Brakes - ZR-1 Net Registry Forums

USAFPILOT · 07-03-2009

My brakes seem to be slightly engaged after a while driving.

At first the pedal is spongy...then after some driving it gets real firm and works quite well...but if I put the car in neutral to coast it feels like it is slowing down on the brakes a little...and once I park it in the garage it wont roll. But it will roll again once it has cooled off.

This is not due to the e-brake not being disengaged. That is the first thing I checked.

I dont want these rotors to warp up...is this normal?

WB9MCW · 07-03-2009

My guess is either the brakes are semi-engaged like you suspect

or you may have wheel bearing on the way out

try the wobble the wheel test while on a stand and see if you have excess play

plus let's see what others think -- even though the wobble test is easy.

tomtom72 · 07-04-2009

Hi, I don't know if this will help as my 90 maybe different from the later cars but in the FSM Brake section there is a diagnostic outlined in the Brake Troubleshooting chart for "dragging brakes". The answer for adjusting the Brake Pedal was the closest match to my symptoms, so I used that soloution as a starting point.

In my 90 it's so simple that I thought it was a miss-print. It said make sure the brake pedal is at the proper height by pulling up on the pedal. I did this and heard some clicks and the pedal moved! When the clicks stopped, the movement stopped. I was dumb founded, but when I tested the car the rear brake dragging was gone!

The only other answer in the chart involved the booster rod. On a 90 the rod tip has to be level with the outside face of the booster ( where the M/C bolts up ). If the push rod is too far out the booster applies enough pressure to the M/C to drag the brakes The push rod adjusts by turning it like a screw.

The only other thing I can remember is that there is an adjustment procedure for the parking brake....but I don't remember it...sorry...

Tom

LT5-Lee · 07-04-2009

I would suggest flushing the fluid. I had this happen one time on another car where it got so bad I had to relieve pressure just to get home. It seems a particle of trash or rust clogged the return port on the MC. I have also seen brake hoses fail and allow fluid to pass from the inner core to the outer rubber shroud and basically pinch off flow.

USAFPILOT · 08-24-2010

Flushing the fluid fixed it...now I am going to replace the pads and install some freshened up rotors and flush again for good measure. I also did a complete flush using DOT4. Ive always heard you can use DOT4 in a DOT3 system but not DOT3 in a DOT4.

I'll be using Hawk HPS pads and some slotted rotors from a previous vette. I wish I knew who made them but I know they are practically brand new and from Canada.

Should I use any additive on the pads before I install them? Ive seen that done before but I don't think it is necessary.

WB9MCW · 08-24-2010

Looks like Dot 4 is a good upgrade.

>>> http://en.wikipedia.org/wiki/DOT_4

I am about to do mine so I will do the same unless there is a reason not to.

"DOT3 has been all but replaced with the superior DOT4 as there is little cost difference between the two."

From >>> http://en.wikipedia.org/wiki/DOT_3

Dot 5.1 looks like the real winner even out performing Dot 5

See >> http://en.wikipedia.org/wiki/DOT_5.1

Wonder if there is any reason not to use 5.1 in our ZR-1's ???

Kb7tif · 08-25-2010

I think the fluid flush is a temp. fix and the master cylinder's rubber is breaking down and master needs to be replaced. mine did this.

USAFPILOT · 08-25-2010

Quote:

Originally Posted by Kb7tif

I think the fluid flush is a temp. fix and the master cylinder's rubber is breaking down and master needs to be replaced. mine did this.

well that should be fun...shiza

pantera1683 · 08-25-2010

Quote:

Originally Posted by USAFPILOT

well that should be fun...shiza

It's not very hard to do.

WB9MCW · 08-25-2010

Where is a good place to get a rebuild kit for the MC on the ZR-1

Tom Henry Chevy? or any dealer? Are they available easy?

I think mine needs it since I too have the low pedal - spongy syndrome now.

Prob the orig Brake fluid in my system 63K miles now.

07-03-2009	#1
USAFPILOT Join Date: Aug 2007 Location: Spring TX Posts: 1,348	Brakes My brakes seem to be slightly engaged after a while driving. At first the pedal is spongy...then after some driving it gets real firm and works quite well...but if I put the car in neutral to coast it feels like it is slowing down on the brakes a little...and once I park it in the garage it wont roll. But it will roll again once it has cooled off. This is not due to the e-brake not being disengaged. That is the first thing I checked. I dont want these rotors to warp up...is this normal?

07-03-2009	#2
WB9MCW Join Date: Dec 2003 Location: McHenry, Il. Posts: 6,607	Re: Brakes My guess is either the brakes are semi-engaged like you suspect or you may have wheel bearing on the way out try the wobble the wheel test while on a stand and see if you have excess play plus let's see what others think -- even though the wobble test is easy. __________________ http://i119.photobucket.com/albums/o...9mcw/SIG-2.jpg http://i119.photobucket.com/albums/o128/wb9mcw/vcm.gif "The Budget should be balanced, the Treasury should be refilled, public debt should be reduced, the arrogance of officialdom should be tempered and controlled, and the assistance to foreign lands should be curtailed, lest Rome will become bankrupt. People must again learn to work instead of living on public assistance." - Cicero, 55 BC " We the people are the rightful masters of both Congress and the courts, not to overthrow the Constitution but to overthrow the men who pervert the Constitution." - Abraham Lincoln

07-04-2009	#3
tomtom72 Join Date: Dec 2004 Location: Jacksonville, FL USA Posts: 4,645	Re: Brakes Hi, I don't know if this will help as my 90 maybe different from the later cars but in the FSM Brake section there is a diagnostic outlined in the Brake Troubleshooting chart for "dragging brakes". The answer for adjusting the Brake Pedal was the closest match to my symptoms, so I used that soloution as a starting point. In my 90 it's so simple that I thought it was a miss-print. It said make sure the brake pedal is at the proper height by pulling up on the pedal. I did this and heard some clicks and the pedal moved! When the clicks stopped, the movement stopped. I was dumb founded, but when I tested the car the rear brake dragging was gone! The only other answer in the chart involved the booster rod. On a 90 the rod tip has to be level with the outside face of the booster ( where the M/C bolts up ). If the push rod is too far out the booster applies enough pressure to the M/C to drag the brakes The push rod adjusts by turning it like a screw. The only other thing I can remember is that there is an adjustment procedure for the parking brake....but I don't remember it...sorry... Tom __________________ 1990 ZR-1, Black/grey, #2233, stock. ZR-1 Net Reg Founding Member #316 & NCM member

07-04-2009	#4
LT5-Lee Join Date: Jan 2009 Location: Houston, Tx. Posts: 57	Re: Brakes I would suggest flushing the fluid. I had this happen one time on another car where it got so bad I had to relieve pressure just to get home. It seems a particle of trash or rust clogged the return port on the MC. I have also seen brake hoses fail and allow fluid to pass from the inner core to the outer rubber shroud and basically pinch off flow. __________________ An Unarmed Citizen is a Future Peasant. Something BLOWbama & Hilary are trying to accomplish now at the UN with the "Global Small Arms Treaty"

08-24-2010	#5
USAFPILOT Join Date: Aug 2007 Location: Spring TX Posts: 1,348	Re: Brakes Flushing the fluid fixed it...now I am going to replace the pads and install some freshened up rotors and flush again for good measure. I also did a complete flush using DOT4. Ive always heard you can use DOT4 in a DOT3 system but not DOT3 in a DOT4. I'll be using Hawk HPS pads and some slotted rotors from a previous vette. I wish I knew who made them but I know they are practically brand new and from Canada. Should I use any additive on the pads before I install them? Ive seen that done before but I don't think it is necessary. Last edited by USAFPILOT; 08-24-2010 at 08:25 PM.

08-24-2010	#6
WB9MCW Join Date: Dec 2003 Location: McHenry, Il. Posts: 6,607	Re: Brakes Looks like Dot 4 is a good upgrade. >>> http://en.wikipedia.org/wiki/DOT_4 I am about to do mine so I will do the same unless there is a reason not to. "DOT3 has been all but replaced with the superior DOT4 as there is little cost difference between the two." From >>> http://en.wikipedia.org/wiki/DOT_3 Dot 5.1 looks like the real winner even out performing Dot 5 See >> http://en.wikipedia.org/wiki/DOT_5.1 Wonder if there is any reason not to use 5.1 in our ZR-1's ??? __________________ http://i119.photobucket.com/albums/o...9mcw/SIG-2.jpg http://i119.photobucket.com/albums/o128/wb9mcw/vcm.gif "The Budget should be balanced, the Treasury should be refilled, public debt should be reduced, the arrogance of officialdom should be tempered and controlled, and the assistance to foreign lands should be curtailed, lest Rome will become bankrupt. People must again learn to work instead of living on public assistance." - Cicero, 55 BC " We the people are the rightful masters of both Congress and the courts, not to overthrow the Constitution but to overthrow the men who pervert the Constitution." - Abraham Lincoln Last edited by WB9MCW; 08-24-2010 at 09:03 PM.

08-25-2010	#7
Kb7tif Join Date: May 2009 Location: S Nevada Posts: 352	Re: Brakes I think the fluid flush is a temp. fix and the master cylinder's rubber is breaking down and master needs to be replaced. mine did this. __________________ 1995 Convertible Supercharged Auto 1974 454 550hp (avatar car) On the blocks- -Scharger install ! 1992-Zr-1 Sold. Watson Headers Ported Plenum, Housings Random tech cats Fidanza Flywheel Chipped, Relocated Mat Woods 165 stat Borlas, Straights 1996 Lt4 Sold 1994 Lt1 Sold 2004 Z06 Sold AKA** Illenema

08-25-2010	#10
WB9MCW Join Date: Dec 2003 Location: McHenry, Il. Posts: 6,607	Re: Brakes Where is a good place to get a rebuild kit for the MC on the ZR-1 Tom Henry Chevy? or any dealer? Are they available easy? I think mine needs it since I too have the low pedal - spongy syndrome now. Prob the orig Brake fluid in my system 63K miles now. __________________ http://i119.photobucket.com/albums/o...9mcw/SIG-2.jpg http://i119.photobucket.com/albums/o128/wb9mcw/vcm.gif "The Budget should be balanced, the Treasury should be refilled, public debt should be reduced, the arrogance of officialdom should be tempered and controlled, and the assistance to foreign lands should be curtailed, lest Rome will become bankrupt. People must again learn to work instead of living on public assistance." - Cicero, 55 BC " We the people are the rightful masters of both Congress and the courts, not to overthrow the Constitution but to overthrow the men who pervert the Constitution." - Abraham Lincoln