All ABS experts inside!

[cuisinartvette]

I have the spongy brake syndrome on my 90. Everything is new, bled, rebled and bled some more. It was like that when I bought it and after all this work its still the same. I dont think Ive ever seen the ABS light come on upon startup or definitely never heard it do the self check once you start rolling.

I took it up to about 75 and leaned on the brakes :confused: :confused:

It sucks, dont stop for beans.

Im not a real techie type guy, where can I start? Couldnt get the ABS to enact. Everything else on the car is great now, except it stops like an old truck..

Where do I start?


Edit: Upon backing out of the driveway this afternoon I thought I heard the ABS check. Never heard it in forward motion or seen an ABS light on the dash.

[gbrtng]

What do you mean by everything is new ? Does that include new front calipers ? What kind of pads ? Condition of the rotors ?
My 91 always had a slightly spongy pedal but I can hit ABS at will. Look in
the compartment behind the driver's seat to see if the heavy red wire is
connected to the ABS unit. If it's not connected, somebody has removed
the check ABS light, and you probably have a bad controller.

[cuisinartvette]

I will check it tomorrow and check for codes (A and H??).

Rotors are new, performance friction pads, calipers cant tell but they are dry. . Booster and master are both good. Seems (from pedal feel when bleeding) that the rears arent getting all their due pressure for some reason. Pedal feel improved some from bleeding fronts. Unless its old school brakes, Im lost. Dont know what a brake solenoid or controller would look like if it hit me in the face.
Thanks for your suggestion:cheers:

[tomtom72]

I'm no brake expert either but my 90 has had the same issue.... the brakes just didn't seem up to it, yea spongy I guess. To me I was remembering the brakes on my 72. Ya know those old iron FIXED 4 PISTON calipers w/ large pads.

Anyway enough of the old school stuff. I had the dealer check my abs against the shop SBDSytem & the abs got a clean bill of health. To get my abs to work I have to go way beyond controlled effort on the pedal...but it does work. I don't speak abs either.:o

Here is what I've done so far and they are better: s/s lines, DRM bias spring, rebuilt the fr calipers & rears will wait till winter, really soft street pads Brut Stop by raybestos, new hardware for the pads, ya know clips & pins & speed bleeders & Valvoline D3 syn fluid.

Now they work much better but still not what I call "stop on a dime & give nine cents change". They work but they feel like they are not. I guess they don't telegraph much back to the driver. If I unload the inside wheel a bunch in a corner & do a bit of braking I can feel the abs react to that unloaded wheel....so I'm confident it works as intended. I grew up on old stuff & pride myself in having learned brake modulation....I ain't no race car driver but I have some learned habits w/brakes pre-abs.

Oh, I did rebuild the M/C when I did the DRM spring...ya know "while we're here" rule. I even bought a new set of stock lines & may try that this winter. OH, yea, another thing if ya think ya got all the old fluid out with 3 qts of bleeding by foot...think again. My fr calipers still had some crap hiding in them. Not that that means anything, just thought I mention it. Oh, yea reason on trying the stock lines again is they have a larger I.D. than my Earl's s/s lines...more fluid movement but less pressure but ya can at least fill the rear reservior of the M/C to the fill line without it spitting fluid out under hard use....not much, very little but it spits some out...even before the DRM spring.

Sorry Ron for rambling & giving ya no exact answer. I just figured if ya had some more info ya might tumble on to something for your situation.:redface:

:cheers:
Tom

[8upZR1]

Something I always do when I am checking brakes/ABS is to pull the fuse for the ABS and take a test drive. With ABS completely disabled the brakes feel totally different and you will realize just how much the ABS system is or isn't doing for you. It is simple and surprisingly insightful.

The brakes on my 90 are awful. The system is functioning properly but there is just not enough bite. For the amount of tire and suspension these cars have the brakes should be able to do there job extremely well. I think a large rotor & caliper upgrade is the only option if you want excellent braking on your ZR1. 14" and 6 or 8 piston monobolcks should get the job done. I rode in an LT1 C4 with 13.5" rotors and 6 piston Brembos. It would put my car to shame. Cost is the only problem as big brakes require big wheels & rubber. Goodluck with the brakes.

[gbrtng]

Something I always do when I am checking brakes/ABS is to pull the fuse for the ABS and take a test drive. With ABS completely disabled the brakes feel totally different and you will realize just how much the ABS system is or isn't doing for you. It is simple and surprisingly insightful.

The brakes on my 90 are awful. The system is functioning properly but there is just not enough bite. For the amount of tire and suspension these cars have the brakes should be able to do there job extremely well. I think a large rotor & caliper upgrade is the only option if you want excellent braking on your ZR1. 14" and 6 or 8 piston monobolcks should get the job done. I rode in an LT1 C4 with 13.5" rotors and 6 piston Brembos. It would put my car to shame. Cost is the only problem as big brakes require big wheels & rubber. Goodluck with the brakes.

Pulling the ABS fuse to disable the controller should NOT make any
difference in braking under normal conditions because the ABS is not
being actuated until the system senses wheel slippage. If pulling the
ABS fuse makes a difference with normal stops there is something
wrong with the system that I have never seen.

[gbrtng]

I will check it tomorrow and check for codes (A and H??).

Rotors are new, performance friction pads, calipers cant tell but they are dry. . Booster and master are both good. Seems (from pedal feel when bleeding) that the rears arent getting all their due pressure for some reason. Pedal feel improved some from bleeding fronts. Unless its old school brakes, Im lost. Dont know what a brake solenoid or controller would look like if it hit me in the face.
Thanks for your suggestion:cheers:

Has the car been like this for as long as you have owned it ?
What Performance Friction compound pads are you using ?
What makes you suspect the rears are not getting all their due pressure ?

My guess about the spongy pedal is that there is one or more fatigued
or cracked calipers - let me explain - under really extreme continued use
on track I have seen stock front calipers spread open so that the pistons
are no longer parallel. If you replaced the front pads you can inspect them
to see if there is a normal wear pattern, i.e., the friction surface should be
parallel to the backing plate. If not, you have this problem. The stock
calipers are made of die-cast zinc, aluminum, or some alloy which
creeps unter stress. It is rumored that the 1996 GS calipers were
reinforced, but I've compared them with stock and can't see any difference.

Please PM me with your phone number and a good time to call; this
needs more investigation.

Glenn

[John Boothby]

One item I have not heard mentioned here is the vacuum power assist. The diaphram in these do go bad and greatly affect the feel of the brakes. When you rebuilt the M/C was this checked? Just my two cents.

[cuisinartvette]

The M/C appears to have been replaced before I got it. I pulled it out to see if there was an adjustment to "unslack" the pedal but there isnt. Ive seen others who throw parts at this same situation to no avail..

If I have my foot on the brake pedal it does not sink as if the master was bad.

However with the car off if I pump the pedal up it doesnt get hard like any other car would.

Now that the car has good shocks and can handle I just want it to stop, would love to try a road course, especailly if I can make it to Vegas gathering. Otherwise whats the use....

Keep the feedback coming, anything is helpfull.

[cuisinartvette]

Ok with the key in the "ON" position I shorted the A and H terminals, no codes. On the other forum I had seen posted that pumping the brake pedal 40 times with the key off resets a modulator valve (under the car???) releasing full pressure in teh rear brakes, anyone ever heard of this? :blahblah:

Id like to get it fixed, otherwise this will be me on the road course this fall (about 30 sec in) :sign10:

http://www.youtube.com/watch?v=9ZF7DJPN-5M

[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]

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.:redface:

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.

:cheers:
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!":sign10:

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!:thumbsup: 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.:blahblah: 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!:o

Good luck!
:cheers:
Tom

[cuisinartvette]

Speedbleeders (and a Hurst shifter :mrgreen: ) 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

[tomtom72]

Ron, I bought directly from speed bleeder. It behaves like Recto-Seal grey pipe dope, ya know the non-teflon based sealer for use on gas pipe and explosion proof IPS fittings? The speed bleeder stuff is red, I think, but it behaves the same as R-seal. It kind of hardens but is plyable. Not a brittle crust like old #7 permatex.

Heck, give me your addy & I'll send you my tube & you can send it back after you're dunn. Truth be told the bleeders come with the stuff on them already which is supposed to be good for I don't know how many bleeds. I, on the other hand being a hack, figured all the issues I was having getting my air out noticed that the sealer was wearing thin on me after all my bleeding. So right before the last go round I ordered up a tube and three more catch bags & hoses just to make sure I could eliminate that as a possible source for me to mess up the bleeding process..:o

8up, the phoenix gun is a reverse bleed pump gun. Phoenixbleeder.com I think is the addy. I bought it for my clutch hydraulics. I fell victum to the bad Q/C on the parts & thought this would help me get a good bleed on the system. Yea, I know, I must not be too good at bleeding things! Ofcourse I bought the gun before I found out it was the slave seals among other things. I'm either the poster child for ineptitude or perseverance, one! But I do love my Z so!:sign10:

:cheers:
Tom

[8upZR1]

Sounds extremely cool though, even if you did not get to use it here. I am sure it will come in handy sometime in the future, you never know. A toy like that could be used for lots of fun things.

[cuisinartvette]

(announcers voice)

"When things just come out a little slow in the morning its Phoneixbleed to the rescue"....
Be the first on your block!
Fun for the whole family!
Amaze your friends!
=D>

[tomtom72]

(announcers voice)

"When things just come out a little slow in the morning its Phoneixbleed to the rescue"....
Be the first on your block!
Fun for the whole family!
Amaze your friends!
=D>

Hey Ron are you saying that ya got brakes?

:occasion1 if ya do!:thumbsup:

[cuisinartvette]

Nah, I was goofing in response to a reply that looks to have been deleted. Speedbleeders just showed up yesterday, Ill throw them on Sat and go for it again.

[cuisinartvette]

Ok, the speedbleeders rock, thats the only way to bleed brakes. I did them a few times and the pedal improved...

-Key off pedal pumps up and is right there.
-Turned the car on and pedal instantly goes to the floor....Hit the pedal again, same thing except this time when it was all the way down I hear an extrememly loud POP! I mean loud!
Then the pedal was normal??????

Drove it around the block a few times, found some water and nailed the brakes so the ABS would come on which it did.
Went back and bled them again. I was told the manual says on the 90 order is:
RF
RR
LR
LF
DID that and pedal has improved...Still doesnt "grab" and have real stopping power...Best I can think of is when I was bleeding I could see the front reservoir occasionally would get an air bubble, so Im assuming there is air in the master .Unfortunately I dont know anyone I can get to give me a hand so this will have to do for awhile.

:sigh:

Its miller time.

[tomtom72]

Ron, I work solo too. Just take out the M/C and do a bench bleed. Going back in at least the air will be confined to the two line connections outside the M/C.

FWIT, that's why I believe it took me soooo long to bleed my brakes. It took forever to get the air from there to the calipers.:o

Things that ya need:
Use a caliper bleed screw from the S/Bleeder swap out on the front port of the M/C.
The rear port is the same as the bleeder from a clutch slave.
A couple of rubber caps for the brake lines, while you're gone bleeding the M/C....proly not necessary but I capped them, same caps that come with a new clutch hose.
Optional tool: use an old slave rod in a wood handle as the plunger for the M/C....it fits perfectly. Oh yea, now is the time to do the DRM bias spring.:thumbsup:

:cheers:
Tom

Yea, them speed bleeders are the cat's a$$! I love them!:mrgreen:

[8upZR1]

I was wondering what type of brake fluid y'all use. Are there any options?

[cuisinartvette]

Thanks. I prefer to work solo too
:cheers:
Im torn between removing the MC and bleeding it or just throwing on a new one "while Im at it"..Thanks for the tips, I just happen to have both of those bleeders laying around.

I used Prestone synthetic Dot3 fwiw, never got into the real fancy stuff. In fact didnt even notice it was synthetic til last nights last bleed. Think Ive gone through almost a gallon of it now.

Not sure if Im getting better at bleeding or cursing at the car, but I AM getting better. :mrgreen:

Time for a morning cruise and some new spark plugs to see if that helps my hesitation...Arghh.


Edit: Tomtom-I used some of that "joint stick" (from a plumbing supply)for the bleeder threads to guarantee I would never pull air in, stuff doesnt break the seal if you use it over and over..Looks like a big crayon. I just kept it off the last 2-3 threads so it wouldnt get in the caliper-Just in case. very small amount was needed. Fwiw...

[tomtom72]

8up I'm using Valvoline Synpower D3, the same stuff everyone here uses, well mostly everyone...the guys that do track days are in a different zip code on the brake fluid.:wink:

Hey Ron thanks for the tip!:thumbsup:

I should have thought of that. I'll mark that down for future reference.

:cheers:

[Nabeel]

Hi, This post of mine is very beneficial and informative, however there are some specific facts or information that I require. If anyone can help me in this matter then please send me a private message. Best Regards,

[cuisinartvette]

Well...Took the advice of one of our members and bled the master while it was on the car. Removed the brake sensor wire, got a metric and standard set of line wrenches from Harbor Frieght (only $15, probably lose them before I need them again) and had a friend pump the pedal, hold it while I cracked the line. Was careful to tighten it before it was done bleeding to not get air in. Did this a couple times, and....


It stops. Very well. FINALLY! Yes, a solid brake pedal! :worship: =D> :occasion1

I think if I give it one more go and maybe make my way around the wheels once more I may get a tad more but it was a huge difference. :thumbsup: