Got a box full of marked 57 to 64 f-100 clutch & brake master cylinders at a swap meet both look exactly the same out side with out taking them apart whats the difference between them my local parts house books say obsolete.

'57 to '60 are different from '61 - '64. '57 - '60 use 4 bolt mounting to the firewall. '61 - '64 use 2 bolt mounting to the firewall. In '61 - '64, only heavy duty trucks would have had a hydraulic clutch from the factory so the indication of F100 is incorrect in that respect although the master cylinder and hydraulic clutch pedal from the larger truck does simply bolt on.
If both look exactly the same, then they are not '57 - '64. They are either '57 - '60 or '61 - '64.

I own and have installed what is suppose to be a NOS clutch master cylinder which fits the '61-'64 firewall and it has a 1 1/8" bore whereas the brake master cylinder, which is virtually identical in appearance, has a 1" bore. I have no info that confirms the bore diameter and one example, NOS or not is hardly sufficient for proof. However, the ratio of clutch pedal movement to clutch fork movement is closest to that of the mechanical linkage with the 1 1/8" bore which offers support that the 1 1/8" bore is correct.

On a brake master cylinder, the brake switch goes where the bleeder screw is on the clutch cylinder. I haven't checked, but if the brake cylinder is a pipe thread drilled all the way through and does not have the seat for the bleeder screw, that may be a way to distinguish them. I do have several brake cylinders I can check.

Pictures, for reference. The same '61 - '64 master cylinder in each pic, as delivered in the first pic, painted and with a metal cap in the second. The plastic cap is too tall to work:




Lawrenceville, GA

The brake cylinder will have a residual valve in the forward end of the bore, the clutch does not.

John - "The Hoosier Hurricane"

FYI, the single cylinders are not to popular price wise as brake cylinders. Duel is safer and outperforms. only for the purist or no-brainer swap out. Still a good find though if you purchased at a decent price. I think Dennis Carpenter sell them at about 65, 70 bucks!

       A  L  A  N   F  R  A  K  E  S   ~  Tulsa, OK    

A rather common way that the dual master cylinders are installed, which includes the way mine is currently installed, is no more safe than a single master cylinder. You must have a pressure differential valve installed as well. These are usually in combo valves. Without this, the faulty circuit is not cut off, and the pedal goes to the floor just as easily. I know because I've been there, fortunately in my driveway, after a flare cracked and allowed the fluid to drain over night. It surprised me because I ,too thought it was suppose to be safer. Then I read more about it.
The dual setup as a whole is safer. The dual master cylinder by itself does nothing for safety.


Lawrenceville, GA

OK more info here they are 4 bolt mount one is actually a Wagner and has the 1 1/16 makings these are cast in to the cylinder its self the others are plain with some numbers but no name or bore size markings one also has a brass splitter block with the brake switch on the end the others have a small brass fitting that just comes straight out the end. Thanks for all the info guys now I know what I got for 10 bucks

Charlie M: That info on dual master cylinders is very interesting! I wonder how many retro fits of dual master cylinders are out there, that are effectively a waste of time & money?..

Paul

I don't know. I notice a lot of the aftermarket brake companies don't offer a differential valve but they also do not advertise a sort of redundant safety feature with the dual cylinder, either. I also assume that they do not have the same requirement as the auto makers to make the product as safe as possible. And in many cases, the people using Baer, or Wilwood, etc, are probably more aware and perform maintenance like they should.

What I know now is that my brake system is far from ideal and I plan to revisit that reasonably soon.
With proper installation and quality components, a failure is not very likely. Mine resulted from a poor flare, as a result of using a cheap flare tool. When I do things again, I'm forking out the dough for a good flare tool. No more of those $15 parts store specials - I threw mine away.

PS. I just discovered that Wilwood do have a combo valve with a non adjustable proportioning valve built in.

Slick,
I think 1 1/16 is correct for the '57-'60 clutch master cylinders. The one with a splitter and switch is probably for the brakes. If they are in decent shape, $10 is good. Even if not, it's probably still less than the core charge for a rebuild.


Lawrenceville, GA

Charlie:

As a reminder to anyone fabricating brake lines, the flares MUST be double flares. Takes a special double flaring kit. Mine came from MAC tools many years ago. The double flare all but eliminates cracked flares. Steel fuel lines should also be double flared for safety. I also find that the current black colored steel lines are more difficult to get a good flare.

John - "The Hoosier Hurricane"