The LF brake had been hanging up so I replaced brakes on both front wheels:
-rubber hoses
-calipers
-pads
-rotors
Then I bled both sides; the RF bled as usual while the LF was slow but eventually did bleed out all the air (I think).
On first test drive it pulled rather hard right on a moderate/hard stop.

Just checked all visible hard lines down the rocker panel for damage and all looked fine.
Then took her out for a short test drive on the interstate:
-still pulled right on hard stop
-once home, the LF wheel was much hotter than the RF.

I'm debating between getting a new FL caliper or just taking her to the local Chevy dealer and say "fix it".

Any other ideas on what might be wrong, save for the damn ABS unit??
Thanks for any suggestions.

 

I would take the rubber hose loose from the LF metal line on the frame and jab the brake pedal. If fluid doesnt come out in a hurry, there is a restriction.

If it is the 88-only ABS module, I have one in my garage I will give you - you pay shipping.

 

Thanks much for the suggestion and the offer; I'll get back to ya after I check it out.

 

Looks like weather is cooling down a bit and time to tackle the front brake issue...again.

Anyone know if I can disable the damn ABS by simply unplugging all the electrical connections??

 

That would certainly disable it. You could also simply pull the fuse for the ABS.

 

Thanks for the confirmation.

 

You could in a safe place with slick or loose surface try to activate abs during hard braking. The valves might free up.

 

Worked on my car!

 

Hello there 65Z01,

I too have a 1988 C4 Coupe and have had my issues with the brake system and unfortunately have learned it too well. You mentioned that your LF brake was "hanging up". Did you grease the slider pin well when the calipers were switched? I find that brakes that don't release frequently do it because they are not able to move easily. I have seen a lot of people replace the caliper using the old bolts without lubricating them and this almost guarantees that you will have one stick or hang up. They make a special high temperature grease just for this application available at auto parts stores. This might explain why the hanging up remains constant while you swap brake lines and other components.

Do Not Try to unplug the ABS system on the 1988 Corvette. The master cylinder has two lines feeding it, one for the the "Fluid In" and the other for the "Fluid Out". The brake systems are be controlled by the ABS and all four wheels are connected to the ABS Actuator directly. Actually there are three lines out, One for the Left Front, one for the Right Front and a third line that feeds BOTH rear brakes. Our entire brake system in 1988 C4's was integrated into the ABS Actuator and there is no way to isolate them, (that I know of).

The device known to us as the "ABS Actuator" is not a pump and has no pump in it at all. It is simply a bunch of solenoids that relays that can be very temperamental. I have been replacing the lines coming out of my ABS box as they all corroded at this point and one burst. Remember that cars after 1964 (?) had to have dual container master cylinders so you have some redundancy in case one of the systems (front or back) fails and leaks out. Don't try this on your 1988, I burst one brake line by pushing harder than normal on it and ALL the fluid drained out of both containers above the master cylinder.

If you really don't want the ABS system then buy a set of the brake lines from Classic Tubing, they sell a kit that allows you to use a conventional master cylinder and no ABS box. The plain old four wheel brake system is still available to those who gave up on the ABS systems. From what I heard from Bosch that system was used in several vehicles in Europe. With proper tools you can cycle the solenoids in the ABS contraption allowing you to properly bleed the brakes.

My 1988 was doing some strange things for a while until I discovered the loose Lateral Acceleration Sensor swing around on its cables. Check your system carefully for stuff like this.

While working on my 1988 I found a small section of brake line that appeared as thought it had eaten a acorn or something. Turned out to be a "Low" spot where the water collected and froze compromising the brake line. When bleeding these cars you need to use pressure to get it through some of the built in air locks. Just imagine an inverted U in a straight section, the air will collect and try to stay there so you have to push it out. I use a Phoenix Reverse Bleeder on my 1988 Corvette and it really helps.

Why the guys at GM did this to we the few, the proud owners of the 1988 C4's is beyond me. It is a last minute solution while they were making a real ABS system for the future models. We are a one year only on both the master cylinder and the brake lines. It does work okay when it works. I too have a spare system just in case I need any parts. Another really GREAT idea is to remove those thirty some year old rubber brake lines at your calipers with some Stainless braided Hoses designed for that application. Rubber Hoses like to swell a bit and this get worse as the brake lines age. The new SS braided lines are made for our cars and make the brakes feel so much better. Just be sure that whatever brand lines you buy that they are D.O.T. Approved. I have heard that there are a bunch of Chinese look alikes out there that are not D.O.T. approved.

I hope that this helps you a bit with your 1988 C4! One thing I really like about the 1988 is the emergency brake is a real emergency brake. It is not a parking brake like the older Corvette came with. I have a 1968 C3 as well so I am familiar with the old system...

Best regards,
Chris

 

If you feel that it's necessary (I don't), you can go to ^that^ extend w/o buying kits, Master cylinders etc. Just pull the ABS assy out of the car, cut back the two front brake lines, flair them and connect the them w/a "T" directly to the MC. Tie the rear line into the rear "T" that's already on the left frame rail. Done.

 

Let me add something: some of the brake pads that I've seen lately are made rather poorly with the metal plates stamped with defects like a bit of flash or some extraneous paint, etc. causing the pads to not move smoothly on the caliper bracket. Corrosion and pitting of the brackets and calipers can also interfere with proper movement of the pads. More often you may need to file and true-up the srfaces of contact to assure the pads and caliper move smoothly and correctly. Just because brakes are new does not mean they will make your braking system feel like new. Worn wheel bearings, bad caliper piston seals, corroded pistons, etc. can also contribute to brake problems. Hope my comments were helpful.

 

Hello there Tom400CFI,

The master cylinder on the 1988 has two ports on it, it is different than any master cylinder I have ever seen.

In the 1988 C4 the distribution of brake fluid comes from the ABS unit. The master cylinder does not have any provisions to go directly to the wheels. You might be able to make it work with enough parts but I would go the longer route of replacing the system with a conventional brake system.

I am replacing all the brake lines on my Corvette just to make it 100% sure it works properly. Brakes are one place I don't like to compromise.

Best regards,
Chris

 

I am having the exact same problem in my 35th....Hard braking will grab the right front harder than the left and i actually ended up sideways and damn near put it in the ditch. This is next on my list......

 

I like this plan better than trying to find ABS parts........

 

10-4. I may have all the ABS parts you need, if you're looking, FYI. I have an EBCM, ABS valve assy, wheel speed sensors, harness etc.

All from an '89 that I removed the entire ABS system from and run conventional brakes on, now.