Brake Woes

[gedmeyer]

Everything seems to be working well after the rebuild...except for the brakes. The pedal has to go to the floor to get any kind of stopping (very minimal at that). I've bled the brakes twice now (the front calipers were removed during the rebuild). The first time, I just bled the fronts. The second time I did the backs as well. I followed the bleeding procedure in the manual, but I still have no bakes. Also, the brake indicator light stays lit.
I checked the vacuum line that runs to the brake booster and it seems like it has enough suction (you can hear it when it's unhooked and it grabs your finger if you put it up to it). Also, if you are at idle and pump the brake several times, it starts to firm up a little bit.
Would you say I still have air in the lines, or do I not have enough vacuum? I did put a different cam in during the rebuild (383 stroker), but I think it should have enough vacuum. The manualis a little vague on the vacuum information.

Thanks!!!
-Gedmeyer

 

[22229stingray81]

I'm assuming you've replaced the master cylinder?? Same problem I had when mine went south, also needed the calipers rebuilt. I'm sure someone else will come along and help. Also I've heard of rotor warp bringing in air bubbles, have you checked the rotors?


-Tatortot

 

[gedmeyer]

I didn't replace the master cylinder. I repaired a leaky caliper and changed the front brake hoses. I wouldn't say warped rotors caused the problem b/c the pedal goes to the floor immediately, not after any driving.

-Tim

 

[22229stingray81]

I would most certainly say it is a bad master cylinder. Someone who knows more will be along soon.

-Tatortot

 

[Corvette-Dave]

i had the exact problem you have described about a month ago. I had a leaking front caliper and i had to push the pedal all the way to the floor. I replaced the front calipers and rotors, but i still had the same problem. I took it to a shop and they told me there was a lot of air caught in the system. They vaccumed out all of the air and it works great now.

 

[gedmeyer]

hmm.. where is all that air trapped? I just bled the fronts again, this time using a clear hose and there was no bubbles to speak of.

 

[JohnZ]

Keep bleeding - you still have air in the system; do the rears first (two bleeders on each caliper, not just one like the fronts), then do the fronts, and make sure the reservoir on the master cylinder never runs dry or you'll have to start all over again. I'm assuming you had a good pedal before you did the rebuild.

 

[gedmeyer]

Yeah, brakes were fine before. After this last bleed, they were a little better, but it still needs more. I mgiht just break down (no pun intended) and pay a shop to pressure bleed them. We'll have to see.

-Tim

 

[GTR1999]

Invest $60 in a Motive Pressure bleeder. They work very good and then bleed starting from the rear calipers doing both sides of each caliper. Be sure you have fluid without bubbles from each line.

 

[Robin7TFour]

Tim if you do decide to continue and bleed them yourself , use this sequence; right rear ,left rear ,right front ,left front. allway work the farthest to closest to the m/c . also, you may want to carefully bleed at the master cylinder also. air will alway try to go the the highest point..
good luck

Robin

 

[Ludigdrums]

I think bleeding sequence might be different for the later years. I have an '81 and the service manual says:
Left Rear Inner, Left Rear Outer, Right Rear Inner, Right Rear Outer, Left Front, Right Front. (Right being passengers side, and Left being Drivers side)

Hope that helps!

- Jeremy

 

[SMKN97GP]

i have a similiar problem. the car still stops fine, but i have to push down the pedal pretty far. im guessing the master cylinder needs to be replaced.

 

[gedmeyer]

I re-bled the front brakes again last night (third time). I went through a little more than those small bottles of prestone brake fluid and it still doesn't feel right. I get a little pulling to one side as well. I'm going to check the pistons this weekend to make sure none are binding. This is frustrating because I am not 100% certain of what the "feel" really should be on a 1981 corvette.

This wouldn't be a low vacuum problem, would it? I do have a new came (comp cams magnum serires 260H I think)

-tim

 

[Culprit]

Howdy,

You might want to read what I wrote in this thread: http://www.corvetteactioncenter.com/forums/showthread.php?t=44819&highlight=speed+bleeders

Sorry I'm not up to speed with inserting clickable links. If that address above doesn't work, just search the C3 forums for a thread titled "Speed bleeders anyone use them?"

The thread talks about a really cool product called speed bleeders, as well as using a vaccum pump. Either method works great, and when used together bleeding breaks is super easy.

Semper Fidelis,
Culprit