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MG MGB Technical - Cannot get clevis pin out of pushrod/SlaveCylinder

Hi everyone,

Anyone have this problem before?

I am replacing my clutch slave cylinder on my 79B.

I have the cotter pin out and for the life of me cannot get the clevis pin out of the pushrod that connect the slave cylinder to the transmission.

Ive turned to hitting it with a hammer and no budging.

Any tips on removal when encountering this situation?

Heat? Its very close to rubber parts and would like to have another option.

Thank you,


James. The pin quite probably has grooves worn into it, preventing it from coming out. Try using some Vise Grip pliers to turn the pin and, hopefully, move the grooves out of engagement with the parts.

Les Bengtson

Not necessary to remove the pin and pushrod to change the cylinder.
Once the cylinder is off, the close rubber is gone.
Seized pin are common. You need a strong C clamp and a hollow spacer (pipe, socket, etc.) that fits over the head of the pin and rests on the release arm. Put as much pressure as possible on it, then smack the end of the clamp screw with BFH. Trying to hammer the pin out against the arm alone is possible big trouble. Penetrating oil, heat, and patience are your friends.

FR Millmore

Thanks for the info guys... I will keep you updated. Just have to find the time now during the week.


Finally got that thing out!

FR Did you mean I could unbolt the slave cylinder then unscrew it from the pushrod so the clevis pin could stay intact? I ended up not going that route.

What ended up happening with the pin is that there is a ton of pressure on the pin itself and definitely had a half moon grove in it the size of the pushrod.

Im not sure if the heat helped loosen the rust or it was the penetrating oil I used the first time. Basically I ended up using needle nose vice grips to turn the pin half way round and hit it with a mallet. Turning it enabled the grove that was created to line up and let the pin rise up a little bit and get out of the grove its been in and created for so long. Then I had to follow up with a hole punch to drive it out.

Here is my follow up question... When I finally drove the pin out Im not sure if the pushrod was exerting the pressure or the Y piece attached to the clutch itself... Cause when I gave the pin the final drive with the punch it shot up and either the pushrod or Y piece let go of whatever force it had on the pin. Im thinking since the clutch was stuck in the open position this was the Y piece slamming the clutch back down?



P.S. It was hard not to heat and burn the rubber on the Y piece when using map gas... I was thinking of using a piece of tin and getting some tin snips to create a barrier between. The gas line is also close as well so be very careful. Im sure heat definitely helped but rotating the pin is what really did it. I broke 2 C clamps!!! When trying to push the pin up and out... I never liked those c clamps anyway... Lesson is... If it is not moving at all, rotate it and try again... There should be at least some movement, if not try again and again... The least dangerous thing I did was hit it with a mallet... I ended up using a metal one that I could hold in my hand as it had parted ways with its wooden handle.

The push-rod is only a push-fit through the rubber boot into a recess in the slave piston. With the slave unbolted you should simply be able to pull the cylinder off the push-rod. doesn't show the push-rod, but it does show the indentation in the outer end of the piston it simply rests in.

The only way you can have significant force on the push-rod, clevis pin and release arm is if the slave piston has seized or somehow jammed in the cylinder, holding the clutch released. You don't say why you were replacing the slave, so that could well have been the case. It would also explain why the grooved clevis pin could not be removed from the release arm and push-rod. Normally there should only be very light pressure on this pivot from the spring inside the cylinder.
PaulH Solihull

Thanks Paul.

I was replacing the slave as it was the last thing I did not replace. Changed the master clutch cylinder, clutch line, clutch hose... Originally replaced the master cylinder as it has a good amount of sludge... Ended up replacing the clutch line as I sheared off the bottom connection trying to get the clutch hose off. Its been a fun time! So after reading your comment it seems the slave is infact seized or somehow jammed... I will let you know my findings when I get back under the car this weekend.

As Paul says about the pushrod. There should only be light pressure on it at rest, and you should be able to push the slave piston back easily by pushing on the arm.

If you cannot, then the piston is either seized or bottomed. Bottomed means the clutch itself has failed catastrophically. Seized means there has been pressure on the release bearing. If the car has been operated like that, that in itself will cause catastrophic clutch failure. If it is seized from sitting and has not run like that, you might be OK just fixing the slave.

Crappy C clamps are cheap for a reason! Good ones are expensive beyond reason.
Hammering on the arm can easily bend the release fork, or even break the ears of the gearbox front cover inside the flywheel housing.

Sheetmetal shields are good when heating in tight spaces; you do need to be sure you are not deflecting the flame to other critical areas. Several layers of heavy aluminum foil are also good for heat shielding.

FR Millmore

Oh I didnt have enough throw to do anything crazy... Just tapping...

Agreed on those c clamps. I have a monster I bought, couldnt find it though.

Yea I am hoping it is seized from siting. No use for a whlie and before that the clutch worked great.

Can I test the clutch itself by trying to operate it by hand?

I will try and do the same with the slave clutch as well.

The original master clutch had a ton of gunk in it and Im hoping that was the case with the slave as well...

"Can I test the clutch itself by trying to operate it by hand?"
Not with your hand. It takes a bar and suitable fulcrum, and is very difficult to arrange under the car. No point either, since you have to fix the hydraulics in any event, so may as well do that first.

"I will try and do the same with the slave clutch as well."
Leave the slave in place and connected.
Remove the rubber boot. Scrape all the crap out of inside, wet with brake fluid. Then tap the piston back - hopefully it will go back. Clean some more and re-wet. Then use the clutch pedal to push the slave piston out. When it comes out, hold and block the pedal down, which will keep all the fluid from running out.
Otherwise, get a new one.

FR Millmore

Already have a new one. Going to put it in this weekend.



reuse the pushrod and clevis pin? might see if I can source a new pushrod and pin locally. Might just reuse till I can get the parts mailed to me.

Doesn't much matter if it isn't so worn it will break. Beauty of a self adjusting system.
But always pleasing to at least replace the pin.
Use AntiSeize on it.

FR Millmore

AntiSeize it is. Glad I put some on the nut that holds the clutch hose in place to where it attaches to the clutch pipe. That was a pain too!

Should be nice this weekend. Cant wait !

Also put a megajolt system on her and have it all up and running. Have to make the wires all nice and neat but its awesome! Runs sooo much better.

Had a combination of distributor problems and a new fitment of SU HS4 carbs on my 79 B so everything was out of sorts. No solid base to work off of. So now I got solid timing now so I can tune my carbs. Pretty sure the guy I bought them from fitted richer needles to go with the K&N filters. Im just happy she is up and running again, its been a while!

This thread was discussed between 07/05/2012 and 18/05/2012

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