Author Topic: 69 RF brake lock up?  (Read 9304 times)

JKZ27

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Re: 69 RF brake lock up?
« Reply #15 on: December 02, 2016, 02:10:00 AM »
Hey Jim, are you saying the wheel locks up when driving to the point the tire skids or it begins to smoke the pads? Or, does it lock up on jack stands and won't release? Either way, what do you do to get it to release?
John
69 RS/SS Cortez Silver, L48 MC1
68 RS Ash/Ivy Gold 327EFI M20

Rufcar

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Re: 69 RF brake lock up?
« Reply #16 on: December 02, 2016, 07:48:15 PM »
While driving, even at 1 mph if you brake more then just a light touch the right wheel will lock up. I have been down shifting for 3 years and then just use an extremely light touch to stop the car.  Anything more than that the right wheel locks up. This afternoon I just received my distribution block. I will try and install tomorrow. If that does not work I'm at a complete loss as its the only part I did not replace.  Jim

1969Z27

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Re: 69 RF brake lock up?
« Reply #17 on: December 02, 2016, 09:53:16 PM »
Is your mc correct for your car? Does it have the correct piston diameter? MC could be defective? Trash in mc or lines?
Russ 
68 RS L22/M20
69 SS L48/MC1

Rufcar

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Re: 69 RF brake lock up?
« Reply #18 on: December 03, 2016, 05:10:12 PM »
MC was brand new last yr and was exactly the same as the one that was on and yes it matches factory. I just now changed out the distribution block and will hopefully bleed today.  Tkx jim

Rufcar

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Re: 69 RF brake lock up?
« Reply #19 on: December 03, 2016, 07:41:46 PM »
update: Today I changed out the distribution block and bleed the system. Tested car right side still locks up. I switched lines same ting. I ran new lines, Same thing, right side still locks up? The only thing I can see is the right side has a GM  stamped caliper single piston and the left side has no markings , single piston. Maybe the previous owner bought a mismatched set? Im going to but 2 new front calipers, should they be single piston or double? It is the only thing I have not changed. Any ideas or suggestions? Tkx JIm F

1968RSZ28

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Re: 69 RF brake lock up?
« Reply #20 on: December 03, 2016, 07:49:12 PM »
Im going to but 2 new front calipers, should they be single piston or double?

Jim,

The '69 Camaro came from the factory with single-piston disc brake calipers.  The 4-piston disc brake calipers were used only in '67 and '68.

Paul

Rufcar

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Re: 69 RF brake lock up?
« Reply #21 on: December 03, 2016, 08:03:52 PM »
That's what I thought too. Im going to order a matched set as its the only thing left. Tkx

KurtS

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Re: 69 RF brake lock up?
« Reply #22 on: December 05, 2016, 01:45:46 AM »
Please clarify the issue. It only locks up when applying the brakes, correct? Whenever your foot is off the brake, the wheel spins freely?
So, if the front is jacked up and you pump the brakes, afterwards it spins free? You've confirmed that?

Sounds like the LH front line is plugged in some form from the distribution block to the caliper.
Both fronts are easy to bleed?
Kurt S
CRG

Rufcar

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Re: 69 RF brake lock up?
« Reply #23 on: December 05, 2016, 03:48:41 AM »
Kurt yes to your 1st paragraph. I ran a new temporary line to the LF and the RF still locked up. To be clear it only locks up when driving at any speed when you touch the brake pedal a tad more then very light to slow down. I have replaced everything now except the calipers. I did not think I had too as they were brand new when I bought the car 3 years ago. Yes they always locked up but then continued to get worse over the past 3 years. Upon close inspection it definitely appears the right piston moves faster than the left. Yes I have taken both calipers off cleaned the pistons, applied light air pressure and the both work on the bench correctly I now believe, upon close inspection, they are not identical and that's could be the problem. Tomorrow I will order a new set from "groundup" install them and see if that solves the problem as its the only things left that I can think off.. Jim

JKZ27

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Re: 69 RF brake lock up?
« Reply #24 on: December 05, 2016, 11:46:27 AM »
 Jim,

Is this a factory disc car or a conversion, can you tell?
Make sure it has all the correct and necessary components including the hold off valve and maybe a proportioning valve.
And, make sure it is plumbed correctly, especially if a previous owner did a bunch of work. If you are not sure post some pictures of your set up or reference some photos of original cars. I hate to see anyone replace a bunch of parts when they're not sure what's wrong. Do the rear brakes work at all?
John
69 RS/SS Cortez Silver, L48 MC1
68 RS Ash/Ivy Gold 327EFI M20

Sauron327

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Re: 69 RF brake lock up?
« Reply #25 on: December 05, 2016, 12:57:29 PM »
Jim,

Is this a factory disc car or a conversion, can you tell?
Make sure it has all the correct and necessary components including the hold off valve and maybe a proportioning valve.
And, make sure it is plumbed correctly, especially if a previous owner did a bunch of work. If you are not sure post some pictures of your set up or reference some photos of original cars. I hate to see anyone replace a bunch of parts when they're not sure what's wrong. Do the rear brakes work at all?

Based on the OP's info, I don't think this is a stock system. In his first post it states an "additional distribution valve" was removed, whatever that was. The factory metering/hold-off valve stops fluid flow to the front brakes until the system sees 30-40 PSI. Without that valve or if it is malfunctioning, the front brakes can lock up prematurely.

I buy GM calipers locally much cheaper than any restoration vendor. They nail you on parts like this.

Rufcar

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Re: 69 RF brake lock up?
« Reply #26 on: December 05, 2016, 07:58:55 PM »
Sauron the old metering valve was removed. The problem from the day I bought the car was under some braking conditions the right front brake would lock up. IN the 3 years of ownership and a full re restoration of the car I bought. It has always done that  and it has done it less without the metering valve. I did not install the disc brakes and there's really no way to know if it came with them from the factory because so many thing have been changed. Tomorrow I get the new calipers and then we will see if that helps. Attached is the set up before I installed another engine last yr. Tkx

Stingr69

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Re: 69 RF brake lock up?
« Reply #27 on: December 05, 2016, 08:25:56 PM »
Crazy idea....right front caliper is hooked up to one of the rear brake cylinder lines and the residual pressure valve is keeping pressure applied.  Trace the lines?  Test - Opening then closing the right front caliper bleeder screw would relieve the pressure in the caliper and the wheel would spin freely again. 

JKZ27

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Re: 69 RF brake lock up?
« Reply #28 on: December 05, 2016, 08:33:19 PM »
Crazy idea....right front caliper is hooked up to one of the rear brake cylinder lines and the residual pressure valve is keeping pressure applied.  Trace the lines?  Test - Opening then closing the right front caliper bleeder screw would relieve the pressure in the caliper and the wheel would spin freely again. 

Sort of what I was getting at. Brake lines look like they're tied in a knot in your photo. Also, I can't tell if that's a 2nd gen combination valve under the master cyl.
Whatever type of system is on there, trace the lines, and make sure they connect where they should.
John
69 RS/SS Cortez Silver, L48 MC1
68 RS Ash/Ivy Gold 327EFI M20

Sauron327

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Re: 69 RF brake lock up?
« Reply #29 on: December 05, 2016, 10:21:41 PM »
Crazy idea....right front caliper is hooked up to one of the rear brake cylinder lines and the residual pressure valve is keeping pressure applied.  Trace the lines?  Test - Opening then closing the right front caliper bleeder screw would relieve the pressure in the caliper and the wheel would spin freely again. 
Photo is unclear but looks like a combination valve like JK says, which is not original on first gens. Original 67-69 system is here: http://www.camaros.org/brakevalve.shtml The combination valve shown in that link is a later version, original combo valves were cast and more rounded. You said you replaced the distribution block which would indicate it is not a combo valve. Distribution blocks have no valving function per se. Read the link. If it is not a bad or stuck caliper, something is exerting excessive pressure on the system.