wolftamer389

Hello,

I have an 86 camaro and it recently started braking oddly. When I first start the car the brakes seem to work fine. At about the 3rd or 4th light I have to really push hard on the pedal to get it to stop. Even pushing that hard the brakes don't seem to "bite" hard enough to stop the car safely.

When I went to check the fluid level I noticed that the rubber part of the cap was bent out of shape like it had been sucked down and held there long enough to deform. I replaced that rubber part today, thinking it was the issue, but it still acting the same.

I am getting ready to bleed the brake lines in hopes that a bleed will fix the issue.

If bleeding doesn't fix it what's the next step in getting this solved?

Thanks for your time.
-Stew

Beeman

Get in the car and pump the brake pedal with the car off. Now with your foot on the brake pedal start the car. When the car starts the pedal should drop as the vacum booster receives vacum. If it doesn't start by checking the vacum hose to the booster and the ck valve. If all cks good you might have a bad booster.

antares57

iTrader: (8)

What Beeman said, check this out.

https://www.thirdgen.org/forums/brak...enly-went.html

sofakingdom

iTrader: (1)

If the master cyl leaks in such a way as to let brake fluid into the booster, a cascade of positive-feedback failure will occur:

The brake fluid will eat the diaphragm in the booster
The booster will leak vacuum into the chamber connecting with the back end of the MC
The vacuum will suck fluid out of the MC, which will leave the cap collapsed as visible evidence
The brake fluid will eat the diaphragm in the booster
The booster will leak vacuum
The vacuum will suck fluid out of the MC
The fluid will eat the diaphrgam
.
.
.

Obviously, a self-reinforcing accelerating downward spiral. You end up with a MC that doesn't work the brakes, and a booster that doesn't boost, and everything eats everything else and makes it get worse faster.

Sounds like that's where you are now.

I'd recommend a booster/MC assy... surprisingly cheeeeep actually.

wolftamer389

So am I looking at needing to purchase this:
http://www.autozone.com/brakes-and-t...?checkfit=true

Or is there a way I can repair the one I have with new gaskets/springs/etc?

antares57

iTrader: (8)

I picked up a used brake booster from the junk yard and haven't had a problem since.

sofakingdom

iTrader: (1)

That looks like the right thing.

JY is probably not the best choice in this situation... gotta have both the booster and the MC since the one is killing the other and now you need both anyway. If it was just the booster alone going bad, then, yeah; but not when both are toast.

wolftamer389

The part is here and it all seems to be in order. I was reading about the need to bench bleed the master cylinder. I don't have a garage or space to do a bench bleed. I was thinking I could install it then use some tubing to bleed it back into the reservoir to avoid there being any air in the cylinder before I connect it to the lines.

A lot of the things I've seen on here about the job say I should bleed the lines too so that the system has completely new fluid. If I am going to bleed the whole thing do I need to bench bleed the MC or will that happen as I bleed the lines?

Thanks again for all the help guys!

bigal55

iTrader: (1)

You don't want to connect the brake lines until you bleed the master cylinder.

I was thinking I could install it then use some tubing to bleed it back into the reservoir to avoid there being any air in the cylinder before I connect it to the lines.

Good idea! You don't want to be chasing that air all the way through your brake system. Bleed the master cylinder. Connect the brake lines. Do a brake system bleed.
Done! GL!

sofakingdom

iTrader: (1)

No that WILL NOT work no matter how much wishful thinking is applied.

Pushing the air through the system doesn't matter in the least.

The REAL problem is, at the angle the MC sits at in these cars when installed, the line fitting is NOT at the top of the cylinder, meaning, there's a certain volume of the cyl (both cyls actually; front and rear) that ends up located ABOVE the fitting. Air CANNOT get out of there and into the fitting, whether you use plastic tubing, the actual brake lines, or anything else. The air will simply float up there untouchable. You can bleed 10 gallons of fluid through it using any method you want every single day, and even do it twice on Sundays, and you will NEVER get that air out, not in a thousand years. Your brakes will STAY mushy FOREVER.

You MUST bench bleed it. Posting a bunch of excuses on here about "it's hard" won't make the air jump down out of there. The parts (and the air) aren't listening to any whining and don't care.

Bench bleed the MC before you put it on. No excuses.

Beeman

Bench bleed the MC first. I use a bench bleeding kit with fittings and clear tubing so you can see the air. Once you're very satisfied you have all of the air out let it sit for a few minutes and bleed again. The install on the car and bleed at the 2 lines where they attach to the MC. Then go and bleed the whole system starting at the RR,then LR then RF then LF.

wolftamer389

All the bench bleed tutorials I see say to place the MC in a vice, connect tubes, add fluid, then push press/depress the plunger on the MC.

Are you saying because it's inclined when installed there will be an air pocket near one end of the cylinder?

Any tips on bench bleeding this thing without a vice or workbench?

Beeman

Air always rises to the top which is why if the MC is pointing upward the air will be trapped at the frt.
If you place it in a vise don't clamp the body, clamp the flange. No vise, no workbench? I'm sure with some ingenuity you can fab something to bolt or clamp the MC.

sofakingdom

iTrader: (1)

Precisely. The pocket is above - farther from the surface of the earth than - the place where the line hooks up. Therefore the air can't get out because it would have to go DOWN, through the fluid, to get there.

Gotta bench bleed it. No excuses. No options or alternatives. You can do it with it sitting on the ground, with nothing but a big stick, if you don't mind making a bit of a mess.

The little plastic tubing things aren't the important part (although they are quite helpful, they're not the total answer); getting the MC level so that the line fittings are at the highest point, IS.

wolftamer389

I got the brake booster and MC changed out. All fairly easily. Now I have a new issue. It looks like the proportioning valve was cross threaded on the last installation.

I have been looking at prop valves all evening looking for the correct part for my car. I've even looked in my parts catalog for it but the catalog only has 70s prop valves.

I found a few on ebay but not sure if that is a safe route to go for this part.
http://www.ebay.com/itm/86-89-CAMARO-FIREBIRD-PROPORTIONING-VALVE-Brake-tpi-87-Front-Disc-Rear-Drum-88-/172007354523?hash=item280c6ff09bhttp://www.ebay.com/itm/1986-1989-Camaro-Firebird-Brake-Proportioning-Valve-Drum-Disc-87-88-/321873331692?_trksid=p2141725.m3641.l6368http://www.ebay.com/itm/1986-1989-Camaro-Firebird-front-disc-and-rear-drum-brake-proportioning-valve-/291627923831?_trksid=p2141725.m3641.l6368
I also found a bunch of aftermarket parts like this:
http://www.summitracing.com/parts/ssb-a0707-1/overview/
and this:
http://www.summitracing.com/parts/wi...8419/overview/

Has anyone used these before?

Universal usually means doesn't fit your car correctly. - My brother(The mechanic)

wolftamer389

Sorry for the image links, not sure why that happened, the preview didn't look like that. My bad