47-55.1 Firewall or Under Floor Mounted Master Cylinder?

[damnyankee36]

I'm in the planning stages for my future 47-53 project.

Can anyone list the pros and cons of these two mounting methods?

[mr48chev]

I'm an under the floor guy because they are just too ugly to be in the engine compartment with the engine you spent all that tme and money detailing. I've spent almost as much on finned and polished cast aluminum for my 292 as I had in the truck when I drove it to the 1973 Street rod nationals in Tulsa from McGregor Tx. Plus I have a pretty big 4 barrel intake going on it. Add in that I want people who aren't totally in the know on Chevy sixes to think and maybe argue that the truck has a hopped up 216 or 235 or even 261 than the 292 when they walk up and look at the engine that will be as close to factory gray as I can get with the polished aluminum. I don't want them looking around a street rod style booster and master cylinder. It's all about what I want others to see when the hood is open.
Add in that I am running a cast iron V8 bellhousing on the original crossmember with an AX 15 behind it. stock floor pedals simplify the clutch linkage as I already have all of it. I'll most likely run a hydro vac rather than a vacuum booster.

Function wise they work great on the firewall as long as you properly reinforce the firewall so you don't crack it out. I had a large square piece of 3/16 or so plate that was maybe 12x12 or larger sandwiched between the pedal assembly and the firewall on the inside to spread the pressure out over a large area when I ran the booster and master cylinder on the firewall. It's simple and it works, works best with an automatic rather than a stick as you don't have to figure out a clutch linkage setup. In truth the firewall mounted unit is a lot simpler if you are running an automatic and aren't concerned about the booster and master cylinder blocking folks view of the engine or aren't concerned about having a perod correct for your build plans engine compartment.

[leegreen]

If you have everything for the floor mount, just upgrading the master to two circuit / adding a booster if you go disk is probably simplest.

If you have nothing now and plan to DIY, retrofitting from a newer truck onto firewall is going to be easiest and cheapest. S10 pedal conversion has been talked about many times by the S10 frame swap crowd.

I worked on a few customer trucks with under floor masters back in the days when those sort of trucks were still daily beater status not collector stuff...under floor masters got the kind of maintenance you'd expect from something that is out of sight and out of mind. And they are a pain to work on compared to standing beside the truck.

If you are going manual trans but with a modern engine & trans, you are going to be figuring out how to make a clutch work and ripping apart the underfloor stuff anyway.

If your truck will be very low the under floor master presents some additional challenges with bleeding, needing drainback prevention etc

[damnyankee36]

Thanks guys. One thing I failed to mention was I plan on doing an S10 frame swap.

Does that throw a wrench into the under-floor system installation?

[dsraven]

if you don't have the parts yet, I suggest to opt for a hydroboost. it will give you awesome assist and take less space. it can also be mounted further back on the frame if desired, just use a longer push rod from the pedal linkage. it is likely gonna be a challenge to get under floor master cylinder with an s10 swap. but hey, thats the fun part, right?
maybe check in with joedoh, he would know what kinds space limitations you will be up against. he also sells the swap mounts.

[damnyankee36]

Good idea. I have been in touch with him on the mounts. I'll see what he suggests on the master cylinder.

[dsraven]

are you trying to keep the engine bay clean by not having anything on the firewall or do you just like to have the pedals go through the floor like the old style? a firewall mount is easier for sure. a frame swap is already enough work for most guys. sometimes that can make or break the project, being in deeper than anticipated for the skill level, the shop and tools available or the time away from the regular household stuff.
just saying, a firewall mount will get you going quicker and can be reversed without too much difficulty later once you have had some time "on the road".

[leegreen]

code504 sells a s10 swap under floor pedal or pedal/booster/master combination. I don't see any option for clutch pedal if that matters. I'd also think about exhaust clearance

joedoh sells a bracket for firewall mount the s10 pedal and the right year clutch pedal will bolt onto that. And think about engine clearance at firewall

[fauXGT]

Under the floor frame mounted power booster two stage if you are in the full building state. Create a new floor access door. Then go disc or split. Keep the fire wall minimal. Then adapt the stock pedal arm to fit the stock foot pad.
Clean and original looking.

[Hcb3200]

I am a keep it under guy.
Just makes that engine bay look cleaner.
And I went hydroboost as well.
I did put a remote fill hidden behind the fuse box in the engine bay due to all the brake and line work I was doing. It can easily come out once all the "build" is done. Insert laughter hear.

[mr48chev]

Originally Posted by damnyankee36

Thanks guys. One thing I failed to mention was I plan on doing an S10 frame swap.

Does that throw a wrench into the under-floor system installation?

With a frame out from under a worn out S-10 you are stuck with the firewall mounted master cylinder and booster. I'd use all of it I could off the donor truck as that helps everything match.

[dsraven]

personally, I would use a hydroboost under floor rather than a dual stage vacuum style booster. it will give you excellent boost the same as it would if mounted on the firewall. a dual vac booster is dual because a single doesn't give enough boost due to square inches of diaphragm available. yes, lots of vehicles are using the dual vac booster. I would say try driving one and then try driving a similar vehicle with a hydroboost. you will see the difference. a hi perf engine can also make a vac booster less efficient as there is less vac at certain rpm's compared to a stock engine. do as much homework as you can before pulling the trigger. more complicated means longer time till driving.
again, just my opinion-not worth much really

[Rickysnickers]

Regardless of where you mount it, I'll also go along with doing a hydroboost system!

[damnyankee36]

Lots of things to think about. Appreciate all the tips!

I'm starting to develop what I think is important to me.

1. I'm not sure how I will like operating a floor mounted pedal. Does it tend to be more of a downward direction when you step on it?

2. I'm not sure if I like the possible issues with bleeding an under floor system. I need to research that a little more.

3. Joedoh said he has a "plate" for a firewall mount. I think it may use the S10 pedal assembly. My chassis won't have that included in the deal.

What about this mount? https://www.performanceonline.com/19...4aAmqmEALw_wcB



I'll would make sure the engine's vacuum specs would be compatible with the booster as I don't like the looks of the Hydro-Boost.

I've been looking at photos of trucks with a firewall mount and it's not too crowded.

[dsraven]

I am betting that if you talk to joedoh he would come up with a chassis swap kit for you as well as the parts required for a complete hanging pedal. if you don't like the looks of a hydroboost you could fab up a nice cover for it, they're not very big compared to a vac booster. thats a personal preference thing but to me hydro boost will give you a better brake system. ask anyone who has one. maybe do the chassis swap first and then worry about what brake booster you will use, possibly more time to think about it and research a bit on which system is better to help you actually stop. I think hydroboost generally has more clamping force available vs vacuum boost. no soft or spongy pedal feel, you will likely be able to lock up the brakes if you want to vs standing on the pedal and hoping for the best. it's your truck so you gotta do it like you want it but if you have no parts yet research which would be your best operating system.
https://www.motortrend.com/how-to/11...ng-your-brakes

[damnyankee36]

Raven, you are correct as I have no parts or even the truck or chassis yet! Soon as the title issues are resolved I'll have those in my possession.

At the moment, it's all just preliminary planning/researching/deciding how I want the truck to look when completed. I have two projects in line to complete first, at least two years before I get on the truck.

[leegreen]

For a S10 swapped AD, vacuum booster will be adequate if you have vacuum.
If you want better brakes put your money into the components at the wheels and a good set of rubber first. The brakes on a 90s 4cylinder s10 are pretty identical in size and design to the 3rd gen v8 Camaro.
Starting point for a mild v8 swap is to put everything into as good as factory stock condition. Common upgrade from stock is dual piston calipers from a 2wd Blazer and a rear disk axle. After that it is just a matter of how much money you have. For best results keep brakes, tires, GVW and horsepower in the same performance envelope

Hydroboost solves a particular problem for a hot rod: lack of vacuum
Yes, they can develop more pressure. They were initially put on medium duty trucks to get more brake pressure without resorting to a huge diameter booster that would not fit under the hood. Boosted cars need either hydroboost or mechanical/electric supplemental vacuum pump. Diesel trucks have made hydroboost a lot more common over the last 20 years.

Putting more pressure into the brake system may make the brakes feel better in that they take less foot pressure, but it does not make the brakes better.

[mr48chev]

2 wheel drive S-10 front suspension and brake parts directly interchange with G body parts with few exceptons.

Vacuum powerd booster / Hydro boost decision might well depend on what cam you are running and or if you are running power brakes with a pump rather than electric power brakes or no power brakes. having had two one tons with hydro boost I really like the feel of it but am still a bit up in the air on front suspension and steering. It's a case of if I go with the Jag XJ I will run Hydro boost along with the Jag power steering and Saginaw pump. If I go MII or Industrial Chassis (Dakota) I'll most likely go with electric power brakes and vacuum booster.


To me the main reason for doing an S-10 swap is on stop shopping, you drag home a worn out standard long bed work truck that you got dirt cheap and as they say about butchering a hog, You use everything except the squeal and sell off the left overs to pay for more parts for the project. That usually means hauling the hulk to the scrap yard as at least in this area there little or no market for used S10 body parts or the guys looking for them don't buy off FB market place or Craigslist as the parts usually are for sale for months. Even if you pull out the 2 wheel drive rear axle and put in a 4x4 rear axle you sell the two wheel drive to a local hotrodder looking for that exact width of rear for his older hot rod.

[joedoh]

Originally Posted by damnyankee36

3. Joedoh said he has a "plate" for a firewall mount. I think it may use the S10 pedal assembly. My chassis won't have that included in the deal.

What about this mount? https://www.performanceonline.com/19...4aAmqmEALw_wcB



I'll would make sure the engine's vacuum specs would be compatible with the booster as I don't like the looks of the Hydro-Boost.

I've been looking at photos of trucks with a firewall mount and it's not too crowded.

what year is your donor? I will add an update dhow to on using the 82-93 s10 brake pedal and column, its literally a 2 hour process and if you have an 82-94 donor you dont even have to crack the brake lines to use it complete.

the plate i sell is a reinforcing plate, the firewall was not made to support brake pedal pushing force, it is a 16ga plate that either doubles the firewall over about 1 1/2 sq ft, or if you are using the s10 booster and master, it can be folded into a 5 degree mount for correctly orienting the s10 master. even with that pedal in your link you will want to double up the firewall in that area.

the s10 master is installed at a 5 degree angle. it is a common misconception that the front outlet of the master is the front brakes and the rear is rear, but its actually the opposite and has been since the 60s on GM. if you install the s10 master without that 5 degree angle, it is possible under hard braking you will starve the rear reservoir of the master from fluid transferring forward, and lose your front brakes. if you compared braking bias in a panic stop, the front brakes are doing 90% of the work, the rear brakes are almost ineffective except to keep weight transfer from swinging the rear around and swapping ends. (this is not the case in other stopping scenarios so dont misunderstand)

I dont like underfloor setups, mostly because of the pain getting to them. if you are looking at an underfloor setup to save work over a firewall booster, it assuredly will NOT save any work. new lines, anti runback valves, peeling up the carpet to check and add fluids, bleeding a master than is lower than the calipers, its a lot.

that hanging pedal setup will work. its pretty expensive. I am doing the s10 pedal bracket swap today or tomorrow, I will take more pics.

if you are using a 94+ s10 donor, it is easier and cheaper to go to a salvage and get the pedal bracket and modify it for use. I do make a 94+ pedal bracket if you insist on one, I think i have done 10 iterations and it works really well.

[damnyankee36]

Originally Posted by joedoh

what year is your donor? I will add an update dhow to on using the 82-93 s10 brake pedal and column, its literally a 2 hour process and if you have an 82-94 donor you dont even have to crack the brake lines to use it complete.

That would be great Russ. I haven't seen the donor in person but it's supposed to be an 82-93. And I'm pretty sure it doesn't have the pedals. I will ask to be sure.

That's why I was looking at that universal bracket and master/booster assy.

[mr48chev]

In my poking around I found this https://www.code504.com/complete-bra...rame-swap-kit/

Code 504 and obviously code 504 SSs. Plus it only seems to be a direct bolt on with their kit. Thing is, if they can build it to work you can figure out how to fab up your own. i keep forgetting that standard issue S-10 swaps have several inches of space between the cab floor and the S-10 frame rails pretty much like a body lift on a 4x4.

[fauXGT]

Originally Posted by mr48chev

In my poking around I found this https://www.code504.com/complete-bra...rame-swap-kit/

Code 504 and obviously code 504 SSs. Plus it only seems to be a direct bolt on with their kit. Thing is, if they can build it to work you can figure out how to fab up your own. i keep forgetting that standard issue S-10 swaps have several inches of space between the cab floor and the S-10 frame rails pretty much like a body lift on a 4x4.

Is what I have. But the pedal mount point was a 90* w/ threaded pedal post. Would not fit thru the stock fire wall hole.
I did this. Incorporate the stock pedal assembly & fit it to the aftermarket booster.
2 threaded screws with a grade 8 self locker in the center for safety.

[mr48chev]

It's a challenge enough to get the pedal shaft to go smoothly through the floorboard without toughing during it's travel anyhow. That is really nicely done.

[dennislbrooks]

Many reasons above that may make better sense for your project. This master cylinder in my 59 has not ever seen rain or a water drenching. I am moving all to the top in another thread, I do not produce SEMA cars just dependable drivers.

I have a hydroboost in my 67 4wd and a on top vacuum booster in the 42 (s10 frame). I like both. Hydroboost can be quite more expensive. Definitely helps overcome taller tires. They use hydroboost in diesels because of no available vacuum. They put hydroboost in cars (2004 Yukon) sometimes because of space.

Regardless of which way you go, the front discs (plus the correct master cylinder and proportioning valve) on the front of the s10 will contribute most.

If money is no object buy a truck already complete. May be less expensive. 8-)

[dsraven]

a used hydroboost from a wrecker like pick n pull is not usually gonna break the bank. it doesn't need to be from a chevy but could easily be. they are more common than uou might think. there are a few threads on how to get the stock donor linkage off and remade to fit your needs. you could buy a donor vehicle with a hydroboost and the engine/trans you want and then sell the rest for parts.
like said, your truck, your money, your project. maybe by the time you get to it you will know exactly what you want. a plan of attack for the project is always good to have before you start buying stuff and cutting things up.