I feel for you bro..... I know how long you've been f...ing with that problem.

 

repeat after me;

#$&%(&^&)()+)*(%^#^)*)^ !!

 

I know what you mean.. If you check every day you will probably find them a lot cheaper.. Just so happened when I looked the other night there were only a couple listed and they were pretty high priced...

 

I guess this might be repetitive, but for future reference:

A soft pedal is a bad master.

A hard pedal is a bad booster.

 

.....i myself realize that but, booster holds and maintains vacuum....

 

jsup, i would recommend going straight to a metal booster, regardless. here's one for $150, p/n B3B 2410908: http://www.hotrodsusa.com/store/boosterchev.html

it will withstand underhood temps much better than plastic....... and if you're doing any worthwhile performance upgrades -- which must start with long tube headers for your L98 -- then metal is mandatory.

plus it is at least $50 less than plastic OE.

 

I posted this a while back - check it out.

http://forums.corvetteforum.com/show....php?t=1725556

Matthew

 

My 89 brakes fine, but the brake feels like a rock. I also have an 89 Firebird and it has a firm brake, but the Vette's brake feels like I'm pushing on a rock. Is this the booster, or something that needs adjusting?

I've also noticed that the steering is kinda hard as well. ???

 

To the OP..If the car stops fine and your pedal isnt sinking, leave it alone!

Im not so sure about that vacuum testing...Most cars Ive had when you hit the brakes from the inside youll hear a whoosh noise, is there a small relief hle of some type in the rear of those?

Josh...89s had quick ratio steering boxes, at least most that I know of. Low speed turning effort is a little higher than "normal". Its when you are at speed you get the benefit of changin lanes "instantly" from the tighter ratio rack. I hate the slower one in my 90.

 

In some cases, but there are more probabilities.

A soft pedal could be a leak anywhere in the system, could have air anywhere in the system, could have old fluid in the system that has gone to sludge.

A hard pedal doesnt mean the booster has failed. It means its a possibility, but certainly doesnt point a straight finger.

If you start the engine with your foot on the brake, in normal cases you would feel the pedal become easier to push as soon as the engine starts up.

If you dont, there is more than 1 probable cause for that, booster is 1, the vac hose to the booster is 2, buggered check valve on the front of the booster is 3, blockage in the vac fitting on the manifold is 4, leaking vac fitting on the manifold is 5, seized brake caliper is 6.... All those are possible.
That doesnt mean a thing.

As long as the front and rear main seals in the booster are good, and the reaction disc isnt damaged or badly worn, the booster will hold vacuum normally until the pedal is applied no matter what else is wrong with it.

The way the booster works will mean it should do that even if the main diaphramn is rooted.

When the brake pedal is released, vacuum is applied equally throughout the front and rear of the booster shell, the main diaphramn is attached to the vacuum piston in the middle. There is a valve in the centre of the vacuum piston, this is actuated by pushing on the pedal.

When the pedal is pressed, the valve will be pushed forward and the reaction disc moves to seal the vacuum in the front half of the booster, and at the same time, it opens the rear half of the booster to atmospheric pressure (from inside the car).

Releasing the pedal will then allow the reaction disc to open the front half to the rear, and at the same time sealing off the atmospheric intake to the rear of the booster, the return spring will push the vacuum piston back to released position, vac level will equalize between front and rear again.

If vacuum was only ever applied to the front half of the unit, the vacuum piston would be drawn forward the minute you apply enough vacuum to it and it would stay there.

 

It has more effort at all speeds. I figured the quick ratio steering just meant the car was more sensitive to steering wheel movement.

 

Ok, I tried adjusting the passenger side line again. That didn't work. I nearly had the thing wide opened, and it still wouldn't pop up on its on. The driver side does just fine.

So, do you think that spring might need to be replaced?

 

What are you talking about??

 

^^^^^^^^^^^^

"....If you dont, there is more than 1 probable cause for that, booster is 1, the vac hose to the booster is 2, buggered check valve on the front of the booster is 3, blockage in the vac fitting on the manifold is 4, leaking vac fitting on the manifold is 5, seized brake caliper is 6.... All those are possible........"

....going by what the forum has told me and what "the book" has said, i know of no other legitimate tests to perform to test the booster.*1 vacuum is high and steady, *2 have replaced and used 3 vacuum booster check valves in the booster and all with the same result, *3 no vacuum leaks in any lines anywhere, *4 integrety of the brake vacuum hose is excellent, *5 vacuum port at manifold is intact and secure, *6 all brake calipers move and retract as they are supposed to, *7 no leaks in hydrolic system whatsoever and none at calipers, *8 new rotors and pads, *9 new s/s flex lines, *10 new master cylinder, *11 multiple flushes with dot 3 brake fluid, *12 abs does self check on startup- 4mph, *13 no codes........yawn....pcolt had very same problem and he wound up doing the j55 band-aid and is working well for him..i believe that the c-4 brakes (mine is 88) should not be this crappy - PERIOD...and so the merry-go-round starts again...one should not have to "j55" there car to get good brakes....pcolt did the same "replacements" as i (even replaced the booster if i am correct) and the abs and he told me that his brakes still $ucked untill he replaced his calipers and rotors (j55)....other then the 1'' increase in rotor size and the obvious associated increase in caliper size, that was the only difference that made a difference......is the j55 caliper able to "generate" more pressure on the rotor then the standard c-4 brakes when the same abount of pressuer is applied HYDROLICALLY?

 

None of that part was dirrected at your post. But since you state all that and forgot to add the ABS prime pipe ill have to ask whether or not your car has it, and if it does, whether or not you bled it, cause if it does, and you didnt, dont expect anything to work factory perfect.

My post to you starts at the line that goes like this:
After that, i explained exaclty how a vacuum assist brake booster works.

What tests did you perform on the booster? By the looks of it and the section you have in italics above, im only able to guess that when you start the engine with your foot on the brake, you feel no brake assist.

You only state the booster vacuum, which means to me you only tested the front and rear main seals on the booster and nothing else. The rear seal could be totally gone and yet the booster will still provide exactly the same level of vacuum assist, cause the rear seal shouldnt be subject to any forces (internal or external) when the pedal is applied. With the pedal applied, the rear half of the booster is subject to atomspheric pressure equal to that in the cabin of the car. With the pedal released, the only seals doing anything are the front seal, the rear seal, and the reaction disc.

You dont state testing the booster with the pedal applied, and if you didnt do that, you may as well not tested it at all. When you release the brake pedal, the vacuum level in the booster WILL drop if the unit is working as it should.

There is no way known it can maintain the same level of vac when it is going from a vacuumed front half and a 100KPa rear half, to a fully vacuumed shell front and rear.

Is there some part of the brake booster function youre not understanding?

The J55 caliper doesnt generate anymore pressure than a JL9, they both use the same pads, the contact area is exactly the same for both, but the J55 are a larger diameter, which means more mechanical advantage.

As a test if you dont allready know, get a long breaker bar and undo a wheel lug nut with it, but first do it by pulling on the breaker bar from half way, then try it again from the same torque level and pulling the breaker bar from the end. The bigger diameter brakes work the same way.

 

********************

None of that part was dirrected at your post.
**sorry 'bout that as i thought it was

But since you state all that and forgot to add the ABS prime pipe ill have to ask whether or not your car has it, and if it does, whether or not you bled it, cause if it does, and you didnt, dont expect anything to work factory perfect.
***unsure as i had not checked it. i have bled the brakes and flushed numerous times and suffer from a hard pedal not a mushy one. the brakes are like fred flintstones' and don't stop worth a "x"hit!....i don't and never had any air in the system to warrant bleeding the abs and i surmise that bleeding the system with the key on or off (if it makes any difference or not) has not changed a thing.
My post to you starts at the line that goes like this:

After that, i explained exaclty how a vacuum assist brake booster works.
***i do know how it works and what it is supposed to do.

What tests did you perform on the booster?
***applied a steady vacuum to the booster via front check valve, killed the vacuum and it held for a sufficient about of time. that in my mind, tells me that the booster is holding vacuum and is not leaking.

You only state it holds vacuum, which means you only tested the front and rear main seals on the booster and nothing else.
**yes i did.

The rear seal could be totally gone and yet the booster will still provide exactly the same level of vacuum assist, cause the rear seal shouldnt be subject to any forces (internal or external) when the pedal is applied.
***if the rear seal was gone, would there not appear a vacuum leak and if not, WHY?

With the pedal applied, the rear half of the booster is subject to atomspheric pressure equal to that in the cabin of the car. With the pedal released, the only seals doing anything are the front seal, the rear seal, and the reaction disc.

You dont state testing the booster with the pedal applied, and if you didnt do that, you may as well not tested it at all. When you release the brake pedal, the vacuum level in the booster WILL drop if the unit is working as it should.
***i have 3 vacuum brake boosters here and all do the same thing (re:vac).. after i shut down the car i can pump the pedal and the pedal will get stiffer to the point that all the vac is expelled from the booster...there is NO vac leak when the booster is applied (other then what it is suppoosed to do)...

There is no way known it can maintain the same level of vac when it is going from a vacuumed front half and a 100KPa rear half, to a fully vacuumed shell front and rear.

Is there some part of the brake booster function youre not understanding?
***not as far as i know...i do know that all 3 boosters do the same things as previously discussed.

The J55 caliper doesnt generate anymore pressure than a JL9, they both use the same pads, the contact area is exactly the same for both, but the J55 are a larger diameter, which means more mechanical advantage.
**i understand that perfectly..

As a test if you dont allready know, get a long breaker bar and undo a wheel lug nut with it, but first do it by pulling on the breaker bar from half way, then try it again from the same torque level and pulling the breaker bar from the end. The bigger diameter brakes work the same way.[/QUOTE]
***i DO understand about leverage.

 

Well why am i wasting my time here at 10 past midnight trying to help you if you know everything about it?

Sounds to me like your brakes are working as they should. If the rotors are within thickness spec and youre using genuine PBR pads they should pull the car up fine.

That was missing from the last 2 posts, if i hadve known that fact i couldve saved alot of time.

Hopefully youll find out what the issue is there

 

hey look, you asked questions and i supplied answers, that's it...i NEVER claimed to know all about it and that is why i am here and asked/responed to the posting!...stock pads too and brakes still $uck......ok, thanks for your "insight"........next..

PS..response well taken

 

I'm gonna have my brakes looked at when I go to the Dealer tommorrow for an oil change.

The brakes are rock hard. It doesn't really feel like I depress the pedel. Though, it does stop. I also notice sometimes what feels like a short "kink" in the brake when I'm turning slow. Kinda like the brake part bumped into something.

 

What brand are you refering to as "stock pads"??