Author Topic: 69 RF brake lock up?  (Read 8954 times)

Rufcar

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Re: 69 RF brake lock up?
« Reply #30 on: December 05, 2016, 10:55:55 PM »
The new distribution block is exactly the same as the cast one I took out the other day. Interestingly I searched 69 Camaro engine compartment images and in over the 100 I looked at none of them had the metering valve! Yes I know its supposed to be there originally but it made no difference when I had the valve! In fact the front locked up even more! Once I replace the 2 front calipers I will report back.
Yes I did trace all the lines. Jim

1969Z27

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Re: 69 RF brake lock up?
« Reply #31 on: December 05, 2016, 11:33:02 PM »
Jim. Here's an interesting read on disc converting.


http://www.pozziracing.com/brakes.htm#Converting_Drums_to_Discs
Russ 
68 RS L22/M20
69 SS L48/MC1

Rufcar

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Re: 69 RF brake lock up?
« Reply #32 on: December 06, 2016, 04:44:39 AM »
Great info I saved to follow steps. Tkx. Ill let everyone know how I make out. Jim

Rufcar

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Re: 69 RF brake lock up?
« Reply #33 on: December 09, 2016, 08:39:38 PM »
Today I installed the Calipers and bleed the system right side still locks up with easy braking? That means I have replaced everything the master cyl, the distribution block, the hoses. Ran new temporary front brake lines and the Right side still locks up. $300+ new parts and nothing made any difference. I am at a total loss. Any ideas?  Tkx Jim F

69Z28-RS

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Re: 69 RF brake lock up?
« Reply #34 on: December 09, 2016, 09:44:44 PM »
*Something* is different for certain...

Have you actually replaced *everything* in the brake system..  Except for the rotors?  For completeness I'd measure the thickness of both rotors... and if they are the same thickness, then use some coarse sandpaper and *scuff/sand* both sides of each rotor.   

Do the rotor surfaces, OR the pads have *oil* on either of them??
Gary W / 09C 69Z28-RS, 72 B 720 cowl console rosewood tint
69 Corvette convertible, silver/black 350 hp,
60 Corvette white/red, 72 Corvette coupe, '70 Mach I 
90 ZR1 red/red #246, 90 ZR1 white/gray #2466
72 El Camino, '55-'56-'57 Nomads, '55-'57 B/A Sedan

Rufcar

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Re: 69 RF brake lock up?
« Reply #35 on: December 09, 2016, 10:20:06 PM »
I microed the rotors and they are exactly the same. I now believe it needs the 1969 disc brake proportioning valve as there is none on this system. I bought this car like this and did not change the set up. So I now believe this set needs that valve, don't you?

69Z28-RS

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Re: 69 RF brake lock up?
« Reply #36 on: December 09, 2016, 11:40:39 PM »
The proportioning valve goes in the line which runs to the rear brakes ONLY..  so I fail to see how that could cause the RF brake to lock up before the LF??   If that was the issue, I'd think the REAR brakes would lock up early...

Note:  I think most of us are responding to your issue and questions as if you have a 'stock' front disk / rear drum system.   A stock system would include the *metering valve* which is installed between the MC front port and the *distribution block*.  Do you have those parts installed in your system, and are the *STOCK*, or are they aftermarket?   I think someone suggested earlier that you might have a 'combination valve' installed RATHER than the distribution block.  The later years combination valves are much different, and if that's what you have in your system, is likely what is causing your problem.   Go read this report... and try to *duplicate* the factory system if you can.
Note:  I have some extra stock '69 Camaro disk/drum parts if you can't find what you need elsewhere.
Gary W / 09C 69Z28-RS, 72 B 720 cowl console rosewood tint
69 Corvette convertible, silver/black 350 hp,
60 Corvette white/red, 72 Corvette coupe, '70 Mach I 
90 ZR1 red/red #246, 90 ZR1 white/gray #2466
72 El Camino, '55-'56-'57 Nomads, '55-'57 B/A Sedan

Rufcar

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Re: 69 RF brake lock up?
« Reply #37 on: December 09, 2016, 11:47:57 PM »
I have been trying to post a pic and its taken me time to resize it so you can see what Im dealing with. Tkx

Rufcar

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Re: 69 RF brake lock up?
« Reply #38 on: December 09, 2016, 11:56:38 PM »
I have the factory distribution block and the new replacement is exactly the same. I have NO metering valve. There was one on the car originally and it was removed by someone who believed it improved that lock up problem as it was than worse then now. I now believe it was faulty and did not work correctly. I commented incorrectly when I called it the proportioning valve. I believe the metering valve is what I now need. If you agree what exactly can I order as all suppliers are calling that the proportioning valve?
Jim

69Z28-RS

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Re: 69 RF brake lock up?
« Reply #39 on: December 10, 2016, 04:34:49 AM »
If it were my car, I'd find all original 69 parts and rebuild them to factory specs.. and install per the factory...  (I'm old, and prejudiced, but I still believe that the hundreds of engineers utilized by GM did a bit better than the one or two shade tree mechanics employed by most 'aftermarket' suppliers...  :) )

Have you read JohnZ's report on brake valves that I referenced??  it explains the purpose of the 'Metering Valve'.. to delay fluid flow to the front disk brakes until the pressure reaches 30-40 psi to the rear brakes. 
Gary W / 09C 69Z28-RS, 72 B 720 cowl console rosewood tint
69 Corvette convertible, silver/black 350 hp,
60 Corvette white/red, 72 Corvette coupe, '70 Mach I 
90 ZR1 red/red #246, 90 ZR1 white/gray #2466
72 El Camino, '55-'56-'57 Nomads, '55-'57 B/A Sedan

Rufcar

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Re: 69 RF brake lock up?
« Reply #40 on: December 10, 2016, 12:52:32 PM »
Yes I read Johns article and several more. Like I stated I inherited this problem and trying to make it right. The only item I can see that is not original type equipment is the metering valve. In all the photos, manuals and parts books I have read there are 3 choices, The 71-77 Pro valve the 69 pro valve and the 67-68 valve Some call them Pro. valves others metering. Most appear to use the 68 or 69 valve. I believe since my car was one of the first hundred made in CA. it had the 68 valve, then later was changed to the 69 valve. My car was someone's dragster for many years and thus many changes took place.  FYI Im 67 so I agree with you!
I blew up Johns pic and found the needed valve on line and ordered it complete with bracket and rubber boot. It will be here next week Ill replumb and report back. Tkx Jim
« Last Edit: December 10, 2016, 01:17:19 PM by Rufcar »

69Z28-RS

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Re: 69 RF brake lock up?
« Reply #41 on: December 10, 2016, 06:28:59 PM »
you posted a photo which did not show a metering valve in place.....  The metering valve would be located with the distribution block under the MC.   A proportioning valve ONLY affects the rear brakes and is mounted on the frame rail in the line running to the rear brakes.

Again, I would suggest you DUPLICATE the factory setup with all factory parts; the proportioning valve seems to be OPTIONAL.   The Metering Valve is NOT optional with the factory setup.

Gary W / 09C 69Z28-RS, 72 B 720 cowl console rosewood tint
69 Corvette convertible, silver/black 350 hp,
60 Corvette white/red, 72 Corvette coupe, '70 Mach I 
90 ZR1 red/red #246, 90 ZR1 white/gray #2466
72 El Camino, '55-'56-'57 Nomads, '55-'57 B/A Sedan

Rufcar

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Re: 69 RF brake lock up?
« Reply #42 on: December 10, 2016, 06:40:19 PM »
I found the original metering valve today, cleaned it installed it plumbed it. The right front no longer locks up yea. But now the right rear does.

69Z28-RS

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Re: 69 RF brake lock up?
« Reply #43 on: December 10, 2016, 06:50:02 PM »
The only difference between the Right Rear and the Left Rear ... is the side of the car they are on.  The pressure is the SAME to both..  so address that problem by concentrating on the two rear brakes.. look for 'grease' on the shoes or drums.. clean thoroughly or replace the pads; solve any fluid leaks first.  Check the springs, brake cylinders, etc.. and Adjust both evenly..  Your problem should be gone.. :)
Gary W / 09C 69Z28-RS, 72 B 720 cowl console rosewood tint
69 Corvette convertible, silver/black 350 hp,
60 Corvette white/red, 72 Corvette coupe, '70 Mach I 
90 ZR1 red/red #246, 90 ZR1 white/gray #2466
72 El Camino, '55-'56-'57 Nomads, '55-'57 B/A Sedan

Rufcar

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Re: 69 RF brake lock up?
« Reply #44 on: December 10, 2016, 07:10:25 PM »
It appears they adjust with the drum off as there is no opening on the rear to adjust?