Brake Power Booster Removal Suggestions?

[LVMYVT76]

If your master is empty in the rear, the fluid is going somewhere, wither the master is leaking or somewhere else is leaking. Need to find out where the fluid went and correct that problem.

 

[dshanks]

So I finally have brakes. The first symptom I had was on Sunday after getting off the highway no amount of force could bring the car to a quick stop. If I pushed down the brake pedal, the car would eventually stop, but ever so slowly.

Ive been wondering if mine is bad. It feels spongy about 1/2 way down. During this spongy part, the brakes dont function at all.
About 1/2 way down, the pedal gets hard but doesnt feel nice. I have to jam on it to get it to stop in a decent distance. Very dangerous...
Also, when it hits the hard part of the pedal stroke, the "brake" light comes on-on the tach(? maybe speedo, theres no guages in the car right now..)

 

[LVMYVT76]

Check the hoses that go to the calipers also, they can make your peddle feel soft. They balloon out when they are week. Stainless ones will correct this.

 

[dshanks]

Check the hoses that go to the calipers also, they can make your peddle feel soft. They balloon out when they are week. Stainless ones will correct this.

All new brake lines. they arent stainless, but they are brand new...

So this wouldnt be the problem. Were talking VERY squishy, like the car would roll on its own with the brakes applied until you hit the hard spot of the pedal stroke...

 

[street carp]

Ive been wondering if mine is bad. It feels spongy about 1/2 way down. During this spongy part, the brakes dont function at all.
About 1/2 way down, the pedal gets hard but doesnt feel nice. I have to jam on it to get it to stop in a decent distance. Very dangerous...
Also, when it hits the hard part of the pedal stroke, the "brake" light comes on-on the tach(? maybe speedo, theres no guages in the car right now..)

You might want to do what SR7D1 did and replace both booster and MC to be safe (as I eventually did as well). My initial feeling was the MC was shot, but the brakes had worked for months even with the spongy pedal. If the power booster went on me at a critical time people including me could have died.

Unlike you my brakes seemed to work good besides the spongy feel and long travel it took to reach the braking.

If you can do it yourself, you can do it for cheap (around $150 total), but as you've read the labor is intensive.

 

[dshanks]

You might want to do what SR7D1 did and replace both booster and MC to be safe (as I eventually did as well). My initial feeling was the MC was shot, but the brakes had worked for months even with the spongy pedal. If the power booster went on me at a critical time people including me could have died.

Unlike you my brakes seemed to work good besides the spongy feel and long travel it took to reach the braking.

If you can do it yourself, you can do it for cheap (around $150 total), but as you've read the labor is intensive.

My braking is not quite good. If it were a female driving it would be impossible to stop...
But theres hope, Im lucky!
My dash is currently apart!

 

[JohnZ]

A spongy pedal means air in the system, and if the "brake" warning light comes on, that means there's a pressure differential between the front and rear systems, which also indicates air (more in one system than the other).

The best money you can spend is $60 for a Motive Products pressure bleeder (www.motiveproducts.com) - bleeds any Corvette disc brake system in ten minutes and you'll have a nice hard pedal; puts any other method to shame.

 

[dshanks]

A spongy pedal means air in the system, and if the "brake" warning light comes on, that means there's a pressure differential between the front and rear systems, which also indicates air (more in one system than the other).

Could air in the system make such a poorly feeling pedal? im not sure if spongy is the right description, it just flat out doesnt work unless you jam on them while in the "hard pedal" portion of the pedal stroke. And the light doesnt come on til they are jammed on...

The best money you can spend is $60 for a Motive Products pressure bleeder (www.motiveproducts.com) - bleeds any Corvette disc brake system in ten minutes and you'll have a nice hard pedal; puts any other method to shame.

Would this take the place of the method of running a hose from the caliper to a reservior of brake fluid (Bleeder bottle)? It seemed to bleed so easy using that method, does air hide in there and always cause problems on these vettes?

Are they always this difficult to bleed?

[EDIT]
I just found this on another forum where Im having a similar discussion. Is he on to something here?

From gliot1 on corvetteforum.com
I agree with above.....when the booster goes bad you usually get an extra hard pedal, in other words it acts like standard brakes of old. What I suspect is the brakes haven't been bled in the proper sequence, a problem I see here often. C3 Vettes don't bleed in the standard way (farthest to closest). They have a bleed sequence unique to Vettes; this is per the GM manual. I bled for hours in the old standard way; never getting a hard pedal. Once I did it in the right sequence I got a hard pedal on the first try. If my memory serves me right the sequnece is LR, RR, LF, RF. It is my understanding that due to the proportioning set up, if you do it the old standard way you will simple move air bubbles back and forth and never remove many of them from the system. I have helped a few of our club members through this as they didn't believe me. I worked with one guy who races stock cars and he swore I was full of crap. I got the sequence out of the manual, and ran it and within one pass he was convinced and apologized; said he never saw that before.

 

[JohnZ]

You still need the bleed bottle to contain the flushed fluid - Motive also makes a neat vented bottle with a tether on it (instead of using jars, cans, etc.) - photo below.

Your Corvette doesn't have ANY "proportioning" valve anywhere - the proportioning function is designed-in via different diameter caliper bores in front vs. in the rear; proportioning valves didn't come into use on Corvettes until the late 70's. The correct bleeding sequence is ALWAYS RR, LR, RF, LF - longest line first, shortest one last (which is NOT unique to Corvettes). The rear calipers have two bleeders - do the inboard side first, then the outboard side.

 

[dshanks]

The correct bleeding sequence is ALWAYS RR, LR, RF, LF - longest line first, shortest one last (which is NOT unique to Corvettes). The rear calipers have two bleeders - do the inboard side first, then the outboard side.

I used a bleed bottle and was very careful bleeding the brakes in the exact sequence that you described here. Shouldnt I already be "all set" and ready to explore other options to fix my brakes?

I hate to spend the money on the device that you were talking about earlier, because Im already broke because of this car, and Im having to pick my battles here...
If at all possible, Id like to be able to bleed the brakes old fashioned way.

 

[dshanks]

Come to think of it, my brake fluid has come up low a couple times since the bleed but no leaks have been noticed on all the brand new paint under there. Could this be a bad master cylinder leaking into the brake booster? And would that cause my brakes to behave the way they do?

 

[SR7D1]

Update.

I got the booster off last night. That last nut was hard to remove. I got the new booster/master on but was only able to access 3 of the 4 nuts. I can't figure out how to attach the difficult nut since I can't get my hand up there and it seems to just fall back into the deep dish socket I am using. I will see what I can get done tonight.

I have a friend that has the motive bleeder and he is going to loan it to me but there is one problem; he doe not have the MC adapter for domestic cars. Yep, that really sucks.

Are there any forum members in the Cleveland area that have a Motive bleeder I can borrow? You can send me a PM or reply to this thread.

Saturday I plan on bench bleeding the MC, then install it.

Take care everyone and have a great weekend.

PS. What is the proper sequence for bleeding @ the calipers? There are 2 different answers in this thread.

A: RR, LR, RF, LF

B: LR, RR, LF, RF

According to Dave L in a another thread:

GM shop manual states the following sequence...LH rear inner/outer - RH rear inner/outer - LH front - RH front.Get one of these..http://www.motiveproducts.com/ best money you'll ever spend for brake bleeding. One man operation. I flush my entire system every 2 years and it only takes about 10 minutes!


Is answer B the correct method?

 

[JohnZ]

With a pressure bleeder, the sequence really doesn't matter, although the "standard method" has always been longest line first, shortest one last (LR, RR, RF, LF).

 

[Art Jett]

JohnZ---I'm confused! In one reply you said RR,LR,RF,LF. In a reply on the next page you said LR,RR,RF,LF. Which is it?

 

[JohnZ]

JohnZ---I'm confused! In one reply you said RR,LR,RF,LF. In a reply on the next page you said LR,RR,RF,LF. Which is it?

RR, LR, RF, LF.

 

[Art Jett]

Thanks. I'm getting my car back from the body shop this week and I'll be finishing up the brake system. Just wanted to get it right.