It was addressed to the thread in general, and anyone who might be having the hard pedal problem in response to the quote.
Just FYI mine also had plenty of fluid moving through all 4 bleeders when you cracked them, so I wouldnt use that to eliminate an ABS problem as a possible solution.
Roy

 

....reply well taken...i was refering to force and quantity of flow from/through the bleeders/calipers and not abs...still unsure as to why i have fred flintstone brakes but, getting closer to the solution to the problem.....

 

So for what I read and understand you can still the job by yourself. After all the ABS system will "autocheck" when it hits 8 MPH, so you would only need to move a little the car and bleed perfectly.

I have already erased the codes the old way without a Tech 1. But I do not have the option of cycling the ABS modulator. Too bad.

It has been a very interesting thread, and the last info posted by Mailman has been eye opening. Thanks !

 

......so, i want to hear about someone else engaging the parking brake 100 times and get their opinion on IF it helped out their braking situation...as for me today, i almost rear ended an suv even after STANDING on my brakes...i couldn't even glance at my dash to see if the abs went off as i stopped about 6'' from the suv!....either way, my brakes $ucked a big one today!!....i am sooo pi$$ed off right now that i may try and work of some steam and replace what checks out to be a working booster!

 

The 90s I found out dont use bleeders on the ABS nor do they require a Tech 1...that is for OBD II cars. I know this thread is mostly about hard peals but seems there are a lot in here with both hard and spongy pedals with lots of views so I hope this helps.

Speedbleeders on order, it has to be air. I did the 40 pump thing like that post said, Ill try tomorrow when I drive it though. Dont see how anything could change. It has to or Im selling it. I talked to a guy yesterday who bought a 90 or 91 ZR1 brand new and it was like that from day 1.


Eventually we will all stumble on the solution and it will be worth it as we can all stop. Someday

 

.....yeah, i am getting tired of this!..there are a lot of members with the same problem and no viable solution other then doing the bias spring "dance" or upgrading to j55 which are only band aids which i refuse to do!..gm designed these cars with adequate braking so there is something that they overlooked in the proceedures when tending to the brakes or something that is crapping out on a regular basis on these cars...

 

I personally think its a bleeding procedure. Ive heard many things from waiting 15 seconds in between your "pump it up and hold it deal" to....

It seems the ABS may be a touch higher than the calipers fwiw. Im going to bleed this thing til I stop or blow my seals out

Upgrading to J55 wont help or throwing parts (I have J55), its internal somewhere. Just gotta be patient and find it.

 

Just a few random ideas - especially to those with soft pedals even after bleeding numerous times here is what i learned the hard way. On my Infiniti G20, I bled the brakes 4 times still had spongy pedal, about to pull my hair out - refer to the factory manual... what do you know, I was bleeding the brakes in the incorrect order - the ole rule of start with the RR then LR then RF and LF - was not applicable to this car because of the way the ABS Brake channels work! I just bought a C4 and will be getting around to this shortly,,, but I threw this example out just on the off chance the factory guidelines are wrong with respect to bleed order.

For guys with hard pedals even after a new master, booster, etc. Try a different pad with a higher coefficient of friction. Another lesson learned... on the edge of the pads are two Letters like FF DF etc.. the frist represents the cold COF and the 2nd represents the hot COF. D <F<G<H etc.. greater = a pad that is more "grabby" with the same level of pressure applied.

I learned this after replacing pads on a car with a good aftermarket brand but the initial stopping power of the car sucked, especially the first few times brakes were applied and at lower speeds. I replaced them with another aftermarket pads with a higher rating, and brake torque ( i think this is the correct term) increased substantially.

Just my 2 cents and real-life lessons despite it not being specific to a C4

 

....well, like i said, i have a rather stiff pedal but all the tests show everything is working (yeah, right!)....i have no air (i think you said that you might) in my lines at all...and i don't throw parts at anything and again, i am not going to bandaid this with the j55 crap i previously mentioned......

 

........well, i gotta tell ya, a stock pad should work on a "stock" car and a stock pad should stop the car effectively. if the braking required a specific pad (ie ceramic, etc) then, the stock pad would be as such.....i am not nesessarily shooting you down, just my opinion....

 

Mail Man, I can understand your frustration. If you have an 88 and you don't know if the ABS kicked in, then your ABS wasn't working correctly. On my 88 and my brother's 89 (same ABS system, non-Z51, stock brakes) when the ABS kicks in you KNOW IT. The ABS activation results in a fast bunch of sledgehammer pulses as the wheels start to lock at max traction and then the ABS releases and repeats. When I do an ABS panic stop test from 50 mph I don't need to check the ABS light, as the car feels like it is being b*tch-slapped by Superman.

 

..i was not paying attention to a darn thing except to the bit_h in front of me as i was just a few inches from her bumper....i really dont know at all....

 

Im wondering if GM didnt have a high defect rate with these master cylinders....Ive spoe to another member at length today who is very adept with these cars.

What solved his spongy problem (he tried everythign too) was to install a M/C off an LS1 Camaro. One fitting has to be changed, the well in the hood will need a very slight shaving to clear the reservoir. Said to double check the rod length as the rod is just a slight tad longer than the Vettes, may need a slight shimming (20 thou?)

Said it fixed his problem completely.

SO, going on that Im assuming these seals may have a high defect rate and may be bypassing internally giving a crappy pedal feel?

Wonder if I wasted coin on speedbleeders today. Ill try anything at this point.

 

I also have the hard brake pedal syndrome!

I have a '91 convertible with 30K miles on the clock. Like many here, I've changed out parts: rotors with upgrade to Baer zinc washed drilled and slotted, new stock pads, braided flexible lines, and bled the system well.....all to little improvement. It does stop better, but it still takes a mighty pressure on that brake pedal. My abs system does the system check on initial movement of the car, and it seems to be fine. I've felt it engage once or twice before.

I'm glad to find this thread because I've always found it hard to believe that a Corvette doesn't stop much better than this. The car has been in my family since new, but I can't remember if it felt like this when it was brand new.

Thanks to Fastmax for posting his solution. I also don't like to take my car to a shop, but I'm going to try to find one here in Dallas that can read the codes on the abs system.

 

Try shorting terminals A and H I believe. No codes on mine.

 

...forget the "soft mushy pedal stuff",.... .. i still want to hear how many people "jacked" their parking brake handles 100 times to make their pre 1990's "hard pedal and insufficient" brakes work better and how many it made an actual difference... .....i can stop my car's engine after running it and hit the brakes 3-4 times and expel all the vacuum in it so i know it is NOT leaking or bad (among other tests)...i have also disconnected the booster and had attempted to brake and they were totally non-existent for all practical purposes....

 

I agree with most of you complaining.
I can not believe that my Nissan will provide trouble free brakings from high speed. I have even found out how fading feels.

But it is incredible that a "true" sportscar is so defective on important issues like braking. I do not even mind the optispark problem compared to the braking problem.
This will only decrease confidence when using the Vette.
I love my Vette but I guess that I choose the wrong sportscar, maybe a 350Z will hold up better, just a thought ( out of frustration! )

 

I bascially agree with this currently. Maybe that’s why nobody can actually find defective parts….design.

94 Vette
After having the car for a while, I realized the car stopped, but not under panic or just harder braking conditions. I had joined the club, but did not know I did until I started reading all the info on the Forum. I do not have a hard or soft pedal, feels like any new or old normal car, just wouldn’t stop, kepts coasting.

My pedal felt normal with engine on or off, but the car really did not stop well and became very cautious when driving. Over the course of time I changed the master, rotors, pads, flex lines, rebuilt calipers and bleed much fluid many ways. With no real improvement, my theory something was absorbing the brake pressure such as a ballast. So I zeroed in on the ABS and replaced the ABS pump. There was no real change again.

The booster was the only item left but exhibited no symptoms of anything wrong and did it all right. I even built 2 plates to test the power of the booster. One steel to see if the rod was compressing under pressure from the pedal, and one thick aluminum which the rod bent to a “V” with very little pressure applied the pedal. Also dreamed up some other weird tests but proved nothing again.

I ended up installing the J55s and got a whopping improvement in performance. Installed the DRM bias spring in the master and had a system that did pretty good in activating the ABS and stopping the car.

My thoughts are is there is some sort of under design of the braking system in regard to pressure distribution. Although being an engineer, I do not possess the skills of a brake design engineer to run the numbers to make this determination. Just seems like something is under size somewhere. I could not find anything wrong with any one original individual part or unit.

We all buy these higher performance rotors, pads and lines to make the system work better, I did to but was a waste of money in regard to fixing anything. But I can buy at Autozone (or whatever) low end basic brake part for any of the other 4 cars I own and have great normal brakes.

It is said some vettes have good brakes and some don’t. But I would need to see someone who says he has good brakes to evaluate his opinion of what good or normal is.

I would like to solve and have the answer to this, but it is not keeping me up at nights because currently the car stops satisfactory. But not have forgotten the challenge.

 

Eh...I did mine 40 times, didnt do squat...Felt pretty stupid doing it too

Ive narrowed it down to some air in the front of the master cylinder, just gotta bleed it . Fwiw, the speedbleeders are awesome, I found air in the LF line- I never would have seen the problem if I had not installed those.

I could stand outside the car while pumping the pedal and see an occasional bubble coming up through the reservoir I couldnt before.

Supposedly you disconnect the wire there, have someone pump the brake pedal and just crack the line open to bleed the MC on the car without having to rebleed the lines. I cant tell you how many times I took the wheels off and on the car this weekend.

Before that I found some water, nailed the brakes to activate ABS and rebled as told...Didnt do much. Now to get the last of the air out..

Used a (TINY amount) "joint stick" from a plumbing supply on all but the first 2-3 threads to guarantee no air gets pulled back in. Those things work great!

There IS light at the end of the tuinnel, finally.

One weird thing I cant figure out...After my last bleed the pedal with key off was "right there". Turned the car on, pedal went to the floor. Pumped it agian, same thing. As I let the pedal back out I hear an extremely loud POP!! I mean LOUD....Everythign works fine though, pedal returned to nrmal immediately. WTF?!?!

 

.........i thought as such.......does anyone really have an 88 (such as in my case) that has NOT done any upgrades (j55's, etc) or using anything but generic stock pads and have great brakes?