Gotta do something about my brakes. Slam on the brakes at 15 MPH and it takes 2 seconds to come to a complete stop. Any ideas how to improve my brakes?

1985 Corvette

 

There are all sorts of threads here about improving braking performance. Try searching for threads using terms like "new brakes" "better brakes", or "improving braking" which can give you a lot of information.

I assume you have tried simple things like new fluid, new flex lines, new calipers or maybe rebuilding them, and new rotors? What pads do you have on the car now? There are lots of good performance pads available for the early C4 brakes.

 

I bled the brakes when I bought the car a year ago. I flushed the fluid too. Everything else on the brake system is as it was since the previous owner had it. Have no idea the pad and rotor brand.

 

brakes are my next project for my 85....I understand that it's the front brakes which are weak...single piston calipers.....got to upgrade the calipers and have them still fit in your wheels....think you can use c5 rotors and calipers if they will fit in your wheels....I stll have 16"..

 

I would start with replacing the flex lines. As they get old, they tend to get weak and when you apply the brakes, they expand and effectively reduce both line pressure and volume of fluid. Goodridge or Earl's stainless lines are both good.

How much material is left on the pads? If they show wear down to say 25% of new, then I would go ahead and replace them. Hawk makes a good variety of performance pads; for something like autocross and drag racing, try the HPS or High Performance Street pad. This is also a good street pad.

Measure the rotor thickness too. The rotors should have a minimum thickness cast into them. If they are at that limit or close, toss them and get new rotors. NAPA, Raybestos Professional Grade, StopTech, and Centronic all have good street/performance rotors.

Without ABS, you will have to get in some braking practice. Get to where you can stop the car hard without locking up a wheel.

For fluid, use a quality DOT3 or DOT4 fluid. While you have already done a flush, a really good fluid will help handle high temps so the fluid doesn't boil. For a good DOT4 fluid, try ATE Typ200. MOTUL is another excellent DOT4 fluid. For a DOT3 fluid, I hve used the Ford MotorSports HD fluid. You can find that at any Ford dealer parts counter. Also Castrol LMA or Valvoline.

Because I use my 87 for primarily autocross and track days, a few years ago I upgraded the front brakes to C5 stuff. The parts were around $700. But this conversion requires 17" wheels. Look at the Vette Brakes website for info on that conversion.

 

Have you thought about selling this car? You have multiple threads on issues on everything starting from the tune you have no idea on how to correct, the engine (after your modifications to it), the missing issues you have no idea how to correct, the idle issues, the transmission, etc. etc. and now the brakes........either you are over your head on this or your car is a P.O.S.

For those who are reading this thinking I am a jerk, read through his other threads whereby our best members try to help, but this guy has better ideas he heard through his friends....and ultimately the car continues to give him grief and he keeps asking us for ideas that he questions......

 

If you are not going to contribute anything positive or helpful, please do not continue to respond to my threads. Thank you.

 

The pads have probably 50% left I'd say. I just want to get it to be good for the street. I don't really care for brake system set up for auto cross. I'll see if I can find the flex lines and pads and change them when I can get around to it. I was going to get drilled and slotted rotors and some special pads from rotorpros.com but a buddy of mine got them and said the braking performance was the same. The braking has never really been sufficient on this car. Also I'm not sure how the brake boosters are supposed to feel in the pedal on the 85s but mine feels pretty hard, nothing like today's brake boosters. It holds vacuum in the booster and was replaced recently by the previous owner. I have the receipt that he gave me actually.

 

You put yourself here my friend, you have some work to do.....

for example when someone gives you advise here, take it (because you are obviously not educated on these cars and do not possess the mechanical ability to handle it yourself) nor do you seem to be in the financial position to hand it over to a knowledgeable/capable technician.......

When that happens I will be happy to give good solid advise from things I have learned;

and stop posting juvenile threads making it very difficult to take you seriously.....it's like talking to a 14 year old.....you are obviously a younger guy, but you don't need to establish your juvenile demeanor.

 

Excuse me for trying to learn.

 

How much vacuum do you see at the line going into the booster? Some big cams may not allow for generating a lot of vacuum and that can make the pedal feel hard compared to other cars even with a new booster.

My '87 only has some mild mods and the cam is a early GM ZZ3 cam which is apparently is not much of an upgrade over a stock Corvette L98 cam for that year, so there is plenty of vacuum at the booster. But the pedal on my '87 doesn't seem to be much different than what the pedal feel is like on my '02. I use stock C5 Z06 pads on the '87 up front and Hawk HPS on the rear. This combo works great for the street and for autocross, and I have never seen severe brake fade doing HPDE's at local road courses

I would suggest getting some stainless lines and try some Hawk HPS pads to start. If the current rotors look OK, maybe just have them checked to make sure they aren't warped and maybe turn them. With most aftermarket pads, it's a good idea to "bed" the pads to transfer pad material to the rotors. Hawk recommends this.

 

Hi
C4Cruiser is on the right track.

Check the front brake pads, i know standard car type pads wont work on a C4. You need a high metal content brake pad to create the friction you need to stop the car, rather than just slowing it down.

(that is what my 85 was like when i first got her, i could stand on the brakes and the car would barely slow down. New high metal content brake pads fixed it, so i just have to lightly touch the pedal to brake hard)

Hawk Hp are great but can be noisy and dusty, i would reccomend the Hawk street brake pads (corvette central have them)

Yes check your booster, run the engine rev it a few times and turn the engine off and listen for any hissing.?????
Inside the cabin and engine bay, if all is quiet replace the brake pads.

REMEMBER if your discs have wear, it is a good idea to get them machined. It will take a long time for the brake pads to "wear" to the disc surface irregularities.

If you do not machine the brake pads, lightly apply the brakes for the first few miles so they wear into the shape of the discks.
It can be really bad with hardly any braking at first, untill the brake pads wear and make good contact over the disc surface.

Good luck, the 84-87 brakes were not bad they worked great with the right brake pads.

 

The biggest single factor in the pedal force to decel relationship is the booster.

Before runout, a functioning booster will multiply the input force by a factor of about 8.

lining friction may vary somewhere between 0.3 and 0.4 under normal conditions, which is minor by comparison

Since these boosters (especially replacements) are very prone to leakage through the pushrod seal, through bolt o rings, diaphragm and/or shell, that's what I'd check first.

Try braking with and without vacuum to the booster. Difference in pedal effort should be night and day if booster is doing its job.

 

Daniel, it is all that torque that you have built into your vette.
Nothing on the market will improve braking.

 

You are NOT being a jerk, you are saying exactly what I have considered saying for the last week or so and you are 100% right.

We have all tried to respond to your questions with help but each time we do you come back with a response that sounds like a child saying "So there, I showed you" I am going to take your advice though, I will never respond to your posts again and if you keep going like you are, I will not be the only one ignoring you.

That's just it, you aren't learning a thing, you are too busy trying to prove us wrong.

 

I agree with 85. Daniel, is there any part of your car that is not broken? If I were you, I would cinch up the seatbelt, don a helmet and test the brakes by applying them just short of hitting a brick wall. Best case scenario is that the brakes don't work, the car is totaled, the insurance pays off and you can start with a newer car with no problems. You have spent much time and energy on your project and you seem to take one step forward and two back at every turn. I am not being a smartass. Sometimes you just need to reboot and start over.

 

When I bought my 85 the car sat for years and the brakes were not working very good.
1) Get new pads front AND back( I just got 25 dollar raybestos)
2) Put new fluid and make sure they are bled properly.
3) Regrease the rods that the caliper uses(sorry can't remember the name) use brake type grease
4) I sandpapered the ridge of rust off the rotors and it stopped making a rough sound.
5) I drive around the canyons and they work 10x better I still need to get new rotors and change 3 more brake lines. My booster seems normal
Good luck

 

Yes, but this doesn't address the engine problems, transmission problems, and the other myriad of problems Daniel is experiencing.

 

To be as brief as I can from a long story on a problem I had when I got my car in 04 and the brakes were scary.

I replaced it all and did hours or research and conversation. I replaced rotors, pads, ABS, flex lines, and master. Booster always worked fine, no leaks so I saw no need to replace it. Also did a lot of testing and bleeding.

I finally replaced the brakes with a J55 system 13" rotors. My braking was dramatically improved with the pads that came with the used system (in pristine shape). When pads wore out replaced the pads with hawks had similar problems. Found Brembo pads and worked excellent (not available anymore).

Fast forward to 2010 my booster went bad with a classic leak. Got a booster from AZ and installed it. My braking power was so dramatically improved I could not believe it. I didn't fully understand it but results don’t lie.

Just saying.

 

So right off the bat you get advice to replace flex lines, pads, etc....

But then you say you will address them when you get around to it? Why bother posting?

I had my master rebuilt by cardone, new metal brake booster, new ss lines replacing the rubber lines, DRM bias spring, rebuilt and PC'd all calipers, and new hawk ceramic pads front and rear. This made a considerable improvement in stopping power and pedal feel. I wish I had known about J55 upgrade before I started.

You have a million problems. The problem is you. Take advice and try to fix it or sell it and get an atv or something because those are the forums you belong on. So many great people here are giving up on you after trying time after time to help you with you not listening or trying their advice.

Mike