1970 911 Sportomatic Clutch Issues

[benny70]

I recently finished rebuilding the engine in my 1970 911 T Sportomatic. The transmission was working pretty good before the rebuild. Before I connected the transmission to the engine I thoroughly cleaned all the gunk off the case. I mostly used old gasoline to remove the old grease/road gunk. At the time I didn't even think about the possibility of contaminating the clutch. After getting the engine running good I tried to take it for a test drive. I couldn't get it in gear. After fixing some pretty significant vacuum hose problems it goes in and out of all gears very smoothly. The problem is that now it will only move under high rpms. The clutch is slipping a lot. I have checked the clutch adjustment. The Haynes manual specifies the bore in the clevis should extend 10-12 mm past the bore in the intermediate lever. Mine extends over 12 mm. Probably closer to 17 mm. I attempted to adjust the clutch. The clevis is rusted in place and I almost twisted the rod in half at which point I stopped trying to adjust the clutch. Is the clutch adjustment the problem or is my clutch contaminated/worn out? Any advice would be much appreciated. Thanks.

[Scott Douglas]

I think it may be a combination of the two if it was working before and you haven't changed anything else from a mechanical standpoint.
Are you attempting to adjust it with the engine/trans in the car?
I hope you didn't twist the diaphragm too much trying to loosen the clevis. Did you loosen the lock nut first?
When you made your measurement, did you 'pull' on the diaphragm too until it stopped while pushing on the intermediate lever?

[benny70]

I dropped the engine a few inches so I could get at the adjustment. I was able to get the lock nut loose. When I tried to loosen the clevis I held the rod with a pliers to keep it from twisting and damaging the diaphragm. When I made the measurement I did pull on the diaphragm while pushing on the intermediate lever. It sounds like I better remove the whole engine to check the clutch and weld a new section of threads onto the diaphragm rod.

[Scott Douglas]

Did you also disconnect the vacuum line on the diaphragm while attempting to pull? If your diaphragm is good, I don't think you'll be able to move it for a proper measurement if you don't disconnect the line first.

[benny70]

Yes, the hose was disconnected.

[Scott Douglas]

You can remove the rod from the diaphragm. I would not weld on it while it's attached to the diaphragm.
If your clutch was working prior to all this I'm guessing your disc is toast from the cleaning process used.

[benny70]

Thanks for all your help.

[benny70]

I finally got around to putting in a new clutch disk and its doing exactly what it was before. It will go in and out of all the gears really smoothly but the only way to get the car to move even a little is to really rev it high. The clutch linkage and control valve seem to be working fine. I started it up, put it in Low gear, unhooked a one of the vacuum hoses at the control valve and it didn't help at all. Could it be a problem with my pressure plate? Any suggestions would be very much appreciated?