Need help with Master cylinder selection

[TA219]

I have read high and low and haven’t been able to find anyone with the same set up that I have, so I thought maybe someone could point me in the right direction here.

I am running c5 brakes up front and 79 - 81 Cadillac disk brakes out back. I have had a heck of a time getting this set-up to stop at all.

I finally took the master cylinder off (67 Vettte manual set up) and discovered that it was leaking fluid where the pushrod goes in. Since I am about to replace it anyways, can someone verify if this is the ideal master cylinder for me?

Originally I planned to stay with manual brakes, but now I just don’t care as long as the car stops well. If I go with power brakes I will need a small diameter 7" booster because of limited space.

Can someone help me figure out what would work best in my scenario?

Thanks

[Apogee]

Wayne, a 15/16" to 1" bore would usually be the recommended starting point for a system like yours. It concerns me that you've been having a hard time "getting it to stop at all"...sounds like a setup issue with the rear calipers and/or you need more pressure and/or friction coefficient at the pads. What sort of symptoms were you experiencing?

Something you may want to consider is running a stepped bore, quick take-up MC option. These can be useful when mixing and matching systems front to rear since they behave like two MC's in one. There are a few people here running the mid-80's S10 unit (24mm/31.75mm) in manual applications with C5/C6 brakes with decent results, however it does require that you machine down the pilot register size on the MC body to fit most car applications. I'm not a big fan of the snap-loc lids either.



Tobin
KORE3

[TA219]

Tobin, thanks for the response! The vette m/c is a 1" so I guess I will stick with that style.

My brakes were almost non-existant for the first 3/4 of the pedal travel, and then they would get rock hard for the last 1/4. I have only moved the car in the driveway, and if I pumped the brakes I could get some good stopping force, but never on the 1st pump.

I know that part of my problem was that my e-brake was not adjusted correctly, which I believe that I have corrected now.

I also had the old rubber "jumper" line that connected the brakes from the body to the rear axle that I had never replaced, so I am going to replace that too while I am at it.

If this doesnt work then I am baffled, I know my bleeders are all in the right spots, the pushrod for the pedal is in the upper hole, all of the other lines are new and tight, I am running out of things that could be wrong.

At least I know that I am not using the wrong style of master cylinder, that takes one of the possible root causes out of the equation.