I need some expert help on this one.. I just got done installing my 4.3 GTUs rear end, that I have swapped a torsen LSD from a miata into. I got the rear subframe all back up and bolted in, changed the rear pads while I was back there, and filled up the rear end with gear oil. I backed it out of the garage to take it for a spin, and almost immediately noticed a problem. If you make even the slightest turn, even at like 1mph, the car will chirp the back tires. Seems like its the inside tire. When I go straight it seems ok, but I only drove it about 5 blocks and then put it back in the garage for fear of breaking my precious 4.3 or Torsen. Now I know that a torsen LSD is the most harsh, but Im sure that this is not normal. Can anyone give any insight as to what the problem may be? It seems like it wont let the rear wheels spin at different speeds at all...

 

I'm sure there's a few people who read this and think your serious.

Glad to hear your modded diff is working out! I hope to follow your steps on this one..

Edit: I've already read it about 6 times.. And admittingly I can't figure out if your serious or not.

Thats normal for a torsen diff.

 

So even the fact that he was coasting backwards slowly on a slight grade, and the rear end bound up enough to stop the car...is normal? I was there, it didn't feel right at all. But hey, none of my vehicles have torsens, all mind are clutch type. *shrug*

 

http://auto.howstuffworks.com/differential8.htm

Well theres a definition of what it's suppost to do..

 

Nope, Im serious. I was expecting a more harsh engagement, but chirping the tires trying to make a slight turn at like 2 mph is not normal....( I dont think...)

 

"The Torsen (from Torque Sensing) works as an open differential when the amount of torque going to each wheel is equal. As soon as one wheel starts to lose traction, the difference in torque causes the gears in the Torsen differential to bind together."

So how does that relate to him coasting and having the raer bind up and chirp the tires? There is no loss of traction. His car is behaving as if it is locked all the time.

 

Yea, granted I didnt drive over maybe 15MPH, mostly for fear of breaking something, but I really dont think it is normal for a torsen LSD to do this. I have heard of aftermarket clutch-type units (KAAZ., etc..) being noisy at low speed, but being noisy, and chirping the tires are different. This was also a stock unit, not aftermarket.

 

So you still have the stock viscous lsd core unit from the Gtus rear?

 

Did you get all of your gear bolt torque the same? I am not sure about torsen type rear end but did you space your diff correctly?? Is the bearing flush with the lsd unit?? Just a question

 

Well..yes all the ring gear bolts are torqued down correctly. I believe it is spaced correctly. Bearing flush with LSD? Not exactly sure what you are asking.. Any more suggestions? If I dont have any ideas Im just going to drop the rear diff again and take it to the local speed shop and have them check it out..

 

Whoohoo! We'll be pros at this....just like taking intake manifolds off 5 millions times.

 

OK, I dropped the rear end again last night. I think in record time too, about an hour and a half, from taking the cat-back off, to removing the diff from the subframe.. ANyway, Im going to crack it back open this morning and try and troubleshoot the problem. If I cant find anything, Im taking it to a shop. Any suggestions while Im at this point? Thanks.

Oh and 88IntegraLS, no I sold the stock viscous unit from the GTUs rear, as well as my stock rear end from my car, so Im pretty much stuck with this one....

 

whoa whoa black13b. Are you running a torsen???
Probally not! Dont talk unless your running one.

RXmfn7 Im running a FD torsen in a 90TII. I use it at driftsession and on the street, sometime. It is the most smooth rear end Ive had in the car. ITs great on the street. It only really locks up when I really give it gas. Ive had a stock clutch and the original viscous. Anyone who wants either of these doesnt know what they are missing with a torsen. Of course an aftermarket one is in a diffrent class. if I start my car in circles it will turn fine and act like any ole car, but once you jump on the gas the rear will lock and walk around the front tire. Ive run it at driftsession with great results. REted has ridden with me a bunch, I know he will vouch for the torsen over any of the other stock crap.
Ok back to your problem. With the rear in the air and the car in neutral will the axles turn in opposite directions? I think thats right. I noticed how intersting the torsen is when i had it back together in the pumpkin, turned the driveshaft and noticed only one axle turns foward. BUT when you put anykind of load on the opposite axle they will lock up and spin foward together. Ofcourse there is a torque bias which means the response is linear. which to me means a smooth lock up. The FD is a 3/1 so the more power I dump to the pot the more it will deliver to the wheel with less traction... To me that isnt harsh. Not like the on/off style of the clutch packs. I wonder if something inside you pot is broken rxmfn. or unless somehow the axles are sharing the same splines, locking them together.
I think so far what you are doing is the best idea for a NA rear end. especially for the dollar. You got all your backlash and tooth contact set right? It took me 2 tries to get it. The first time I took the car out it whirrled beyond 40mph. Scared the crap out of me. But now its simple. Good luck!!!!

 

No I dont think the backlash is set correctly, so I am probably going to take it to a shop and have them set it for me. When I spin the driveshaft, both axles turn forward. When I spin one wheel, the other one spins the same direction. Both of these things I believe are opposite of whats supposed to happed. Would an improper backlash adjustment cause this? ( *crosses fingers and hopes..* )

 

No Im sorry. It really sounds like something inside of you torsen is binding or perhaps somehow there is something stupid stuck in one of the worm gears. Did you really look at it when you had the unit out? When you take it apart you will be able to tell. Did you take the ring and pinion out of another car or is it the whole gtus pumpkin. If its all from the same car you can probally handle setting the backlash yourself. Usually the tooth contact is close when you just change the pot. If you switch gears most likely it will be alittle more time consuming. I tried mixing 2 sets I have but I gave up and used the original pot and pumpkin.

 

Either you're got a problem with something binding the diff or the pre-load is too tight?


-Ted

 

Welp, turns out that the S5 viscous LSD rear ends use different size axle stubs. So I got a set of equal-length stubs from an 88SE, and that solved the binding problem. I suppose the longer stub was crossing over into the other side of the LSD unit, locking them together. So I got the rear end back in the car (3rd time now..) and I have another problem. The rear end is making a very loud whirring noise, sounds like a jet engine taking off. Also a "clickity-clack" sound can be heard. Now, Im assuming that this could be the fault of an improper backlash?

 

Oh yes, we get to do it again.

 

Just a bump to see if anyone would know what would cause a loud (very loud) whirring/whistle sound on the rear end. Im going to take it to a shop and have the backlash adjusted and bearings checked, but would like to have an idea. Thanks

 

ANY kind of persistant noise is due to misadjustment or bad/low fluid.&nbsp Please get this checked ASAP!



-Ted

 

Oh dont worry Im not driving it like this. I already have the rear end back out. Thanks

 

hey thats great. WOw I didnt know there were diffrent axles between koukis and zenkis. I put the FD torsen in a zenki pumpkin with Zenki halfshafts. I havent had prblems. How much diffrent are they on the NA?

 

we just got our FD Torsens in the mail today, any advice/instructions how to swap them, what to look for etc???

 

bump

 

hmm interesting. Ive yet to replace them but the diffs out so I might as well begin.