Have about 2k miles on a new cusco 2 way diff. and wondered if I might be using the wrong type of oil.

I've been using NEO 80/90 and after talking to some roundy-round racers, it seems that they never use synthetic oil in their locker rears.

Any opinions, as the clunking around slow corners and the unstable feeling around long sweeping turns is about to drive me nuts.

btw, the rear was assembled by a pro.

Jack

 

I use sythentic gear lube in my 7 and our IT7 race car and never have problems.

 

You might try some GM lsd friction modifier to quiet the diff some. I tried several types of gear oil (synthetic and non) and other friction modifiers in a GM 10-bolt. Most synthetics will say that friction modifier is not needed with their lube. Nothing worked until I used the actual GM additive. Smoothed everything right out.

 

I have a cusco rs 2way. I use synthetic. I only have bad clunking when the steering wheel is at full lock, at slow speeds. It was very bad in the beginning. It seemed to break in and almost go away. And it's not as bad as before.

As for the unstable feeling when you let off the throttle around sweeping corners. 2way means the diff locks when the throttle is on and when it is off. Now it only happens when you are in the middle of a long sweeping turn. My advice, try not to come off the throttle suddenly in that situation. If you need to let off the throttle, do it, but not all the way. Also, try to have the car set in the turn with the throttle off, then start to excelerate.

Not too many people have a cusco diff or a 2way. I assume this is normal, since I have no experience with a 2way diff. I do not think it was assembled wrong. and I never felt like the car was going to go out of control. I actually got used to it, and became more aware of what the car and I was doing. The rear end seems to tuck itself into the turn if you need to let off the throttle.

Anyone with a 2way.......speak up

 

Swepco 80/90... good for the gear box, good for the diff.


M

 

FWIW I just read in the "How to modify your RX-7" bible that the GM LSD additive I mentioned is recommended with the factory Mazda LSD. Give it a try.

 

royal purple 80/140 with a little of lucas oil stabilzer works great never had any problems

 

I beleive Cusco makes their own oil, I would use that, if it is not available, I would use redline, or Amsoil. Carl

 

That's nice to know I know many racers who have all had good results with the GM friction modifier. Many people swaer by it.

 

Jgtcspec7

I think there might be only 3 of us on this site with the Cusco rear. (scrub is the other).

I think my clunking, grinding when pulling away and turning at the same time is magnified because of my Ls1/T56/spec3 clutch combo which makes it almost impossible to pull away smoothly. The aftermarket cam probably adds to it.

After 2k miles, the cusco should be broken in, so I hope the friction modifier will help