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GT6 GT6 Clutch Failure - Where to Look First

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dklawson

dklawson

Yoda
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Our GT6 has been parked for 3 months (ran when parked). When starting the car and moving it this weekend we found the clutch is not working... it will not release and the pedal feels VERY light.

The level of fluid in the reservoir is high and where I expect it to be. I do not see the level change when an assistant pushes the clutch pedal. No resistance is felt in the pedal until it gets very near the bottom of its stroke.

My gut feeling says the master has failed. Do you have any suggestions for what else to check?

I am also considering getting one of TSI's remote bleed kits so I don't have to pull the tunnel next time. Do any of you have experience with the kit?

Thanks,
Doug L.
 
I don't know much about the GT6 clutch configuration, but I would try bleeding at the MC outlet first. I'm thinking some sort of leak may have allowed the system to fill with air during storage and the MC is just air locked. If you can't get the MC to at least blow some bubbles through the loosened fitting, then it's time for a new MC. But if it starts working, you may be looking at a leak at the slave or some other issue.

On the TR3 & Stags, once the MC is full of fluid, I can almost always bleed the rest just by pumping the clutch up as far as possible (being careful to not use any unusual force), waiting a few seconds for the bubbles to rise, then releasing the pedal. Repeat that 8 or 10 times until the pedal feels firm. Any last little bit usually works it's way out as I drive.
 
You could also try putting a piece of wood to hold the petal to the floor. Leave it like that overnight. You might want to put something underneath to catch the fluid in case the slave seals have gone bad.
 
dklawson said:
I am also considering getting one of TSI's remote bleed kits so I don't have to pull the tunnel next time. Do any of you have experience with the kit?
Click to expand...
I'm confused; why would you need a remote bleeder on a GT6? The slave cylinder is pretty much right there, accessible from the engine compartment. Granted, this photo is from a car with no manifolds in the way. Still....

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I'm going to guess it's the clutch disc stuck/rusted to the flywheel. It's happened to mine twice (in 32 yrs.) and I recall that no resistance feeling at the pedal both times.
 
3798j said:
I'm going to guess it's the clutch disc stuck/rusted to the flywheel. It's happened to mine twice (in 32 yrs.) and I recall that no resistance feeling at the pedal both times.
Click to expand...
Any explanation for how that is possible? If it was just the friction plate stuck to the flywheel, then the pedal would still be moving the pressure plate away from the friction plate (against the springs), hence the pedal should feel normal. Mine certainly did, when it happened to me.
 
TR3driver said:
Any explanation for how that is possible? If it was just the friction plate stuck to the flywheel, then the pedal would still be moving the pressure plate away from the friction plate (against the springs), hence the pedal should feel normal. Mine certainly did, when it happened to me.
Click to expand...
Felt certain you would ask Randall. And no I don't. But still recall the pedal lacking the normal resistance - which returned as soon as the clutch became un-stuck.
 
Andy, you are right... I can see the bleed nipple but getting in there with a hose and wrench is really a little easier said than done.

I do not expect this to be the result of a leak as the reservoir is completely full and I have not added any fluid. Regardless, I will try bleeding first, both for the master and for the assembled system. If I do get a pedal back I will still commit to at least new seals for the MC and slave.
 
If you haven't yet look around the system for hydraulic leaks, also, if you have a wife or buddy, get under the car and see if the clutch depression corresponds to movement of the clutch release coming out of the side of the tranny, although I agree the most likely diagnosis is a bad master cylinder or hydraulics, you could have a broken taper pin on the clutch fork (assuming they are like the TR4-6 in that regard)
 
Unfortunately with the slave up high and tucked under the tunnel cover (with insulation) you cannot see what's going on regarding motion of the throw out arm or slave pushrod. I do not think this is the friction disk seized to the flywheel as the pedal is extra "light" compared to what we are used to. I have had a car that we only drove once or twice a year and it did have regular problems with the clutch seizing to the flywheel. The problem with the GT6 just doesn't "feel" like that.

Let me say again, this is not a leak. The reservoir is full... right where it has been for a year.

After weeks of no rain we finally have storms that will prevent me from getting to even look at the car for another week. When I do get back to the car I plan on disconnecting the master and seeing if it will pump and bleed as Randall suggested. If the MC pumps, I'll get in there and bleed the system. Tom, thanks for the Matco link. That is a very affordable set of crowsfoot wrenches... especially since they are the flare nut type. I already have a regular set of crowsfoot wrenches so I may see if I can crack the nipple free with a regular socket, then use my existing crowsfoot wrenches to open and close the nipple during bleeding. Thanks for the suggestion.

Thanks again to all who posted suggestions. When I get this sorted I will post what I found.
 
I finally got time and dry weather which allowed me to look at the GT6.

I started and ended by bleeding the clutch. Once bled, the clutch felt right and worked right.

As there was no leak in the system I am confused about where/how air got into the system. I may replace the master to eliminate that as a potential source. Should the situation return after the new master is installed I will turn my attention to the slightly harder to access slave.
 
I purchased a clutch master cylinder and installed it today. I disassembled the old MC.


Inside I found that the "front" seal that controls the flow of fluid out of the reservoir had failed. It was gooey and had sluffed off some material that was probably blocking the valving. The bore was pristine.


This car has had used DOT-5 fluid since its resurrection 22 years ago. All the brake and clutch rubber was replaced back then so I am very surprised to see seal failure. I guess 22 years is not bad for seal life. However, it's made me think that perhaps I should rebuild the brakes soon... just in case.


Doug L.
 
Had the same issue with my MK2 a number of times as it wasn't my daily user .

I normally used a length of wood to depress the clutch, selected 1st and rocked the car or a flick on the starter either one was normally enough to free thing if that doesn't work could be that your clutch diaphragm plate is faulty , which is doubtful though

cheers
Steve

3798j said:
Felt certain you would ask Randall. And no I don't. But still recall the pedal lacking the normal resistance - which returned as soon as the clutch became un-stuck.
Click to expand...
 
Forgot to add that a regular change of clutch fluid is always helpful as many fluids are hydroscopic.. I use silicone brake fluid now as it doesn't strip the paint if the master cylinder leaks

cheers
Steve
 
Steve, the problem was the master cylinder, not a stuck friction disk and the fluid is DOT-5. It has had only DOT-5 in it for 22 years and all the rubber was replaced before the switch to DOT-5. That is why I was surprised to find the front MC seal had turned to goo.
 
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