Shudder! Shudder! Buck Buck!

[rennch]

So..my 69T 3.0 project is on the road. Here's my current dilemma. If I let the clutch out a little too fast, there is MASSIVE bucking and vibration from behind me...I'm assuming it's the engine and transmission, but none of the mounts appear to be loose. It's getting harder and harder to get out of first gear, and I can't seem to pin it down.

Any thoughts?

It's a 3.0 from a 79 with a 915 from a 72.

Thanks!

[JP911]

Sounds like it could be a warped flywheel or a failing pilot bearing.

[rennch]

That would be unlikely, I think. It was fine before the car swap, and the engine and transmission never came apart.

Any other thoughts?

[rennch]

So, to shed more light on this, I don't think it's a bent flywheel or any internals because it only happens *sometimes*. Someone suggested that it was my "Bowman" tube, or something like that. Right now, my clutch cable goes right into the transmission, with no curved routing. Does that sound right?

[Jeff]

emptyo,

Sounds like your Bowden tube needs to be adjusted and then re-adjust your clutch. You want about 1/2 to 3/4 inch of thread showing.

[StayGold808]

and the bowden tube should bend upwards

[rennch]

What is a Bowden tube, and where can I find it?

[Early_S_Man]

You will find the Bowden tube on the driver's side of the 915 transaxle ... between anchor for clutch cable and the firewall. It is the plastic-covered sheath for the clutch cable, and there should be at least 3/4" of preload on it. Make sure the forward nipple of the Bowden tube is firmly seated in the dimple at the firewall!

#53 in this diagram:

[rennch]

When you say "3/4" of preload, do you mean 3/4 of an inch of 'bow" from being perfectly straight? Mine is perfectly straight, and I have no idea how I can get more "kink into it. I might have to use washers with my 69.

[Early_S_Man]

No, you need 3" - 5" of upward 'bow' from horizontal ... ~3/4" is how much the end of the sheath [threads] have to move to get the proper preload.

[rennch]

I don't think I have any way to adjust it. It's possible that something went missing when the car was being assembled. I was thinking about stacking washers on the transmission side to get the bow...otherwise I have no adjustment. I"m going to pull it apart and see what's what though. I tried to take some pics, but my camera is not cooperating. I have a question about how to route the cable as well.

[rennch]

Ok, I got some pics. Notice the bad routing....I wasn't sure what to do about it.

But, if it needs to be more bowed, it would probably route easier.



Note the space here...there's about 1/8" of gap between the ferrule and the transmission. This is what I was thinking of shimming up to get a bow in the tube. Thoughts?


Bad Routing.

[Early_S_Man]

Couple of problems in the 1st & 3rd pic ... Bowden tube is interfering with throttle rod and bellcrank! You shouldn't need the 'auxilliary throttle return spring' ... after the Bowden tube interference is removed!

Bowden tube route needs to be above the mounting pin for the bellcrank! The clutch cable or Bowden tube may not be correct part for the car. Considering the apparent age of the parts in the pics ... I suggest a new '72 clutch cable, which should come with the correct Bowden tube.

[rennch]

Thanks Warren. I've got it out now and I'm rerouting. Can I shim up the juncture at the transmission? With Washers perhaps?

[Early_S_Man]

I just got to thinking that the clutch cable probably is the original '69, and the Bowden tube is probably wrong, and probably too short. Hence, you need a new '72 clutch cable, which will come with the proper length Bowden tube.

The problem I see with trying to shim that Bowden tube enough ... is that the stepped guide sleeve will be entirely out of the transaxle body, and the cable will be free to act as a slow-speed mill cutting away at the Mg mounting lug! If I was going to try shimming that cable as-is, rather than finding a new '72 cable ... I would want to build a new stepped guide tube from a piece of tubing and a couple of thick washers welded/brazed on -- to slip behind the old Bowden tube.

[rennch]

Warren,

I was thinking the same thing. I'm sure I need the Bowden tube from a 72 or later...that's the issue. I'm off to Carquip to see if they have one.

Thanks so much for the help.

[rennch]

Ok, so good news. My temporary fix (two nuts and one washer) solved the shuddering. I'm in the process of looking for the Bowden tube from a 72 so it fits my transmission. I think I need a longer clutch cable too...it's really tight at the moment.

So, that's that. Thanks Warren.

[Plecostomus]

Haha. I thought this was a sexual question.