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Brakes

Tiny
STEVE1000
  • MEMBER
  • CHEVROLET CAMARO
I have a 1967 Chevrolet Camaro with manual drum brakes on all 4 wheels. No power assist. Standard transmission with 250 cu in 6 cylinder engine. Approximately 101200 miles. Problem: Brake pedal goes next to floor before getting some braking action on rears and no action on the fronts. Have replaced the master cylinder several times with different well known auto supply store new units. New lines. New brake wheel cylinders installed several times on all wheels. New brake pipe distribution block/switch assembly (brake safety switch is located in this block). Bled the master on each installation. Lines bled good and confirmed with Monroe store that they were free of air and who just scratched there heads on this one. New shoes (up-grades to Bendix). Have double checked the clevis pin location to make sure it is in the right hole in the pedal assembly. Have checked several times to make sure the rod is seated in the deep socket master cylinder and that I have 1/16 to 1/4 inch free play as the spec call for. Dash brake light is on indicating there is a pressure imbalance in the system but I can't find it.
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Monday, October 29th, 2007 AT 5:24 PM

19 Replies

Tiny
2CARPRO JACK
  • MECHANIC
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That is a good one. I take it the shoes are adjusted properly? Check the pin under the rubber boot on the side of the proportioning valve to see if maybe it is stuck all the way one direction, could have happened during brake bleeding.
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Monday, October 29th, 2007 AT 6:03 PM
Tiny
STEVE1000
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Thanks for the response. There isn't a proportioning valve on this car. Yes, the shoes have been adjusted out to where there is a slight drag on the drum with rotation.
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Monday, October 29th, 2007 AT 6:19 PM
Tiny
2CARPRO JACK
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Sounds like the master is by-passing the fronts, is the rod the original one? When bleeding using th epedal, does fluid shoot from the bleeder or just dribble out? BTW 1st Gen Camaros are the best ones, had a 68 myself
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Tuesday, October 30th, 2007 AT 7:37 AM
Tiny
STEVE1000
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Yes, the rod is original. I get a good stream of fluid. Bet you wish you still had that 68 :)
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Tuesday, October 30th, 2007 AT 11:42 AM
Tiny
2CARPRO JACK
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Sure do, but my driving record thanks me. LOL. Can I ask why you are messing with drums instead of installing power disc. Brake hoses are new? Does it push fluid out if you loosen the hard line for the front at the master cyl?
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Tuesday, October 30th, 2007 AT 1:01 PM
Tiny
STEVE1000
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  • 15 POSTS
It's my son's car and neither of us has the money right now to upgrade. Have to find the problem with the brakes we have. All new hoses. Have taken line loose at at all connections to see what kind of flow I get and to bleed lines. It is good at all points. The master pushes fluid. The problem is the pedal goes all the way to the floor and the front brakes don't move enough to provide any braking action even though they are adjusted out to a slight drag with no pedal applied.
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Tuesday, October 30th, 2007 AT 4:03 PM
Tiny
2CARPRO JACK
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The block you spoke of before might be the problem. If it has hydraulic pressure at the wheels, the brakes should work. Try using unions and by-passing the junction block and see what happens. BTW did you bench bleed the master cyl?
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Tuesday, October 30th, 2007 AT 4:22 PM
Tiny
STEVE1000
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The block is new. Yes, I bench bled the mc before installation. The brake light switch is also located in this distribution block. The switch, as you most likely know, is activated when it sees higher pressure on one side. The dash brake light is on and I believe it is giving a reliable indication that there is a problem on the front side since the shoes don't hardly move except when the pedal is almost to the floor. And I mean almost to the floor. I have checked and re-checked things so many times that I've lost count. Still, I must be over looking something!

Steve
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Tuesday, October 30th, 2007 AT 7:23 PM
Tiny
2CARPRO JACK
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Is it hooked up properly? Could have a shuttle valve in it that is stuck to one side. Try slamming th ebrake pedal hard with your foot, have seen this re-center valves before. Worth a go
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Wednesday, October 31st, 2007 AT 7:27 AM
Tiny
STEVE1000
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  • 15 POSTS
Yep, it's connected as per assembly manual and service manual instructions. I tried your "slamming" technique several times but it had no effect. Any more ideas?
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Wednesday, October 31st, 2007 AT 3:52 PM
Tiny
2CARPRO JACK
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Is the brake light on when you arent applying pedal pressure?
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Wednesday, October 31st, 2007 AT 5:13 PM
Tiny
STEVE1000
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Yes. It is illuminated when the ignition switch is in the "on" position and will remain on when the car is started and running.
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Wednesday, October 31st, 2007 AT 6:09 PM
Tiny
2CARPRO JACK
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I would try by-passing it with unions. If the light is always on, then the valving is biased to one side internally. Sounds like you have tried everything else
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Thursday, November 1st, 2007 AT 7:29 AM
Tiny
STEVE1000
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  • 15 POSTS
I took the mc off as well as the distribution/brake light switch block. Re-checked the mc to make sure no air was present. Was ok. With all hydraulic lines disconnected from the block I connected the electrical connection and checked the brake dash light and it was off. So, the block switch valve had reset. I reconnected everything and let the mc gravity bleed the block and then reconnected the lines going to the wheels. Did not pump the pedal. Turned the ignition switch to on. The brake light was on. Can't explain how that is possible when no pressure was applied.
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Thursday, November 1st, 2007 AT 6:53 PM
Tiny
2CARPRO JACK
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The e-brake switch uses the same light.
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Friday, November 2nd, 2007 AT 7:20 AM
Tiny
STEVE1000
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Yep, and the e-brake was off.
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Friday, November 2nd, 2007 AT 7:57 AM
Tiny
2CARPRO JACK
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Then A- the master is preloaded and shuttling th evalve at all times or B- the e-brake pin switch is bad or C- the wire is grounded out somewhere. Lets seeif we can fix this, then we will get back to the pedal.
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Friday, November 2nd, 2007 AT 10:07 AM
Tiny
STEVE1000
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  • 15 POSTS
Jack

According to the service manual the mc should have check valves in the outlet holes. I noticed that when bleeding the mc that in the chamber feeding the front brakes that upon releasing the pressure there is a, what I'll call a small geyser, like squirt that comes from the bottom of the chamber. This does not occur in the chamber feeding the back brakes. This squirt is not air and it appears to me is fluid returning to the chamber. Do you think this indicates that the hole feeding the front brakes does not have a check valve then?
Steve
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Saturday, November 3rd, 2007 AT 9:02 AM
Tiny
STEVE1000
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  • 15 POSTS
I just wanted to let you know that I investigated my own question with the technical folks at Cardone (supplier to Advance Auto and others) and NAPA Brake systems. Both said that neither of them were putting check valves in their drum brake mc's. Cardone offered to build one for me with the check valves and exchange it for the one I had at no additional cost. NAPA didn't want to do anything but insisted their mc would work. I took Cardone up on their offer. The new Cardone mc with the installed check valves corrected the problem! We have excellent braking with a high firm pedal. I believe Cardone will be manufacturing these with check valves from here on out but one would be wise to ask the store you are buying from if they can assure you they do have check valves installed. The NAPA tech said he still did not believe that the check valve was needed so I guess they will not be installing them. I told him the proof was in the pudding.

Steve
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Thursday, November 15th, 2007 AT 5:29 PM

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