The Stovebolt Site Forums The Parking Lot Big Bolts Need a Mesurement (Deco)

I am working on a master cylinder conversion on my 1940 GMC 3/4 ton. I will be using the brake and clutch pedals from a big bolt, and then use a frame mount 2 chamber MC.

The brake pedal I am using has a rod and clevis attached to it that pulls a frame mounted lever, when the brake pedal is pushed. The frame mounted MC is then actuated by the same lever in a pushing motion.
I am trying to locate on the frame where that lever bracket should be. My truck doesn't have any of the holes in the frame as it was not originally equipped with this setup.
Can somebody give me a measurement from the back vertical edge of the bellhousing crossmember to the first rivot of the frame mounted lever?

Thanks in advance
John

The measurement should be the same for chevy and gmc trucks from 1939-1946.
Thanks
John

bump

I just got the Master cylinder. Some measurements would be really nice so I no where to put it. Please Help if you can.

John

Hi BBSD,

I think readers are slow to give you info because it is probably different across the board especially when you leave the 1/2 ton size, and use different pedals etc. This is a fabrication type deal which means everyone will probably do it a little differently. Mount the pedals, then if you have a rod, there is your measurement. If not, then mount the MS to the frame in a convenient location, within a reasonable distance from the pedal and make, find, buy an adjustable rod. I haven't done this yet on this year of truck, but will be on a 2 ton. I'm not concerned about mounting location. I'll be focused on the rod length when I'm done mounting things up. Just my two cents.

I guess your advise is sound. I was trying to stick close to the stock geometry. Since I am using factory pedals, factory bellhousing, and crossmembers, I figured I would put these things where the factory did. I can guess where they should go, but as my cab is not on my truck at the moment, I will have no way to reference where the pedal should be.

I am asking for a simple measurement, but apparently there is too much snow still on the ground.

Thanks

my 38 1.5 has the same set up it sounds like you are describing. i notice you cut it at 39. do you think 38 would be different?

Probably not, but the crossmember might be different. I'll take the measurement anyway if you are willing to give it to me. The rod that goes from my pedal is about 23 inches from center to center of the holes, or 24 inches overall.

i'll see about the measurements later today

The rod from brake pedal to the lever on my 38 is also approximately 24". distance from back of bell housing to the first rivet appears to be 20 1/2". top of lever bracket is about 3/4" from inner top edge of frame rail

Thank you! That measurement looks pretty good on this end.