Does a mod using a ’39 clutch & brake pedal work correctly?

Re: Does a mod using a ’39 clutch & brake pedal work correctly?

Ok I know I'm not a rocket scientist but I have stayed at the H Inn. All you guys say I'm wrong but never prove the point. If I'm doing something wrong I dont mind being told that, That is how you learn about anything. If I'm wrong I'll concede and say thanks for taking the time to explain my error. I know this is starting to get like a soap opera but the result will get Roberts car to shift correctly. The following is my ploting of the shift lever action that requires the longer lever to be used not the shorter or a shorter lever. If this is incorrect tell me why.
 

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Re: Does a mod using a ’39 clutch & brake pedal work correctly?

So what they did on the 40 was make the clutch shorter,This makes is eaiser
about 8 to 1,then the 40 shorter to 2 5/8" This fixed the problem with 39 clutch problems.Why take parts from the 40, just bend the arm shorter.
AS I have said because it have a 39 and had the same problem.
I had a 32 arm on mine , 4" plus and that was why mine had problems.
Shorter equals more travel.
If you had a large clock with 12" hands and moved the hands from 11 to 1 oclock,
then you had a pocket watch and moved the hands the same amount ,
witch would you have to move more from 11 to 1.
Shorter more travel.
 
Re: Does a mod using a ’39 clutch & brake pedal work correctly?

I'm sorry, Dick, I can't understand your sketches.

The bottom line is that the clutch release shaft needs to achieve a certain degree of rotation to move the release fork tips far enough to get the required travel on the bearing.

If you don't want to change the pedals, you only have a certain amount of travel available at the pedal end of the push rod. The clutch lever end of the push rod will travel the same distance, it's travel guided by having to follow the arc of the lever.

Science tells us that there is a certain point along the length of that lever that the push rod needs to be attached at to achieve the shaft rotation required.

If you attach the push rod closer to the shaft you will get more rotation, if you attach it further away, you will get less rotation.

If Robert wants to use the pedals he has, without modifying them, and the clutch assembly he has, then to achieve release he needs to keep using a shorter lever until the required travel is achieved.

Ideally both levers should be at 90 degrees to the push rod at mid travel.

This is the most important point. But the setup is virtually factory correct, the chassis used is so similar to a 39 that it should all just bolt together.

I can do some diagrams, but it will take some time and may not be necessary.

Robert, why dont you make up a temporary clutch lever and drill it with a series of holes. find the one that does the trick and modify a genuine ford lever to that length.

That's what I would do if I didn't quite know what I wanted - just mock it up and see.

But the fact remains, there is something wrong with the 10" clutch assembly. It should release with the standard stroke available from a 39 pedal and release lever.

If the lever used is a genuine 39 lever then there is something wrong. If you want to go the route of a special shorter lever to make your clutch work, then that's ok, but it will end up being heavier than it should be.

I've had 40 years in the automotive industry and this sort of stuff is bread and butter to me.

Mart.
 
Re: Does a mod using a ’39 clutch & brake pedal work correctly?

On my 35 the frame had to be bent to clear the pedal and the then the exhaust pipe as well. I also have to have the pedal all the way to the floor to shift into second or first from a stop.
 
Re: Does a mod using a ’39 clutch & brake pedal work correctly?

Mart said:
I'm sorry, Dick, I can't understand your sketches.

The bottom line is that the clutch release shaft needs to achieve a certain degree of rotation to move the release fork tips far enough to get the required travel on the bearing.

If you don't want to change the pedals, you only have a certain amount of travel available at the pedal end of the push rod. The clutch lever end of the push rod will travel the same distance, it's travel guided by having to follow the arc of the lever.

Science tells us that there is a certain point along the length of that lever that the push rod needs to be attached at to achieve the shaft rotation required.

If you attach the push rod closer to the shaft you will get more rotation, if you attach it further away, you will get less rotation.

If Robert wants to use the pedals he has, without modifying them, and the clutch assembly he has, then to achieve release he needs to keep using a shorter lever until the required travel is achieved.

Ideally both levers should be at 90 degrees to the push rod at mid travel.

This is the most important point. But the setup is virtually factory correct, the chassis used is so similar to a 39 that it should all just bolt together.

I can do some diagrams, but it will take some time and may not be necessary.

Robert, why dont you make up a temporary clutch lever and drill it with a series of holes. find the one that does the trick and modify a genuine ford lever to that length.

That's what I would do if I didn't quite know what I wanted - just mock it up and see.

But the fact remains, there is something wrong with the 10" clutch assembly. It should release with the standard stroke available from a 39 pedal and release lever.

If the lever used is a genuine 39 lever then there is something wrong. If you want to go the route of a special shorter lever to make your clutch work, then that's ok, but it will end up being heavier than it should be.

I've had 40 years in the automotive industry and this sort of stuff is bread and butter to me.

Mart.
Click to expand...

Good explanation!
Bill
 
Re: Does a mod using a ’39 clutch & brake pedal work correctly?

Awareness.....a word, or a state of mind, that I have been preaching for years comes into play here. Are we aware that the clutch activation can be great or, rather poor, as in my case, or, even worse, not workable. Have we ever, really considered this in depth when mixing & matching parts? My issue ( not problem, because it is acceptable as-is ) will be solved by modifying one of the many arms I have found in my stash. ( yes, I am a hoarder ) In the attached photos, I have a perfect looking arm with # 01W 7524, and according to the green bible, it states '41 - '48 truck. It even has an elongated surface area that I can drill another hole which can be at 2.450" c/c ( really short ) The existing one is at 2.875" c/c. The only problem with this arm is that the mounting holes are indexed in the wrong location. ( angle ) I also have another one from an unknown application ( black one ) and measures at 3.375 c/c. If mine is a modified and bent to fit, it must have come from a similar # part. This one is indexed correctly, and I shall cut, weld, bend to fit to test. I will be shooting for 2.700” c/c. ( sorry Dick )

junk yard kid……and this is that awareness situation stated above. You have a similar problem, it seems, and I do not believe there are only a few of us here. Installing ’39 pedals in a ’35….well, this is next in line for me also with my ’35 3W project. My eye and ears are wide open once more with your input.

The interesting part about this discussion is not about competing math skills, but to properly identify the proper dimensions, angles, whatever, is needed to have a comfortable operation of our clutches. We have 9”, 10’ and 11” PP…. ( I see occasionally 9.5”…never seen one, nor does the green bible state such an animal ) I guess we will eventually have to have a chart on the throws required to release the disc on each one of these….are they the same or different??
 

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Re: Does a mod using a ’39 clutch & brake pedal work correctly?

I didnt install my pedals but i did put in the 39 box and i put the arm that came with the car on the 39 box. I found it acceptable but wanted it better on a late night a few months ago and found the dent in the frame and a park on the exhaust pipe and heated it and then pushed the clutch down hard. That 1/8 -1/4 inch helped a lot. On a different car i had the pedal threads hitting the floor boards.
 
Re: Does a mod using a ’39 clutch & brake pedal work correctly?

OK - how 'bout this: everyone is right...at some point.

I think what Dick may be trying to illustrate is when pushing that shorter lever with offset pivot points, you can, in some circumstances, get to a theoretical maximum deflection where you're not going to push the short lever any further, the pushrod just sort of goes up and down - think in terms of a connecting rod and how it quits moving the piston, yet the crank continues to turn a few degrees - you can actually increase the piston dwell at TDC by lengthening the rod and keeping all else equal. In the case of two levers, it's almost an over-center condition, or very near it.

I don't know that's what's happening here, and I rather doubt it, but I think that may be Dick's point - if this were the case, lengthening the clutch lever would actually help...to a point. Make no mistake, it's a pretty small window of tolerances that would have to stack up to find yourself here...

I think under most normal circumstances, if you want to achieve more throw, the other guys are correct: longer pedal lever, shorter clutch lever = more clutch fork travel. I also think it will solve this current problem. However, I think there's an issue with the 10" clutch or disk that needs to be ferreted out...
 
Re: Does a mod using a ’39 clutch & brake pedal work correctly?

Flat Ernie...Thank you for your input. I am more than curious on the 10" PP, if this is the issue or not. In the near future, I shall be making tests on the 9, 10, and 11" PP required travel to release... I have all of these here in my stash of parts, as well as quite a few 10" PP and flywheels to accomodtae both the 10 & 11".......for comparison sake.

Time to end this posts, before we get to dizzy.

Thanks all for your participation and future results will be posted by me.

THE END.......Robert
 
Re: Does a mod using a ’39 clutch & brake pedal work correctly?

I just took my first ride in the 32 after the clutch disk replacement. It has all stock levers and other parts. Before, The clutch was chattering. I put in a new disk which is thicker than the old used up one. I also adjusted the clutch PP arms to make sure they were even. I used blocks under the PP and measured up from the flywheel face. I had to lengthen the clutch adjustment which is expected with a thicker disk. The supprise is the clutch must now be pushed in further to disengage. It must be in the operating angle of the PP arms. All the parts are the same except for the disk.
 
Re: Does a mod using a ’39 clutch & brake pedal work correctly?

The new disc probably has more waviness in the metal layer between the friction surfaces, so it gives more during engagement to make it smoother. Consequently the travel to release may be a tad longer as the waviness adds to the travel. The old plate may have less waviness or none at all.

Obviously only theory, a bit of a guess, but one possible reason. There may be others too.

Mart.
 
Re: Does a mod using a ’39 clutch & brake pedal work correctly?

I was looking for some Flathead info and came across this pic,

Ford new they had a problem with the 39 pedal,so the redesign shows what they did.
The pedal clutch lever was made longer by 1/4" and the trans lever was extended to frame and was made shorter. New lever was shorten to 2 5/8".
The adjustment should have 1" free play at pedal and maybe 1" or more off floor.
This must have been plenty as this setup was from 1940thur 1948.
picture.php
 
Re: Does a mod using a ’39 clutch & brake pedal work correctly?

39 pedal linkage worked fine. The reason for 40 change was to clear up room for the column shift linkage.

George/Maine said:
I was looking for some Flathead info and came across this pic,

Ford new they had a problem with the 39 pedal,so the redesign shows what they did.
The pedal clutch lever was made longer by 1/4" and the trans lever was extended to frame and was made shorter. New lever was shorten to 2 5/8".
The adjustment should have 1" free play at pedal and maybe 1" or more off floor.
This must have been plenty as this setup was from 1940thur 1948.
picture.php
Click to expand...
 
Re: Does a mod using a ’39 clutch & brake pedal work correctly?

Looking for some info from an old timer. A friend has a 34 Ford hot rod (sorry) with an unusual master cyl & pedal. His dad built the car in the late 50's so he has no idea where some of the parts came from. The brake master cylinder and pedal bracket are one entire cast unit. the pedal is pivoted in this bracket and has the usual pushrod going into the master cylinder. the top of this cylinder/bracket has 4 studs made into it facing up so it can be bolted to a horizontal bracket between the dash and firewall. He has one for the brakes and one for the hydraulic clutch, mounted right next to each other. We're thinking it might be early GMC truck but there are no numbers on it. Sound familiar to anyone?????
 
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