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Right front wheel locking up on braking
Posted by: aircooledairhead ()
Date: December 29, 2019 10:45AM

I've been helping my son sort out some brake issues with his 65 Monza 4 spd 140 coupe.

Initial problem was a rock hard pedal with little actual braking.

We changed the brake shoes with new ones from Clarks changed springs, clips, lubed adjusters, etc. Drums looked fine, shoes we replaced had minimal wear.

Little change -- pedal hard, minimal braking.

PO had installed new master cylinder and apparently new flexible lines, new lines in back about 4 years ago. He told my son pedal was hard.

Next effort was to replace the 4 wheel cylinders and bleed the system. Initially the pedal was still firm but the braking was much improved. After driving around for 20 minutes, the right front wheel began to lock up, causing that tire to scrub while the other 3 braked. The wheel cylinder in the right front wheel was leaking when we took the drum off to replace the cylinder (but not when we replaced the shoes a month prior). It is possible that some fluid got on the shoes, though they felt dry and the inside of the drum was dry.

I tried loosening up the adjustment on the right front wheel to see if possibly the adjuster was malfunctioning and tightening it up too much. There was only a slight improvement. Brake application still locks the wheel. Adjustment on the other wheels was checked and was fine. There is no leakage at any of the fittings.

At this point, I've gotten 2 suggestions. Contaminated brake lining on right front wheel or damaged flexible hose. Since the problem occurs on brake application and the locked wheel releases as soon as I let off the brake, I don't think there is an issue with the flexible hose. The fluid that was bled out was in great shape -- no particles and same color as new fluid. I flushed enough through each wheel to replace the existing fluid, using up almost a quart.

I'd greatly appreciate any suggestions. Thanks!
Fred Gillam

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Re: Right front wheel locking up on braking
Posted by: steve c goodman ()
Date: December 29, 2019 10:58AM

I realize you just replaced all 4 wheel cyl. My typical experience has been the opposite of grabbing brake is the culprit. It is not working correctly either stuck or partially stuck. There will be other opinions too. good luck

best wishes, Steve
Rear Engine Spec. Inc. Golden, Colo.

1962 spyder 3.0L turbo---1965 Crown V8
1967 monza 110/4---1968 monza 110/4
1971 amante gt 110/4
CORSA/RMC/PPCC/V8 Registry

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Re: Right front wheel locking up on braking
Posted by: MattNall ()
Date: December 29, 2019 11:10AM

I'm with Steve G.

You now have ONE wheel / brake working...


I had a '66 that had sat for years... turned out 3 of the four had at least one piston frozen!

MODERATOR
Sea Mountain, between Charleston Harbor and Coos Bay! SW Oregon Coast
Click HERE for My Website...Click HERE for My TechPages!
..............................110-PG.................................................Webered-Turbo

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Re: Right front wheel locking up on braking
Posted by: TerribleTed ()
Date: December 29, 2019 11:40AM

A new wheel cylinder should not leak unless perhaps it is defective or the drums are way oversize and it is over extending perhaps. Are the drums within spec or are they worn beyond limits?

---------------------------------------------------------------------------------------------------------

Avid Corvair hobbiest since 1984.
I have personally performed ground up restoration on over 20 Corvairs.
I currently work full time at restoring and repairing Corvairs.
Located in the Atlanta Georgia area.
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Re: Right front wheel locking up on braking
Posted by: aircooledairhead ()
Date: December 29, 2019 11:44AM

Matt and Steve,
Thanks for your suggestions. If all 4 wheel cylinders weren't new (fronts from Clarks, rears from Rock Auto) I'd definitely agree. It's hard for me to believe 3 of 4 would be bad right out of the box.

So, the logical assumption is I did something wrong when installing or bleeding.

In each case the brake line was removed, the old cylinder removed, the new cylinder installed. At each wheel, I attached a clear hose to the bleeder with the other end in a clear plastic cup. I opened the bleeder and my son pressed the pressed the pedal to the floor and held it. I tightened the bleeder, my son released the pedal, I loosened the bleeder and he pressed the pedal to the floor. We repeated this about 7-8 times, long after any air bubbles came out. (The end of the plastic hose was under the level of the brake fluid in the plastic cup.)

The drums had a small ridge behind the area where the shoes touched, so the adjuster was loosened a bit, the drum went on and the adjuster was tightened so that the wheel went about 3/4 of a turn with a gentle push. All 4 wheels were done this way.

Yet, I still believe that you are both correct as the pedal seems unnaturally firm. I never had this issue with any of the Corvairs I owned back in the 60's - 70's, and it has been brake calipers, disc pads and rotors since then.

I guess I can pull the drum on the left front wheel and have my son very gently depress the brake pedal and see if the cylinder is working. If not, is it possible I may have to re-bleed the three wheels?

Thanks again for your suggestions!

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Re: Right front wheel locking up on braking
Posted by: aircooledairhead ()
Date: December 29, 2019 11:51AM

Ted,
Thanks for your reply. You brought up something I hadn't considered. The drums looked fine, no grooves or deep scratches. However, I did not have them checked for excessive wear. In retrospect, I probably should have had them resurfaced.

I do know that only about 3 - 4 threads on the adjusters are showing at each wheel when they are adjusted. At 5-6 threads, you can't turn the drum, even with the wheel/tire on. I would think they couldn't be too worn with that level of adjustment, but I don't know that for sure.

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Re: Right front wheel locking up on braking
Posted by: aircooledairhead ()
Date: December 29, 2019 11:57AM

Ted,
Also, the leak was in the old right front cylinder that was replaced along with the other 3 wheel cylinders. There are no leaks at any wheel cylinder, or brake line connections. I am concerned that some brake fluid may have gotten on the lining at that wheel, though the linings looked dry and there was no liquid or film on the drum contact area.

If you have any other ideas, please send them along.
Thanks!

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Re: Right front wheel locking up on braking
Posted by: 66vairman ()
Date: December 29, 2019 12:24PM

Some good comments so far. Some additional things to look at.

Verify all the brake parts are in the correct location, easy do get wrong.

Brake fluid will soak into the brake shoe lining and it takes very little to cause trouble. A couple spray cans of brake cleaner and a wire scrub brush MIGHT clean up the linings (remove linings first). Also clean the inner drum area. If cleaning fixes the problem for a little while, but it comes back then the contamination is coming from deeper in the lining when the shoes get hot and they will probably need to be replaced.

I had one lockup problem caused by excess lining to shoe glue that oozed on to the drum and lining contact surface. The other time a little bit of shoe to backing plate grease got on the lining to drum surface. Both cleaned up fine with brake cleaner.

The "hard pedal" issue has been covered here a few times. It can also be either a brake shoe lining that is too hard, or brake shoes that don't have the same arc as the brake drum (limited contact area). I finally found a shop that turned my drums and arcs each set of shoes to a specific drum - lowered pedal pressure and stopping was much improved.

Good luck.

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Re: Right front wheel locking up on braking
Posted by: jjohnsonjo ()
Date: December 29, 2019 12:27PM

How did the backing plate pads look when you re-did the linings? Also, are you sure all the primary shoes made it to the front position?

J.O.

65 Corsa Turbo Vert
79 Honda XL 500S
69 Honda CL 160 D
2010 BMW F 650 GS
2003 Bounder 36D
2013 KIA Optima SX turbo-AKA ZIPPY (wife,s car)
69 Newport Holiday Sailboat
Baja 150 dune buggy cart
Coleman HS 500 UTV
2016 KIA Sorento SXL Turbo

Bethlehem,Pa


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Re: Right front wheel locking up on braking
Posted by: 66vairman ()
Date: December 29, 2019 12:46PM

jjohnsonjo Wrote:
-------------------------------------------------------
> How did the backing plate pads look when you re-did the linings? Also, are you sure all the primary shoes made it to the front position?

Good comment. Note many have reported the new shoes are the same lining length on BOTH primary and secondary shoes. It's been covered here with how to cut the linings to proper primary and secondary lengths. I recall Ken Hand posted the procedure with pictures.

By 100K miles most backing plates have shoe contact grooves that need to be welded (or brazed) to fill.

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Re: Right front wheel locking up on braking
Posted by: FLSteve ()
Date: December 29, 2019 12:53PM

Remove drums and take pictures! This will answer most questions. Move the rubber lines from one side to other and test.

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Re: Right front wheel locking up on braking
Posted by: MattNall ()
Date: December 29, 2019 01:00PM

Pull all for drums and put short tiedown strap around shoes... Have someone step on the pedal and see of both shoes move.

MODERATOR
Sea Mountain, between Charleston Harbor and Coos Bay! SW Oregon Coast
Click HERE for My Website...Click HERE for My TechPages!
..............................110-PG.................................................Webered-Turbo

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Re: Right front wheel locking up on braking
Posted by: aircooledairhead ()
Date: December 29, 2019 01:20PM

Lots of good leads to chase down! Thanks to all for your suggestions!

I can respond to some ideas.

The primary and secondary shoes are in the correct places.

The contact bumps on the backing plates were in good shape -- no holes or sharp edges that could cause issues.

I will definitely try Matt's suggestion to see if all 4 wheel cylinders are producing movement. I recall trying to push the rods that connect the cylinders to the brake shoes in prior to installation, with no fluid in them and not feeling much give which seemed odd.

We have plenty of brake cleaner and we can clean the shoes on the right front wheel and drum and see if that helps, or if the issue recurs, and we need to get new shoes for that wheel. The drum was cleaned with brake cleaner prior to being put back on over the new shoes.

If I have to, I'll change the flex hoses from side to side to double check them. I hate messing with them, but will definitely do so if needed.

My son is 4 hours away, so it might be a few weeks until I get back up there and update. I really appreciate all of the good suggestions.

Thank you all again!
Fred

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Re: Right front wheel locking up on braking
Posted by: RexJohnson ()
Date: December 29, 2019 01:28PM

Swapping the hoses is a good idea but I would swap the shoes side to side first.

RJ tools
Salem,Oregon

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Re: Right front wheel locking up on braking
Posted by: Wagon Master ()
Date: December 29, 2019 02:21PM

RexJohnson Wrote:
-------------------------------------------------------
> Swapping the hoses is a good idea but I would swap the shoes side to side first.


If you wind up swapping shoes, pull back the wheel cyl. boots to insure you see no moisture.

'29 Ford Model A Tudor
'61 700 Lakewood 110 4 speed
'69 Monza Convert. 140 Auto.
'70 Dodge Challenger R/T 440 4 speed

Been aircooled since 1973
Northwest Ohio

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Re: Right front wheel locking up on braking
Posted by: steve c goodman ()
Date: December 29, 2019 02:21PM

Cynical outlook on my part BUT just because a part is new doesn't mean it is good.

best wishes, Steve
Rear Engine Spec. Inc. Golden, Colo.

1962 spyder 3.0L turbo---1965 Crown V8
1967 monza 110/4---1968 monza 110/4
1971 amante gt 110/4
CORSA/RMC/PPCC/V8 Registry

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Re: Right front wheel locking up on braking
Posted by: joelsplace ()
Date: December 29, 2019 02:58PM

I had a front shoe with brake fluid contamination that made it lock up. I did the standard brake shoe break in and it burned it off. It was fine after that. Try that first.
Bleeding will only help pedal firmness. The pressure has to be the same in the entire system so it can't make one or more wheels not work. This is assuming you have the stock single master cylinder. Even with a dual air will only cause front to back issues not pulling.
I would check the wheel that locks up for a leaky wheel cylinder. As Steve said new parts aren't always good that's just reality.
I'm going to have to disagree with Ted on the wear. (I think this is a first) The pistons would have to come completely out of the cylinders and then you would lose all pressure. I'm pretty sure the 65 has a stop to keep that from happening. I would agree with him if they were old wheel cylinders and the worn drums allowed the seals to get into some corrosion or pitted area that made them leak.
If nothing looks amiss swap front shoes left to right and see if the problem moves. If it does you know you have bad shoes.

Joel
Northlake, TX
5 Ultravans, 113 Corvairs and counting...




Edited 1 time(s). Last edit at 12/29/2019 02:59PM by joelsplace.

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Re: Right front wheel locking up on braking
Posted by: MattNall ()
Date: December 29, 2019 03:03PM

Master cylinder has too Large of a Bore?

MODERATOR
Sea Mountain, between Charleston Harbor and Coos Bay! SW Oregon Coast
Click HERE for My Website...Click HERE for My TechPages!
..............................110-PG.................................................Webered-Turbo

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Re: Right front wheel locking up on braking
Posted by: joelsplace ()
Date: December 29, 2019 03:09PM

That would certainly cause a hard pedal. I was focused in the lock up and ignored that part. Hard pedal is great in my opinion when the brakes work correctly.

Joel
Northlake, TX
5 Ultravans, 113 Corvairs and counting...

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Re: Right front wheel locking up on braking
Posted by: aircooledairhead ()
Date: December 29, 2019 03:58PM

Again, thanks for all of the great ideas! You've given me many solid leads to track down. I'm looking forward to returning to my son's house to test them out and hopefully solve the issue so we can move on to the steering box. (And after that a complete reseal, restore the heater and hoses, rebuild and reinstall the secondary carbs, start replacing suspension bushings....it was a lot easier in the 60's and 70's!)

Master cylinder (single, not dual) looks to be the exact replacement. Next time I'm at my son's, I'll look and see if there are identifying numbers on it, either part # or bore size. If incorrect, I'll put in the correct master cyl.

The shoe swap is a great idea, definitely on my list to try. Car was only driven about 5-6 miles with the old wheel cylinders in, so if contaminated may be fixable. If shoe swap reveals shoes are issue and brake cleaner and the break in procedure doesn't fix it, the logical thing would to see if Clarks will sell me the shoes for one side so friction characteristics are the same on both front wheels. So, first, shoe swap. If no difference, hose swap.

Thus far, no liquid on any wheel cylinder, but I haven't peeled back the rubber seals, so I'll do that.

Steve G, a new wheel cylinder could be defective, in which case your observation that the side opposite the one locking up (left) could well be the problem. Matt's idea about checking for movement outward of the shoes should help me make that determination. Even the Delco wheel cylinders came from China!

Thanks again for the great ideas.

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