1 Pot Master Cylinder to 2 Pot Master Cylinder Conversion??

[Operation68Travco]

So, even though I have a 68, it looks like the brake system is solidly 67, which of course makes sense, because that's when the chassis was built.\n\nProblem: the one pot master cylinder - not a fan of them!\n\nSecond problem: the 68 heavy truck 2 pot master cylinders (and frankly pretty much every one of them up until 72 and probably beyond) mount on with 2 bolts, as opposed to the 4 bolt mount for the 1 pot. Basically, unless you fabricate something, it's not gonna work.\n\nWhich leads me to another potential "idea". The 71 and up drum brake car master cylinder that went on practically ever car - even Fury, Imperial, and the giants of that era - all have 4 bolt mounts.\n\nSo my question is: the bore on the car Master cylinders is 1 and 1/13. The bore on the original 1 pot MC is 1 and 1/4. The bore on the heavy truck 2 bolt MCs is 1 and 1/8.\n\nCan I install the car MC and expect a good replacement? Or am I asking to much? Or does anyone know of a heavy truck master cylinder with the 4 bolt mount?\n\nThanks!

[Acesneights]

I understand your thought of having a 2 pot master for safety reasons but modifying a braking system could cause legal problems down the road. These things are heavy and if it was ever involved in a fatal accident and modificatons you did to the braking system could make you liable .\nChanging from 1 pot to 2 would also involve a different proportioning valve or addition of one if none is present. I am not familiar with the earlier Travco but my 73 Ford F600 has a single pot and has always worked fine and have had 5 ton on the truck plus the weight of the truck.\nIf you re considering an upgrade a better one would be to find a junk late 73+ 270 and just take the entire system out as it is disc in the front and the disc brake units stop a heck of alot better.\nHope that helps although I know it wasn't exactly what you were looking for.

[Operation68Travco]

Uh, I'm going to say that if I lived my life fearing a lawsuit, there's pretty much no way I would have purchased a Travco. Like, ever. \n\nFor those that are looking for a conversion, I've found that some of the A100 and P300 trucks of that period do offer a 4 bolt mount-on MC, but the bore on the MC is almost a 1/4 inch smaller. The car 4 bolt mount MCs are 1 1/8 tops, which is a lot closer. \n\nThe search continues, but I may just get the OEM 1 pot for the time being.\n\nUPDATE: Interesting information from http://www.mpbrakes.com/master-cylinders-faq\n\nWhat bore size do you need for manual brakes?\nIf you use anything larger than 1" then you will have an extremely hard pedal.The smaller the bore the more pressure that is output to the wheels.\n\nWhy should I eliminate my single piston master?\nSafety. By going to a split system the possibility of a complete brake failure is virtually eliminated.\n\nSo it looks like a power 1" MC would work, although pedal effort would be lessened. Something to get used to, I guess.

[77Travco]

I say go for it and report back what the results are. Could turn out to be useful info for future "older" Travco owners.

[Operation68Travco]

I say go for it and report back what the results are. Could turn out to be useful info for future "older" Travco owners.

\n\nWell, my Travco fix-it trip is over, so I won't get to it until spring. But agreed. The 1/8 difference in the bore is very limited, and if it accounts for less pedal effort, you'll get no argument from me...