car jerks with new lsd

[aurora61]

i recently installed my tomei 2 way lsd...

However, my car seems to suddenly jerk while driving on straight-aways. This jerking is not constant, but suddenly happens every minute or so. This jerking seems to happen more on higher rpms (maybe around 2500 and up), and it usually becomes fine in the lower rpms...especially cruising in 5th gear. Also, flooring the clutch to shift gears suddenly jerks the car. (The car jerks more right than left if that matters)

The installation of the lsd seemed to go pretty well, and i went through the initial break-in procedure involving doing figure-8s. I also changed the diff oil after the break-in. Also the differential pumpkin has no leaks. The alignment does not look bad either.

So does anybody have any ideas to fix this problem?

[TougeMS13]

Did you set your backlash correctly?

[aurora61]

Seeing how the backlash was fine while the stock open diff was in, i figured that it would be fine with the new clutch-type lsd...not to mention, the shims are in there tight, preventing side to side motion.

Another thing to consider is, when i go in reverse sometimes, something grinds in the rear (this happened even before the lsd went in). I believe its the brakes.Could this be a possible cause?

[Bronze MFP]

you may want to pull the lsd back out and check the lash between the pinion and ring gear. sounds like they might be damaged. even if the stock diff was fine, installing the tomei might have thrown the lash off. its a gamble, some times it needs adjustment, sometimes not. but better safe than sorry. i'd crack that puppy open asap and check it.

[aurora61]

how do u adjust the backlash between the pinion and ring gear? ...i always thought it involved adding/removing shims. But seeing how the last shim i put in was a really tight fit, i dont think i could add anymore...not to mention, removing shims will make it too loose.

[Bronze MFP]

you have to take it to a trans shop or to nissan. it does involve shims, but they add/ take away different size shims to move the lsd/ring gear assembly left/right in the pumpkin.

[rogoman]

However, my car seems to suddenly jerk while driving on straight-aways. This jerking is not constant, but suddenly happens every minute or so. This jerking seems to happen more on higher rpms (maybe around 2500 and up), and it usually becomes fine in the lower rpms...especially cruising in 5th gear.

Generally if the differential setup is incorrect, there will be a lot of noise/vibration at low road speeds (low RPMs).

Maybe there's a problem with the motor itself rather then the differential.

[aurora61]

anyone have the price range for getting the backlash fixed by nissan/transmission shop?

[thegreatfallofjosh]

ahhhhhhhh, i had the same problem with my 240sx. sadly i sold it because of problems with transmission and lsd. when i reversed and made sharp turns or just drove at low rpms it would have this car shaking bump coming from the back......might have been a dented rim but i got it checked and never could really figure out what the problem was......

[180fan]

price range? go call around your local area. different areas will have different prices.

[Bronze MFP]

i asked a local shop and they quoted me $80 if i brought the diff pumpkin in. if they have to take it out of the car and put it back in expect at least double that if not more.

thegreatfallofjosh, if you had a clutch lsd, the rear end will knock around some, but the car shouldnt drive itself as you described. maybe it was possesed? good thing you got rid of it if that was the case

[K]

For what it's worth, i'd actually check the backlash before you take the diff into a shop. It's cheap to check. Just buy a tube of Permatex Prussian Blue (amazon.com has it for $4).

If the backlash is off, and hopefully the diff isn't already screwed, then take it to a shop to have it properly shimmed.

K

[aurora61]

i guess ill check out my backlash...

but one question: if worse case scenario my differential (i.e. all the parts excluding the tomei lsd) is screwed, i probably wont have any problems with the lsd itself right?...cause even if the teeth of the final gear/pinion gear are chewed up, it shouldnt affect the lsd.

[K]

Both of the gears and the diff can be damaged if it is really off. To be honest, if you don't hear an odd whine at all times, then most likely it's fine. But it's a cheap and quick test, so do it anyway.

K

[180fan]

80 bucks sounds like cheap peace of mind. I'd do it.

[Bronze MFP]

when i read the title of this thread i'm thinking its about 'jerks' with lsd's. like omg i wish i could have one, you guys with 2 ways are jerks. anyways good luck with everything. hope you get it fixed

[aurora61]

thanks for the help guys...

i actually have another s13 differential laying around, and i was thinking that i could just start over fresh (w/o mistakes this time) with this other differential. BUT there are suttle differences between the open-differential (with the tomei) i have on the car, and this other differential

-this differential has some kind of connector coming out from the driveshaft end of the differential (i think its meant for abs but im not sure...my car is non-abs)

-the diff cover is slightly different...the fill plug is on the face of the cover rather than to the side of the cover. Other than that, shape-wise its similar to my open differential cover

-this diff can stand upright on the circular plate that the driveshaft bolts to. My current diff cant because the circular plate cant lie flat cause theres a nut exposed on the bottom

Can someone I.D. this diff for me? Physically the diff bolts up fine to the car. I want to know whether i could use this diff despite the differences (especially if its for abs and my car doesnt have abs). But most importantly, can my tomei lsd fit in this other diff?

Modified by aurora61 at 3:00 PM 2/1/2007
Modified by aurora61 at 3:05 PM 2/1/2007