Clutch release arm crack

D

Dave Mellor NJ

Well-known member
This happened to me a few years ago and i know of about 4 others, You can't release the clutch. I got it off and got a foreign replacement from Brattons it was slightly small. Trying to beat it on it ruined the fork. I got an original,pulled the rear, trans,and bell, drove the shaft out and removed the bad one, reassembled the fork and original arm with pins,put the trans and rear back and swore not to buy any more foreign crap
 

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Dave Mellor NJ said:
This happened to me a few years ago and i know of about 4 others, You can't release the clutch. I got it off and got a foreign replacement from Brattons it was slightly small. Trying to beat it on it ruined the fork. I got an original,pulled the rear, trans,and bell, drove the shaft out and removed the bad one, reassembled the fork and original arm with pins,put the trans and rear back and swore not to buy any more foreign crap
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I had the same problem, cracking the arm. Obviously my feet are too heavy.
But don't blame this on 'foreign crap', this arm was a bad engineering from Henrys men...
 
Dave Mellor NJ said:
This happened to me a few years ago and i know of about 4 others, You can't release the clutch. I got it off and got a foreign replacement from Brattons it was slightly small. Trying to beat it on it ruined the fork. I got an original,pulled the rear, trans,and bell, drove the shaft out and removed the bad one, reassembled the fork and original arm with pins,put the trans and rear back and swore not to buy any more foreign crap
Click to expand...

I think the problem arrised from you “bearing” it on.
 
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I agree with Tom on this. The original design has a smaller pin and when that was increased in diameter the arms started cracking. I carry a spare arm. I wonder if a heavy duty hose clamp or two would prevent the arm from cracking.
 
Besides being of questionable design, after almost 100 years of use, we are seeing more and more cases of this arm failing due to metal fatigue these days. I have replaced three in the last year alone! Old-timers in the hobby can attest that this wasn't a major problem 20-25 years ago and has increased in frequency since then. The new repo arm is much stronger, although the staking pin area will always be the Achilles heel. Too bad that you'll probably have to replace the new arm again in another hundred years. :)
M.
 
If it was a design problem there would have been a service bulletin.
If it was a common problem when the cars were less than 10 years old Pep Boys and other aftermarket parts catalogs would have them advertised.
Yes to have them start failing after 75 years is a design failure— they were made too good.
 
There used to be a billet steel version of the clutch arm available, but I don't see it now. I think I may have one laying around somewhere...
 
This happened to me approx 30 years ago. The replacement had a bigger round part and worked well. It looked like a forging, not a casting. I do not remember where i got it.


Vic
 
There are two versions of the A-7511 clutch release shaft arm being sold currently. One is a replica of the original, while the other uses significantly more material. Both claim to be US-made.

A-7511-B.jpg


3721-600x800.jpg


Tom Endy wrote an article in which he speculates that some instances of broken clutch arms may be due to an erroneous service bulletin that recommended modifying A-7511-B arms to accommodate a larger pin, while the A-7515-B fork would need to be replaced as it could not be safely adapted. He hypothesized that this advice was reversed from what the engineers intended – that the fork be modified and the arm replaced.
 
The second one alexiskai shows is longer than the original to make it easier to disingage the clutch. I have been using those for years, no problen, no fit problem either.

Ford eliminated the woodrof key when they went to the larger pin on both the fork and arm (Service Bulletins page 351).
 
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Y-Blockhead said:
The second one alexiskai shows is longer than the original to make it easier to disingage the clutch.
Click to expand...

The longer arm would also require more force at the pedal end to release the clutch. Which would be worse, more force at the pedal or less force at the clutch?
Ed
 
TomInCologne said:
...but the longer arm makes it easier to crack it... ;-)
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The force applied at the shaft is determined by the resistance from the pressure plate springs. If the shaft did not turn then yes, the force applied would be higher with the longer arm (assuming this same push by the leg), but since the shaft does rotate, no the longer arm would not make the bracket more prone to breakage.
 
JayJay said:
The force applied at the shaft is determined by the resistance from the pressure plate springs. If the shaft did not turn then yes, the force applied would be higher with the longer arm (assuming this same push by the leg), but since the shaft does rotate, no the longer arm would not make the bracket more prone to breakage.
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and then, when the clutch is totally released, your foot works against the stop. with a longer lever. Don't ask me how i know, explaining it will be embarrassing for me.


Edit: only true if the 'stop' is within the clutch and not within the pedal mechanism...
 
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