Triumph Repair: slipping clutch, cone clutch, slipping the clutch

Question
I purchased a 1979 triumph online. The clutch was slipping when I picked it up. Took it to a shop and they replaced the clutch. turned down the flywheel. When I picked it up it was still slipping. The clutch came form England. The mechanic says it could be a warped flywheel or the overdrive unit bad. The OD works and can only get it to slip in first and second gear. What do you think?

Answer
Hi Denny,

The most strain on a clutch is not in 1st and 2nd gear but is in 4th gear. So if you have a clutch that slips in 1st %26 2nd but not in 3rd %26 4th the problem is not in the clutch.

You need to have a mechanic that knows the overdrive unit well to test it. A warped flywheel can't make a clutch slip and especially one that was just resurfaced.

If an overdrive was wrongly engaged in 1st %26 2nd it could slip. A simple test would be to disconnect the OD solenoid and run the car to see if it still slipped. That would only test the spring loaded cone clutch in the OD (if the solenoid is adjusted correctly)If the solenoid is out of adjustment, hydraulic pressure could be trying to shift the cone into OD and because of the slower road speed of 1st and 2nd gear can not fully engage the cone, thus a slipping cone clutch.

This is why you need an experienced over drive mechanic to test it.

Howard