Originally posted by revzalot
Do you guys have a systematic ways to know when to throw away the diff balls?
Boomer is absolutely correct!
When your diff begins to feel notchy, itís the outside flanged bearing. These bearings are not designed to be used the way we are using them. A higher quality bearing will last longer but it will eventually be destroyed and therefore, will need to be replaced. You can buy/build yourself an outside thrust bearing but that adds expense and additional maintenance issues but most importantly, weight!! I tried a ceramic bearing on the outside but while it did make the diff smoother, it did not seem to last as long as a high quality steel bearing.
Revzalot: As to your question about when you replace your diff balls, do it when your diff stops feeling smooth and free. You should be able to completely lock up your spur gear and the diff spin freely. I put ceramic diff balls in my car last May and I also use Niftech rocket rings which I have found to be the hardest, lightest big rings. I race at least once a week, sometimes more and I am still using the same diff balls and rings that I put in last May and my diff is always locked but free. So free that when I use the compressor to blow the dirt and fuzz off of the car after each run, the rear wheels will spin up when hit with the air.
Bearing tip: Check your local phone book for a bearing distributor near you. Go by there with a sample of the bearings you want to replace. You will be amazed at the various grades of the same size bearings and how cheap the highest grade bearings are. Remember that the hobby shops, kit builders and on-line aftermarket vendors buy their bearings someplace. Why not cut out the middle man and have high quality, cheap bearings to keep your car in tip top shape at all times. And if you want to try ceramic bearings, try KGB (http://www.kgbracing.com/
) they have unbelievable prices on ceramic diff balls and bearings.