Brake Overhaul on 88 IROC... need help
 

Fellow Thirdgeners, I need your help. For reference, here are some threads from the fall.... Here and Here.

Long Story Short... brakes pulling to one side, bad hose and found a rotor measuring out of spec. Decided to do Stillen Rotors and Pads in the rear and a Powerstop Kit for the front. New bearings, seals... you know the deal. Also, added Russel braided lines. Not building a track car, but while I am in there might as well use more up to date parts.

I can't seem to get a firm pedal. Even got a re-manufactured Master Cylinder to eliminate it as a cause. Bench bled it until it was firm, and the re-bled all the brakes. Still not firm... then MI winter came and just didn't have garage time. With Spring here, it is time to get back to the garage. I am just not sure where to start trouble shooting. I am usually really good with figuring things like this out, but this one has just got me stumped.

Rear brakes are adjusted to where they almost drag, parking brake works excellent and so do the brakes when the pedal is pushed. Parking brake travel at the arm is also in spec. To get to 12-14 clicks requires you to either really yank on it hard and quick or use a lot of force to slowly pull it up. The fronts seem to also work great. I can't find any leaks around any of the hose fittings, was never losing fluid. I can build a firm pedal with the car off, but once turned on and the booster comes into play, the pedal will just sink, not completely but has to travel very far to hit a hard stop.

When I say bleed... I have sent pint after pint through this thing at each corner to try and be damn sure I have all the air out. Using a vacuum operated system to pull it through.

Now I do see air bubbles sometime when bleeding, but I have confirmed this seems to be from the seal at the bleeder screw. If I don't use the vacuum system and have my son push the pedal, solid stream of fluid comes out. Is there possibly air entering elsewhere? If so, shouldn't fluid be leaking there too?

What should my next steps be?

Re: Brake Overhaul on 88 IROC... need help
 

I guess this stumps others and I am not alone.

Any ideas/suggestions appreciated.

Re: Brake Overhaul on 88 IROC... need help
 

Can you adjust the rod from the brake booster into the master cylinder. Had the same issue with my dodge Shelby daytona, adjusted the rod. The rod was too short with the new master cylinder, so there was some space between the rod and the master. Lengthened the rod coming out of the brake booster a bit (was adjustable from factory)

Re: Brake Overhaul on 88 IROC... need help
 

Seems reasonable. I wasn't happy with the brake travel before, so it's something worth checking. I figured it was due to old fluid and old rubber hoses. I think it is worse now than before I started so I didn't think that would be the culprit, but at this point anything is worth checking. I am sure there is a factory specification on length, but you said you had an issue when you changed masters. If I am reading between the lines, you would have adjusted yours out past the spec due to the replacement master. How did you determine your new length?

Re: Brake Overhaul on 88 IROC... need help
 

try bleeding the rears with the parking brake applied. It's possible that you have a leak in the caliper.
Also have you confirmed no leaks at any of the fittings?
If you need the dimension I have my master and booster out of the car. I can measure the push rod out of the booster.
PM me if you need it I am on TGO a few times a week...
Dave

Re: Brake Overhaul on 88 IROC... need help
 

Well, no information is bad information. I will shoot you a PM, but having posted on here may help someone searching threads in the future.

I am pretty sure I bled the rear brakes with the parking brake applied, but not a 100% sure. I know for sure between bleeds I cycled the parking brake and pedal, just can't remember if I did it with the parking brake still applied.

I have the front up right now.

Any ideas on how to isolate the front/rear. I have not seen any fluid leaks, I have a feeling the issue is in the fronts, but can't confirm that. The rear parking brakes and when I had my son pressing the pedal in the car just seemed to work better than expected but that's all off visual and feel. The pads are close, withing a couple of thousandths of an inch from the rotors. The calipers that were on it when I bought it are still there. Didn't have fluid loss issues and don't see anywhere it had leaked around the bore or fittings except when I took them loose to replace the hoses and of course on the drivers side I had to disconnect the hard line.

Re: Brake Overhaul on 88 IROC... need help
 

I'm going to bet that everything is fine. It's probably your pads. Your not racing so ditch the racing stuff. If you want a "firm" pedal (factory?) then you need regular old pads. I don't recommend ceramic as a first choice. Go with semi metallic if you can. I had the same problem after I replaced all four corners with all new stuff. It took a while for the pads to settle in but now they bite hard, no random pulling to one side, and a light pedal to stop. It just took some driving and the problem went away. Weird I know.

Re: Brake Overhaul on 88 IROC... need help
 

You mean the pads are too thin? This is pedal travel non-moving. Just straight up travel until the I get a firm stop of travel, not of the car. Once the brakes are pumped up, the pads should set close to the rotor just as if they had worn and the pedal travel should remain the same no? To be honest, I do not feel it is safe to drive in the condition it is in to try to settle them in. The fronts were broken in before I tore the rear apart, but the car had more pedal travel than it should have to begin with and after the fronts were replaced. At the time, I had not touched the rears. So, I figured it would be better after doing the rears.

Also, there has been plenty of pedal pumping and bleeding, then more pumping... rinse wash repeat.

Re: Brake Overhaul on 88 IROC... need help
 

Rear Pads - call for street use.

Front Kit - Z23 Evolution Sport High Carbon Ceramic Brake Pads Engineered for the enthusiastr that wants to get the most out of their vehicle without sacrificing everyday driveability

So I hope I am not in that same spot.

Re: Brake Overhaul on 88 IROC... need help
 

Are you by any chance using Silicone brake fluid? That crap is hard to bleed.

Re: Brake Overhaul on 88 IROC... need help
 

That is DOT 5 if I am not mistaken. I am using This DOT 3


Keep the ideas coming. It has to be something.

Re: Brake Overhaul on 88 IROC... need help
 

a quick question, why do you have to ;put the parking brake on to bleed the rears?

Re: Brake Overhaul on 88 IROC... need help
 

Correct. Nothing unusual about bleeding Dot3

Re: Brake Overhaul on 88 IROC... need help
 

Re: complete brake overhaul in progressIf you still have the old rubber lines put them back on and rebleed. Then clamp off the rear rubber hose, bleed the front, if nothing changes in pedal travel leave rear clamped and clamp right front and bleed left, if nothing changes clamp left line off and bleed the right. If nothing changes you have eliminated the calipers/wheel cylinders or calipers/calipers. I have replaced a few remanufactured master cylinders that have done this very thing. They were bad from the store.

Re: Brake Overhaul on 88 IROC... need help
 

Here is the photo of how far the rod sticks out of the booster. The photo is with the tape measure in the top side of the rod.
https://cimg7.ibsrv.net/gimg/www.thi...2c70a2942a.jpg

Re: Brake Overhaul on 88 IROC... need help
 

With the Iron rear calipers the parking brake is a multi lead screw that pushes the piston out to clamp the pad to the rotor.

Re: Brake Overhaul on 88 IROC... need help
 

Yup, so it actually pushes the cylinder forward and should fill with more fluid. More volume to pull air from. Then when you release, it goes back to the MC.

Re: Brake Overhaul on 88 IROC... need help
 

I put a master cylinder on because of this issue. It didn't make it any better. This was the reason I suspected the old one.

Somewhere in the other threads I mentioned I had the MC capped while I installed it, and pushed the pedal without the car running(no booster). It was firm as could be.

Re: Brake Overhaul on 88 IROC... need help
 

Well, I got the C4 ready to go last night. Will be putting hands on the IROC soon.

Re: Brake Overhaul on 88 IROC... need help
 

Car has had all fluids checked and has been started, brought up to temp and all that good stuff from sitting over the winter. I can't tell you how much a Batter Tender and Stabil are my friends.

Taking the advice above, I started at the beginning. Brake pedal mount is nice and firm with no play and same for the actuator rod attached to the pedal assembly. Seems silly I know, but starting from the beginning.
Usually a booster failing doesn't cause a soft pedal, but ran it through the checks anyway. Pull the vacuum hose off and inspected it. Looks like it is fairly new. Blew through it and the check valve is working properly. Allows suck, but not blow. Then I started the car, yup pedal goes to almost bottom of travel. Let it back up, shut car off... pressed the pedal 4 times. Each time got a little more difficult and the pedal got higher. Then while holding pressure on the brake pedal, started the car and the pedal went down easy as vacuum built (Watching the Boost/Vacuum gauge - didn't take long). Shut the car back off and the pedal slowly got harder to hold down.

So it seems all is well as far as the booster.

I guess the next step is to remove the master, re-bench bleed. My only issue there is that means having to re-bleed the entire system before I can check again. What would happen if I left the rear channel connected, took the front lines off and used the nylon bleeding plug to seal it and secure the plug with a large C-Clamp. Thus isolating the rears. I have the old Delco Morain calipers that are know the be a PITA, but have a hunch my issue is not in the rear that I would like to confirm.

Re: Brake Overhaul on 88 IROC... need help
 

Left the rear Channel connected, disconnected the front, and pushed on the pedal with no booster. When the proportioning valve shifted, it gave a nice squirt out of the line normally connected to the master. LOL. So that is what happens.

Not using the booster the brakes still didn't feel as tight as I would like. So, I went ahead and removed the master to confirm there was no trapped air. I don't care what anyone tells you, you can't bench bleed a master properly while mounted in the car on a thirdgen. The angle is just too steep. Got it in the bench vice and started pushing on the bore. Unfortunately, no bubbles. Meaning, I had it right the first time and it is not the problem.

What I did notice, and I think I mentioned it before, is the instructions called for .125" of play and I believe I have .250" of play. I am going to measure it tonight and then possibly make a spacer for the plunger to take up the extra .125".

I also hit the pedal while both channels were plugged. There was the dead area in the pedal (likely caused by the above gap), and then bam! Like pushing against a wall. So, I feel at this point I have eliminated the master, booster, check valve, and anything in the pedal assembly.

Re: Brake Overhaul on 88 IROC... need help
 

On with the saga. Daferris stopped by last night and brought one of the heavier proportioning valve springs. This is not as simple to do with a supercharger and strut tower brace in the way. :D

Everything is back together and it is time to re-bleed everything. Hopefully starting that this evening. Hoping for the good firm pedal when this round is done.

Re: Brake Overhaul on 88 IROC... need help
 

Family obligations, grass, and work got in the way of getting to the IROC, but finished the rears last night. Hopefully I will get some time to get in the garage tonight and do the fronts.

Re: Brake Overhaul on 88 IROC... need help
 

Finally got some garage time. Got to bleeding the fronts and I think I may (or may not who knows at this point) be onto the soft pedal cause. While bleeding the fronts I found that no matter how long I let it gravity bleed for, eventually I will always see an air bubble. Then, if I use the vacuum bleeder, I can see constant air bubbles.

So, where I am at is:

Booster: Passed all checks
Proportioning Valve: Passed all checks and has an upgraded spring
Master Cylinder: Checked good, nice and firm on the bench, and then while still plugged after installation was nice and firm using the pedal (No Booster)
Rear Brakes: Bleed great, parking brake works great, no pad rattle.
Front: No matter how long they bleed, still see air.

New theory. The washers that came with he Russell kit were not very wide in diameter. Possibly allowing air when the pedal pulls back or vacuum is applied, but the leak is not bad enough to let fluid out. Or, possibly just not enough cycles of the brake pedal to get fluid to come out of the seal area to be noticed. Well, At least I hope that is what the problem is because the next thing in line will be trying new calipers. Which, the ones on the car are from the power stop kit. Hoping to find an hour or so of garage time this week. New washers will be here Tuesday.

Re: Brake Overhaul on 88 IROC... need help
 

Got some time and... well... There probably wasn't much of a problem to begin with other than the rear brakes having a bad reputation and my expectations for how much replacing rubber lines with stainless will improve pedal travel.

I picked up another set of front reman calipers. replaced the passenger side first. Went through the bleeding process and etc. Pedal still not what I wanted, but left it there until daferris stopped by to just give me his thoughts.

I did notice a few things on my Power Stop remaned calipers. as I was inspecting them. Mainly the hose was hitting the casting pretty good. While I couldn't see a leak I was concerned this was keeping the crush washer from sealing equally all around.
https://cimg3.ibsrv.net/gimg/www.thi...3138092e32.jpg
https://cimg3.ibsrv.net/gimg/www.thi...c6be41ea7d.jpg


I ground this area back to make a bit more clearance. The Stainless is much harder to just have it where you want it.

When daferris came over, we did a little more bleeding on the front doing the 2 man method. A few little bubbles came out, nothing major... but pedal was firm at the bottom of the travel. Between firewall flex, travel in the master, and just general 3rd gen brakes I am not getting the pedal travel I was hoping for.

So, I reinstalled my pretty red caliper last night and will get my son to help me with the 2 man method again and go out and try to bed the rears in. As long as the pedal has a firm stopping point, I may just have to write it off as my expectations where greater than my wallet paid for and move on to the next projects.

Thanks again to daferris for the second opinion.

It should also be noted I removed the spacer I made. It verified without removing the booster that the actuator rod is correct. With it installed, pedal travel decreased. However, it was partially actuating the master and prevented the system from bleeding.

I can pretty much do a brake job on the early 4 wheel disc brake cars with my eyes closed now.

Re: Brake Overhaul on 88 IROC... need help
 

Took it out last night. Brakes are awesome. I did use the parking brake to squeeze the rears during the bedding in process (Followed Stillen's). Then drove around for a while on the country roads to cool them down. Did a few Emergency stops... the brakes are great.

Re: Brake Overhaul on 88 IROC... need help
 

With all the changes I'm sure it got lost in the background noise, but did you notice a significant difference with the new proportioning valve spring and which one did you go with? I ordered some 19lb springs for 86 and 91 and may get to trying one out in a bit.

GD

Re: Brake Overhaul on 88 IROC... need help
 

It did get lost in the background. I do not notice a difference because the brakes were compromised when I bought it and I only drove it long enough to bed the front brakes in before the real adventure started. I will say, the brakes stop better than I remember and feel more solid. However, before I owned this car, it had been since 2004 that I had driven a Thirdgen. So, it is hard for me to honestly make a statement on difference. As much as I am against making multiple changes at once... since I had the MC out and knew I would need to bleed the brakes it just seemed like an appropriate time to slap it in there while I had room.

I believe it was the 1NCR5. Daferris gave me an extra from his upgrade. So, I am using what he is using. I believe he said it was the 1NCR5, but I will let him confirm that.