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

[Robert Dip]

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

The reason being is that a lot of guys ( gals are guys too ) use the '39 pedal set-up when updating the '35 - '38 brakes to hydraulics. I recently changed the clutch on my ’39 from a stock 9” to a 10”, which also includes using the flywheel from a ’48. In the adjustments, I now have almost no pedal play, and when shifting gears, I need to have the pedal down completely to the floor to prevent gear grinding. I measured the arm on the pedal, and it is short at 1 3/8" arc....and came to the conclusion that this is the one that needs to be increased to at least 1 3/4". The stock ’39 arm on the trans case is also shorter than most, so I would not touch this one. I am also presently doing this conversation on my '35 using the ‘original ’39 pedals. The '48 uses the 10" clutch, and that, to me, has always been the one to use. The question is…does the 10” PP need more travel than the 9” to release? The PP I use is the conventional 3 adjustable finger type. Thanks...Robert

 

[Mart]

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

In my experience, no. I have run my roadster (30A on 32 rails) with both 9" and 10" clutches and the clutch pedal operation is similar in both cases. If you are using a lot of travel to release your clutch (regardless of size) then you either have a mis-match in lever lengths, or there is a reason it is not releasing (warped disc or something)
Do you have a 39 lever on the gearbox?

I don't know the relative lengths, but if the 39 trans lever is shorter than a 35 and you're using a 35 (for example) then the pedal travel will be long (and light)

Mart.

 

[Barn Junk]

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

Here are some "approx" lever arm lengths (distance pivot point from shaft center):
1932 -- 4 3/4 inches
1933-34 -- 4 inches
1935-38 -- 3 !/4 inches
1939 -- 3 1/2 inches

Of course the pivot position varies also from left to right.

 

[George/Maine]

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

The 39 pedal has a very short throw making the pedal longer is no good.
The trans arm on 39 case is shorter.3 1/2" as above.
Lokking from side when making contact with presure plate my guess you lose the same contact point.Most throw would be 1 oclock to 11 oclock.
Make all adjustment with floor in place if removed.

 

[Robert Dip]

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

Mart...on the case of the '39, I used the same original '39 lever on the trans...in other words, no linkage was changed. The 10" disc is brand new and not warped.

George/Maine....the idea is not to make the pedal longer, but to modify the lower lever which only 1 3/8" arc. Increasing this would solve all issues...this would also increase the pedal pressure, but it's not that stiff to begin with. just curious what others have actually experienced.

Thanks guys...Robert

 

[George/Maine]

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

If it worked good before,you changed the point of contact.
Say the pedal half way down,the fork should be 12 oclock.
You may need to changed pin location on lever.
If you made the shaft end longer would it hit the floor.
I had that problem on my 39 car,found out i had a 32 lever.Grind gears

 

[Pete]

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

I have always used the 9 inch clutch.
Smaller in diameter so less weight....easier to balance....less pedal pressure...engine spools up faster...easier shifting...can be made to handle 400 hp.

 

[DICK SPADARO]

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

The throw out lever on the transmission must be a 39 lever to work with the 39 pedals. You did not indicate what car this conversion is being done on so the pedal to trans rod length makes a big difference. If you are relocating the pedals, the stock rod may not be the correct length. Further explain your conversion to accurately get a solution to your issue.

 

[Robert Dip]

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

Dick S....As written in the initial wording, I changed from a 9" to a 10" in my '39 Coupe. Used the same trans clutch arm, and naturally, have not touched the clutch pedal, just re-adjusted the existing rod. The reason I also mention this is when one converts to hydraulics on '35 to '38 cars, does this short arc on the popular '39 pedals affect other setup, since it did affect mine, using all of the existing components. Hope I was clear on what I wrote.

Pete...400hp on a 9" clutch.....not in a million years in my books....just calculate the surface area on the disc and the pressure needed to handle that much power....must be close to the 'Theory of Relativity'.

 

[Bassman/NZ]

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

Uh.... dont doubt anything that Pete has to say.... he's been doing it all his life and has more knowledge than 20 of us mortals combined.

 

[Pete]

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

Dick S....As written in the initial wording, I changed from a 9" to a 10" in my '39 Coupe. Used the same trans clutch arm, and naturally, have not touched the clutch pedal, just re-adjusted the existing rod. The reason I also mention this is when one converts to hydraulics on '35 to '38 cars, does this short arc on the popular '39 pedals affect other setup, since it did affect mine, using all of the existing components. Hope I was clear on what I wrote.

Pete...400hp on a 9" clutch.....not in a million years in my books....just calculate the surface area on the disc and the pressure needed to handle that much power....must be close to the 'Theory of Relativity'.

You better go back to engineering school. You have been reading the wrong comic books.
I ran a 345 ci blown Olds at Bonneville with a 9 inch clutch. That engine made 430 on the dyno. I had several 315 ci and 324 ci flatheads in the 50's and 60's that made over 400 hp on 100% nitro and picric acid.
All had 9 inch clutches.....Granted they were not stock but they were single plate.

 

[DICK SPADARO]

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

Robert, I guess your question first started about 39 pedal conversions in 35-38 chassis so I assumed that you were doing a conversion with 39 pedal not having a 39 car with the correct pedal assembly already. Now you say its on your 39 then you revert to saying you are doing this conversion on a 35. Any way if you are having clutch adjustment difficulties with the stock parts in your 39 there is an issue.

Lets start over I'll be dense so which car is giving you trouble the 39 or the 35? If the 39 is giving you an issue with the release on the clutch with the stock parts something is installed or adjusted incorrectly. The pedal free play should be adjusted with the floorboard installed or a stop in place to replicated the floorboard position with the clutch pedal.

To adjust the pedal you should disconnect the pedal push rod from the clutch throw lever. Now rotate the clutch throw lever forward so you can feel the throw out bearing contact the pressure plate. With the bearing contacting the pressure plate and the clutch pedal in the up position, the pedal rod should be adjusted so the rod end aligns with the clevis pin hole and then turned back 2-3 complete revolutions to get a freeplay spacing. Your clutch should be full disengaged about 1 1/2" off the floor. If the clutch is fully disengaged at that distance and the input shaft still is driven by the clutch then there are additional issues. What do you have for distances?

 

[russcc]

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

Doubt the ability of 9"clutch to handle anything, read "Flathead Introduction" on this site. You will come away convinced that Pete is dead on. No need to go to 10". Not sure about the leverage, but if something changed, that likely is the problem, if worked before. Unless we are using a Chinese clutch versus a Fort Wayne rebuilt Ford clutch. Than all bets are off.

 

[Robert Dip]

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

Pete....I've been at it for 50 years....been there done that too....but i'm not a Bonneville guy just going in a straight line, cause that's another story on using a clutch. In drag racing, with even as low as a E stock with 300 horses, a 10" racing clutch with 3,800 lbs pressure, it was the only set up that let me run without blowing the clutch due to slippage and overheating....and making holy messes out of stock alum bellhousings...went immediately to NHRA certified scattershields before loosing my toes. ( before going onto C/MP and Alterds. Not only am I an engineer, but real life experiences does not place me in your ballpark on using clutches. I guess Ford engineers were also out to lunch when they decided to go to the 10" clutch on the '41 to '48 models. Anyway, we could debate this for many years to come, but that is not the issue. The question still remains is that why is the exact same setup giving me this situation that was not there with the 9". There is always a simple explanation somewhere, just trying to identify it.
The PP i am using is a Ford unit that ran in a '48 very well. The disc is new and no Chinese junk is ever used by me...goes against my principles.....but who knows, the PP could be a potential problem, however doubtful. Today, I sat down and 'designed' a modification piece that can be added to the original '39 lever, increasing it from 1 3/8" to 2 1/8" to give me that extra throw.

Dick S....Yes, the issue is only with the '39 and using all of the same hardware. The '35 is a work in progress, and not an issue today. My question is simply put in this manner...I do not have enough throw now having installed the 10" clutch. I did not have a chance to measure the different PP arms to see if the 9" and the 10" are the same. Maybe it does take more throw on the 10" and making the geometry different. I am sure there are lots of guys using the '39 pedals with the 10" PP, so it would be nice to get some reference feedback here.
Presently, I drive the '39 as is without a big concern, but, it is still not the way it should be....and that's what we are here for....to uncover this little mystery on my end.
Pete...your comments are also welcomed.......Robert

 

[George/Maine]

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

I had a 10" clutch in my 39 with a 51 engine 8ba,PP mercury 1949,and with the 39 pedal stock and 39 lever worked ok.
My guess the flywheel maybe thicker, or disk,PP
When the lever makes contact at PP,the lever on trans should be to back say 1 oclock pedal all way down say 11 oclock.
Those trans are you looks not raceing.

 

[Robert Dip]

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

George/Maine....thanks for the input. It would not make a difference on the flywheel thickness or throw-out bearing, that's what the adjustment rod does. I used the 10" wide disc. ( probably a HD police or ambulance unit that was originally commented on by a F Barner ) as it uses the total surface of the PP, as compared to the standard size. I also miked it to check the thickness, and it compared to within .015" of other brand new discs. Photo shows the difference of the wider disc as compared to the standard one. And yes, modifying the pedal clutch lever are to a longer throw will bring it very close to the floorboard, but manageable. I wanted a more durable clutch, especially with the 25T L-Z gears, as a 'get going' from a dead stop requires a little more 'clutch work'. It's all a matter of getting use to it...works out fine. Robert

 

[DICK SPADARO]

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

Robert, Just a question did you remove the throw out lever on the clutch shaft or replace it at any time? If you did, did you re install it with the correct orientation? The shaft pin hole is indexed to the clutch rod hole and if installed backwards changes the angle of the clutch throw arm relationship to the pedal arm.

 

[Robert Dip]

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

Dick S.....as seen in the photo ( hope it's clear enough ) the clutch arm was placed back in the exact same position as when I removed it to re-build the transmission. It is also in the correct 1 o'clock position. Curious situation, is it not ? Robert

 

[TomT/Williamsburg]

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

OK - I'm no guru but I will weigh in here just by my experience using a 39 pedal setup with a T5 adapter but I had the same issue(s). Here's what I did:

1 - I got longer adjustable arms from the clutch pedal to the 39 clutch arm on the ******
2 - readjusted things with the new items and still had issues although it was better.
3 - the piece you pictured, Robert Dip: I actually modified it and cocked it further toeards teh back of the car, making for a longer throw and was then able to properly adjust the arm to get good clutch pedal throw. We did this by welding a piece into the slot where the adjusting arm would reside. Since at rest it's already slight pointing towards the back, this worked out very well.

Now, this is a non-stock solution for a non-stock setup but perhaps something here will trigger something and get 'er done for you.

I've posted the only picture I have for my setup and it really does not show too much but I add it for reference ....

Good luck ....

 

[George/Maine]

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

Tom thats one way,mine had a 32 lever over 4" on trans.I shorten mine to about 39 lenght.Just think 39 is a one year lever and only so many to go around.
With a new cutch there could be some drag till worn in,also splines want to be clean and not binding.When I had my problem i was going to make pedal longer but it would hit my exhaust pipe.