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Old 02-14-2021, 04:21 PM   #1
JayJay
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Default Clutch pedal question

I noticed that on my new (to me) 30 Town Sedan that there was excessive clutch pedal play - around 4", and the clutch grabbed almost at the floor - too low. So I went underneath the car to adjust it, and got poking around and in the end decided to remove and clean the adjusting link and the cross-pin that goes in the clutch pedal. The pin was a little more difficult to get out than I thought it should be, and lo and behold, once it was out I figured out why. It had worn so that there were wear shoulders where there shouldn't a oughta be. See pic.

That got me thinking about the condition of the clutch pedal, specifically the arms that the cross-pin fits. Well, the hole is quite elongated so it's gonna have to be repaired.

My thoughts on repair strategy, and I'd appreciate feedback, are:
  • Jig the pedal in the mill (maybe after replacing and reaming the main bushing, it's got play there too) and overbore the hole to concentric.
  • Braze or weld in material to both ears of the clutch pedal.
  • Rebore to 5/8". Make new cross-pin and install.
Is this a common problem, and the right route to a repair?

In the interim (until I do a major tear-down) I'm thinking I just put everything back together in the configuration it was when I took it apart, at least things have "worn in" to a usable configuration. Alternatively I could turn the cross-pin upside down, but I'm afraid that might make the load on the two ears of the clutch pedal asymmetric and break something.

Thoughts? Thanks.

JayJay
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File Type: jpg IMG_2680.jpg (37.6 KB, 71 views)
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Old 02-14-2021, 04:50 PM   #2
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Default Re: Clutch pedal question

For know I would just put everything back and if you can adjust it for about 1" of play.

While you have the pedals out, if they are not installed I would install a zerk in the bottom clutch and brake pedals.

I am not sure the best way for the repair.
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Old 02-14-2021, 05:20 PM   #3
The Master Cylinder
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Default Re: Clutch pedal question

The trunion nut and most of those parts are available from the vendors.
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Old 02-14-2021, 06:38 PM   #4
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Default Re: Clutch pedal question

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Originally Posted by The Master Cylinder View Post
The trunion nut and most of those parts are available from the vendors.
Master - thanks for the input. I know the nut/pin is available from the vendors, that's not a real issue. I can either buy or make a new one. The issue is the "horns" on the pedal assembly that the pin rides in. They should have circular openings (I'm guessing nominal 5/8"/0.625" because the existing pin measures 0.621", which would give a 0.004" slip fit - appropriate for that application). The openings are quite elongated in the direction of the pull, undoubtedly due to the same wear that is showing on the pin. The elongation needs to be taken out of the openings.

I suppose I could ream to whatever opening will work and make a larger pin to fit, I'll think about that. The biggest deal is the setup in the mill, after that it's simple.

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Old 02-14-2021, 06:56 PM   #5
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Default Re: Clutch pedal question

Can you bore, bush, and ream back to 5/8?
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Old 02-14-2021, 07:32 PM   #6
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Quote:
Originally Posted by nkaminar View Post
Can you bore, bush, and ream back to 5/8?
That's the general approach I was thinking of. Rather than to use a bushing I was thinking of brazing or welding in filler steel to get the web thickness back up. I'll have to take a look at how elongated the holes actually are, and how far out I have to bore.

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Old 02-14-2021, 11:23 PM   #7
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Default Re: Clutch pedal question

I have seen trunions worn worse than this and still function.

Turn the trunion around so the pedal rides on the un-worn side, grease it up real good and put it back together. It will last another 90 years. The wear in the pedal probably will not hurt anything.

If you every have the pedals out of the car, you may want to do something about it at that time.

My opinion,

Chris W.

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Old 02-17-2021, 01:51 PM   #8
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Default Re: Clutch pedal question

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Originally Posted by CWPASADENA View Post
I have seen trunions worn worse than this and still function.

Turn the trunion around so the pedal rides on the un-worn side, grease it up real good and put it back together. It will last another 90 years. The wear in the pedal probably will not hurt anything.

If you every have the pedals out of the car, you may want to do something about it at that time.

My opinion,

Chris W.
Chris, thanks. I reinstalled as you suggested (which aligned with my original thoughts) and it's working fine. This will do for now. And I'll deal with the pedal when I pull the engine for rebuild, both it and the brake pedal are sloppy on the pedal shaft so I'll need to renew those bushings too. Want to leave this right for the great-grandkids in 90 years .

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Old 02-17-2021, 03:00 PM   #9
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Default Re: Clutch pedal question

Quote:
Originally Posted by JayJay View Post
That got me thinking about the condition of the clutch pedal, specifically the arms that the cross-pin fits. Well, the hole is quite elongated so it's gonna have to be repaired.

My thoughts on repair strategy, and I'd appreciate feedback, are:
  • Jig the pedal in the mill (maybe after replacing and reaming the main bushing, it's got play there too) and overbore the hole to concentric.
  • Braze or weld in material to both ears of the clutch pedal.
  • Rebore to 5/8". Make new cross-pin and install.
Is this a common problem, and the right route to a repair?
I have encountered this enough where I obtained the A-7520 Clutch Pedal Assembly and built a couple of jigs to assist in restoring a pedal assembly. I also copied Will Cronkrite's idea of using the lathe to machine the bores instead of a Bridgeport. I will tell you they are a very complicated piece to restore properly with most used Clutch Pedals out of specs. To begin with, most pedals are bent which requires a jig to straighten them to.

As for some measurements to help you restore your shaft, the bore size of the pedal where the A-7508-B bushings locate should be reamed to 0.940". The bushings are to be "line burnished" (i.e.: honed, -not reamed) to 0.8760" - 0.8775". The Trunnion bores are located at 1.1250" from the ℄ of the Pedal Shaft bore to the ℄ of the Trunnion pin bores, and the hole is centered 90° perpendicular from the ℄ of the Pedal Shaft Bushings to the forward face of the Pedal Head. The Trunnion holes are to be reamed at 0.6240" - 0.6255".

Additionally there is the limiting stops which are usually worn that will need to be rebuilt (welded and machined) and they index off of the A-7507 Pedal Shaft Collar. As you probably can tell, the Trunnion bores locate from a straight(ened) A-7519-B Pedal Shank, -so to restore the pedal assembly properly, you really need to straighten the shank beforehand. Then the fixture I made uses the tool post to set the height off of the Pedal Shaft, and the limiting stops set the rotational height of the Trunnion Bores.

.
.
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File Type: jpg TrunionGrindingFixture.jpg (33.1 KB, 47 views)
File Type: jpg A-7520 Clutch Pedal 01.jpg (26.0 KB, 46 views)
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Old 02-17-2021, 03:14 PM   #10
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Default Re: Clutch pedal question

Quote:
Originally Posted by BRENT in 10-uh-C View Post
I have encountered this enough where I obtained the A-7520 Clutch Pedal Assembly and built a couple of jigs to assist in restoring a pedal assembly. I also copied Will Cronkrite's idea of using the lathe to machine the bores instead of a Bridgeport. I will tell you they are a very complicated piece to restore properly with most used Clutch Pedals out of specs. To begin with, most pedals are bent which requires a jig to straighten them to.

As for some measurements to help you restore your shaft, the bore size of the pedal where the A-7508-B bushings locate should be reamed to 0.940". The bushings are to be "line burnished" (i.e.: honed, -not reamed) to 0.8760" - 0.8775". The Trunnion bores are located at 1.1250" from the ℄ of the Pedal Shaft bore to the ℄ of the Trunnion pin bores, and the hole is centered 90° perpendicular from the ℄ of the Pedal Shaft Bushings to the forward face of the Pedal Head. The Trunnion holes are to be reamed at 0.6240" - 0.6255".

Additionally there is the limiting stops which are usually worn that will need to be rebuilt (welded and machined) and they index off of the A-7507 Pedal Shaft Collar. As you probably can tell, the Trunnion bores locate from a straight(ened) A-7519-B Pedal Shank, -so to restore the pedal assembly properly, you really need to straighten the shank beforehand. Then the fixture I made uses the tool post to set the height off of the Pedal Shaft, and the limiting stops set the rotational height of the Trunnion Bores.
.
Wow, thanks, Brent. I'll get a look at the print. I think I can do this with some setup, I may need to make a simple fixture or two but they will be one-off, not production like you need to do it repeatedly. Very helpful analysis.


Of course, once I think about it I might just say to hell with it and send the clutch and brake pedals to you!


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Old 02-17-2021, 04:27 PM   #11
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Default Re: Clutch pedal question

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Wow, thanks, Brent. I'll get a look at the print. I think I can do this with some setup, I may need to make a simple fixture or two but they will be one-off, not production like you need to do it repeatedly. Very helpful analysis.
You will be fine. I guess it all boils down to how 'good' do you want it to be. My typical customer is looking for this level of restoration. Most hobbyists are not that detailed, ...especially when they realize the the amount of time (work) that is involved to restore a component to factory specifications.
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