rugerm44

I have fooled with my brakes till I'm blue in the face.Decent pedal but too much pedal travel.I don't like the looks of the hydroboost unit but I'm tired of bleeding and bleeding.It will lock up the brakes but its to close to the floor for my taste.

DRIVESHAFT

Hydroboost wont change that.
A brake booster does 1 thing. It makes the pedal easier to push.
If you have a low pedal now it will be low after changing the booster.

rugerm44

New everything.Checked everything.With mastercylinder outlets plugged one inch of brake pedal travel.New oringed calibers,booster,mastercylinder,SS flexlines.Nothing wrong with booster or mastercylinder.Just tired of screwing with it.Bleed it with a diaphragm pressure bleeder.No leaks in the system.So you tell me.

HamadUP

Are you sure you used both nipples on the rear calipers to bleed the fluid? .. I had a similar situation and the reason was that I wasn't aware of the second bleeding nipple on the rear calipers.

you can pin point the problem source if you have rubber brake hoses, use a vise grip to lock all four hoses and push the pedal, if its the same, then the problem will be from the m/c, if it turned hard, then release the vise grips one by one to figure out which caliper is causing the problem.

noonie

These old GM systems always were soft compared to modern ones.
I used a larger 1-1/4" master to raise and harden the pedal feel a bit.
Just a different alternative.

rugerm44

I can bleed the brakes on a 69 camaro in 20 minutes.This thing takes the cake.The camaro has pb and dosent have the travel this one has.Just frustrated guys.Yes I have bleed the rears inside bleeder first.I have never delt with a car this stuburn to get a decent pedal on.The camaro dosent have the travel the vette dose.The car was a manual brake car to start with.Everything is new.I know the rod behind the mastercylinder is the right length because the pedal only travels about an inch and gets rock hard with plugs on the mastercylinder.That's with the engine running.Booster works fine.Plenty of vaccum.No leaks anywhere that I have found.Brake light is out.Brand new brake light switch or proportioning valve as some people call it.The only thing I have noticed is I can't get it to gravity bleed.I get plenty of fluid to bleed with the pressure bleeder.Like I said it will stand on its nose if press hard on the pedal.When I bleed the front calibers I notice if I let the pressure drop to 10 to 15 lbs I get nothing but tiny bubbles out of the bleeder but as soon as I increase the pressure up to 20lbs the bubbles clear up.The rear dosent seem to do that.The brakes on a wide body aircraft don't give me this much grief.The only thing I haven't done is put a longer Clevis on the pedal rod.Like I said with mastercylinder blocked off there's very little travel.So I don't think the length on the pedal rod is the problem.

Jeff_Keryk

Difficulty in bleeding brakes is the #1 issue with these cars. I have worked on cars all my life and have done 2 complete brake jobs on C3's. I could never get a pedal. My only succees was using a Motive Bleeder and adjusting carb idle mixture screws for maximum vacuum. It should not be this hard. If my 68 were not so original, I would install a hydroboost.

rugerm44

I even went one step further and bought a Branic pressure bleeder with a diaphragm to separate fluid from the air.My car has the original block and heads,trans and rear end but I would still put in the hydroboost if it would fix the problem.I have only driven it a couple of times this summer.It's just unnerving with the pedal that close to the floor even thou it stops great.

72LS1Vette

I've had a hydroboost unit sitting in my garage for almost a year and haven't felt the need to install it because the stock brakes work fine. The pedal doesn't feel soft and doesn't have excessive travel. I did rebuild the calipers with VB&P O-rings and the vacuum booster and MC had been replaced a few years ago. IIRC the rod to the vacuum booster is adjustable so maybe you could get a better pedal feel by adjusting it. There should be specs either in the AIM or the service manual.



Rick B.

rugerm44

Its adjusted all the way out.The only thing I could do is modify the clevis.I have both manuals.

HamadUP

If you don't get a good stream of fluid at 10-15 PSI, then definitely you have something wrong, some blockage in line maybe or even a brake hose that starting to deteriorating from the inside. I can get a good stream of fluid at 8-10 PSI very easily.

rugerm44

The po put SS flex lines on it 5 years ago changed out everything and put dot 5 in it.I have read everything I could find on how to deal with the dot five fluid.I don't have any calibers hanging up or pulling to one side.I have read that othere people couldn't get them to gravity bleed either.The calibers are brand new o ringed variety.I changed out the hard lines going to the rear calibers.Like I said it will lock up the brakes without any problem.It's just that the pedal is only about an inch off the floor when it dose it.It's a big pain in the butt to get to the pedal clevis with the vintageair ducts I put in but I might go to a longer clevis.The thing is it dosent have that kind of travel when block off the ports on the mastercylinder.Just when the system is hooked up.It didn't take me this long to put the va system on.I'm going to get to the bottom of this if its the last thing I do.If I have to put an entire aftermarket brake system on it.I'm not going to rest till I get this dam thing figured out.

noonie

If the pedal is at or very close to the top limit of travel, a longer clevis won't help. Pull the clevis pin and see if the pedal will move higher.

jotto

Did you bench bleed the new MC before installing it and what fluid are you using? You mentioned DOT 5 but is is standard fluid or silicone based?

rugerm44

Silicone,tilted mastercylinder and bench bleed.Third new mastercylinder.Blocked off outlets and with engine running pedal hard as a rock.I'm at work right now but when I looked at it last time there was only about 3/4 of an inch left that I can pull the pedal up.Then you run into the brake light switch and bracket.

jotto

Was the system completely disassembled and flushed through completely before using the new fluid?
I have seen it turn to mush when mixed with a tiny amount of glycol based fluid.
Also, as water sinks in it, any moisture in the old system can be trapped at the bottom of the calipers causing a similar issue.
Hope you get it sorted soon.

rugerm44

Me to.I have flushed probably 2 gallons of fluid thru it.The po changed mastercylinder and calibers and flushed the lines back in 2006.I converted it to power brakes and put new booster,3 new mastercylinders,new hard lines to mastercylinder.New hard lines at rear calibers.New brake switch under the hood.This has been an ongoing problem for about a year now.I have spent more time fooling with the brakes than putting on the vintageair system.Wouldn't be so bad if I was getting some place with it.

bucky katt

sorry for the dumb question but i am a total novice when it comes to Corvettes and really, GM products in general. what IS hydroboost?

rugerm44

Hydraulic brake booster.Runs off power steering pump.Comes factory on some trucks,busses.

MN80Vette

The Hydroboost on my '80 came from a '97 Chevy 3/4 ton pickup. I needed to do something with my brake booster because it was leaking (evidenced by hissing). A few other guys in our car club switched to Hydroboost. I liked the way their brakes worked, so we did the same on my '80. I am really glad I did the conversion. Our son is a CNC machinist. He made a mounting plate to make the Hydroboost rod length the same as the vacuum boost rod length so the distance to the brake pedal is the same.

Here's the link to my Hydroboost install thread:

Hydroboost install complete with pics