checking backlash on lsd
 

so im gonna be picking up a s4 tII lsd , thinking about rippping it apart and shimming it. Just curious about putting it back in is what is intimidating me, any tips/how tos on setting up the backlash etc? what tools will i need? a friend said its easy and to use a feeler gauge.

I'm interested in this as well....

A magnetic dial indicator. Place the dial on the ring gear and turn it one way till it contacts the pinion, then reset to zero. Turn the ring gear the other way till the other side of the gear contacts the pinion and the readings you want to end up with should be around .0010 or ten thousands of an inch.

I suppose if you have a digital micrometer that has a depth measurement at the bottom you could get close that way, but I don't see how you could pull it off with feeler gauges.

or you can paint the ring gear and see how it eats

Or you can just throw some grease on one of the teeth and spin the ring gear to tell you where the gears are meshing, but when were talking about long term reliability I would just pick up the dial indicator.

hmm i read this thread this morning.. then went out to harbor frieght and forgot about it.. lol. they did have this
http://www.harborfreight.com/cpi/cta...temnumber=5645

and i guess team it up with this?
http://www.harborfreight.com/cpi/cta...itemnumber=623

could those work? I wasnt sure so i didnt buy em..

I might just put the lsd on with new fluids
http://i43.tinypic.com/2dr86c9.jpg
forgot to check the millage on my friends car. i couldnt get the freaking halfshafts out of the carriers *tried a torch and hammering, pb blaster etc..* so i took the whole subframe *tho i gotta put the subframe back on the chassis when i get these off so the car can roll* lol... Ill try a bigger mallard and heat again.

dam i probably could have got away with using those harborfrieght tools huh.. i wasnt too sure on them because i figured it would have been more specific to it.. oh well.

I think ill just throw the diff in my car wiht new fluids first and leave it for a while. since i got a proper jack and a feeling on how to it myself, Ill probably just wait to rebuild the whole lsd sometime in the future.

lsd install
 

https://www.rx7club.com/2nd-generation-specific-1986-1992-17/torsen-lsd-install-write-up-691575/

here is how i installed my torsen. if you are planning to do this don't even start without getting the proper tools. dial indicator with magnetic base and gear marking compound which is available from summit racing. Also a tool to rotate the adjusters, which looks like a bar with studs sticking out of it. i would start by measuring the backlash of the diff before you take it apart just so you can familiarize yourself with what the readings are supposed to be and also using the tool. i messed mine up the first time, backlash was too loose and it whined on decel. second time it was good. have a way to mount the diff housing securely, don't do it my way. get new seals if they are needed, i only changed the axle seals. changing the pinion seal would require setting the pinion depth, which is something i am not familiar with. don't use grease like others stated, it is a pain to clean off.

http://www.kenyabirds.org.uk/pics/mallard.jpg




:scratch:

bah ill rebuild it some other time.. i put it in today as is with fresh fluid.. the old fluid looked pretty good and the lsd label was rotated in a not factory position so i figure someone probably changed it before *and the car it came off was completely stock so im confident its in good condition.

Anyone know where I can find a pinion seal?

Well, to check the backlash you really just have to take the cover plate off. But if you want to see if it's close enough I guess you could just hold the pinion with one hand and give the half shaft yolks a little turn and see if there is a ridiculous amount of play.

If you notice a hard transition between accel and decel that wasn't there before that would be your answer.

Nice write up. The FD Torsen is a T2 not a T2-R correct? If not do you know the bias ratio?

Changing the pinion shaft seal does not require resetting the pinion depth. The pinion depth is set by changing the thickness of the spacers on the end of pinion shaft. The changing of spacers is not usually required unless you are changing the R&P set to a different ratio. This is where the gear marking compound comes into play. Actually, I've used both grease, and gear marking compound, and I prefer the grease. The pinion depth is adjusted until the proper gear contact pattern is obtained. Changing the pinion shaft seal would require resetting the pinion bearing preload.

Although a magnetic base for the dial indicator would make life easier, I always used the clamp on dial indicator base without any problems. Also, tool to rotate the adjusters would be useful, but it is not necessary. Actually, you can easily make one of thes tools with an aluminum bar and two bolts with nuts.

This wasn't mentioned, but you'll need a 7-8 inch micrometer to set the carrier side bearing preload. Mazda was the only rearend that I've seen that requires a micrometer to do this. Most other car manufactures specify side bearing preload in thousandths of an inch, and the dial indicator is also used to set preload.

Hot_Dog
90 RX7 GXL

Any way to tell if you have a S4 T2 or S5 T2 Diff without taking it apart?

Well, as you probably already know, a quick test for deterining whether or not you have a clutch type LSD would be to jack up the rear of car with tranmission in neutral and rotate one wheel by hand. If opposite wheel turns in same direction, than rear end is a limited slip. I doubt that this method would work on an VLSD. VLSD achieves its limited slip capability in a gradual manner. I believe that the VLSD used unequal length side flanges. You could pull the side flanges and check thier lengths to determine wheter or not the differentail is a VLSD.

Hot_Dog
1990 RX7 GXL

nobody thought my post was funny?


fine.

If the duck had a stogy, you'd have my vote...

It should be fine, I mean it's only 2-3 hours to drop and put in.

torsen
 

I dont know the exact bias ratio of the FD torsen, but i have seen some claim it's 2:1. I dont think it would really matter as i probably couldnt feel the difference unless it was a dramatic change.

Changing the pinion seal CAN be done without disturbing the bearing preload. By staking the pinion shaft, nut and yoke in-line to mark everything. After changing the seal just make sure all lines match up EXACTLY.

its not a duck, its a MALLARD...THAT WAS THE JOKE :facepalm2:

Only problem, it came off the car already and is sitting on my porch. =(

pull out the stub shafts and see if they are equal length or unequal length.