Few Questions

[drwikboz]

Well,

 

[drwikboz]

very strange how this system works. Anyway, I just got my first vette (1981) and have few things (hopefully minor) to take care of. The entire brake system is new, however, the brakes seem spongy. I bled them and they got better, but after two hours of driving, back to the same old. the brake light comes on and clearly the car barely stops. The other problem is that it is really hard to start in first gear. I have to come off the clutch very slow. This means no tire spinning - I assume this car could spin the tires. The car has a mild cam installed, the carb (as you can see in the pic) and an intake (i believe). The speedo is also off by about 15mph. When I'm doing 70, it reads 55. Thought this might be a gear issue as I'm not sure if they've been changed or some other issue. Any thoughts would be appreciated.

 

[junkman104]

I purchased a SSBC kit for my 81 in December and had no idea the work involved in a vette brake job. The book that came with the kit was excelent in showing how it was done. The run-out on the rotors are what causes the most problems as if the rotors have more than .005 run-out it can actualy suck air into the system past the piston o-rings. After installing the kit by the book I have put about 1000 miles on the car and the brakes work perfectly. Also I put a power brake bleeder together from items that can be bought from Lowes for around 35.00 and makes bleeding a 10 minute job.

There is alot of info here also: wiki.corvettefaq.com

 

[red70vette]

I agree with the junkman. If your brakes get spongy shortly after being bled then you have air getting into the system. Run out in the rotors are one potential culprit but it would help if you knew what was done with the prior brake job. Did they do pads only? New seals? New sleeves? New Calipers? Rebuilt calipers? Who did them?

When these systems get old (25 years is old) the calipers get pitted and leak around the seals. The calipers usually have to be rebuilt with stainless steel sleeves and pistons to keep from leaking. If they were not rebuilt properly they may as well not have been rebuilt. Look on the inside of your wheels the tires should show which if any of the calipers are leaking by the telltale trail of brake fluid. If they are not leaking then they are sucking air in from somewhere and the rotors are as good a place as any to start.

 

[drwikboz]

I agree with the junkman. If your brakes get spongy shortly after being bled then you have air getting into the system. Run out in the rotors are one potential culprit but it would help if you knew what was done with the prior brake job. Did they do pads only? New seals? New sleeves? New Calipers? Rebuilt calipers? Who did them?

From what I was told, the entire brake system is new (mc, lines, calipers, proportion valve, everything). I'll try re-bleeding. Perhaps since there are two bleeders I might have missed one somewhere.

On another note, I have a lot of rattling as well. I hear that that may be caused by sagging floor pans? Is this correct, and if so, has anyone had this problem and found an easy fix?

 

[red70vette]

If the entire system is new find out who did it and bring it back. That is not how a brake systrem should work if it was recently overhauled. Something was not done right. Get it done right, brakes are something you want to work properly all the time.

 

[drwikboz]

If the entire system is new find out who did it and bring it back. That is not how a brake systrem should work if it was recently overhauled. Something was not done right. Get it done right, brakes are something you want to work properly all the time.

I would think so - I can't stop!!!! Anyway, I'm going to have someone look at them this weekend. I don't have anything to measure the rotors. As far as who did them.. the person I bought the car from, so that might be a problem. I'm annoyed because the problem existed the first time I looked at the car and he said it would be fixed by the time I picked it up.. I assume he bled the brakes and so the car ran fine for a while..... hard to fight w/someone when you buy a car privately and their sold as is... it becomes a hassle even though he guaranteed the brakes to be working.

 

[red70vette]

Don't let him fool you. He knows the brakes don't work. It is probably the reason why he sold it. He put a lot of money and time into those brakes and they still don't work. See if he will pay to get them repaired properly. The worst he can say is no. By telling you everything on the brakes are new he implys that they will work fine. You know that is not the case and so does he. Rule number 1 unless you know the seller for a long time believe only what you can see. Otherwise get it checked out by someone who knows.

 

[GTR1999]

I agree the owner probably knew there is a brake issue. Regardless these cars have a bad rap on the brakes from people who don't know how to fix them. This includes many garages that do fine work on the everyday driver but are lost with these. I've rebuilt plenty of vette brakes and once they are done correctly are better then most on the road today. You don't need fancy rotors, brake hoses, or pads either. You have to start with the basics.
Look at the rotor thickness, get the runout under .003" I set them to under .002" ,check the bearing endplay, and do yourself a favor and but a Motive bleeder($60) Use oragnic pads for street driving and go through the system wheel by wheel. If you store the car in the winter or for several months the best thing you can do is pump the brakes a couple of times a month. If that isn't possible then bleed the brakes after removing from storage- another reason to get the Motive. DOT 3 fluid will absorb mositure and turn to an acid based brown muck. If you have any questions let me know.

 

[drwikboz]

Thanks all. Unfortunately for me I only get to play with the Vette on Sat & Sun as it stays at my family's house, but I will take all of the advice given and will post a reply as soon as I've fixed the issue.

 

[drwikboz]

Thanks all. Unfortunately for me I only get to play with the Vette on Sat & Sun as it stays at my family's house, but I will take all of the advice given and will post a reply as soon as I've fixed the issue.

Go figure, the mc was bad! so he said this was the second new mc - guess he's buying crap parts. Anyway, the brakes are working now so I can drive it! I think the tranny has been replaced though. My speedo is off, but I doubt the gears were played with.

So here is what I've found wrong with the car:

*defroster blows through the ac vents
*rear defroster does not work
*passenger window needs to be realigned.
cruise control does not work
power locks do not work
*I think the floorpans have sagged - rattling against tranny??

* are things I'd like to fix before I start playing with the engine - which already has a mild cam, carb, headers, and I believe an intake. Does anyone have any recommendations on how to get good power out of the L81 engine?