Author Topic: 69 RF brake lock up?  (Read 8956 times)

Rufcar

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Re: 69 RF brake lock up?
« Reply #90 on: December 21, 2016, 12:08:09 AM »
That is a possibility.  Someone suggested I losses the MC a bit and see if that helps. I did that didn't help.

jvb6648

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Re: 69 RF brake lock up?
« Reply #91 on: December 21, 2016, 02:30:42 AM »
You lost me. You mentioned the right side twice. If the large orifice was the inlet and it still locks up then I'm back to square one. Use one of the old blocks and if you can set it up as the 69s are go for it. My only concern is that you treated the symptom and not the disease.
Jim
68 Z/28

Rufcar

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Re: 69 RF brake lock up?
« Reply #92 on: December 21, 2016, 02:41:22 AM »
I'll elaborate,  the block has 3 holes which I cked.one large 2 smaller It came to me with one small to one side  one small to supply one large to rightwheel, though I didn't know that until today.  I re plumbed it one large to supply 2 small hole each to one wheel. Still locked up rf wheel.
I'm looking into an in line reducing type valve.

Dave Siltman

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Re: 69 RF brake lock up?
« Reply #93 on: December 21, 2016, 11:35:07 AM »
Is that last picture your car.....I'm so confused! If so, why all the fittings at the end of the lines where they connect to the valve? And, is the m/c new? Old? Rebuilt/refurbished? There is a missing link here and/or an old part that hasn't been addressed. In my mind, there is no reason this can't be rectified by duplicating the factory set-up. What in this system isn't new???

Rufcar

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Re: 69 RF brake lock up?
« Reply #94 on: December 21, 2016, 12:56:55 PM »
Dave in earlier post I explained every detail with current pic and factory pics I have replaced everything except the booster and the 2 main twisted supply lines. I blew those out I even ran temporary line to both to test. I explained in the previous post those reducers were temporary just to test. I changed the plumbing 3 times I did use factory specs I rebuilt the rears too because 1 leaked. The car always stops and the RF always locks up 1st and then releases. Nothing has changed in 3 years and 6k mi and this is the 2nd time Im doing everything. I have had several 40yr experience mechanics stop at my shop and advice from many on line and nothing works. I try something new every few days I even tried a different distb. block with larger holes to the RF. Im at a total loss.

Dave Siltman

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Re: 69 RF brake lock up?
« Reply #95 on: December 21, 2016, 03:12:53 PM »
Does the r/f lock up with no weight on it? If the car is off the ground will the problem occur? I'm wondering if the issue isn't brake related but suspension. Earlier in the thread, Charley made mention of a wheel bearing and nobody really followed up on it. I'm asking about the lock-up or "dart" while driving because if it doesn't occur in a static state, possibly the r/f steering and/or suspension pieces could have irregularities. I'm also wondering if the subframe is "tweaked" with a difference in wheelbase from the left side. If the lock-up does occur while on stands or a lift, then this theory would all but be overruled.

Rufcar

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Re: 69 RF brake lock up?
« Reply #96 on: December 21, 2016, 04:04:22 PM »
Dave I spun the wheels on my lift and rf still locks up. Thus a.m I re plumbed yet again and ran the left front to the largest hole and rf to the smallest hole in the distb.block and it rf still locks up. FYI my garage is 100 ft long. I back off the lift to the door drive aprox. 59 ft and just push on the brakes to stop as normal rf always locks up and releases once foot is lifted a bit. I have now plumbed to every combination,  replaced everything except booster and hard lines to wheels. Nothing helps. I may need to order a complete booster mc kit and start over. I also may try an line reducer valve.

69Z28-RS

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Re: 69 RF brake lock up?
« Reply #97 on: December 21, 2016, 04:10:02 PM »
Personally, I think you have a 'combination valve' installed rather than a 'stock distribution block'... they appear to be alike on the outside I believe, but several have commented that the 'new one' you installed appears to be aftermarket (and I agree).   Where did you purchase that part?  I'm unaware of any seller of the original distribution blocks...  ?
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 #98 on: December 21, 2016, 04:57:41 PM »
I bought it from Groundup 396. I checked both the old original and new replacement and both are cast and the only differences I can see are all 3 front end holes are all 1 drill size larger then the original . That also is 1 large and 2 small holes. The one to the left of the brake switch is the larger in both cases and the front center and engine side are both small. I have plumbed both all 3 possible ways and made no difference.

1969Z27

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Re: 69 RF brake lock up?
« Reply #99 on: December 23, 2016, 12:35:20 AM »
Jim,
 Have you checked the bake pedal pushrod clearance? There should be a little brake pedal movement before pushrod engages booster. Also have you checked which hole is pedal pushrod in? Pushrod should be attached to the lower hole for power assist brakes.
Russ 
68 RS L22/M20
69 SS L48/MC1

Rufcar

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Re: 69 RF brake lock up?
« Reply #100 on: December 23, 2016, 01:47:14 AM »
Yes that was one of the 1st things I ckd its,all to spec.

Charley

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Re: 69 RF brake lock up?
« Reply #101 on: December 23, 2016, 02:03:41 AM »
I would be looking outside the box for something goofy that you would not think could have a effect. Ball joints, worn spindle, etc.

Rufcar

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Re: 69 RF brake lock up?
« Reply #102 on: December 23, 2016, 07:24:35 PM »
Charley I am. Tkx Jim

Mike S

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Re: 69 RF brake lock up?
« Reply #103 on: December 23, 2016, 07:42:37 PM »
 I've been following this thread with interest. This is more interesting than watching the presidential elections.  ;)
Question: When you checked on the lift to see when it locks up, are the rear wheel brakes engaged too whereby the drums are locked? I'm wondering if maybe it is the left front brake not grabbing the rotor making it appear the right front is locking.

Just a thought (and grasping at straws!)

Mike
67 LOS SS/RS L35 Hardtop - Original w/UOIT
67 NOR SS/RS L35 Convertible - Under restoration

Dave Siltman

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Re: 69 RF brake lock up?
« Reply #104 on: December 23, 2016, 08:53:17 PM »
I initially thought the same thing.....what if the left front brake isn't working making it FEEL like the right one was overworking, but I think we're past that.