Hydroboost brakes.. Thanks CaptainFab

[Lugnut64052]

marking this thread.

Great info here.

[toms84ss]

Digging this thread up. What are you guys doing for the pressure line? Are you splicing your existing P/S line or replacing the P/S pump with a Hydro unit with two pressure fitting? I was looking at the pickapart yesterday and was curious what was the easiest solution. I plan on running an F body serpentine system and will have to see if the Astro P/S pump will fit my bracket. I doubt it as that would bee too easy to solve one of my problems.

[Chevy-Art]

Will this work for a 70 Longhorn?

[muddpile]

I've always liked hydraboost, way cleaner than vac, plus the ablity to run a stupid-big cam

[62 mark]

i really like the idea of the hydroboost brakes,but alas, i have a 62 with a 235-6...no stock power steering mount that i'm aware of...does anyone have a pic of a truck like mine with hydroboost?

[Captainfab]

The hydroboost pumps don't have 2 pressure ports, they have 2 return ports, one from the hydroboost and the other from the steering box. I've seen them done both ways, with a hydroboost specific pump, or just a tee in the return line. I would think that either a Astro van pump or a '88 and up pump from a truck with hydroboost would work. Unless you already have the F body system, I would look for one of the ones I mentioned. The accessory drive off of a 4.3 in a Astro will fit a small block.

Originally Posted by toms84ss

Digging this thread up. What are you guys doing for the pressure line? Are you splicing your existing P/S line or replacing the P/S pump with a Hydro unit with two pressure fitting? I was looking at the pickapart yesterday and was curious what was the easiest solution. I plan on running an F body serpentine system and will have to see if the Astro P/S pump will fit my bracket. I doubt it as that would bee too easy to solve one of my problems.

[Captainfab]

I have the brackets to make it work on the '67-'72's There's a link in my sig.

Originally Posted by Chevy-Art

Will this work for a 70 Longhorn?

[Captainfab]

I'm thinking that to install a power steering pump on a 235, you'll have to fabricate some brackets. And then I don't know what you would do for pulleys. I'm really not that familar with the 235's, so hopefully someone that is will chime in.

Originally Posted by 62 mark

i really like the idea of the hydroboost brakes,but alas, i have a 62 with a 235-6...no stock power steering mount that i'm aware of...does anyone have a pic of a truck like mine with hydroboost?

[toms84ss]

Really? Two return lines and only one pressure line? Well, that makes it a bit easier. I already have the F body set up so I guess just "T" in to the return line.

[toms84ss]

I have another question. My parts counter guy said the master cylinder is different between the hydro system and a typical vacuum system. Any one have any input on this?

[suville]

Goin ta class here!

[Captainfab]

I will have to check on that some more as I haven't installed the hydroboost yet. I know Reid has on his Chevelle, hopefully he'll chime in on this. In the meantime I'll see what I can find out.

Originally Posted by toms84ss

I have another question. My parts counter guy said the master cylinder is different between the hydro system and a typical vacuum system. Any one have any input on this?

[72bigred]

Originally Posted by toms84ss

I have another question. My parts counter guy said the master cylinder is different between the hydro system and a typical vacuum system. Any one have any input on this?

I have used both and I have had no issue with either. You will notice that your boost unit has a short rod so make sure you use one that does not require a longer pushrod. I personally like the newer style MC's they open easier, can spot your fluid through the side.. Plastic container on top of an aluminum bridge. Under 10$ at any pick and pull make sure you grab it off a truck or I have used the Chevy astro van's MC also, if you are worried just pull one off the front of a hydroboost unit and you will be fine. The one I am working with now has the older style MC and I want the platic style yet it has been to muddy/wet for me to sluge through atm.

I am not sure what the difference would be, I know that your typical Vac pressure is half of that of the hydro , yet with the fluid providing the power it is not a jerky stop it is smooth. Once the system is free from bubbles etc your breaking power will start within 1/16' of the pedal and you will be fully stopped within 1' of your pedal.

I will check some part numbers but if I remember correctly we pulled the a plastic/aluminum MC off a later model chev truck with a VAC, looked exactly the same as the MC off the hydro but I will have to see if the part numbers are the same.. His btw works fine, stops on a plug nickle.

Reid

[72bigred]

Ok I did some checking and did find the difference. I compared the MC's for Vac boost to the MC's for the Hydro boost and there is a spec difference on the bore size for the Chevy trucks.

Brake Master Cylinder Bore Size : 1 1/4 For Hydro
Brake Master Cylinder Bore Size : 1 1/8 For Vac

Line ports 4 we only use 2 thus the reason I normally use the Van MC


I was not aware of this 1/8th of a difference in bore size. I know a true brake guy could tell you exactly, it to me says a smaller amount of fluid is allowed through thus improving the braking power for the Vac booster. This would also tell me that with the Vac MC it would increase pressure to your brakes with the hydro unit.

For the Astro Van there are some differences.

Bore Size on both are 1.25 or 1 1/4 they have two different MC's one listed for Vac and one listed for Hydro... Yet the bore is the same.. hmm why would the truck Vac MC be 1/8th smaller yet not the astro van.. This a brake pro would be needed to answer.

Line ports 2

Either way it shows us this. The vac booster MC is 1/8 smaller bore size for the truck MC so to error on the side of caution stick with the Hydro MC's.


Ok so.. And I havent check this but I must be running a smaller bore size in my chevelle as I am using a Vac MC not a Hydro MC. It has not caused me any problems with braking but you now have me interested in looking further into the bore size and finding out if indeed 1/8th is something I should be concerned about, especially running over 500hp 5speed 4.56 rear end.

Brakes are very important this was a great question that I personally have never bothered with due to never having a problem, but there is a difference and I myself will pay more attention to it in the future.

Thanks for that question as it will help me and others deliver safe information on the swop.

Reid

[toms84ss]

Good to know, thanks for the reply and great info.

[rcrahn]

Nice looking bracket CaptainFab!

I installed hydroboost in my 1969 Firebird that has disc brakes on all corners.
Initially I did have some problems with brake drag because everything was brand new (I mean everything) and the brake clevis needed adjustment. Just 1 to 2 turns on the clevis adjustment makes a big difference.
Everything works fine now and the car stops on a dime.

A few tips

1. Use Synpower power steering fluid to reduce foaming in the PS pump.
2. Pay attention to the plumbing of the 2 return lines and how they come into the "T".
3. Mastercylinders are either "deep style" (1969 or earlier) or "shallow style" (1970 and later) depending on pushrod length. I purchased a shallow style (1 1/8") 77-79 C3 corvette MC to match our hydroboost.


Lastly, if you are wary or uncomfortable using salvage yard brake parts in your truck I recommend a place in San Jose called Power Brake Exchange. You can google them. They sell new and reconditioned hydroboost units, MCs, calipers, rotors. Reasonable prices and good service. Ask for Michael.

[crakarjax]

Subscribed! I was looking into replacing my booster and MC. Looks like this will not cost much more, so I'm in! I also don't like the huge booster on my truck (68 C-20).

Does anyone have any specific info on the fit of a 68 C-20? I haven't really looked at captfab's brackets up close, but I am guessing they are required if you don't want to drill into your firewall?

How exactly do you spot whether these units are good in the junkyard?

[72bigred]

Originally Posted by crakarjax

Subscribed! I was looking into replacing my booster and MC. Looks like this will not cost much more, so I'm in! I also don't like the huge booster on my truck (68 C-20).

Does anyone have any specific info on the fit of a 68 C-20? I haven't really looked at captfab's brackets up close, but I am guessing they are required if you don't want to drill into your firewall?

How exactly do you spot whether these units are good in the junkyard?

For the ease of install and the minimum cost I would talk to CptFab.. John is a great guy and his products are excellent.

As far as spotting a good one I personally start out by looking at the cleaner units, this doesnt always mean anything but if they are clean and I have ran into this a few times you might get lucky and see the "reman" stamp on them, generally in yellow or white. Other than that I check to see if the backup cannister spins, if it does walk away as it needs to be tight/sealed. If its tight the only other place I have had seen these leak is in the back, others may have see something different but you can generally push the boot back inside and if you have some greasy powersteering fluid on your hands then walk away. I myself have just not ran into many that were leaking although I pull mine mostly off the 4WD astro vans. The plates on these are easier to remove so you can get Johns installed. I personally take a hose cutter with me and cut enough of the metal lines that go into the booster and into the steering box, then I walk my ends into a hose shop and have them brazed on.. There are also adapter fittings you can buy as well..
On the cars I have installed them on I do this because I like my hoses really long and generally run them between the fender/inner fender so they are out of the way. On the 60 im doing they of course will be visible as that is not posssible. Once you get it you will see the pushrod wont work, I generally cut the end off and thread it, if memory servers the other end on the later 60's is 3/8 course but dont quote me atm.. But I grab some all thread and some couplers and go for it. As you go through just ask, once I have completed this set up I am going to do a write up with pics.

Reid

[protrash64]

I'll throw in my .02. A guy I know that builds, restores, customizes, and services cars said he uses the same MC on all of the stuff and its never made a difference. Not very scientific, but good to know that he hasnt had any problems using similar ms/cyl on different applications...hydro and vac.

[crakarjax]

Originally Posted by 72bigred

As you go through just ask, once I have completed this set up I am going to do a write up with pics.

Definitely post back here with a link when you do your write-up (I smell a faq in the making). I was going to get a new booster/mc but I think I'll try to make do with what I have for now so that I can go to 'dro in the future.

'dro is an open source trademark, btw.

[bubba327]

Subscribed.
I have one of Captain Fab's brackets with a 75 impala booster and master cylinder , but a medium stupid cam and (and low to medium vacuum ) in the 6 cylinder. Brakes could be alot easier to push IMO.
I was thinking about a vacuum booster pump but this might be a better way.

This should be a sticky in the FAQ's

[chillware]

sub'd .. great info guys! thanks!

[66farmer]

I would like to bring this thread back up again. My question is what proportioning valve should be used with a hydro booster. I'm using 78 front disk and rear drum setup.

[padresag]

Originally Posted by 62 mark

i really like the idea of the hydroboost brakes,but alas, i have a 62 with a 235-6...no stock power steering mount that i'm aware of...does anyone have a pic of a truck like mine with hydroboost?

any 235 or 261 I6 p/s pump brkts should work.There were quite a few passenger cars between 55-62 that had them. I know that there are also getting hard to find now. 261 engs were used in Canadian Pontiacs from 55or 57-62 and GMC trucks.
ron

[padresag]

hydra-boost do put out more line pressure than vacuum. when I first got my 4 x 4 back in 90 it had a hydra-boost on a drum-drum setup due to the detroit in it, On 2 separate occasions that the brakes had to be applied "now", I cracked 2 drums.
ron