Master cylinder selection help with & without Hydroboost, TOFIC?

[bosshoff]

I've got a 73 with 4 wheel drums, non-vacuum assisted. I have gathered all of the parts to do a Chevy disc conversion for the front, and am working on gathering the Cadillac/B.C. Broncos conversion parts for the rear. Due to time and reality not cooperating, I intend to have a local shop do the drum to disk swaps. My situation is this. After the 4-wheel discs are in place, I intend to do an Astro Hydroboost conversion. As you know there can be a lot of trial and error with this, so I intend to tackle it myself. I intend to use a Vette Master Cylinder to go along with my Saginaw pump. Should I have the 4-wheel disk Vette MC installed in place of my stock MC at the same time as the 4-Wheel disk conversion? I am thinking I should, but I don't understand if it will fit without modifications. Is the Vette MC compatible with the stock Bronco MC, i.e. they have the same "throw"? Will the Vette MC bolt up without any problems? Thanks.

 

[bosshoff]

Two days and not one reply?

 

[Kenny]

I don't think you can use the Vette M/C in place of the stock EB manual M/C.

If you look at the back of the stock Bronco MC where the brake pedal rod connects, you'll see a hole that is somewhere between 1 - 2 inches deep (can't remember exact depth). In comparison, the Vette MC has a small hole/indentation that is maybe 1/8 inch deep. Not only is the EB rod too long for the Vette M/C, but you need a deeper hole (like the Bronco MC) to hold the rod in place. Imagine if that rod fell out of that 1/8 hole/indentation while driving......no brakes.

 

[BG's 68 Bronco]

The Vette bolt spacing is slightly different than the EB's stock one. You plan on putting the vette MC on before installing HBoost, but you will have 4 wheel discs already installed, correct? I can't remember if the port sizes between the two MC's are the same size or if they are on the same side. Two things to look into. The other issue with running the vette MC is I don't know how it will feel without some sort of power assist. It will work but it might be a lot firmer pedal than the EB MC, but it will be temporary. Once you have the Astro booster installed the Vette MC will bolt up no problem.

Also with the Vette MC the front reservoir is for the front brakes. It is slightly larger than the rear res.

All in all it is a relatively simple upgrade. Good luck!

 

[Madgyver]

Seems like you want to do your brake system in phases. I say system because they all work together as one.
I'd say get everything that you need and do it all one time.. If you can't do it that way then this is the order I'd recommend doing it in.
Do the astro hydroboost conversion/vette MC first, and then the front discs swap and then the caddy rear discs....

 

[Kenny]

I think Madgyer is on to something, but if you do it in stages. I'd probably do the front discs first, then hydroboost, then rears discs.

There's a pretty strong consensus that hydro doesn't really make your drum brakes work better.....just easier (less pedal effort). More importantly, if you have the random left or right drum brake pull at panic stops, it could be more pronounced with hydroboost.

 

[weasel]

I have disc front, drum rear with astro hydro astro M/C: the bronco brakes so much better then the vacuum booster setup I had. It does pull to the left a little.

I've read that others preferred a Lincoln M/C for disc to disc with hydro. Not sure on the difference between the vett M/C and the Lincoln M/C.

 

[Broncobowsher]

My thoughts. Do the work in zones, complete one zone before going to the next.

The front disk brakes will work with the stock master cylinder. Maybe not perfect, but it has been done many times.

Going through the effort to mount the corvette master cylinder just to remove it and install the hydroboost is a waste of time. Just do everything involving the master cylinder in one shot. Otherwise you will find yourself having to replumb stuff you just did. I don't even know if the Bronco pushrod is compatable with the Vette either, so there may be another issue you will have to deal with, just to take out and toss when you get around to the hydro.

My phases, if I were doing the above.
Front disk. Added capacity, take care of the darting that would only get worse with...
Hydro. Now you don't need superman legs to stop.
Rear disk, if I have time and money left over. I still never got to this, not sure if I ever will. At this point I just want a working park brake.

 

[TOFIC]

Lots of opinions here, heres mine.
You did not say if you had PS, i assume you do.
1. Saginaw dual return PS pump and get it working on the Bronco. get this one out of the way quickly and shut the ford pump whine up.
2. Hydroboost install next, lots of opinions which one, I like the Lincoln one, get it working with the drum brake system. Guys are going to disagree with me on this, pointing at the HB and drums. I say do it and get HB working.
3. Front discs installed next, alter the Drum master to activate the front discs. (remove the pressure wafer in the front brake outlet.)
4 Rear discs and all disc master (lincoln naturally). Last step and will cause the most work.
TOFIC
HOW about it Todd? whats your nickels worth.

 

[toddz69]

Lots of opinions here, heres mine.
You did not say if you had PS, i assume you do.
1. Saginaw dual return PS pump and get it working on the Bronco. get this one out of the way quickly and shut the ford pump whine up.
2. Hydroboost install next, lots of opinions which one, I like the Lincoln one, get it working with the drum brake system. Guys are going to disagree with me on this, pointing at the HB and drums. I say do it and get HB working.
3. Front discs installed next, alter the Drum master to activate the front discs. (remove the pressure wafer in the front brake outlet.)
4 Rear discs and all disc master (lincoln naturally). Last step and will cause the most work.
TOFIC
HOW about it Todd? whats your nickels worth.

I'm with Bowsher on this one.

Todd Z.