s15 helical diff grinding

[gpeele]

this is a s15 helical diff installed in a spare s13 non abs pumpkin with the correct output shafts and brand new shims, bearings and seals. all installation was done by a shop sometime ago but the shop has since closed.

just today i had the pumpkin swaped out with my stock one and it was making a loud grinding noise, like loud enough to be heard when the rear is jacked up and the wheels spin freely when the accelerator is pressed. when on the road the noise is much louder and reverbs through the car. i cant take it back to the original shop for obvious reasons, so what could be the problem, bad shims, crappy fluid (75w90 gear oil is in there now). are helical lsds themselves known to go bad? any help will be appreciated.

thanks.

[jdm_master_X]

this is a s15 helical diff installed in a spare s13 non abs pumpkin with the correct output shafts and brand new shims, bearings and seals. all installation was done by a shop sometime ago but the shop has since closed.

just today i had the pumpkin swaped out with my stock one and it was making a loud grinding noise, like loud enough to be heard when the rear is jacked up and the wheels spin freely when the accelerator is pressed. when on the road the noise is much louder and reverbs through the car. i cant take it back to the original shop for obvious reasons, so what could be the problem, bad shims, crappy fluid (75w90 gear oil is in there now). are helical lsds themselves known to go bad? any help will be appreciated.

thanks.

well from my understanding, you're saying that you swapped the current s13 pumpkin for another one?

well if you had to remove the final drive assembly, when reconnecting the pinion side gears, you must adjust for backlash between the ring gear of the final drive as well as the main pinion drive. if its not aligned correctly or within its specs, grinding can occur.

who did the swap? if you did it by yourself, i hope you had a dial indicator on hand to measure the backlash on the ring gear and main drive pinion. and make sure to have the backlash specs. hopefully not hard to find, but in any regard, that is probably what happened during the pumpkin swapping process. adjustments are normally cured with side gear adjustments to move the ring gear and pinion in the right place.

[gpeele]

a local shop did the swap, they had ordered the all the shims that they needed for the swap as well as new bearings. the sound is like someone added a whole lot of gravel in with the diff fluid. as far as measurements, the shop is reputable and ive never had a problem with them in the past. they said they would measure for the correct sized shims for the swap, whether they did that or not is now in question. should i trust a regular joe smoe transmission shop like cottman to diagnose this and give me a straight answer?

thanks again.

[s13sr20chris]

a drivetrain shop may be able to help you. i would start by pulling the diff out and checking inside the case. check for metal powder and binding in the gears or bearings.

[gpeele]

ok will do on doing a visual inspection myself to try and identify the problem. ill write more on this if i find anything odd.

this is a bit off topic but if you remember me asking about where to get my pfc tuned a while back, i found a shop up in baltimore that specializes in tuning both versions of the pfc for the 240. i have yet to take it up there since money is kinda tight but the plugs show normal wear characteristics so im going to wait a bit longer to get it tuned. the place is called ma motorsports in case anyone else in the mid adlantic region asks about where to get their pfc tuned.

[jdm_master_X]

in regards to the measurements, gear clashing between the ring gear and pinion would be corrected with the properly sized shims. however, where you PLACE those shims is also critical, so if anything, get it done right the first time and go to a professional shop. "broke-anics" are the worst with rear ends, unless they obviously show competency in repairing it. but yeah, if they did use the right shims, do you know if they placed the shims in the right sides of the side gears?

and on a final note, make sure that you pull the proper specs for backlash and make sure you compare with the shop. its always nice to show a shop you mean business. haha. every adjustment requires backlash measurements to be safe.