Marxxpress

Ok, here is what I did. Everything was fine- no noise. I decided to change my manual transmission and rear differential gear oil. I used 80w90. I did this with the car on drive ramps. I pumped gear oil into the filler hole until it started to drip out. Repeated the same process for the rear. Drove it home (about 5 miles) This is when I noticed the noise coming from the rear end. Sounded like slipping or chattering sound especially when making a right turn. I relate it to the chattering sound you hear in first gear when taking off that the engine sometimes makes. It's a noticable shaking feeling like something is not quite caught up with the speed of the engine. (Not a clutch slip, I know that much) The noise/slipping/chattering is only felt taking off from a dead stop in first gear and felt in the rear. The day after, I realized that I screwed up and should not have concluded that the proper levels were acheived just because the oil had come out the filler hole. The oil would have come out a lot sooner had the car been on a level surface. I thought this might be the problem. Too much oil, and possibly seeped into places it shouldn't have. Day after, parked car on level surface, and opened filler holes and drained a cignificant amt. of oil out. Drained it until absoluetly no more drips. Replaced filler plug. Noise is still there. What I noted before the project is that the oil level in the rear was lower than what is recommended (oil level should be at bottom of filler hole) I can only conclude that I have oil seals that have deteriorated and are allowing oil to seep somewhere where it shouldn't. Is that a correct assumtion? Anyone know? What should I look to do to correct this problem? Prices/parts/suggestions???? Many thanks in advance

GavinJuice

If your hearing this from the back then your differential is in need of a "friction modifier". The reason being your clutches in your LSD are chattering, as like you said, especially when you turn right. Torque is trying to be applied to the other wheel through the use of the clutches, but w/o the aid of the friction modifier they're not grabbing one another and producing the noise your hearing.

Your differential is fine, you haven't runined anything.

Amsoil, redline, royal purple, almost any brand out there produces a friction modifier, but hopefully you used a synthetic. Amsoil will work with either or.

dirty86

good info

DriveFast7

iTrader: (1)

Go to your local Ford or Chevy dealer and ask for "limited slip additive". take the rubber cap off the breather on the top of the diff housing and squirt the additive in. drive around in circles and listen to the chatter go away!

Marxxpress

Sounds like an easy enough solution. Great!! I am thrilled that it is not something major. I hate it when something goes wrong. I am very meticulous with my Rx-7. It's my cream puff! I'll get that additive in today! Thank you guys.

GavinJuice

do figure 8's so as to get it worked in on both sides.

Marxxpress

Copy on the figure eights.

LongDuck

You guys are all over that one. Good call.

I recently changed my LSD oil for the Mazdatrix recommendation, and they sell the GM LSD additive for about $12 and added it to my order - all in one shopping!

Future readers should note that only the GSL and GSL-SE models are equipped with LSD rear ends, however - so you only need the special oil additive if you're driving one of these models (look for rear disk brakes to help make the ID).

Marxxpress

Temporarily until I purchase the limited slip oil, is it bad to drive without it??

Snapshot

I've gone through 3 LSD in my 81. Have purchased used ones that have been good for a few years. Theres nothing like a loud "clank" & lurch to get your attention. Sorry, dude, you need a new "chunk".