1275 Ribcase transmission in Bugeye - Which slave and pipe?

[Gerard]

Fred, check for lost travel at all the pivot points. Clevis pins can have grooves worn in them making the diameter essentially smaller (loose) and well as holes they fit becoming oval. The same goes for the fork pivot in the gearbox. Also, do you have the right cover and fork on the gearbox? There are two different ones and they sometimes get swapped by people that don't know the difference. They have different fulcrum points. You may also need to adjust the pushrod at the master cylinder. I wouldn't necessarily assume the setting you had before to be correct, especially since the clutch and gearbox are all different. There is a very limited range where it's just right. Check too that your fork is not bent. Using a too long pushrod will eventually bend the fork, giving you the problem you have. Lastly, unlike the brake side, a clutch MC does not have a residual valve, so it can be very difficult to remove all the air from the clutch circuit. There are many surefire ways to get it done, but my personal choice is to use a remote bleeder. I can provide details if you want to try that, but you need to check all the aforementioned issues first. They will have a cumulative effect on a poor performing clutch. You'll also find going to a 3/4" bore to be a significant improvement.

 

[TulsaFred]

Thanks Gerard. From my examination so far it seems clear that I am not having a problem with the hydraulics.

I know this because I had my daughter push the pedal while I was under the car looking at the slave with the rubber dust boot off (but still actuating the pushrod and clutch mechanism). The piston came all the way to the end of the cylinder.

If my analysis is correct, the problem has to be distant to the slave - pushrod, fork, throwout bearing, pressure plate, clutch disk, flywheel or pilot bearing.

I tried a longer pushrod, switched out the 2 3/8 for a makeshift 2 11/16. Didn't correct the problem (though it did seem to bottom out the pressure plate fingers).

I don't think the fork is bent, but it is hard to be sure with it installed.

The fact that it randomly worked properly for a short period of time is a clue, but I'm not sure what it is telling me.

 

[Gerard]

Distance would only be a factor if the fork was bent. If you have all the right components in place, and they are in good order, then the clutch hydraulics are self adjusting. The only adjustment variable is at the master cylinder pushrod. That is how you would adjust for freeplay. Look at my page on the subject to compare a straight fork to a bent one.

Did you use the 1/4" thick cast plate on the rear of the engine, not the one used on the 948?

If you clutch is not releasing, when everything else checks out, then either the disc is backwards (seems unlikely if intermittent), the input shaft is binding in the back of the crank or the disc is stuck to either the flywheel to pressure plate. The other possibility is failure of the carbon release bearing, which could include a retaining clip coming off, wrong release bearing, or a bolt or spring becoming lodged against the disc. I have experienced all these conditions over time with different cars, so they are real scenarios, even failure of a carbon release bearing that looked to be in good condition when installed.

Thanks Gerard. From my examination so far it seems clear that I am not having a problem with the hydraulics.

I know this because I had my daughter push the pedal while I was under the car looking at the slave with the rubber dust boot off (but still actuating the pushrod and clutch mechanism). The piston came all the way to the end of the cylinder.

If my analysis is correct, the problem has to be distant to the slave - pushrod, fork, throwout bearing, pressure plate, clutch disk, flywheel or pilot bearing.

I tried a longer pushrod, switched out the 2 3/8 for a makeshift 2 11/16. Didn't correct the problem (though it did seem to bottom out the pressure plate fingers).

I don't think the fork is bent, but it is hard to be sure with it installed.

The fact that it randomly worked properly for a short period of time is a clue, but I'm not sure what it is telling me.

 

[TulsaFred]

After removing the inspection cover from the bell housing, I watched the clutch action as the pedal was depressed. The carbon throwout is visible and appears fine, and the pressure plate fingers are all intact and operate in apparent normal fashion.

Based on this, I am suspicious that, as you say, the input shaft is binding to the flywheel/pilot or the clutch disk is stuck to the flywheel or pressure plate. That's why I tried to break it loose (put in gear on lift, rev, push in clutch and then brake). Unfortunately, it didn't work.

Running out of ideas, so it seems I'll need to take the engine and trans back out, but sure hate to do that.