Hi
FRICTION is what you are missing, you need a high friction brake pad in a early c4.
this is a typical symptom of standard soft brake pads, they will protect your rotors from wear but need a lot of pedal effort to slow your car.

Try hawk hp plus brake pads, they are perfect for track days. Corvette central stocks them, they will give you a massive improvement needing minimal brake pedal effort.

A brake bias spring for better rear brake balance is available, or just fit an adjustable rear bias valve in the rear brake line under the car.
They are great for tuning your brakes for the track, or when multiple front piston callipers are used.
the rear will lock without a bias spring or adjustable brake bias valve to control the rear brake bias.

Standard road car brake pads may only do a few laps before disintegrating, they cannot stand the heat.

I had the standard early c4 brakes for many years before upgrading to larger brakes for track use and can assure you they work well with a high friction (metal content in the pad material)
if you are not going through 3 to 4 sets of brake pads, before needing to replace your disc rotors you don't have enough friction.

That is how modern road cars work shedding brake pad and disc material (including heat)
my c4 pedal feel is no different to a modern car, easilly slows the car minimal effort required.

If the booster leaks you will hear a hissing sound, DO NOT FORGET ABOUT THE ROD FROM BOOSTER TO MASTER CYLINDER, that needs to be adjusted correctly.

 

If that is the case, there is something wrong. Either the booster is bad or your pads are glazed. A booster can be bad without having a crack in it .

 

I agree.

 

Well its been a busy month, work ate up all my time so im finally just now getting back around to working on my vette. I'm leaning towards glazed pads, they seem new but don't have any grip, I'm planning on doing a brake revamp since my E-brake will apply but won't release unless you load her up a bit. I made the decision yesterday to move forward with LS swapping my vette just in terms of reliability and economy so thr brakes will be one of the thing I need to improve by the end of that project. I measured the brakes on my truck and they're 13" with a larger pad then the C4 so I may try mocking it up at some point, but for now just gonna get the brakes operating as they should. Gonna give the high friction options a shot.

 

i will share my experience and thoughts.

First, for the poster who has to really stomp on his/her brake pedal/pads, been there with my 85,86, and 87. two things fixed it to the point where i took the car to the track and did roughly 15 minutes sessions and it was great for an entry level driver like myself. remove pads and place them pad side down onto a piece of sandpaper and sand the face off. created lots of dust. and i used one of those sandpaper sponge blocks i had to sand the face of my roters. this is just a scuffing. then i bled my brakes, using the one person into coke bottle method which is the only way i have found that assures no air gets sucked into the threads of the caliper bleeders. its possible you have crap for pad compounds. you can buy great pads for factory c4 brakes that work great. this is for street and for your first couple times on a hpde track day. also, im not sure why, but if you have abs (86+) i have found that excercising the abs on a small patch of gravel road (im talking find a gravel road, and drive for 20ft, then stomp brakes and let them cycle. im not saying go for a drive on the gravel road) will absolutely increase the pedal feel. i read this on the forum years ago and it really solved my hard / dead pedal on my 87 and still do not know why it worked it just did.

but once you get past your second track day and your sessions are lasting over 15 minutes, you pretty much have to upgrade. my first upgrade on my 86 was to grandsport j55's which were the stiffest and had the least flex. these really did awesome for me. i used the "trackday" kit pads and rotors from powerstop. plenty of dust! but great stopping.

i used those for this whole past season and to be honest i probably would have used them again this season had it not been for a true racecar driver instructor sitting down behind the seat of my car (now a 91 zr1 with factory j55's) and he made me poop my pants just a little bit and exposed the great weakness in my car as ....the brakes. it didn't take more than 3 laps and they were cooked. this is becuase at the higher levels you brake VERY HARD to get most of your slowing down in as short a time as possible and it seriously heats up the brakes. honestly i might be allright with j55's for another season because i don't think im ready to go as fast as my instructor did....but when i do upgrade i am skipping the c5's and going to a non slide pin version such as the c6z06 or ctsv gen 1.

so, my thoughts are that if you are street driving only or spirited, even with very early days of track time, just get a track day kit on your existing setup! there is no street driving that wouldn't end up in going off the road that the early brakes cannot handle. as long as they are bled good, not glazed. good luck in your decision!

 

I'll give the sanding a try, I'm also thinking of doing a brake flush as its got a weird color to it and see how that goes. Car suddenly doesn't want to run so, it's got no or weak spark, won't even run on starting fluid so got more gremlins to sort out before I can focus on brakes.

 

corvette central had a caliper bracket for J55 caliper on early C4. I think this is the bracket used on the challenge cars. They were @$100 each if I remember right. They will fit under 16x9.5 wheels. carbotech bobcat pads don't have hardly any dust and stop good on street.

 

I see this post is over a year old but I am interested in ibvetn2’s j55 brake adapters if you still have them….let me know thanks rickman903

 

using hawk brake pads makes a big difference.

 

https://www.corvetteforum.com/forums...-to-j55-2.html


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