Tilton twin disc clutch issue

[Stealth_RT]

So, I've been running the Tilton twin disc/aasco motorsports flywheel, HTOB setup since last year. No real problems with it (except the howling it makes when first pulling out from a stop). But, last month I took the car to Pittrace (formerly Beaver Run Pittsburgh International Race Complex) track for a PDE, and had an odd problem crop up. Started the 25 min. sessions just fine, and no issues while on track. Since the track is on the small-ish side, 1.5 miles around, and the straights are short-ish, I could run the whole time in third gear. Pulled out of the corners ok, and topped out in 3rd gear at 7k rpm and 120 mph. Came off the track fine, down shifting into 2nd and 1st going back to the pits. But, when I tried to shift into reverse to back into my spot, the trans wouldn't go into any gear, and I had to coast it backwards into the spot. After sitting for a bit 5-10 min, it would shift into gears fine again. Also, there is a fluid loss from the clutch reservoir. Not major, but noticeable. I did not notice any wet spots on the ground under the car.

From the symptoms, I'm guess that a) the HTOB is leaking, and b) the HTOB and/or fluid in the clutch lines doesn't like the heat from running hard on the track.

I bought the whole setup used from another member on the 'other' site. I had originally sent the flywheel/clutch assembly back to Aasco for evaluation as we couldn't get the clutch to release at all when first installed. Got that fixed and the pedal adjusted and it all works fine. Never any trouble on the street driving it.

Any ideas why I can't shift into gears AFTER coming off the track, and why it works after sitting for a bit? Should I get a new HTOB, or get this one rebuilt? Is anyone ducting air into the bell housing for heat managements when tracking the car? The less I have to have the trans pulled to correct this, the better.

Thanks

[KeithMac]

Plates will expand slightly when hot, if the release distance is marginal when cold it could cause dragging issues when hot.

Does it drag in 1st gear when hot?.

Seems strange as clutches normally only heat up during slipping (ie hard launches).

My OS Giken R3C has had no issues with releasing, but it uses the standard clutch fork, does the clutch pedal still feel firm when you experience the fault?, you could be boiling the fluid (maybe try a higher grade fluid in there?).

[Stealth_RT]

Don't feel any clutch dragging. It downshifted fine coming off the track. Using Motul 600 fluid in the clutch, just like in the brakes, and the brakes have never faded on me. Unless I got a small air bubble in the clutch lines when I changed the fluid out, and it's not enough to affect normal street driving.

[Erron Spalsbury]

Sounds like you may have a bad HTOB or the seals are starting to go. My guess would be one of two scenarios. One, since you see some leaking, the seals are gone or going. Or, you did get it hot somehow. That's not excessive track time though, so that may be the first signs of something else going on. Was the transmission excessively hot? If you did overheat it, it works just like brake lines in the way that you would lose hydraulic actuation and not disengage the clutch fingers all the way. (potentially had boiled the fluid) I run RT700 brake fluid in both my brakes and clutch line. What fluid did you have in there?

[Erron Spalsbury]

I'll add to this, on my setup I don't have any of the rubber nubbie/vents on the transmission. Nor do I run the lower plate that shields or closes off the bell housing next to the t-case. (when you lay under the car you can clearly see the flywheel) I do have the engine bay sealed off below though, not really a good chance of getting anything up there. I probably wouldn't do that on a car that sees any dirt use, which mines doesn't.

[Stealth_RT]

Dunno if the trans got excessively hot or not. Shifted fine driving home from the track and driving it since then, but that may not tell me if there was a trans problem. I also don't have the rubber boots or lower plate installed. Using Motul600 brake fluid in brakes and clutch. HTOB is used, so it could certainly be bad or going bad. Just weird that it would heat soak only after I came off the track.