Failed to find tranny problem...

[Komenda Fan]

Hey guys, I've been trying to solve a problem and failing at it, so I'd appreciate your input. I'll try not to be too long winded...

Sitting in traffic at a light the other day, clutch in, shift to first, hold clutch in maybe five to ten seconds and then THUNK - thought I was rear ended but it was actually the car and with clutch pedal still depressed she started rolling off...fortunately traffic started moving at the same time and I pulled her over on a side street.

Shut her off, tried to start her again with clutch in, first gear selected and it wants to drive off as if the clutch were out... The clutch pedal is visibly lower than where it normally sits, I would estimate perhaps 1 to 1.5" lower.

Towed her to my buddies, checked pedal cluster, shift coupler, clutch cable, throwout fork and bearing, pressure plate, and clutch, all seem to be fine...

We had her up on jacks and ran her, in neutral one wheel turns gently at idle, it can be stopped by hand - is this just drag on the system, or is this abnormal? There was some odd thunking periodically. We could shift to first and second (didn't try the higher gears).

Any thoughts? I'm thinking I need to open the tranny, but I'm not excited about doing so until I know I am not missing something simple.

[john walker's workshop]

the clutch is obviously dragging. may be a broken release fork. they crack and don't pull the p/plate very well after that. doubt it's trans related from the description.

[Komenda Fan]

That was our first thought, but nothing was visibly wrong with the fork when we inspected it. Could the damage be such that we could have missed it when we inspected the fork? Forgot to mention too that the clutch pedal is down an 1" or 1.5" from where it originally sat.

[Fast Corners]

From your original description I thought it may be the cable anchor (the plastic anchors break off then you are on your way) but from the remainder of your post I believe that you would have spotted that with the rest of the inspection.

One wheel spinning "gently" when raised at idle is normal. It is interesting tha you could shift the car from first to second. I'm assuming that the clutch was used to do this so there is atleast some functionality to the clutch.

The lower pedal issue is the one that I believe tells the problem. If we figure out why the pedal is lower that will point us to the problem.

You say that the throwout fork is ok but if it is bent or cracked (it is really hard to see without dropping the motor) it would reduce the effectiveness of the clutch.

Is the tranny the original mag case tranny or has it been updated to a later aluminum one? I ask this to see if you are using an "over the center spring" or the standard straight lever arm.

Check the firewall where the clutch cable goes into the center tunnel. If the tube seperates from the firewall due to rust the clutch becomes practically useless. I have not heard of to many 911's failing at this point but all of the 914 guys know this failure all to well.

Is the bottom of the tranny bell housing wet?

Keep us posted.

[john walker's workshop]

you can't see much of the fork unless the engine and trans are separated. the slightly lower pedal is consistent with a cracked fork. they crack at the base of one fork arm and that arm bends back a bit. the remaining arm pulls at the p/plate on one side only and can't fully release it.

[Komenda Fan]

Hey guys, thanks for your input!

We dropped the transaxle and engine, inspected the parts and didn't see any damage from our visual inspection. The fork itself appears to be undamaged, no cracking or bending that I saw. The fork appeared to fit into the throwout bearing without anything looking askew, and the cable appears to be functioning appropriate, with nothing visually wrong with it at any point from the pedal cluster through to the lever arm (I probably should have just replaced it anyway).

The car has its original transaxle as far as I can tell, it doesn't have the spring on the arm as I would have suspected if it had come from the 77 that donated the engine.

The transaxle had no leaks - I say had, because being ham-fisted, I think I damaged the gasket around the shifter rod when I took her out of the car, and when I ran it on jack stands yesterday the nose of the transaxle started to drip tranny fluid...so basically I'm accomplishing nothing but doing some damage!

[Flieger]

When I read Wayne's 101 Projects about clutch replacement he mentioned about a pin that secured the throwout bearing fork onto the pivot shaft, IIRC. The later cars (1978?->G50) did not use this. Could this pin be broken, allowing the fork to shift radially on the shaft?

[Alan L]

Here is another thought;
There is a threaded fork in the clutch pedal lever assembly - up front behind centre console (PITA to get at).
It contains a bushing - plastic - that may have collapsed - leading to more travel/slop.
Or one leg of the fork may have broken off allowing it to twist out of line and alter the distance - ask me how I know?
Alan

[john walker's workshop]

another pedal cluster thing that breaks is the roll-pin that holds the clutch pedal to the cross-shaft. it can partially shear, which drops the pedal. the pedal itself can bend. look at the Z-bend in the pedal shaft to see if it looks twisted. the clutch cable can partially break where you can't see it unless it's removed for inspection.