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T-Series Stranded at work: clutch won't operate

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100DashSix

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Well, this seems to happen to me every two years. This time I was driving on the highway when the engage point for the clutch suddenly dropped near the floor--though the pedal itself felt normal. I was able to shift, but it became progressively harder to synchronize the gears. I was unable to shift entirely, and was only able to get into third gear with some revving and grinding. I was luckily able to guide the car off the highway, through two green lights, and into a parking lot--right across from my building.

The fluid level of the clutch master cylinder didn't drop, and no drops of fluid appeared to fall from the slave cylinder when I put a towel under it and actuated the clutch a number of times. My tools were limited, so I placed a guitar pick on the top of the slave cylinder push rod and actuated the clutch. It fell off, indicating to me that the clutch fork is being actuated--though perhaps not far enough. The clutch pedal feels normal and stiff, not spongy, not mushy, not weak, etc.

Perhaps the clutch has stuck to the flywheel, and the springs failed to push it off? Can that happen? I should've banged on the side of the bell housing with a tool. Any advice?
 
wonder if your clutch hose has collapsed? if there is no leak and I can't see that the clutch would freeze while moving. leaves only the thrust bearing or the hose. I'm betting the hose
 
Oh, or your fluid might be full of water.
 
I could replace the hose to the slave cylinder and bleed the system, but I observed that the clutch withdrawal lever was being actuated when the pedal was depressed. Is it possible that it's visibly moving, but not being pushed far enough?
 
If the seal in either the clutch master or slave cylinder has failed the pedal will feel as you describe. The fluid will be partially bypassing the seal and possibly move the clutch rod but without enough oomph to disengage . Bob
 
Hm, interesting. I'll start with the hose, as I've replaced the brake hoses with stainless, but not the clutch line. Is there a way to isolate a hydraulic failure from a stuck bearing or other clutch failure? Is the only way to rebuild the master and slave cylinders on the bench? I think the master cylinder has been rebuilt ten years ago or so.
 
Interesting problem! The way you discribe it the hydraulics are working ok. Normally if the hydraulics are giving a problem you can feel it in the pedal.If the slave was bad you would see a drop in fluid and there is only one cup in there so nothing to bypass. The master has 2 seals as i recall. I guess it could bypass one seal. Most of the time the flex hose gets hard and clogs from the inside and does not release pressure. I would think it would be pretty rare for a pressure plate or disc to fail. Release bearings fail over time and not per your discription. If a pilot bushing was bad enough to hold the input shaft it should have been screaming for a while and even then i doubt it would cause your problem. If i had to take a wild guess i would say go for the master cyl rebuild. You can put a kit in it while its in the car BUT you can not look at the bore good enough to tell if there is pitting in there. I wish there was a better clue but thats all I can think of right now. Things like clevis pin wear also do not cause a sudden problem. Keep us informed. Bob
 
Thanks for the advice. I'll start with the hose and move up to the clutch master cylinder, and rebuild it on the bench. I wouldn't be surprised to find out the previous rebuild was shoddy, and would also do the brake master cylinder as a result.
 
My educated guess would be the same as Bob, master cyl.
There should be a couple of inches travel at the slave. Less and it is not going far enough to release the clutch properly.
Good luck and keep us informed.

Dave :savewave:
 
Re: Clutch won't operate [pics!]

I had some time to inspect the clutch master cylinder, and check this out:


Both the pedal and the push rod linkage have been wallowed out as they worked against the clevis pin. There's about 1" of pedal travel before the pedal and pin press against the push rod. It's pretty obvious the PO didn't actually rebuild the cylinder.
 
Re: Clutch won't operate [pics!]

That is definatly a problem but that did not happen on your way to work. Thats years of friction. Next question would be was there 1" of play for a while or was the pin somehow rotated in there and all of a sudden shifted and now the pedal feels different? If nothing major changed in the pedal free play then its probably not whats causing your problem. Nice clear pic! Bob
 
Re: Clutch won't operate [pics!]

Yeah, I didn't mean to imply that that suddenly happened! I've seen wear like that on this car before, just from its years of driving. The wishbone arms had holes like that.

The pin itself is still cylindrical and wasn't jammed in or anything; the pedal always felt like that, I just didn't know it was unusual. I think the worn push rod indicates there may be enough wear to the seals or cylinder itself to cause the failure. At least, I hope so (it's better than pulling the engine and transmission).

And thanks! Macro mode is the best.
 
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