Wacko brake issues on a 1987 Corvette Convertible

I have manged to get into a very odd brake system issue (ABS/ base) with my 1987 Corvette convertible .

About 1.5 years ago I picked this car up in the Fall on a lark, it was cheap, not bad looking, new top, fair tires, and drove well. The car was driven for about 5 weeks then put into an enclosed for the winter, sometime in February the battery died and due to the lack of height in the trailer I was unable to jump start the car.

Spring arrives and I decided to drift the car out of the trailer and put a battery in it. I push the brake pedal down and pull the shifter into neutral (all good) and start to drift out, pressed the brake pedal again but this time the pedal went strait to the floor!! Grabbed the E-brake and was able to get the car onto flat ground without any other issues.

While putting the battery in the car I noticed the master cylinder was empty? Looked under the car and no leak? Looked in the trailer and the wood floor was damp but there have been a number of leaker's in the trailer over the years. Filled the M/C and was unable to get a pedal or a leak?

Race season starts with a bang, as in a blown engine and a required roll cage update for the race car so the Vett sits, till fall. Then come fall the girlfriend unit gets sick, twice. I decide to deal with the car next year. Because 2020 will be better (LOL).

So now I have the car up on jack stands trying to bleed the brakes, was able to get all the bleeders open but no fluid? Grab a vacuum bleeder and can get fluid from the right front and right rear, but no, none, zipO fluid from the left front and left rear of the car? Checked to make sure the bleeders were clear, they are and I cannot see any isses with the steel lines or rubber lines.

So I decided to have a look at the ABS module, well I have to say what a PIA place to put it on the car. It is behind the drivers seat, below the speaker in a pocket that has  three inches of standing water! Clean the drain hole and find the ABS relay  filled with water and someone has been in here before as the orange/ black with was cut off at the relay and rigged back together.

At this point I know I am fighting at least two different issues need more information.

1) Anyone have a clue what happen to the brake fluid in the first place?

2) Can the ABS module block off half the system but not the other side?

3) Since the relay is more than likely toast can I use a stander 4 pole relay?

4) What about the ABS module itself, can it handle being submerged ? 

5) What would be involved in deleting the ABS system? Any kits?

Thanks, Paul

In reply to Donebrokeit :

This is digging back into memories I've tried very hard to repress, but on my 85 I recall having problems bleeding the rear brakes. Even though the lines looked good & there were no leaks I think I either had to replace a section of hard-line and/or pull the brake hose & use pressure to blast the line out.

Can't help you with the ABS stuff, but it's possible that your master cylinder is leaking into the booster.

Recalling my wife's C3, 'vettes of that vintage were known to have brake issues that primarily concerned corrosion within the caliper bore.  Maybe still a thing in '87?

One of the first things I did with my RX-7 was delete the ABS, as the pump was leaking, new pumps were not available, and used pumps were crazy money.  Been a good while now, but as I recall I sourced a new non-ABS master cylinder and found good non-ABS hard lines to all four wheels at the junkyard.  System has been perfect in the roughly 20 years since I did that work.

Did some '87's come without ABS?  I'm guessing yes, maybe?

Had a chance to do some searching, seems I might have two stuck brake calipers as RedT2 said. The ABS system seems to be an issue with the verts and a number of people have deleted the system without any valving issues due to a lack of parts.

https://www.corvetteforum.com/forums/c4-tech-performance/2481899-another-removing-abs-thread.html

https://www.appletreeauto.com/METRIC-BRAKE-HOSE-TEE-113-611-755/?xid_176f4=a2c35f84973a307a20c210fa303e00ca

I could definitely see a solenoid or something sticking due to rust, but it sounds like you may have already figured out what is up.

cmcgregor (Forum Supporter) said:

Can't help you with the ABS stuff, but it's possible that your master cylinder is leaking into the booster.

This would be my guess.  That's a classic failure mode and not just for Corvettes

Swollen hoses will make bleeding a nightmare.  Loosen the hose from the hard line and see if you get fluid.

It's entirely possible you have a leak that you can't see on the trailer floor.  Brake fluid is glycol and will evaporate/soak in eventually.

A fluid leak that goes into the booster often shows up as big clouds of white smoke out the tailpipe, but sometimes only when you turn left.  The vacuum line sucks brake fluid into the intake.

87 should be rear ABS only, right?  Deleting it shouldn't be awful.  Bypass the hydraulics, pull the fuse for it, and take the warning light bulb out of the dash.  I can't think of anything else involved with the system.

In reply to Curtis73 (Forum Supporter) :

i don't know of any corvette with RABS / RWAL. those systems were used exclusively on light trucks and vans AFAIK.

According to an article I found on Hagerty's website, Bosch antilock brakes became standard on all Corvettes for the 1986 model year.