Gold SMC Axel Clutch leaking


Active member
Working on clutches today to get ready for Mid-Ohio and Charlotte. I have a couple of questions.
What is the most common place for these clutches to leak?
Do you heat up drum and collar in oven to remove bearings?



Premium User
Most times they leak tbrough the big O Ring seal in the collar. Most times a new O ring seal fixes it, but of the 3 ones I have there is one I could never fix the leak. I even try to soak the bigrubber O ring overnight on brake fluid since I was told that makes them swell and get thicker but that didn't work either. I think their big enemy is heat and especially trying to asjust them while they are hot without removing at least one of the pluges to reduce the internal pressure that builds on them. I think once the case or collar grows because of heat it is hard to fix them unless those parts are replaced, Hoppy. I can still use the one that leaks for dirt or short sprint tracks but obviously not for long road races.

Chris Cooper

Premium User
Check the seals as well. But, as Santiago said - Most times they leak tbrough the big O Ring seal in the collar. Most times a new O ring seal fixes it. We just got back from a road race @ Hallett - new o-ring in the speed collar and new seals - very little oil leakage on a piston port laydown all weekend.

One other thing to try - after you run a long practice or make a major adjustment on the speed collar, open one of the fill plugs and let the pressure settle. This also helps to reduce leakage.


Pay attention to the studs as well. These can come loose and leak. Happened to me more than once.

Bruce Peck - Indy


New member
I agree with yamadog,and others above, usually loctite the studs and don't over-tighten gear nuts. Also when installing the big o-ring do not allow it to twist.


Premium User
Yes, I agree, both the studs and the O ring are the areas to watch, but it is easy to see where the leak comes from, especially if it come from the O Ring.