63 brake issue help!!

[Datsolow]

Hi all , Happy new year"from UK -1deg in London

My 63 corvair has a braking issue front passenger side and rear drivers side skid when braking
I have changed drums and internal parts , is it an auto adjustment issue or more serious?
I have bled the brakes all is good great pedal feel ( better than my 74 vw camper)
Please help regards Paul

[bbodie52]

Assuming that your tire wear patterns are normal and OK, and that the tread depth is OK and tire pressures are set correctly (approximately 18 psi front/28 psi rear), is your 1963 Corvair still fitted with the original style single master cylinder, or has it been fitted with an upgrade to a dual master cylinder? You mentioned changing the brake "internal parts". Did this include rebuilding or replacing the wheel cylinders? Sometimes internal corrosion or surface problems can occur in the wheel cylinders and cause the pistons to bind, which could cause uneven application of pressure to the brake shoes.

Tire pressure.

The factory recommended tire pressure settings were selected to dial in understeer and provide a comfortable ride on bias ply tires being the important conditions. Although radial tires are much more forgiving, you should still maintain a pressure differential of 8 to 10 pounds front to rear, but you can improve the responsiveness and handling by raising the tire pressure up to about 27 front, 35 psi rear for street use (don't exceed the maximum tire inflation on the sidewall).

Clark's Corvair Parts has posted a warning about aging flexible brake lines that can swell internally while still looking normal externally. If this occurs the internal brake fluid passage can become restricted, and this could be different from wheel to wheel. Could this be a possibility on your Corvair? If so, it might affect the brake fluid pressure applied to each wheel cylinder. (See the bottom of page 144 below).

http://www.corvair.com/user-cgi/catalog ... w_page=144

[MCataldo]

The '63s came with self adjusters which are specific to the right and left sides. (The adjusters on one side are left hand thread and the other side are right hand thread.) Be careful that you don't get them mixed up. If the adjusters are inadvertently switched from side to side, they will adjust the opposite of their intent and really mess up the brakes. You can check them with the drums off by moving the adjusting arm down to engage and move the star wheel on the adjuster. If the adjuster expands when actuated, that's correct. (It's been a while, but I seem to recall the adjusters have an "R" or "L" on them to help identify them. I could be wrong, though.)

Since you have two wheels that are locking up, I suspect those two have the correct adjusters and are doing all the work. The other two wheels have adjusted themselves the opposite way (loose) and aren't contributing to the effort.

[64powerglide]

Did you check all 4 wheel cylinders or did you just work on the 2 that are locking up? Sounds like the two that are not skidding are not working. Even though you bled them you could have pistons seized up.

[Datsolow]

Hi thanks for replying , I've changed one rear and one front slave cylinder and these seem to be not working , single circuit brake system still being used . Foot pedal feels great . I've bleed the brakes totally using correct fluid could the new wheel cylinders be a different size bore/piston? Should I rebuild original cylinders so they all match?
Many thanks

[66vairguy]

The self adjusting parts wear out. Even with self adjusting brake shoes you can make a manual adjustment. I had a buddy with uneven brakes. Some of the wheels were adjusting, others were not causing uneven braking.

Another problem is the brake shoe backing plates can get grooves on the brake shoe resting pads that will cause poor braking response.

The other issue is missing or weak brake return springs.

Yes disk brakes are simpler then drum brakes, but with some effort you can get those old drum brakes working fine.

[Datsolow]

Thanks I will endeavor to rectify , I got my parts from rock-auto are they any good?

[Datsolow]

Hi why were the factory metallic parts rare I don't understand? In the Clarksville catalogue .

[bbodie52]

Hi why were the factory metallic parts rare I don't understand?

As shown in the Clark's Corvair Parts catalog page below, the standard front EM wheel cylinder diameter is 7/8", and the rear EM wheel cylinder diameter on all cars is 15/16". To some extent this acts like a brake pressure proportioning method, by allowing engineers to balance the front/rear brake shoe hydraulic pressure balance needed (as determined by the front/rear weight differences, friction coefficients, etc.) The optional metallic brake shoes changed the friction coefficient with the different brake shoe material, so the front wheel cylinder size was changed by design engineers from 7/8" to 1" to help compensate for the increased pressure needed by the metallic brake shoe material.

The 1962-63 master cylinder diameter was also changed by GM engineers from a standard of 1" i.d. used in all 1962-1966 cars to 7/8" i.d. found only on 1962-63 Corvairs equipped with the optional metallic brakes (RPO J65).

The brake specifications for 1962-1963 cars is shown in the bottom table, which shows the differences in line pressure, braking ratios, and distribution of braking effort, shoe materials, and piston diameters when comparing the standard brakes and the rare metallic brake option.

http://www.corvair.com/user-cgi/catalog ... N&page=143


http://www.corvair.com/user-cgi/catalog ... N&page=144


http://www.corvair.com/user-cgi/catalog ... N&page=145

1963 Corvair Brake Specifications (from 1963 Corvair GM Heritage Center Specifications)

[Datsolow]

Thanks very much

[Richard1]

Easy to check self-adjusters.
Just go to a parking lot or empty street and drive forward and backward 10 times or so, braking hard at each stop to change direction. Then lift car (or individual wheels) and see if all have the same slight drag when spinning. Might need someone to lightly apply the brakes to get drag. They should have all adjusted equally.

When I do brakes on self-adjusters I leave them super loose and then drive back and forth til adjusted. I've had employees get back from a mountain trip and report the need for brake service. I go out and drive back and forth 5 minutes, then show them it is fixed.

[64powerglide]

I would assume there are lots of younger drivers who don't know you have to brake forward & backward to make the self adjusters do their job. About two months ago my brakes felt a little soft so I did the forward / backward method & the pedal firmed right up as it should. Yes I was a driver when self adjusters were something new.

[Datsolow]

Thanks richard1 I will do this , could I have installed wrong diameter cylinders ? Front left n right or rear left n right ?
The front left (drivers)side and rear passenger side not working .they didn't before I changed wheel cylinders so no change . I did manage to bleed them ok but no cigar !

[64powerglide]

[Datsolow]

Awesome thanks 64 power glide

[Datsolow]

Can anyone explain in basic terms metallic linings as I've ordered brake shoes unaware of any difference
Thanks in advance