51 Buick Roadmaster Double Master Cylinder

Anyone have any info on change to double

I have seen disc brake options on Ebay

& Wilwood brakes but no double option

Skyking227@me.com

617-201-6897

This is what I've gathered from other threads on here, which leads me to conclude that if/when I do this, I'll just take the car to a hot-rod shop and have them do it (at least the frame-mounted parts of it).

1. There's a thread on here somewhere someone changed from single to double master also while making the conversion to disk brakes. They also did NOT use a power booster. Not sure what good that really does, because it's going to be pretty high pedal effort.

2. Someone else commented that the pedal-to-master travel ratio is much different from non-power to power-assisted brakes. So the pedal-to-master connection needs the correct force/travel ratio.

3. I've also seen that the line size is different disk-to-drum, so bolting on front disks would work even better if the front brake lines were all re-made from the correct size line for that type of brake.

4. If maintaining the down-low master location (lower than the wheel cylinders), check valves may also be necessary to keep the fluid at the wheels. I don't understand this because the system is sealed, but maybe rattle/vibration of the caliper &/or pads can drive the piston back if there isn't a check valve to keep a little fluid pressure at the caliper.

5. I've also seen it written that getting a good-sized power booster (bigger than 7") is going to be a trick with the under-the-floor master situation.

6. Somewhere I saw a photo of a remote-mounted power booster in a pre-'56 Buick frame. I'm not sure how this works, but it looked like the master cylinder itself was in the usual position (below/behind the driver's foot), with a rod extending back to a larger booster back under the back seat area. I would think with these systems one would also want to add a vacuum reservoir, such that the brake has one "push" left in it for holding the car on the next engine restart, as well as to keep the brake power assist going when the engine isn't keeping up.

So to do this right, you're in for new lines, new master, power booster, mounting & linkage changes, check valves, vacuum reservoir, lines for the vacuum system, labor... and that's after the $800 or so for the "at the wheels" kit.

So, no, there's not a bolt-in kit, nor is there a "standard" recommended booster/cylinder combination. If this still sounds interesting, I would recommend getting your car to a hot-rod shop and having them take a look. But you can see the packs of parts they sell for the wheel end of the disk brake system is just the entry fee.

This post will now be followed by 10 posts telling you the drums, if adjusted & maintained, are better than any conversion. Much better on the wallet, that's for sure.