
 

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Discussion Starter #6 (Edited)
Ok a bit of a break to make some notes at this point. The primary/secondary shafts are supported by tapered roller bearings. They willl have the races sometimes still in the differential cases(sometimes loosely, sometimes not). If you do take the races out they will have been shimmed. Make sure that the races and shims are kept with their respective bearings. Also make sure that the orientation of the shims are the same. Some of the washers will be concave(called diaphragm springs) and will need the inner edge to face the outer bearing races. The stacking order from the cases will be..case>flat shim>diaphragm spring>outer bearing race.

Unless you absolutely have to take gears/synchros off the primary/secondary shafts, youll be able to reuse the races(provided they arent scored or pitted). If you DO need to replace gears, the bearings will have to be pulled and new bearings/races willl have to be pressed on.

This will be a royal pain in the ass if it does happen(we are getting closer as to why, ill get there soon)

remove the differential


transmission In all its glory


The bearings from the original diff wont be reused and neither will the races which should be press fitted in the diff case halves. These need to be removed. If you have a race removal tool this would be the time to use it. If not youll have to get creative. Heres what i did.

first remove the axle seals and youll then be able to see the face of the bearing races


I then used the largest pin punch I had and tapped the bearing race out.


I used the highest angle I could while still keeping the broad base of the pin punch flat on the race. I tapped firmly but lightly 180deg on the race and "walked" it out of its recess. Light taps and a flat base are the key. Too hard a hit and too much of a sharp edge will marr the bearing race(youll see why this is important in a sec)

races removed.

There will be shims here as well but its not as critical to keep them in order.

FYI...clean the magnet.


And here is what we have been working towards. BEHOLD!! the stock differential

 

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Discussion Starter #7 (Edited)
Ok. We take a bit of a pause at this point to contemplate things. The next step is "the point of no return". Up to this point if things arent going according to plan at WORST you can simply bolt things back together and be back on the road. The next step is a one way proposition. If things go wrong after this, theres no hope of speedy repair. It was a very exciting thing to have my box of parts returned from the machine shop, but then the reality of what I had done was sobering. "theres no going backwards. Theres a million parts of my transmission in the basement and Ive just broken the diff....this HAS to work. I have no choice".

ok. lets continue then.


The stock differential needs to donate its ring gear to the new diff, As you can see it is riveted on to the body of the stock diff. The rivets will need to be removed (drilled out, pressed out, use the force, whatever).



While you have the stock diff at the machine shop getting the rivets removed, get the new bearings and speedo gear pressed onto the new diff.


comparison




Now its simply a matter of installing the ring gear onto the Guru diff with the supplied hardware.

The diff is very well made and is made to be self centering to the ring gear for minimal runout.

42ft/lbs and Loctite Red (as per Gurumotorsports) is the answer to your question.

 

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Discussion Starter #8 (Edited)
Another pause for the next very critical step of things.

Remember I said that there was a reason to get a reputable shop to do the install of the diff? Well heres the reason why.

The bearings used to support the differential and the primary/secondary gear shafts are tapered roller bearings. They are strong, durable and wear well . However they *have* to be tensioned correctly to give that long life. Too much/little tension on the bearings will have them fail quickly.

Mazda has an elaborate SST that spaces the transmission halves a precisely measured amount and has a bearing/race adaptor that expands to give the precise tension necessary for the bearings to live a long life. The tension (measured by a torque wrench that has incredibly low inch/lb values) is 4.3in/lbs of torque before the diff starts to rotate in the bearing assemblies

When the adaptor expands there will be a gap between the two halves. This gap is measured and with some calculations, the the closest shim to that measurement is used to provide the tension the bearings need when the transmission halves are closed. Mazda has a listing of 28 different thickness shims to be used and specify a maximum amount of 2 shims to be used in combination to get to the correct gap thickness.

I do not have this special service tool. The local dealership had not seen the item in years (and what it would cost I feared to ask). They remember it well, but car manufacturers have made it so it is not cost efficient for dealerships to do warratee work internally to transmissions. (Yay for our modern age of "modules")

This is an absolutely critical step, I couldnt really skip it. Since the new diff and bearing combination renders the old shimming tension obsolete, this HAS to be done.

You can now see why I was glad that my sychros were in good shape. If they werent, I would have had to pull the bearings and gears and then have to reshim/retension the new bearings for the primary/secondary shafts. All this WITHOUT the Mazda SST? A shop would be the sensable option......except for one thing.

The shims.

I had mentioned that there were 28 different shims in varying thicknesses to correctly pretension the differential bearings. These are items that are needed to make this whole escapade work. There are none available.

Ill say this again so there is no misunderstanding....of the 28 different shims listed that are necessary to pretension the differential bearings, there is a grand sum total of ZERO available....in any size.....in any dealership in the United States..

Oh yes Ive checked, trust me. Even Mazdaspeed motorsports, who keeps a stash of parts on hand hidden in dealerships around the country, couldnt locate them. Last I spoke to them they were seeing about other parts of the world. ......(ok I didnt check our Canadian neighbors..are you guys holding out or what?).

Speaking of other parts of the world, it seems that all of the Aussies got theirs installed by either Gurumotorports or local transmission rebuilders.(smart people). Rebuilders usually are unable to contain vast arrays of parts for every single transmission out there. They will purchace the parts from the Dealerships(or if you are lucky the aftermarket).

Speaking of the aftermarket. The 1st and 2nd gear synchros are apparently no longer available available from the dealership. This is in the US at least. Other parts of the world may be luckier. Look to the aftermarket if there is one for synchros. Where did I get mine from you ask? The secret stash from mazdaspeed motorsports. (Nope they dont sell to the general public)

Ok so you now have a better picture of what it takes to install the diff in the H-type transmission. No shims available to properly shim the diff, special tools to ensure proper tension unavailable, a torque wrench that goes from 0-40inch/lbs?, synchros MIA. What do you do at this point?

Well if you were me, you would get blazingly pissed off and frustrated that for a simple metal ring that cost 2cents a project of this magnatude can be completely derailed. The Irony is thick here.(oh yeah I was steamed :damnmad: )

Then, you get determined.

I found this excellent writeup on an installation on a Japanese spec Integra Type R LSD.

Honda-Tech.com: Acura Integra: Tranny Overhaul & JDM ITR Final Drive/LSD Install (56k...not so much)

It covers the same things in this thread and makes for a good comparison. The things that interested me about this is the issues and solution Honda came up for the bearings. They too used tapered roller bearings but later superceded the part with a ball bearing. Ball bearings DONT need to be pretensioned. You just need to shim them to take up the slack in tollerances of the transmission cases and keep the assembly correctly aligned.

I liked this idea but was unable to make it work. Mazda did not follow suit and supercede the roller bearings with ball bearings(it was a long shot on a car out of production for many years). The other reason was I was unable to find a replacement balll bearing to use. It seems that mazda has speced an odd sized bearing to use to suspend the diff (75mm OD, 45mm ID and 20mm thick). The closest I cound find was 75x45x16mm. Trying to use them would leave a 10mm gap to find a way to fill. No thanks. Besides I ldidnt like the idea of using a smaller bearing will less load capacity than I had to.
If anyone can find a 75x45x20mm bearing this will save people who attempt to do this on their own a lot of issues. The same idea could be used to replace the bearings on the primary/secondary gear shafts if thee gears or synchros need removal.

(sorry I didnt take measurements of those because I reused mine as I didnt have to remove them)

EDIT: its come to my attention that because of the high side loading exerted on the diff bearings from the torque of the F2T, ball bearings (as mentioned above) are not an acceptable substitute. Use tapered roller bearings in this application.
 

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Discussion Starter #9 (Edited)
So I was still left with tapered roller bearings and no shims. and had to make things work with minimal tools. So heres what I did to get things to work.

With the bearing preloader dealio SST its a simple one time process to find out what thickness shim is necessary. The other way is to install the bearing races into the transmission halves, install the diff, close the diff halves and torque the bolts(I used every other bolt) down , test the resistance, disassemble, add a shim(that we dont have) under the bearing race and repeat the process with ever increasing thickness shims until the desired torque is reached.

This is a long PITA way of doing things, but it was the only option available to me at the time.:(

The torque value needed is 12.2 - 17.4in/lbs.

First we need a way to insert and remove the bearing races.

Installing is easy. Place the old bearing race on top of the new and gently tap it in with a light hammer

(youll have to excuse the hammer in the picture, it happened to be the smallest thing I could find at the time). Tap the new race at four points to ensure that its going in straight. Light taps, light hammer.

Removal was as mentioned above. Just like removing the old races with the difference being I was extra careful here. The old races I didnt care about because they werent going to be reused, but the new races are important. Too heavy a hand or too much angle and I could have scored or dented the race making it useless.

To get close to the necessary shim size as possible, so I wouldnt have to take too many chances removing the race in this manner, I assembled the diff and races first and lightly tapped the race onto the differential bearing. This opened a gap between the race and the transmission case. You can barely see it here.


I tested the tension and when it was close to the desired torque I measued the gap with the feeler guages.

Using this I got close to the correct thickness shim and then worked from there.

No shims available? Make your own.

K+S is a company that makes stock for hobbyists. Round tubing, square stock, rods etc in various metals(brass, aluminum, steel). They also have metal sheeting in very thin measurements.

I chose brass. The sheets came in thicknesses of .04, .06 .08, .10 and .12mm .

I used the stock shim as a template and simply cut my own shims using a pair of scissors.


The shim that was in the diff already was .20mm. After a bit of trial and error(uninstall races, install races) getting the tension right I settled on an additional .10mm and .06mm shims for a total thickness of .36mm.

Notes. Brass is a softish metal. It was easy to work with and easy to trim. There may be a chance that over time it could compress by a certain degree with the heating and expansion of the transmission. How likely this is I am not sure. I did lean towards the higher side of the torque range of the bearing tension just in case. Still I wonder if brass was a poor choice instead of (the slightly less easy to work with)aluminum or steel. Time will tell.

How does one test the torque of the differential to see if the tension is set correctly? As said, youll need a torque wrench that is able to read as low as 1in/lb. I struck out with auto parts stores who tend to have "clicker" torque wrenches which only went as low as 20in/lbs. They were also expensive. Then I ran accross this.

Park tools TW-1


Turns out torque wrenches that go this low are commonly found in bicycling circles. Its a beam type torque wrench and thats a good thing as clicker wrenches have no way of telling you how much above or below their preset value you are. A beam type wrench will give the resolution you need.

Youll need to turn the diff through the axle(a hole). The torque wrench is a 1/4" drive with a 3/8" drive adaptor. Clearly an interface is needed between the two. Something that can mate into a hole centrally and offer a mating for a 3/8" drive. Naturally Mazda has a special service tool for the job, but we dont have one of those. We need something else.........WOOD!


Compressable enough to be hammered into the axle hole of the diff and grab on to the splines


and soft enough to be whittled down to accept a 15/16" socket that will conveniently mate to the torque wrench.



now it simply a matter of lightly tugging on the torque wrench to see how much force is necessary to get the diff to turn.


Many tries were attempted before I got the torque values I wanted. When I did get the right tension on the bearings it was time to reassemble the transmission. Install new seals if you need them. Take care regarding the shims and the placement of the bearing races on the primary/secondary gear shafts. Torque bolts to their correct values and use Loctite on the bolts you dont want to come out. Permatex grey is an excellent item to seal the transmission case. Reassembly will be in the reverse order that got you to this point.

Reinstall transmission and fill with your prefered transmission fluid
 

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Discussion Starter #10 (Edited)
Odds and ends.

As I said, "if youre in there you might as well....."

And so I changed the clutch, pressure plate, flywheel.

Also in the picture is a new throwout bearing and pilot bearing.

I had forgotten to get a replacement main seal for the crankshaft. Luckily it supple and was in excellent shape with no leakage. The pilot bearing was also in great condition and was kept.

Comparatively this was an easy installation compared to the diff.

Unbolt, disassemble




and then reassemble.





The only hiccough was that I did not have a clutch alignment tool. So I made my own.

Worked pretty well.

other items..

Transmission mounts



and finally, to stop the leaking from the valve cover, a new mazda valve cover gasket.


People have mentioned that the factory item is a good item to get. The difference between the factory item and the generic replacement is plain to see. Not a drop of oil as yet and it was pretty cheap.

There were other additions to the car but Ill leave them to another day.


If you are with me this far, you are as tired as I am. Its been 250miles of 600miles to break in the clutch and differential.

The diff theoretically does not need any break in period, but its a good idea anyway. Whatever bits of shavings may be left from the machineing process and from the rubbing together of the gears will be flushed out with the first fluid change. I used the cheapest ATF I could find to do this(only going to be used for 600miles so 4$ down the drain wont worry me)

Thanks to MazdaMX6Turbo, Mazdameister, Manifest and others that I bugged for information about what to look for when opening the transmission. This was my first attempt at working with a transmission and their information helped to demystify things a lot.

OH GOOD LORD IM TIRED!!

comments, critiques...all welcome.

Gavin
 

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Haha I am all too familiar with the inside of these mazda trannies ;)

Couple shortcuts I have found--no gear puller necessary for 5th. Just put a couple flatheads under there and pry up.

ANother... you can get the diff out without taking your 2 gear shafts and forks out. Just pull up on the gear shafts together and have someone wiggle the diff out. I've done this several times for both taking it out and putting it back in. Actually just did it 2 weeks ago ;)

As always, excellent write up gavin. I am thoroughly impressed. I hope it all works out for you. good ideas with those shims, you are a pretty resourceful one...

And to anyone wondering, if you do not set that tension right, you also run the risk of stripping your ring gear!
 

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Holy shizzle, if this doesn't deserve karma, I don't know what does.

Questions: Fidanza flywheel? Mazda pressure plate and disk? How much did those cost from the dealership? Can you feel the difference between 6 spring and 4? And finally, is there any evidence that the disk you took off was aftermarket or Mazda? My original disk was a 6 spring and replaced with a 4 spring Exedy, just wondering as your 4 spring disk obviously came directly from Mazda.

Nice write up :tup: :tup:
 

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WOW!!!!! Nice work!!!!

Looking the inside of our stock diff (complete...haha) I dont see how the PG LSD is installed. I know that some shaving of the diff. gears are needed but looks like A LOT of shaving to me.

Great work again.......
 

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mx6GT91 said:
WOW!!!!! Nice work!!!!

Looking the inside of our stock diff (complete...haha) I dont see how the PG LSD is installed. I know that some shaving of the diff. gears are needed but looks like A LOT of shaving to me.

Great work again.......
Maybe that's why yours is making "noise"? Didn't you get it done at a shop?
 

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You must spread some Reputation around before giving it to gavin again.

well done Gav.
u did it again, another superduper write up a really really excellent how-to.
many credits to u for thisone.
im sure lots of guys ordering the Torsen have to read this and print it and help them get the project to succeed.
 

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Discussion Starter #20
just a bit late, but not too too late :)

At the behest of sleepcounter I looked into ball bearings and while I found numbers similar to what you have posted(albeit in imperial measurements) the end result was....I couldnt find ball bearings in the size that would fit the dimensions of the differential anyway. In other words, it was a dead end.

I used the stock shim as a template and simply cut my own shims using a pair of scissors.


The shim that was in the diff already was .20mm. After a bit of trial and error(uninstall races, install races) getting the tension right I settled on an additional .10mm and .06mm shims for a total thickness of .36mm.

Notes. Brass is a softish metal. It was easy to work with and easy to trim. There may be a chance that over time it could compress by a certain degree with the heating and expansion of the transmission. How likely this is I am not sure. I did lean towards the higher side of the torque range of the bearing tension just in case. Still I wonder if brass was a poor choice instead of (the slightly less easy to work with)aluminum or steel. Time will tell.
I have had to pull the diff and reshim it. Although I had set things as per the manual (well...sorta. More shims than recomended) things seem to have shifted back to below spec. I developed a "clunking" in the transmission and believed it to be the diff tension. Upon checking the diff, the breakaway torque was much much lower than the minimum spec. Clearly the soft brass shims had compressed too much. I have now reshimmed the diff to an over-spec tightness(22in/lbs) using stock shims(thanks Rami!) with the assumption that after a few drives things will loosen up a bit and things will fall back into spec. Ill see how this goes.
As of 9/25/08....Transmission has been working excellently after a year of autocrossing.

Gavin
 
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