What are the signs of a bad Diff?
 

Hey all, I am pulling the engine and trans and getting a J-spec trans to replace mine.

I figured i would take alook at the diff fluid while everythign was apart (I have had the car for 4 years and neverchecked it....in my defence it hasn't run in the last 3. Either way it should have been one of the regular maintenance items.


Getting back on topic. I pulled the drain plug and there was quite a bit of microscopic metal shavings on the magnetic plug. But how much is too much? How do you know you need a new diff?

The reason I ask is because I can get a low mileage TII diff shipped with my transmission and save $125 in freight, but I don't want to get it if I don't have to. Also the current diff is leaking at the pinion seal, so if I use the current diff that is on the car I will have to replace that seal.


Also, what lubes do you guys preffer? (brand/weight?) for diffs and trannies. Have any of you used Mobil 1?

Metal shavings are pretty common in the diff. If they are bigger than grains of sand, there may be a problem. Was there any howling coming from it while driving? Any clunking?

TII rear ends tend to hold for up a long time. Mobile 1 is a fine choice for oil. I prefer redline.

i use redline 75w90 with the added lsd stuff.

peace

I had this problem with my z28 before.
Listen for weird high-pitch huming noises coming from the dif while driving, it that happens then you already have a bad diff. one of the teeth is messed and is vibrating evertime it makes a revolution. i had no clue b4 so i thought it was nothing, later on the noise became louder and then one day BANG. and i lol i heard crunch then BANG BANG bang then car stoped moving.
sry for making a short story long but yea i was 17 so i didnt know anything about that shit. high pitch huming noises that come and go are a begining sign.
to many times i would fucken race off red lights, or floor it from stop.
now with my rx7 i wait till i get going and dont burn out as much then i drop the torque that these cars so elegantly provide :)

high pitch noise is ring and pinion

most diffs go bad by clutches wearing out.


ps i do have a brand new mazdaspeed 2 way lsd for sale, pm me if interested.

https://www.rx7club.com/showthread.php?t=748796

what does a clicking/clunking sound mean? my S4 TII will sometimes do this when making tight turns

the clicking and clunking means that one or more teeth are already bad, and the diff is already bad. the clicking turns to clunk then it gets louder , then the car wont move.
do you do alot of burnouts? : )

A clunck going around corners can also be a locking diff unlocking so the wheels can turn at different speeds.

Brian

When you hear a knocking sound on the rear of the car, definitively you have a differential problem.