4 wheel disc brakes master cylinder......

[jimmy18thing]

Just put a rear disc conversion on my 73 and was thinking I should replace my master cylinder... What have you found to be useful in a 4 wheel disc situation, What type of cylinder have other people used... other than a hydro boost setup (I have spent too much money right now or I would). My bronco like I said is a 73 but has a 76 front axle with disc, rear setup is BC broncos disc and it has a Vac assist, which I believe is the stock due to when installed they smashed the wheel fender in to make room. Any help and suggestions would be greatly appreciated

 

[Scrapper_MV]

This is a source of much debate.

I recently replaced my M/C with a stock original 1973 manual. It works OK with the four wheel discs, but I will convert to a hydroboost when I have the funds.

 

[tasker]

same here, have a manual stock with my 4 wheel discs...

 

[rtreads]

I just bought a hydroboost from a 95', I think, Mustang GT. It came with a MC. Since that car had disc/disc I think I should be ok because I have all discs. I hope to get it on this weekend and I can report back as to how well it works!

 

[mkaenel]

I had a brake booster set up on 4 wheel disk and I swapped the brake booster out for Hydro. Day and night difference. It stops like a modern car.

 

[tasker]

you win it on ebay? i wsa bidding on one about a monthy ago

 

[gravy]

I have explorer rear disk and disk in the front. I run 76/77 vauum booster and master cylinder 1 1/8 bore. It stops perfect with no proportioning valve. Check JBG for the master

 

[Mherriford]

I run disks on both ends and modded a early-mid 80's corvette disk/disk MC to fit my vacuum booster, just had to widen the mounting holes a little.Works great cheap too, only runs like 25-30 bucks

 

[fordtrucks4ever]

A master cylinder just displaces fluid. Larger bore yields more volume with less travel and harder pedal. Smaller bore pushes less fluid requires more travel, but less resistance on pedal. Some master cylinders have little rubber residule check valves underneath the seat where line fits in. Usually an 8 lb pressure valve is used for drum applications. Some disk applications may use a 2 lb valve. Than can be added or removed easily for specific purposes. Difference in drum and disk master cylinders is fluid capacity. Older cast iron models would hold more fluid for disk. Early drum/drum masters mostly had equal partitions. Later models carried more for the fronts. Many newer masters with a common reservoir have less capacity than older drum models. Your main reasons for choosing a master cylinder is bolt pattern, line location and bore size to give best pedal feel/stopping power without excessive travel. Power brake applications will usually have a larger bore than the same manuals. Pivot point on power brake pedal is usually located farther away than on manuals. This is what might make a power brake conversion overly sensitive if bore size or location of pivot point on pedal is not taken into account when changes are made. On models with master cylinders mounted on angle brackets using bellcranks, location of pushrod and pedal attaching points from pivot may be different. This is the adjustment for getting adequate stopping power without excessive pedal pressure. Larger master cylinder bores produce more volume with harder pedal while larger wheel cylinders or caliper pistons give more stopping power with less pedal effort.

 

[TBS-POPS]

If yours has been converted to PB already as you explained, then it already has a M/C capible of operating rear discs. Usually a 1" or 1 1/8" bore M/C is supplied with those. run it!!

P.S. If you do your homework, you can do hydroboost for under $200...

 

[chuck]

A master cylinder just displaces fluid. Larger bore yields more volume with less travel and harder pedal. Smaller bore pushes less fluid requires more travel, but less resistance on pedal. Some master cylinders have little rubber residule check valves underneath the seat where line fits in. Usually an 8 lb pressure valve is used for drum applications. Some disk applications may use a 2 lb valve. Than can be added or removed easily for specific purposes. Difference in drum and disk master cylinders is fluid capacity. Older cast iron models would hold more fluid for disk. Early drum/drum masters mostly had equal partitions. Later models carried more for the fronts. Many newer masters with a common reservoir have less capacity than older drum models. Your main reasons for choosing a master cylinder is bolt pattern, line location and bore size to give best pedal feel/stopping power without excessive travel. Power brake applications will usually have a larger bore than the same manuals. Pivot point on power brake pedal is usually located farther away than on manuals. This is what might make a power brake conversion overly sensitive if bore size or location of pivot point on pedal is not taken into account when changes are made. On models with master cylinders mounted on angle brackets using bellcranks, location of pushrod and pedal attaching points from pivot may be different. This is the adjustment for getting adequate stopping power without excessive pedal pressure. Larger master cylinder bores produce more volume with harder pedal while larger wheel cylinders or caliper pistons give more stopping power with less pedal effort.

Because I agree with all you have typed here when I was looking for a M/C for my P/B kit I went with the 79 Lic 4 wheel disc bk M/C which is a 1 1/8" bore M/C that fits the ford booster and the brake lines on the correct side and no res. valves.