65 356 C braking issue

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Jerrold Powell
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65 356 C braking issue

#1 Post by Jerrold Powell » Wed Aug 07, 2019 5:07 pm

Hello experts--Need help,

SYMPTOMS:
Car pulls left with LF wheel skipping(Rubber squeal of tire on pavement) under HARD breaking. Normal breaking, car tracks straight.

WHAT I HAVE DONE:
Pushed calipers(4) in/out 3-times.
Checked pad lining for thickness and uneven wear--all good.
Flushed break fluid-ATE gold.
Rotated tires front to back.
Checked all 8 pistons for 20 degree orientation.
Performed 4 wheel alignment.
Replaced steering box with ZIMS rebuilt one. This is a separate issue but want to give you all the information.

OTHER:
Car has been owned by me for 28 years and have never had calipers rebuilt/replaced.
Average millage is 1,700/year.
Car never driven under stress.

Please give me an suggestions on where to go from here--I am at a loss!

Jerry

Geoff Fleming
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Re: 65 356 C breaking issue

#2 Post by Geoff Fleming » Wed Aug 07, 2019 5:25 pm

It sounds like you may have to remove the pistons from the cylinders and see what the units look like. Even a small amount of accumulated rusting will begin to cause problems. Since you have owned the car 28 years without having work done, it may be assumed previous owners also never did, so now is the time. The flexible brake lines are certainly in need of replacement. These tend to disintegrate internally and eventually fluid can't pass properly. Often, they will allow fluid to activate the brake but there is not enough pressure to allow the brakes to 'relax', once they aren't in use, so a caliper will remain partially engaged, hence the skipping .
Cars that are not driven enough or 'stressed' will show more corrosion than those used more vigorously.

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Al Zim
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Re: 65 356 C breaking issue

#3 Post by Al Zim » Wed Aug 07, 2019 5:40 pm

My vote goes for new rubber brake lines. You can easily bleed the system by filling the reservoir, gently depressing the brake pedal a few inches down and then opening the bleeder valves. Gravity will bleed the system. Make sure the inner and outer bleeders have been opened. As the inner bleeder starts to drip, close it and then the outer bleeder will start bleeding. Thank you for your patronage, al zim
 

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Jim Breazeale
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Re: 65 356 C breaking issue

#4 Post by Jim Breazeale » Wed Aug 07, 2019 7:11 pm

I'm with Al. You probably have a partially blocked rubber brake hose. Most likely on the RF. Replace them all. Bleed the system and your problem should be gone. Our cars are like their drivers. We develop circulation issues as we age. Cars are much easier and a whole lot cheaper to fix than their drivers, though.

Jim.
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Vic Skirmants
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Re: 65 356 C breaking issue

#5 Post by Vic Skirmants » Wed Aug 07, 2019 7:23 pm

"Breaking" or "braking" There is a difference.

Jerrold Powell
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Re: 65 356 C breaking issue

#6 Post by Jerrold Powell » Wed Aug 07, 2019 7:54 pm

Braking is the correct word.

Also, brake discs thickness is within spec., although I don't know about run-out. Dust seals have all come apart.

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Vic Skirmants
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Re: 65 356 C breaking issue

#7 Post by Vic Skirmants » Wed Aug 07, 2019 8:21 pm

The dust shields on our race cars always come apart; that's why we don't even bother to install them. But they come apart because of heat. I wouldn't expect that to be an issue on a street car.

Jerrold Powell
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Re: 65 356 C breaking issue

#8 Post by Jerrold Powell » Wed Aug 07, 2019 8:23 pm

I like the brake line diagnosis. How about the ZIMS SS braided set for $100?

Jerrold Powell
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Re: 65 356 C breaking issue

#9 Post by Jerrold Powell » Wed Aug 07, 2019 8:42 pm

Al, I need to know if I should get the rubber or SS brake hoses.

Please advise so I can order.

Tim Berardelli
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Re: 65 356 C breaking issue

#10 Post by Tim Berardelli » Thu Aug 08, 2019 7:48 am

Plus 12 on replacing the rubber brake lines-even if not the total culprit they are long, long due for replacement.

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Vic Skirmants
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Re: 65 356 C breaking issue

#11 Post by Vic Skirmants » Thu Aug 08, 2019 8:01 am

Stay with rubber for the street. Yes, they will degrade in about ten years, but they will not fail suddenly, which is possible with the stainless braided ones, if you don't inspect them regularly. That braiding covers a very fragile plastic (Teflon?) hose that has no strength without the braid.

Jerrold Powell
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Re: 65 356 C breaking issue

#12 Post by Jerrold Powell » Thu Aug 08, 2019 8:39 am

Ordered four rubber hoses from ZIMS. Thanks for the diagnosis--will let you know results after install and road test.

Jerrold Powell
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Re: 65 356 C braking issue

#13 Post by Jerrold Powell » Tue Aug 13, 2019 2:08 pm

What I did:
Replaced 4 brake hoses with ZIMS rubber ones.
Flushed brake fluid.
Took test drive.

Results:
Symptoms did not change:
Pulls to left under HARD breaking and LF tire skips.

Pads and discs are old but within specs.
Dual master cylinder installed 20 years ago without any issues.
The only break parts I haven't changed are calipers and hard line components.

Appreciate your suggestions on what I should do next.

Thanks,

Jerry

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Doug McDonnell
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Re: 65 356 C braking issue

#14 Post by Doug McDonnell » Tue Aug 13, 2019 3:13 pm

After a spirited drive get out and feel how hot each wheel is. If left front hotter then rebuild the caliper.
1965 356C There is never enough time to do it right, but always enough time to do it over.

bil brown
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Re: 65 356 C braking issue

#15 Post by bil brown » Tue Aug 13, 2019 3:26 pm

I would rebuild both front calipers, not just one.
Bill Brown

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