All ABS experts inside!

[8upZR1]

When you pump up the brake pedal with the car off, should it get hard like most cars do after an easy initial pump? What would be considered normal in this case?

[8upZR1]

When you pull the fuse for the ABS the brakes should feel WAY more sensitive to a moderately heavy foot. It should be extremely easy to lock the fronts, requiring almost no effort. After a while you will no longer notice it, but initially it should be very obvious.

[gbrtng]

Originally Posted by 8upZR1

When you pump up the brake pedal with the car off, should it get hard like most cars do after an easy initial pump? What would be considered normal in this case?

With the engine not running, you have 2 or 3 pedal applications of vacuum
stored in the booster. After that runs out, the pedal gets hard because there
is no further assist from the booster.

To your comment about "pumping up" the brake pedal: the pedal should be
in the same position for the first and every push. If not, there is brake
rotor runout which causes the pads and pistons to back away from the
rotor surfaces so the first pedal push will be lower (closer to the floor).
After that, the pads are seated on the rotors and there is no further slack in
the hydraulic system.

[cuisinartvette]

Im going to try and reverse bleed it this week by pumping fluid in from the caliper and see if that helps. Hope this problem isnt related to some solenoid in the ABS somehow. It feels like air in the system, thats all. Been told there is no bleeder screw on the 90 ABS units? This has to be something simple

[tomtom72]

Yes Ron, that is correct about the 90 ABS unit, it has no bleeder screw. Ya gotta crack the lines. Or have a Tech1A to use with a pressure-bleeder to cycle the solenoids when applying pressure to the system during the bleeding. That's why I brought mine to the dealer, I don't have a Tech1A.

My humble opinion.....there is air in the system. If I told you that I used 3 bottles of fluid you would think me incompetent...I proly am but it took me forever to get the tiny bit of air in my system out. The FSM says the system is very difficult to bleed manually. The preferred method is a scanner + a pressure bleeder. I tried something the last few times I rebleed the system. I was thinking that maybe there is a point where the lines get as high as or higher than the M/C. So when I put the car up on stands I had the back bleeder screws higher than the fronts. I don't know if that was my charm or if I just was finally bleeding the system enough at one sitting??? That trick I remembered from my 72.

Another observation from my bleeding ordeal. I noticed a good bit of air at first. Doing each caliper 10 pumps, then if I continued after feeling the pedal for pump up, it would take another 20 or so pumps before I would start to see another shot of air. The second shot was way smaller bubbles than the first. I had to use a flash light on my collection tubing to see it, but it was there. I had never went that far and waited that long in between pumps. The FSM says 10 to 15 seconds in between pumps! The last time I bleed the system I followed the FSM to the word! The speed bleeders helped as I work alone.


Tom

[cuisinartvette]

Ya know Tom, Im just going to get some speedbleeders...I spoke with Mark Haibeck this morning and he said also on the 90s(as you did) there is no bleeder on these. The tech 1 thing to cycle solenoids according to Mark is used on 92(93?) and up cars...It has to be air, sure feels like it. It seems the ABS is a little higher than the calipers, maybe thats where its getting trapped, but what do I know. I did (from the rear) not see any huge air bubbles but lots of teeny tiny ones. Hopefully air isnt getting drawn in somewhere else, but Ill give it my best shot. I too used a couple cans of fluid, guess Ill be stocking up for round 3

I understand the speedbleeder size is 10x1.00, is this right? Wheres the best place to get them from.

Fwiw, Mark recommended that I NOT forcing the fluid in backward from the caliper up like I wanted to do (and did with my clutch slave which worked great-gear oil pump works wonders) on the brakes at least.

[tomtom72]

Ron, I got so frustrated with bleeding my brakes that I considered using my pheonix gun for the job.....then I said "self, don't do anything rash to make it worse!"

Sooooo, speedbleeders.com.....get the 4 bleeders + 1 tube sealer + 4 bags W/ hoses and you're good to get her dunn for under $50.00....it's gotta be the best tool I've bought so far! They ship fast and their stuff works like a charm.....it's just the stupid car that is a PIA & doesn't wanna help!

Oh, yea, even before I rebuilt the fr calipers I got most of my air from the fronts, big bubbles. The rears gave tiny ones.....that is till I got the wild hair up you know where to rebuild the front calipers & do the DRM spring & throw new guts into the M/C....then it was big air from both ends but the air stopped coming from the rears long before it stopped coming from the fronts. But yea, the tiny bubbles seem to be the sign that you gotta bleed more but it's almost dunn! I think the waiting inbetween each pump has something to do with the outcome of the job too. The last attempt I did, which turned out to be the final bleed because I waited at least 5 seconds between pumps plus the time it took me to go look at the line to the bag and walk back to the pedal before the next stroke. I did each calliper 10 x. Then tested the pedal for air. After doing the whole circuit, I started again with the same steps and on the third go round is when I saw the tiny bubbles. After that I blead them till no more tiny bubbles, the rears stopped 1st and then the fronts. Test the pedal, it was good, but I did one more full trip just to be sure.

I'm convinced that had I followed the FSM instructions on manual bleeding from the git go that I would have been finished long before by doing it my way!

Good luck!

Tom

[cuisinartvette]

Speedbleeders (and a Hurst shifter ) should be here by this weekend !

[8upZR1]

What is a phoenix gun?

[cuisinartvette]

Tom, what kind of sealer do I use? I got my speedbleeders from Summit, dont know if it comes with it.
Im tempted to put a MC in just to do it (if the seals are bypassing internally) but Ill try this first. Pedal doesnt sink anyway