Could use some input here.... 56 caddy coupe is missing its original bendix treadle vac. Originals are hard to source, pricy to buy and rebuild, and I hear a general consensus that theyre not the most reliable system to use. Im considering adding a more modern 7" dual master and booster, modding the bracket to accept it and running it with all things stock otherwise. 4 drums. My understanding is that I'll need some sort of pressure release valve to properly apply pressure to the front and rear. Essentially I want it to be cost effective, reliable, and not have to modify things too much (I saw online one guy had to cut into the Radiator mount bracket so itd fit). All the ones I find on ebay are for disc/disc or disc/drum. Do you guys know of one thatd work? Thanks.
I would go for it, you could do with out the booster but its a lot of car. Use a master like on a late 60s full size gm drum brake car. If the front of the firewall is clean you might want to adopt the later swinging pedal as well and move the master assembly up higher.
Outside of this one element, Im planning on the car staying stock. Theres heater core boxes on both sides of the firewall, so I'll be mounting it on the same location.
The pedal ratio on a Treadle-Vac system is incompatible with a conventional booster and master cylinder. You will have a very hard pedal, and ineffective brakes. You will need to change the pedal, too. Luckily there are plenty of universal ones, and yards are full of ones that can be adapted.
Have a look at my post, while not a cattletruck, you will be able to use the same thought process. My Olds is my daily car, not weekend, not 4 days a week, everyday. So it needs to be safe and reliable. I have a scarebird kit and have had no luck getting it to work, so I'm still on drums. The MC and Booster came from Speeday 8" dual diaphragm and the MC 1 1/8th. Pedal is mid 90's camry as much as I hate to admit it. but 'G' body works too. I had a treadle vac and drove the car with that for a few years. I spent big dollars on having it stainless steel sleeved and rebuilt and all. Made no difference it was still crap. I would love discs, but as I said, can't get the kit to work, so stuck with drums until I can sort the 'bolt on' kit out. http://www.jalopyjournal.com/forum/...-brake-and-booster-swap.991789/#post-11171224
Can you school me on this? I dont understand why Id need a different pedal......To me, the rest of the system looks the same as my 50 cadillac -(manual single master cylinder) into regular brake lines and drums.... On the 56 a straight rod comes from the firewall to the master cylinder/booster, couldnt I just adjust the rod to get the right ratio? Edit: Are you referring to those MC's designed for disc/drum and/or disc/disc? I recall reading the pedal feel would be stiff if using that because discs require different fluid pressure than drums. In all honesty, I really dont have any issue with my 1950 cadillac brakes - just stock manual master and 4 drums. I suppose I could go non power if need be but Id rather go closer to what the car had.
I had a 55 Olds years ago. I took the box off the drivers side of the firewall and made a flat 3/16" plate to fit in its place. Then I mounted the brake pedal assembly and master cylinder out of a 68 Chevy pickup(dual master for drum/drum) through that plate. I ran it manual with no booster and it stopped the car just fine. Old faithful by droplord49 posted Sep 26, 2008 at 5:16 AM
Have you checked out any Cadillac forums? The Treadlevac is a well known problem on Caddy and other cars of the fifties. Somebody must have figured out a solution by now.
Right on the first page of my '55 Cadillac build I showed how to build a bracket and new brake pedal and use a 7" booster and Corvette master cylinder...AND put it in the stock location, thru the floor.... http://www.jalopyjournal.com/forum/threads/the-best-1955-cadillac-build.329070/#post-3539178 Scroll down after opening the thread, you'll see it... R-
The difference is where the actuating rod attaches to the pedal. The stock set-up gives roughly a 2:1 pedal ratio. Far to low a ratio for a more modern vac booster set-up. You could move the attachment point higher up on the pedal to get more like a 6:1 pedal ratio, but you also have to raise the master cylinder mounting point on the firewall to keep the actuating rod in alignment.
I assume a 56 has power steering, how about a hydroboost? It would probably work with the pedal ratio, and they're fairly small. Not very HAMB friendly maybe.
I appreciate it, and love your build, but Id like to keep this in the stock location using the factory bracket (with minimal modification).....the 56's are located over the upper control arm.
Compute your pedal ratio. The last two that I computed, albeit not a Cadillac, were about 2-2.2:1. You need a ratio of about 6:1 for good leverage. If your pedal can be tweaked to make this happen, then you can use it.
Gimpyshotrods is correct on the pedals, I just picked up a standard pedal and dash to firewall brace for a friends 55 chevy.For 56 cad you may have to search/or pay , to find a pedal swap. Or find someone to mfg , If thats not up your alley. As to the booster, I would go with hydroboost , I have a dozen cads not exactly light weight.
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