Slipping clutch

[nbracken]

I have a SBC with Tremec gearbox and the custom bellhousing arrangement from RePower with external hydraulic slave cylinder. The car has done about 20,000 troublefree miles since the clutch and gearbox were installed.
Today I noted a slight slippage when going up inclines and with full throttle from about 2000 rpm in 2nd gear. The clutch is engaging near the top of its travel.
I have about 8mm from the back of the clutch fork to the end of the slot in the bellhousing. I recall this was about 10mm when I installed teh clutch and gearbox.

Question: is it normal to have to periodically adjust these clutches or am on the way to buying a new set of clutch plates? 20,000 miles doesn't seem far and even though I have done a few track days and a few drag starts it isn't really heavy. And I do have 2 HD plates in there.
Ideas/comments welcome please

[dingocooke]

Hi Neil
I'd check that the clutch hasnt just worn, because as it does, the release arm moves, and eventually you can lose the free play you originally had.
Unbolt the slave and see if it was preloaded, then you need to either adjust the clutch slave pushrod to regain the clearance, or shorten the pushrod.
Clutch pushrod shortening was an old e type jag dodge to give another 10,000 miles or so 'adjustment' to a worn clutch; usually after 30,000 miles or more.
If youre not heavy on the clutch, i.e. you dont ride it/slip it/drive with your foot resting on the pedal (a big clutch killer) etc, then 20,000 miles is a short life, but if it has been installed with a not much free play to start with, and youve been driving with a preloaded clutch for some time, you may have worn it prematurely?

So, adjust some slack in if you can, and do make sure you have not run out of fork travel.
Hope this helps a bit.

[nbracken]

Steve thanks. Have adjusted the fork to get back free play and all now seems OK again. Thanks much mate.