four wheel disc don't stop car

Posted By: JimDiesel

four wheel disc don't stop car - 02/18/13 04:51 AM

I am having trouble with the brakes on my road runner. They dont stop the car very well. They seem to require an extreme amount of pedal pressure to work. panic stopping from 40 MPH I couldn't get the tires to lock up. I think it is a SSBC kit that was installed mid 90s. The pedal feel is ok, pumping them doesn't seem to make them work any better. I don't have a brake pressure gauge, but i can but one if needed. Right now the car isn't driven due to brakes. The brake lines look kinda scary.
The rotors are like 10.5 rear, 10.75 front, but only about 0.75 inch wide. Are they undersized?

Anyone know what kit this is?
Are they any good?
What spindles do I have?
Are the rear caliprs on upside down? bleeder appears to be on bottom.
Do any vendors make brake line kits for this setup?
Do i need a power booster?
It has a crate hemi using schumacher mounts - so not sure if I an fit one in.
Advice on how to assess/fix.

Help me get

again
Pics

Attached picture 7592868-IMG_7247.JPG

Posted By: JimDiesel

Re: four wheel disc don't stop car - 02/18/13 04:52 AM

Drive side rear
bleeder is on lower part of caliper

Attached picture 7592870-IMG_7248.JPG

Posted By: JimDiesel

Re: four wheel disc don't stop car - 02/18/13 04:52 AM

pics 2

Posted By: JimDiesel

Re: four wheel disc don't stop car - 02/18/13 04:53 AM

pics 3

Posted By: JimDiesel

Re: four wheel disc don't stop car - 02/18/13 04:53 AM

Posted By: JimDiesel

Re: four wheel disc don't stop car - 02/18/13 04:54 AM

scary looking brake hose routing

Attached picture 7592876-IMG_7251.JPG

Posted By: JimDiesel

Re: four wheel disc don't stop car - 02/18/13 04:54 AM

SSBC proportioning valve

Attached picture 7592878-IMG_7253.JPG

Posted By: JimDiesel

Re: four wheel disc don't stop car - 02/18/13 04:55 AM

Posted By: JimDiesel

Re: four wheel disc don't stop car - 02/18/13 04:55 AM

Posted By: amxautox

Re: four wheel disc don't stop car - 02/18/13 04:57 AM

Bleeders go to the top,-- ALWAYS -- so the air can rise to the top and get pushed out.

What is the bore size of the front calipers? The rear calipers?

What is the bore size of the master cylinder?

What is the equalizer valve in the system? porportioning valve?

Posted By: JimDiesel

Re: four wheel disc don't stop car - 02/18/13 04:59 AM

more pics

Posted By: JimDiesel

Re: four wheel disc don't stop car - 02/18/13 05:00 AM

Drivers side front

Attached picture 7592894-IMG_7258.JPG

Posted By: JimDiesel

Re: four wheel disc don't stop car - 02/18/13 05:01 AM

pic

Posted By: JimDiesel

Re: four wheel disc don't stop car - 02/18/13 05:08 AM

Quote:

Bleeders go to the top,-- ALWAYS -- so the air can rise to the top and get pushed out.

What is the bore size of the front calipers? The rear calipers?

What is the bore size of the master cylinder?

What is the equalizer valve in the system? porportioning valve?

I dont have any information on the setup as this was done by the previous owner about 20 years ago. I was hoping someone might be able to identify the parts based on pics. I can search for part numbers, but would need direction on where to look.

The bleeders on the rear are kind of in the middle, but closer to the bottom than the top.

Posted By: Viol8r

Re: four wheel disc don't stop car - 02/18/13 05:12 AM

Quote:

4

Going to take a stab at it and say that is a early GM/ Corvette style M/C size 1 1/8" bore. That is most likely the start of your problems. They would assume that with that size bore you would have some power assist behind it. Not a great combo for a manual set-up.

If you are willing to spend some cash, go hydroboost and all your problems will magically disappear. Less adventerous folks would say get a 4 hole to 2 hole adapter and put a 15/16 M/C bore on there.

Posted By: PHJ426

Re: four wheel disc don't stop car - 02/18/13 06:05 AM

In that picture of the rear brake lines on the Y block on the rear axle there should be a vent pipe that clamps that Y block to the rear axle to hold it all in place. I didnt see one and it looked to me as if that Y block is just hanging there. Am I correct?

If so fix that problem as well. It has nothing to do with the brake pedal feel but should be corrected if its not bolted to the rear axle.

Maybe the rear calipers are switched from left to right side if the bleeders are pointing down. Do some looking around back there and see if that might be the case? Hard to tell without thoroughly inspecting the setup in person.

Posted By: JimDiesel

Re: four wheel disc don't stop car - 02/18/13 06:08 AM

This shows the bleed valves (red arrow),
assumed caliper center (orange line), and
brake hose near the bump stop (yellow arrow).

I am not sure a hydroboost will fit with a hemi.

Attached picture 7592998-IMG_7250.JPG

Posted By: AndyF

Re: four wheel disc don't stop car - 02/18/13 06:10 AM

The rear brakes are probably okay, the fronts are garbage for a car like yours, as is the master cylinder. That is a typical problem with those kits.

If you have 15 inch wheels then your best bet is to put a factory 11.75 kit on there. It should work okay with those rear disc brakes. You'll want to get the right master cylinder too while you're at it.

Cass at www.doctordiff.com can set you up with all the right parts. He is the best guy to talk to on a deal like this. Good luck.

Posted By: Kern Dog

Re: four wheel disc don't stop car - 02/18/13 08:11 AM

You can bleed the rear calipers even if the screws are pointing in the wrong direction by doing the following:
Remove the calipers from their brackets. Measure the space between the pads. This will mimic the thickness of the rotor. Wedge a piece of wood of that size between the pads. Place the caliper in a way as to point the bleeder straight up and bleed the brakes as normal. After all the air is gone and the pedal feels right, reinstall the calipers on each corner.

Posted By: BigBlockMopar

Re: four wheel disc don't stop car - 02/18/13 09:47 AM

If you have to take off the calipers to bleed them it would be silly not to change them over to the correct side right away.
But even with air in the rear calipers, the fronts should be able to lock up the wheels alone.

And yes, move that brake hose away from that bump stop and make sure the splitter-block is mounted to the axle securely by use of the vent-tube.

Cheap solution;
- get a smaller diameter MC
- swap rear calipers.

Posted By: dickdale

Re: four wheel disc don't stop car - 02/18/13 11:16 AM

Change the bore size of the master cylinder...

Posted By: feets

Re: four wheel disc don't stop car - 02/18/13 02:39 PM

Smaller master cylinder. That will get you going until you're ready to do some upgrades.
Take care of those lines like the others suggested.

If the pedal isn't spongy there is no reason to bleed the rears.

If you do need to bleed upside down calipers it's easier than you think.
Open the master cylinder cap.
Unbolt the caliper from the axle.
Hold the caliper at a funky angle so the bleeder is the highest point.
Open the bleed screw and let it gravity bleed for a few seconds.
Reinstall.

I had to do that on my TSM rear brake calipers.

Posted By: Skeptic

Re: four wheel disc don't stop car - 02/18/13 03:51 PM

I just wanted to add that those GM calipers go bad frequently and if the pads aren't adjusted tight they'll never work-in addition to everything else put out here. The parts store "rebuilt" units are hit-miss on working out of the box, get them with a lifetime warranty, or try to get new ones on ebay.

Posted By: savoy64

Re: four wheel disc don't stop car - 02/18/13 05:46 PM

the picture shows the hose going in the top and the bleeder is at the bottom---cant bleed it unless you put the car on its top---the other problem is chevy masters work the opposite of mopars--on the mopar the back line goes to the front brakes--on a chevy the front line goes to the front brakes----i would go back to mopar stuff---yeah yeah yeah--chevy gave us the sbc---ford gave us the 9 inch--mopar was the leader in brakes---mopar was so superior that wilwood copied it....bob

Posted By: JimDiesel

Re: four wheel disc don't stop car - 02/18/13 10:06 PM

Thanks for all the replies.
I appreciate the help.
Since the car can�t be driven as is, I am committed to spending some money to fix/upgrade.
I am ok with switching the rear calipers side to side and buying a new MC. I just don�t want to throw good money after bad, if this setup is always going to be sub-par, then I think I would be better off replacing the whole thing. I guess the rears need to be switched or replaced either way. The front rotors seem pretty small for a 4,000-pound car.
At some point I want to be able to take my little girls for a Sunday drive, and it needs to be able to stop.
The wheels are 16x8 torque thrust style aluminum wheels. The tires need to be replaced, and with the lack of appropriate 16-inch tires, I will likely be going to back to 15-inch steels that I have in the garage.

Posted By: Supercuda

Re: four wheel disc don't stop car - 02/19/13 03:46 AM

Quote:

I just wanted to add that those GM calipers go bad frequently and if the pads aren't adjusted tight they'll never work-in addition to everything else put out here. The parts store "rebuilt" units are hit-miss on working out of the box, get them with a lifetime warranty, or try to get new ones on ebay.

You are talking about he rear calipers with the built in E brake I assume? That would be correct. If the E brake isn't functioning properly and used regularly slack builds up between the pads and rotor causing a lower amount of braking to occur. This could very well be the issue here, along with the other ones mentioned.

Posted By: JimDiesel

Re: four wheel disc don't stop car - 02/19/13 04:02 AM

The E brake doesn't do anything.
The pedal goes to the floor with no effect.
I havent looked into it yet.
I was focusing on getting the car to stop first, not knowing that could be a symptom of other issues.

Posted By: feets

Re: four wheel disc don't stop car - 02/19/13 06:09 AM

Quote:

the picture shows the hose going in the top and the bleeder is at the bottom---cant bleed it unless you put the car on its top---

Wrong. You pull the calipers off, hold them at a funky angle where the bleeder is highest, and gravity bleed for a few seconds.
I did that using the exact same calipers on the hot rod (before the AMG conversion)

Quote:

the other problem is chevy masters work the opposite of mopars--on the mopar the back line goes to the front brakes--on a chevy the front line goes to the front brakes-

You realize that the master cylinder has the same size bore all the way through, right? It makes no difference which bore leads to which brakes. When you push on the pedal the exact same fluid movement and pressure is found in both lines.

The only difference will be if one reservoir is larger than the other. The larger reservoir needs to feed the larger caliper. That way you don't get too low on fluid as the pads wear.

Posted By: Challenger 1

Re: four wheel disc don't stop car - 02/19/13 03:04 PM

I am not sure about anything, but that master cly looks like it's for drum brakes??

I used to work at Hader Industries here in Cincinnati, they made master cylinders and pistons. I ran a screw machine making those pistons inside the master cylinders.

Posted By: feets

Re: four wheel disc don't stop car - 02/19/13 04:52 PM

If the bore is the proper size and there are not residual valves it doesn't matter what the original application was.

However, if it doesn't meet that criteria there will be problems.

Posted By: Viol8r

Re: four wheel disc don't stop car - 02/19/13 04:52 PM

Quote:

I am not sure about anything, but that master cly looks like it's for drum brakes??

I used to work at Hader Industries here in Cincinnati, they made master cylinders and pistons. I ran a screw machine making those pistons inside the master cylinders.

http://www.rockauto.com/catalog/moreinfo.php?pk=309131&cc=1232020

RAYBESTOS Part # MC36439

Looks like this is what you have a 1 1/32" bore Drum Brake M/C. Definetly the wrong set-up for your combo.

Posted By: Supercuda

Re: four wheel disc don't stop car - 02/20/13 04:06 AM

Quote:

The E brake doesn't do anything.
The pedal goes to the floor with no effect.
I havent looked into it yet.
I was focusing on getting the car to stop first, not knowing that could be a symptom of other issues.

The rear GM calipers are designed to use the Ebrake as a method to take up sack as the pad wears. The lever the ebrake cable attaches to mechanically applies the piston via a one way ratchet mechanism. If the ebrake isn't used or isn't functional the pads will have a larger and larger gap between the pad and rotor. This will affect the feel at the pedal, to the point of being ineffectual if it the gap grows larger enough. Here's an interesting link

http://classicbroncos.com/tech/rear-disc-brakes-cadillacgm-calipers

Posted By: hemi-itis

Re: four wheel disc don't stop car - 02/21/13 04:29 AM

Have you tried adjusting the prop valve??
Those GM rear calipers NEVER worked well.I've seen that alot especially on Eldorados

Posted By: Viol8r

Re: four wheel disc don't stop car - 02/21/13 05:42 PM

See the first post from the OP. His pedal feel ok. If you have never run these GM Calipers, the first thing you notice when they are out of adjustment is you get excessive pedal travel.....this is not the case. Granted, they may need adjustment but this is not the root of the problem.

He has the wrong combination M/C to Calipers. Simple fix.

I also run these aluminum rear Wilwood Metric Calipers in place of the Stock GM calipers. Much better for track use and competition.
http://www.summitracing.com/parts/WIL-120-7197/

Posted By: DoctorDiff

Re: four wheel disc don't stop car - 02/21/13 06:07 PM

This is an SSBC front and rear brake kit.

It uses late '60s Mustang front calipers and late '80s Thunderbird rear calipers. The bleeder valve is located in the banjo bolt at the top of the caliper.

The least expensive remedy is a 15/16" bore master cylinder and aggressive front brake pads (ie EBC Yellow).

Posted By: JimDiesel

Re: four wheel disc don't stop car - 02/21/13 07:01 PM

sorry, i have been down with stomach flu.

I did play with the prop valve and it didnt seem to have much effect. It defintely didn't improve things. I need to check the plumbing to see if it is even installed correctly.
I will try to get some better pics of the master.

Posted By: Viol8r

Re: four wheel disc don't stop car - 02/21/13 07:04 PM

Quote:

sorry, i have been down with stomach flu.
I did play with the prop valve and it didnt seem to have much effect. It defintely didn't improve things. I need to check the plumbing to see if it is even installed correctly.
I will try to get some better pics of the master.

Save yourself the trouble and go with Dr. Diff's advice..... get a different Master Cylinder. We saw the earlier picture....it looks to be a earlier A-body M/C.