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Thread: Recommended clutch slave cylinder pushrod clearance

Discuss the Austin Healey Sprite and the MG Midget. Two different but similar cars sometimes referred to collectively as the Spridget.

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    Question Recommended clutch slave cylinder pushrod clearance

    Hi All,

    I'm reassembling the clutch on my project and getting it ready for the first drive. I already know that my clutch slave cylinder pushrod is far longer than replacements (3.75" from hole center to end); it appears to have an additional section welded to the original length. I believe this is too long (especially with unworn clutch components) because I must move the clutch fork (with great effort, as if it is being operated) in order to even install the clevis pin. With the clevis pin installed, is there a prescribed clearance between the slave cylinder and pushrod? This clearance would measure negative (interference) for me at the moment and I don't think this can be right. Am I thinking correctly that a long pushrod could cause the graphite release bearing to be engaged permanently and prematurely wear? Bentley does not address this and just says, "the pushrod is non-adjustable," but mine has been tampered with. Should I just use the replacement pushrod (2.375" per Moss) and leave it alone?

    (This has nothing to do with the clutch pedal to master cylinder pushrod clearance, totally different subject)

    Thanks!

    Mark
    Mark Matzke
    1962 MG Midget MkI 948
    http://markmatzke.wordpress.com/

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    Jedi Trainee DanLewis's Avatar
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    Re: Recommended clutch slave cylinder pushrod clearance

    Hi Mark,

    Is there a chance that your clutch fork is bent? When I replaced the engine and transmission in my bugeye, I discovered that the clutch pushrod that goes into the slave cylinder had been lengthened. Someone had brazed an extension onto the end of it, making it about 3/4" longer than its original length. When I took the transmission off the rear of the engine, I discovered why - the clutch fork was bent. I bought a new pushrod and managed to straighten the fork using heat and a hammer. Put it all back together and everything is fine.

    Dan

    1959 AH "Bugeye" Sprite: 1275 cc, ribcase, 3.9:1 diff, headers, 40DCOE, 9:1 pistons,
    Accuspark electronic ignition, Schneider 256-64F "street" cam

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    Re: Recommended clutch slave cylinder pushrod clearance

    Quote Originally Posted by DanLewis View Post
    Hi Mark,

    Is there a chance that your clutch fork is bent? When I replaced the engine and transmission in my bugeye, I discovered that the clutch pushrod that goes into the slave cylinder had been lengthened. Someone had brazed an extension onto the end of it, making it about 3/4" longer than its original length. When I took the transmission off the rear of the engine, I discovered why - the clutch fork was bent. I bought a new pushrod and managed to straighten the fork using heat and a hammer. Put it all back together and everything is fine.

    Dan
    A good chance Dan is right, but can't advise you since you don't specify engine or gearbox. There are several factors to the right combination, including which fork you have, which clutch and which release bearing. See my Tech article.

    https://gerardsgarage.com/Garage/Tec...tobearings.htm
    Gerard
    http://gerardsgarage.com/
    1960 Bugeye Vintage Racer #50
    1960 Bugeye (partially restored)
    1960 Morris Minor Pickup
    1964 Morris Minor 4 dr Saloon
    1970 Austin Mini (for sale)
    1946 Austin 10


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    Yoda
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    Re: Recommended clutch slave cylinder pushrod clearance

    Thank's Gerard........very informative. I was not aware of all those combination's.

    Kurt.
    65,66 Midget
    57 Berkeley, MGA
    Working on quality rather than quantity

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    Re: Recommended clutch slave cylinder pushrod clearance

    I really envy you guys talking about these things. I just got back from having my bugeye transported to my mechanic. I entered it in a car show and got a first place about a month ago and on the way home the transmission started acting up and the end result was I was able to get it home and the next time I tried to drive it I was unable to shift it at all, and then the fluid from the master cylinder drained out through the slave cylinder onto the garage floor. I am hoping that it is only the slave cylinder and not the clutch as there will be a big price difference between fixing the two. I have my fingers crossed that it is only the slave cylinder.

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    Yoda
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    Re: Recommended clutch slave cylinder pushrod clearance

    Quote Originally Posted by 59diamond View Post
    I really envy you guys talking about these things. I just got back from having my bugeye transported to my mechanic. I entered it in a car show and got a first place about a month ago and on the way home the transmission started acting up and the end result was I was able to get it home and the next time I tried to drive it I was unable to shift it at all, and then the fluid from the master cylinder drained out through the slave cylinder onto the garage floor. I am hoping that it is only the slave cylinder and not the clutch as there will be a big price difference between fixing the two. I have my fingers crossed that it is only the slave cylinder.
    Bet its a disintegrated carbon throw out bearing. Just went through the same thing a couple of years ago with my BE.
    Have the mechanic make sure that the clutch fork isn't bent, out of line or sloppy on its pivot if it is TO bearing.

    Kurt.
    65,66 Midget
    57 Berkeley, MGA
    Working on quality rather than quantity

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    Re: Recommended clutch slave cylinder pushrod clearance

    My mechanic called me with the dire news. The slave cylinder is shot along with a bent carbon throw out and the clutch fork is also bent and I need a new clutch.He is pulling the motor and transmission today to get at everything. I have had the car since May 2012. It was restored in 2003 by a restorer in Washington for the grandmother of the grandson I bought it from after she died. So I don't know anything about what the restorer did to it. My mechanic is very good and has kept the car in good shape so far.He is doing me a big favor by getting right on the problem. He probably has at least a two year backlog of work to do on so many other British cars. When i got to his shop there were two Morgans, a Triumph, a Bugeye and several other British cars being worked on by him and his assistant. He is the best in San Diego County. He is in such demand that he is reluctant to go to British Car Shows because he gets swarmed with questions. It's like when I play golf. I don't tell anyone anymore that I am a retired CPA for the same reason. I did once when I was playing with a retired undertaker and we were joined by two young guys. I told them they were playing with "DEATH AND TAXES".I will just have to pay the Piper.

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