Need some feedback on brake setup

971 Views 11 Replies 4 Participants Last post by kso, Sep 17, 2021

cerial

Discussion Starter · Sep 13, 2021

Let me run this revised brake setup by you guys and confirm thats what is in my head will actually work.

I have a 1994 2wd s10 that had a 2.2 5 speed (standard cab).

I want to use those factory front calipers because they fit inside some 1st gen 14" rims.

Out back I have a unmodified 9" from a 78 F150 4x4 with a inline 6 and 4 speed.

In the middle I have a balance bar 6/1 ratio floor mounted pedal and two 7/8" bore master cylinders.

I will be using a push lever brake switch so the switch will not be part of the brake system.

Now I am thinking of just running 3/8" (nicopp) line to the front, to a T, then more hard, to flexible lines, to the calipers.

In the rear just running a 3/8" line, to a flexible line, to a T, then hard line to the factory 78 wheel cylinders running the factory drums.

Rather simple and cheap "factory" setup that I wont have a issue finding replacments for.
Everything is shot and will be replaced brake wise.
I believe the stock s10 front calipers and stock 78 F150 rear wheel cylinders will work with the 7/8" masters. Unsure about what diamiter line to run and the fittings.

Before I start buying stuff I want to check to see if I would be better off running "this" line or "that" wheel cylinder.

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johnsongrass1

· #2 · Sep 13, 2021

You;ll like the 3/4 MC bore better on a 6:1 pedal deal if you have to get it anyway. 7/8 will work too.
Line size makes NO difference.
1/4" to 5 inch it's all the same.
3/16ths is most common and cheap fittings.
Even easier to plumb are are the nylon brake line kits found all over.

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cerial

Discussion Starter · #3 · Sep 14, 2021

I have the 6/1 pedal with the 7/8" masters.

I think it will work with the stock 94 "small" calipers. Totally unsure about the 78 wheel cylinders.

Both setups used a power booster and single master. Going to dual full manual.

I will run 3/16 line.

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kso

· #4 · Sep 15, 2021

Wouldn't running two 7/8" bore master cylinders (.508 sq. in. each, 1.016 total) in parallel be about the same as running a single 1 1/8" unit (.994 sq. in., if I can do math...)? Would make for a very hard pedal.

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johnsongrass1

· #5 · Sep 15, 2021

kso said:
Wouldn't running two 7/8" bore master cylinders (.508 sq. in. each, 1.016 total) in parallel be about the same as running a single 1 1/8" unit (.994 sq. in., if I can do math...)? Would make for a very hard pedal.

He's referring to a pedal assembly with one pedal, two Masters, one for front and one for back, independent of each other with a threaded rod between the two that allows some adjustablity for for front/rear balance

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kso

· #6 · Sep 15, 2021

Yep, so that would be one master cylinder sized to normally (and un-assisted) run 4 slaves but instead running only two, and another master the same, running off a single pedal (via balance bar). Total ratio of masters to slaves would be same as if running a single 1 1/8 master to drive the four slaves.

I guess you'd just need to have the right pedal ratio for it, probably 6:1 or so.

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curtis73

· #7 · Sep 15, 2021

3/8" line will likely explode. Way too big for brakes. You only need 1/4" or 3/16".

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cerial

Discussion Starter · #8 · Sep 16, 2021

Ok the thing uses a single pedal that pushes a balance bar pushing two master cylinders. I can adjust the balance bar to asjust the front and rear balance.

Ok here is my reasoning.

The factory 94 s10 was 3/4" and I believe the factory 78 F150 was 1" both trucks power boosted.

But because I am going to full manual and want a bit more "power" feel I should be good using 7/8 masters and the rears may lock up slightly before the fronts. But I think I can adjust it out or use a diffrent cylinder in the rear.

Not 100% though.

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cerial

Discussion Starter · #9 · Sep 16, 2021

Ok I need to read this a few times.

Master Cylinder Math - JOES Racing Products

www.joesracing.com

How do you calculate wherl cylinders?

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kso

· #10 · Sep 16, 2021

cerial said:
Ok I need to read this a few times.

Master Cylinder Math - JOES Racing Products

www.joesracing.com

How do you calculate wherl cylinders?

Just measure the piston-bore diameter, then "pi x radius-squared" to get area.

The linked page spends a lot of time on that but not on the matter of one master cylinder vs. two master cylinders, except to come around to what I mentioned above from another direction and note that if you are pressing 300 lbs into the center of a dual-master system with a balance bar you are only getting 150 lbs force at each master.

I.E., if you had a one-master system and were pushing 300 lbs into it from where the linkage comes off the pedal, each wheel cylinder would be seeing the pressure result from the 300lbs, but if you change to two masters running off a balance bar and are pushing same 300 lbs into the middle of that, each master is only getting 150 lbs. of push and each connected wheel cylinder is only seeing the result of 150 lbs. Different settings on the balance bar get of-course the same, averaged.

So, keep in mind to size cylinders and mechanical leverage accordingly when going from a one-master system to a dual. To have a dual-master system be producing the same pressure at the wheels as a single for a given amount of push at the pedal, either the total area of the two masters has to be equal to what the original single one was, or the pedal ratio has to be doubled, or (most likely) some combination of the two.

btw as I tend to say, I ain't the expert, just a bit of experience here/there.

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cerial

Discussion Starter · #11 · Sep 16, 2021

I found a better calculator.

Need to dig into it or do more searching on how to apply drums to this.

Drums should be fine stopping this. But I am going back and forth on running disc on the rear. It is more expensive and requires more flexible line. But I loose some unsprung and maintenance is a bit easier. Sure would make calculating this much easier at this point.

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kso

· #12 · Sep 17, 2021

Most of my projects have used rear discs but in general I kinda prefer rr drums as the parking brake scheme works so much better, but they act on their friction surfaces in such a different way than discs that trying to calculate gets a little crazy.

In thinking about what I said earlier, I wasn't really considering the matter of a normal "single" master cylinder being split into front/rear systems. See what I mean about not being the expert (eye roll at myself)? Oh well it's a discussion, and hopefully everybody including me learns or at-least considers different things. Here's a fact: The brakes on my Challenger at left suck, they need a smaller master and I really missed it when I chose the size (which I will correct on the next go-round). Other cars I've done...really, all other cars...worked excellent, maybe I got over-confident.

You can always just get empirical about your design and figure, a stock S-10 works well as it is but you're making such-and-such a change, so you make what seems like an appropriate adjustment for that change and just try it. Making sure to leave room for such adjustments, such as being able to change pedal ratio a little via multiple holes or using a master system where different bores are available, helps, and your balance bar will of-course make f-r adjustments a cinch.

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