Hydroboost / master cylinder issue?

[hotrodf1]

Hey guys,

I just got through installing a Hydroboost unit and 1 1/8" master cylinder, along with a 90 IROC steering box on my camaro, DIY style. I'm having problems with the brakes.

I used a hydroboost from a 93 Chevy pickup, diesel of course, was told it was a 4x4, but I don't think that matters too much.

So I fill the system, start the engine, and the power steeing seems to do okay, but I get nothing from the brakes. I was trying to bleed them (tried first without engine running, then tried with it running), and I can't get any fluid out of the system by pressing on the pedal.

Almost seems like the boosters rod isn't pushing far enough into the MC to apply the brakes. Is that possible? I didn't think you had to match any specific MC to the hydroboost unit. The MC is a mid seveties Corvette, power brakes, brand new from Tru Torque. I of course bench bled it, and used the technique where you block the ports off and keep pumping until the bubbles quit and the piston only moves about a 1/8".

Does anyone know what the problem might be? Thanks for any help.

Jer

[hotrodf1]

Any ideas out there? Does it matter which hydroboost you pair with a master cylinder, or do they all fit up the same? I gotta figure out what to try on this thing tonight.

[scherp69]

I know with the Hydratech boosters, you have to match the booster unit to the master cylinder. It all depends on whether it is a shallow or deep master cyldinder and the length of the pushrod. Go to http://www.hydratechbraking.com/ and read about it. Hopefully that will help.

[1969CamaroRS]

When I talked to Paul @ Hydratech he told me that the 1-1/8" was the most common size M/S to be used as most people did not like the twitchyness of the 1" and especially the 7/8".

[hotrodf1]

Ah. I see the problem now. Apparently I have the old style "deep" master cylinder that requires a long pushrod. But I have the shorter pushrod late model Hydroboost unit.

Below is the pic that was posted on Hydratech's site.

I guess this means change out one or the other. Master cylinder should be cheapest. It probably means my brake line ends will no longer be the right size.

Anybody know what kind of master cylinder I should look for?

[SHANE 73Z]

Cut a spacer to take up the slop & call it good........

Shane

[newby]

go to nastyz28.com and search for hydroboost there. we have talked / r&d'd this topic to death over there. there are guys welding custom rods, making adjustable rods, custom boosters with swapped rods, etc.

there is even a known ideal pedal ratio you should be shooting for.

[hotrodf1]

go to nastyz28.com and search for hydroboost there. we have talked / r&d'd this topic to death over there. there are guys welding custom rods, making adjustable rods, custom boosters with swapped rods, etc.

there is even a known ideal pedal ratio you should be shooting for.
I had read a little bit over there. Enough to know the first gen guys were doing a 15 degree bracket, and using the power brake hole in the stock brake pedal. Dunno what pedal ratio that is exactly, but it's what is aligned the best when I installed the hydro on the 15 degree incline.

I maybe could have done the spacer like was mentioned, but I was a little aprehensive to do that since any kind of unforeseen "failure" there would be catistrophic to the car, me, and probably someone else as well. Also may have been a bit tricky to get it to stay in there while I installed the MC, since the rod would try to slide out.

Based the "shallow" vs. "deep" pic that I posted I decided the easiest and quickest thing to do would be to swap MCs. I think it's 76 or 77 is the year the GM changed.

For $17.77 at Advance Auto I bought a rebuilt 78 Corvette master cylinder that is the late model "shallow" style MC. I got likely that the ports on the MC were exactly the same size as the one I removed, so the swap was nice and easy. Only issue I ran into (and one I had read about, thankfully) was that the master wouldn't go all the way up to the flange on the booster. Sort of rocked back and forth - of course the problem was that the rod on the booster didn't match the shape of the indention in the MC very well. My carbides made short work of that. Couple of tries and she fit just fine.

So I hooked everything up, bled the brakes and took her out for a spin. What a difference. I'll have to set my idle up a bit. If I nail the brake it wants to kill the motor from the extra HP sucked up by the pump I guess.

The power steering is very nice too. That IROC box feels great! Now I realize how poor my handling is. But that's okay, I have plans for that, too.

Anyhow, thanks for the ideas, the replies, and the info. Just thought I would report back on what worked. :cheers:

Gotta love the info sharing out here in cyberspace :yeah:

[Taylor1969]

I had read a little bit over there. Enough to know the first gen guys were doing a 15 degree bracket, and using the power brake hole in the stock brake pedal. Dunno what pedal ratio that is exactly, but it's what is aligned the best when I installed the hydro on the 15 degree incline.

I maybe could have done the spacer like was mentioned, but I was a little aprehensive to do that since any kind of unforeseen "failure" there would be catistrophic to the car, me, and probably someone else as well. Also may have been a bit tricky to get it to stay in there while I installed the MC, since the rod would try to slide out.

Based the "shallow" vs. "deep" pic that I posted I decided the easiest and quickest thing to do would be to swap MCs. I think it's 76 or 77 is the year the GM changed.

For $17.77 at Advance Auto I bought a rebuilt 78 Corvette master cylinder that is the late model "shallow" style MC. I got likely that the ports on the MC were exactly the same size as the one I removed, so the swap was nice and easy. Only issue I ran into (and one I had read about, thankfully) was that the master wouldn't go all the way up to the flange on the booster. Sort of rocked back and forth - of course the problem was that the rod on the booster didn't match the shape of the indention in the MC very well. My carbides made short work of that. Couple of tries and she fit just fine.

So I hooked everything up, bled the brakes and took her out for a spin. What a difference. I'll have to set my idle up a bit. If I nail the brake it wants to kill the motor from the extra HP sucked up by the pump I guess.

The power steering is very nice too. That IROC box feels great! Now I realize how poor my handling is. But that's okay, I have plans for that, too.

Anyhow, thanks for the ideas, the replies, and the info. Just thought I would report back on what worked. :cheers:

Gotta love the info sharing out here in cyberspace :yeah:

What did you do for lines? I have an IROC pump and hydroboost already installed, but no lines to the hydroboost yet.

[CliffsBlueCamaro]

Did you have to do anything special to mount the Hydroboost to the firewall? Sounds pretty awesome. :)

[dipren443]

Did you have to do anything special to mount the Hydroboost to the firewall? Sounds pretty awesome. :)

To all first gen owners, I am working on a CNC'ed aluminum firewall mounting bracket. Please contact me via email for details. You can also search my username on NastyZ28 (same as here). I already made brackets for the second gen guys. The prototype is done and will be test fit in the coming weeks....

[email protected]

https://static1.pt-content.com/images/pt/2008/02/1stgenhydraboost7_5-1.jpg

https://static1.pt-content.com/images/pt/2008/02/Firewall-1.jpg

[CliffsBlueCamaro]

Any updates? Could you snap some pics of how you mounted everything, and how you ran the lines?

[hotrodf1]

Sorry it's been so long since I wrote anything here. I'll try to snap some pics for you guys and post them up. Hard to see the lines past the Vortech, but I'll see what kind of shots I can get. Who knows, I might have taken some pics when I did it, can't remember.

[hotrodf1]

What did you do for lines? I have an IROC pump and hydroboost already installed, but no lines to the hydroboost yet.

I used lines from a Diesel powered Olds Toronado, maybe 89 vintage or so, think I have it written down somewhere. They are available at Advance Auto or wherever you buy "stock" parts. I did have to make some extra bends in the steel portion of the lines to make them fit, but I think they turned out pretty decent. Not quite as neat looking as the stainless braided, but MUCH cheaper. Note: these lines are the new style O-ring fittings, so you'll need a late model style PS pump, or at least change out the fitting on the pump to the late model style. That whole valve piece can be swapped out I think.

it's funny, I was in the process of doing a full blown write-up, but then thought that most people probably wouldn't gain anything from it. I guess there are a few guys kicking ideas around out there after all.