Another Hydroboost ?

[UNmolestedTA]

I pulled a master cylinder and hydroboost unit from a 1983 chevrolet C20 truck. I think the master cylinder is a 1.250" bore. Will this be a good setup for my front and rear LS1 brakes? Also, my plan is to run an LS1 or LS2 six speed pull out from a GTO. Will the late model power steering work well with the hydroboost? Thanks for the replies.

[MuscleRodz]

I pulled a master cylinder and hydroboost unit from a 1983 chevrolet C20 truck. I think the master cylinder is a 1.250" bore. Will this be a good setup for my front and rear LS1 brakes? Also, my plan is to run an LS1 or LS2 six speed pull out from a GTO. Will the late model power steering work well with the hydroboost? Thanks for the replies.

Too large of a unit for your car. It is designed to stop a 6000 lb truck not a 3800 lb car. steering pump will work fine

[UNmolestedTA]

Thanks for the information. So the hydroboost would cause my ls1 brakes to be hypersensitive? I'll probably use it on my 93 extended cab z71.

[LONE*STAR]

what the deal here, no way to use one of these large truck units? What would be the symptoms?

[UNmolestedTA]

I don't know but I am going to try it first and see what happens but not on the street.

[MuscleRodz]

units are designed to stop 7000 lb trucks with 7000 lb trailers. What do you think it will do if you put in on a 3500 car? Not all hydroboosts are the same

[wedged]

don't you just love non-answers ? Or questions "answered" with another question ? I'm curious too. What would happen ?
My thought is that nothing bad would happen. Some tweaking and adjusting would likely be needed. Pedal ratio being the main adjustment. It's possible it may not generate enough pressure, but that could be altered by using a smaller bore master cylinder.

[MuscleRodz]

don't you just love non-answers ? Or questions "answered" with another question ? I'm curious too. What would happen ?
My thought is that nothing bad would happen. Some tweaking and adjusting would likely be needed. Pedal ratio being the main adjustment. It's possible it may not generate enough pressure, but that could be altered by using a smaller bore master cylinder.

Simple brake mathmatics. Larger vehicles require larger brakes and larger braking pressures to stop. Larger wheels require greater brake pressures to slow the extra rotating mass. You put a hydroboost off a 1 ton truck on your 3500 lb car and the brakes will lock up. They are simply too large to put on a car. No amount of tweaking and adjusting will fix it. And if you put a smaller master on it, it will increase the brake pressure even more and make it worse not better. Pedal ratio would not fix it either, just delay the enivitable. Does that clarify it enough?

If people are hell bent on retro fitting a booster, get one from a Mustang and go to Carl C's website for install info. They are designed for an equilvent mass vehicle, equivilent size wheels, equivilent size brake lines, and work fairly well.

[protour_chevelle]

Simple brake mathmatics. Larger vehicles require larger brakes and larger braking pressures to stop. Larger wheels require greater brake pressures to slow the extra rotating mass. You put a hydroboost off a 1 ton truck on your 3500 lb car and the brakes will lock up. They are simply too large to put on a car. No amount of tweaking and adjusting will fix it. And if you put a smaller master on it, it will increase the brake pressure even more and make it worse not better. Pedal ratio would not fix it either, just delay the enivitable. Does that clarify it enough?

If people are hell bent on retro fitting a booster, get one from a Mustang and go to Carl C's website for install info. They are designed for an equilvent mass vehicle, equivilent size wheels, equivilent size brake lines, and work fairly well.

All of the hydroboost units that GM uses are the same, from the astro van to the trucks to the escalade. Just the mastercylinder differs. I'm running a escalade hydroboost unit with no issues. 78 Corvette mastercylinder, disk/disk.

[mnm99]

They are the same. Here's the one that was on my car. Selling it now due to turbo header space issues.

[MuscleRodz]

They make look the same, but they are not. The internal piston size is varied depending on application to be used for. Again, what is designed to work on trucks is not designed to work on a car.

According to your logic, a LEE prepped steering box is identical to the original steering box in my 69 Camaro and performs the same.

[wedged]

Simple brake mathmatics. Larger vehicles require larger brakes

correct

and larger braking pressures to stop.

Not always, but possibly, or maybe even lower pressure. You are leaving out rotor diameter, pad size , caliper size, etc.

Larger wheels require greater brake pressures to slow the extra rotating mass.

Not really, it depends on the rest of the system- too many variables.

Does that clarify it enough?

You are saying it is simple "mathmatics" (sic), but you didn't take into account all of the variables.

It's kind of like saying an 8-71 blower won't work on a small block because it was made for big truck. Is using a truck hydraboost the BEST choice ? maybe not. I'll agree with that. Can it be made to work ? very possible with some effort. We're talking about hot rodders here, not backyard oil changers. Someone will consider it a challenge and make it work.

[MuscleRodz]

Just because it can be bolted on, does not mean someone should. Look at it this way. Hydroboost is a lever arm. Brake pressure is the same roughly on all around 1600-1800 psi. The difference is in piston diameter. Larger piston diameter mean larger brake force applied, most the time the hydroboost rod is located in the manual pedal rod location further multipling the force further. Add in bigger brakes and you can lock up a brake system easily with parts designed to be used with one another.

With the increased piston diameter of a truck unit applying extra braking force, you have to reduce the braking force to a managable level to be used on a vehicle half its weight. You could go to a larger master on a smaller unit to reduce pressure, but not an option on the larger units, as they require the larger master to stop a large truck to begin with. Oh, and I checked the 1 ton master on my truck and it is 1-5/16" bore. You would have to go larger than that to reduce applied brake pressure. So larger master not an option.

Larger brakes would be an option on a smaller system. Pressure is pressure, but the extra surface area of the caliper pistons require more fluid to move them. With the larger hydroboost, you now have the ability to move all that fluid making the brakes extra sensative.

You have 2 more changes available. larger brake lines, and changing where the booster connects to the brake pedal. By increasing the brake lne size 1/16" won't make hardly any difference as the extra volume of fluid would be minimal. You can only move the arm down so farbefore you have binding issues, or the master won't hold any fluid.

In short, by overcompensating with the first part of the system, the problems that have to be overcome have been multiplied, where if a person just used the correct part to start with, that person would not have to reinvent the wheel. Why create a problem with one used part, when you can buy another used part that will work?

[UNmolestedTA]

I agree with what Mike is saying. The hydroboost is designed to stop a larger vehicle and will most likely lock up the ls1 brakes but curiousity is getting the better of me. I will most likely pick up and astro or mustang unit but I want to toy around with the truck unit first.
Thanks for the replies and info.

[LONE*STAR]

Is there a stamping on the GM units to tell which model you have?
Can I change a internal part as not to buy a whole new unit?
I don't really like the mustang units because of the line provisions being located on top, are the mustang units even that great?
I already have Nick Diprenda's bracket and just need lines, and to thread the rod....... so this sucks

[MuscleRodz]

Is there a stamping on the GM units to tell which model you have?
Can I change a internal part as not to buy a whole new unit?
I don't really like the mustang units because of the line provisions being located on top, are the mustang units even that great?
I already have Nick Diprenda's bracket and just need lines, and to thread the rod....... so this sucks

Just turn it upside down, it is what many people do. Same unit.

[LONE*STAR]

Ya but my bracket is machined with a provision so it wont spin and you cant turn the bracket upside down, because of the 15 deg angle on the face.

[LONE*STAR]

Btw a astro van has a 4310lb curb weight, isn't that about 500lbs off from my 1st gen. My question is my question what would be the actual symptom? The final foot pound is at 100% input is the same on all unit correct? Would the ramp from 0% braking force to 100% be just to quick? Whats the deal?

[Bowstring]

I bought a used hydroboost from a 2003 Chevy 3/4 T pickup.last winter. Roughly what, a 5200 lb. vehicle? Installed it on my '74 Camaro with 4 corner Wilwoods, and a 4 wheel disc Trans Am M/C and love it. It isn't the least bit touchy and stops the car unbelievably well. It modulates well and now having the push rod threaded will be easy to adjust for heel / toe. I don't for one minute buy that an Astro van unit is too big otherwise mine wouldn't be working either.

[MuscleRodz]

I bought a used hydroboost from a 2003 Chevy 3/4 T pickup.last winter. Roughly what, a 5200 lb. vehicle? Installed it on my '74 Camaro with 4 corner Wilwoods, and a 4 wheel disc Trans Am M/C and love it. It isn't the least bit touchy and stops the car unbelievably well. It modulates well and now having the push rod threaded will be easy to adjust for heel / toe. I don't for one minute buy that an Astro van unit is too big otherwise mine wouldn't be working either.

What do you think your 74 weighs? I bet very near 4000 or more. What wheels are on it? 40 lb steel wheels or 22 lb forged? Are they 6 piston Wilwoods or something smaller? Lots of variables why you might be happy and someone else is not