Hey guys- I have utilized the search feature on here before posting due to being a member at several other sites and know to always use that as first resort. However I didnt find anyone saying they had the same symptoms as I am having. Heres the deal...
My father bought a 86 corvette with the TPI motor in it. I got it running really good and replaced the valve seals, exhaust, and a tune up and it seems to run strong now. However I am having a major issue with the brakes.
They are extremely firm and barely are able to stop the car. Even when you shift from reverse to drive while not moving and applying a great deal of pressure to the pedal it still lunges and creeps forward. I replaced all the rotors and pads, as I could tell they needed to be replaced regardless.
I checked for any vacuum leaks and cant seem to find any. So next on the list is the brake booster, which seems to be only a couple years old. I found a brake booster test online and ran them it did seem to fail one of the test. After running the car for several minutes and then shutting of it says the pedal should go down a good amount and get slightly firmer with each following press of the pedal. Well I did that but the first press was still hard as a rock, as though I was pushing a brick wall and it only moved very slightly.

My question is there anything else I should suspect before replacing? Could anything else cause this? Or am I on the right track and proceed to replace the booster? Thanks for all you help.

 

I would suspect the booster as well. Does it hold a vacuum? You may want to try running the car, pumping the brakes, then turn the car off. Disconnect the vacuum line from the booster, it should hiss.

 

I vote something wrong with the booster, or the line going to it. No way the pedal should be that firm.

 

Booster, Vacuum.......

 

Do a search in the archives there are some good tips on R&Ring it

 

including one that describes removing the drivers seat and lying on your back at one point in the R&R process..

 

Can you verify that the calipers are clamping front and rear and side to side? Perhaps on the rears are working or something similar. I would expect that problem to come to light as you replaced the pads but maybe you didn't actually check. Do check the piston and opposite side in case the caliper is not sliding.

 

Or the lubrication on the pins...they could be dry

 

You could always do a C5 brake upgrade as well ... Well worth the 800 bucks I spent on mine... but if you are having pedal issues it's got to be the Booster...

 

ok well i will pul the vacuum line off and see if it hisses, is it posible that its just the check alve on the booster itself? When i did the pads they were all worn right down to the metal, no actuall pad left. So I had to put a c-clamp on the calipers to compress them back in to fit the new ones width. They all moved freely and had no issues from what I could tell. Thanks for the responses so far....!!!

 

What you describe is just what it felt like years ago when I had a power brake booster fail.

The brakes were hard as a rock but would still stop well if I exerted enough pedal pressure.

 

Alright thanks guys. I took the booster out and it appears to be in good condition, but that doesnt mean much considering its a plastic unit. I ordered the new one and should get it tomorrow and ill let you know as to the results! I hope this does it. Thanks again!

 

You pulled it that quick?

 

Ya it was actuall realy easy to get it out I thought. It only took me about 30-45 minutes to get it out, not bad at all. Thats stricty to unistall it, and I got the new booster this morning and instanlled in the same amount of time. A lot easier than expected.
Anyways, IT DID THE TRICK.
Much better, its stops effortlessly now. Who new these cars actuall have pretty good brakes when everything functions properly! Thanks guys for all the input, ill be spending a lot more time on here i think. Especially seeing that I now have to fix the broken antenna that is stuck in the up position with no signal what so ever.

 

One down, one to go !! You may have a broken nylon rod that pulls/pushes the mast.
Diagnosis here
http://members.shaw.ca/agent86/Power%20Antenna.pdf