Clutch Master Cylinder or Pedal Problem?

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LC - 07 Feb 2005 04:26 GMT

I have about an inch of travel on my clutch pedal before I meet with
resistance from my clutch master cylinder. When I do, the resistance is
immediate, and shifts without problem.
What do you guys think... Is it a problem with the clutch master cylinder
or the pedal?

Thanks for the help!

-Larry

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John B - 07 Feb 2005 13:56 GMT

> I have about an inch of travel on my clutch pedal before I meet with
> resistance from my clutch master cylinder. When I do, the resistance is
> immediate, and shifts without problem.
> What do you guys think... Is it a problem with the clutch master cylinder
> or the pedal?

It could be a problem with either. If it's the pedal, the cause would be wear
on the metal where the pedal is pinned to the master cylinder piston. If you
stick your head down there and look (might need to remove knee bolster), you
would see an oblong hole in the clutch pedal rather than a circular hole.

If it's the master cylinder, it would likely be leaky seals, though it could
also be the return spring inside the cylinder (I replaced one of these springs
myself a few months back). Taking the cylinder out isn't extremely difficult,
but you will have to bleed the clutch when you are done.

John

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Dave Hinz - 07 Feb 2005 15:25 GMT

> It could be a problem with either. If it's the pedal, the cause would be wear
> on the metal where the pedal is pinned to the master cylinder piston. If you
> stick your head down there and look (might need to remove knee bolster), you
> would see an oblong hole in the clutch pedal rather than a circular hole.

I _just_ had my clutch m/c on my '86 900 fail. The bolster can stay,
but if you have an air distribution duct (black plastic thing), that needs
to be moved out of the way to see what you're doing.

In the case of mine, the "saddle" wore through & broke off the end of the
pushrod going into the m/c. I'm going to drill and tap a thread into the
pushrod, screw the saddle back on, and _then_ braze it together
(belt & suspenders approach).

> If it's the master cylinder, it would likely be leaky seals, though it could
> also be the return spring inside the cylinder (I replaced one of these springs
> myself a few months back). Taking the cylinder out isn't extremely difficult,
> but you will have to bleed the clutch when you are done.

If the bore of the cyl is good, you can do the whole job from inside the
passenger compartment if you enjoy being upside-down more than you enjoy
getting at that one fitting. But, unless you have huge forearms, it's
easy enough to go the one extra step and take the fitting out of the front of
the m/c.

Dave Hinz

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LC - 09 Feb 2005 05:03 GMT

How hard is it to bleed the clutch clyinders once you put the new MC on?

>> It could be a problem with either. If it's the pedal, the cause would be
>> wear
[quoted text clipped - 29 lines]
>
> Dave Hinz

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Dave Hinz - 09 Feb 2005 15:19 GMT

> How hard is it to bleed the clutch clyinders once you put the new MC on?

Not too bad. Couple of ways to do it, and if you're
careful and get as much air out of the m/c first, and if
the tube is still full of fluid, you might be able to do without.

Dave Hinz

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ma_twain - 07 Feb 2005 21:43 GMT

> I have about an inch of travel on my clutch pedal before I meet with
> resistance from my clutch master cylinder. When I do, the resistance is
[quoted text clipped - 5 lines]
>
> -Larry

You can tell by pumping the clutch pedal. If the resistance point
moves, it is probably the cylinder. This is because the pressure is
built up as you pump. You may also notice the travel is more when the
the car is cold - this is the cylinder.

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John B - 08 Feb 2005 00:49 GMT

> built up as you pump. You may also notice the travel is more when the
> the car is cold - this is the cylinder.

I've had that symptom every since I rebuilt my MC... either I screwed it up
somehow or the seal kit I put in allows a small leak. Maybe the bore is a
little scratched from the broken return spring I was replacing.

Whatever the cause, it's good as new once the engine is warm. And it's way
better than it was with the broken spring, even when cold. In short: not nearly
bad enough to warrant taking it apart again.

John

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hippo - 09 Feb 2005 09:48 GMT

>I've had that symptom every since I rebuilt my MC

Did you pressure bleed it? If not, that could be the problem. Else maybe
worth doing again to see if it fixes it. How's the slave cyl? Prob worth
checking 'cos they're not too horrible to fix.
Cheers

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John B - 09 Feb 2005 15:58 GMT

> Did you pressure bleed it? If not, that could be the problem. Else maybe
> worth doing again to see if it fixes it. How's the slave cyl? Prob worth
> checking 'cos they're not too horrible to fix.

Yes, I did pressure bleed it. I bled it again when I was doing the brakes a
month or two later, just to be sure, and I think that improved the situation
slightly. Anyway, it doesn't bother me nearly enough to do anything about it
just now. Maybe if I have time to kill over the summer.

John

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