jimdvan

I have a 63 that consistently pulls to the left during braking. The harder I brake, the harder it pulls.

The car is set up with all stock components. The drums are brand new, yesterday, and have been checked for roundness on the inside diameter. The rest of the system has about 3400 miles on it. All stock shoes, springs, etc. They are power assisted using a new replacement 63/64 power master cylinder.

When I first built the car last year the brakes, with freshly turned drums, did the same thing but lessened as time went by but always pulled to the left to some extent. Back then the drums and shoes were swaped up front with no change. Last night I went to a local cruise-in and a guy with a 63 told me he had the same problem. Any suggestions?

SWCDuke

Are you ABSOLUTELY, POSITIVELY sure that the wheel cylinders are the proper ID and the same side to side?

What is their history?

Duke

achapman

Just replaced the brakes all around on my 63 SWC and it brakes straight and true. I bought the complete set from VBP just to be sure everything matches. I replaced the shoes, wheel cylinders, hoses and springs. I sent the drums out to be checked and turned and they were within spec. The only problem I had was finding an auto machine shop that does drums.

Subfixer

I had the same problem on my 64. Turned out to be the lower control arm bushings were shot. Because they were so worn, the lower control arm wold shift, changing the attack angle of the tire. Drive real slow, and have someone watch the wheel for lateral movement when you step on the brakes.

corvetteed

I had the same problem. Everything was according to spec. Nothing visible was wrong. Finally changed out the brake hose, again, even though it looked fine. That fixed the problem. Must have had a kink internally that I couldn't see. Have not had a problem with it since, which has been a few years.

Tom Piper

Are your backing plates grooved where the brake shoe edges ride?

This can cause erratic braking.


Tom Piper

jimdvan

The hoses and wheel cylinders were replaced at the same time everything else was. Both front cylinders shared the same part number. The front control arm bushings are new as well.

I've been told that the arc of the shoes being slightly different from side to side will have an effect since the contact surface varies between the two sets.

jimdvan

I'll check the backing plates. Corvetteed, was the bad hose on the same side that was pulling?

pittsaj

I had a problem like this and it turned out to be the flex hose..
Since you are swapping things around anyway, try swapping sides with the flex hose.. If it pulls to the other side, you found the problem..

Note:
It will pull to the good side since that is the side that is working properly

Tony

K2

You may indeed have something, as mentioned by other posters, that is causing the problem but be aware that shoes that aren't properly arced to the drums will not fit properly and can result in unequal friction contact areas from side to side. In the old days they would normally arc the friction linings to the drum diameters and consequently the brakes required little break in time for the linings to conform to the drum. Now-a-days no one ever bothers to arc the linings to the drums and the result is uneven friction and long break in times. If you are using new drums and used linings, you can bet that the inside radius of the drums is different and it will take a long time (if ever) to conform properly. The other thing that happens if the lining doesn't fit the drum correctly is that it can cause deflection in the shoe itself as pressure is applied and thereby compounding the potential for uneven braking. If you pull the drums and inspect the contact areas of the linings you will no doubt see that contact is uneven and intermittent over the length of the linings. All of the other ideas and suggestions previously mentioned obviously could effect brake balance as well. Drum brakes work great when everything is right but the potential for problems when things aren't right is greater than for disks. One more thing ( as if you need anything else) New green cast drums will sometimes distort as they stress relieve with heat cycling and may require re-truing.

Good luck and keep us informed on what you find.

JohnZ

Any competent brake shop will have a machine to arc-grind drum shoes to the same measured diameter as the drums - makes a big difference in performance. When I restored my '57, I had all four sets of shoes arc-ground to the measured diameter of the turned drums, adjusted them once at 500 miles, never touched them again over the next four years and 5,000 miles. Have had the same thing done to C2 parking brake shoes, makes a BIG difference in holding power of the parking brake.

jimdvan

Thanks, John, I'll probably look into the arc grinding option. I think that is going to be the problem. However, living in Kalifornia, it may not be legal to grind brake linings here but I'll check.

A friend of mine is an old time mechanic and told me of a trick he learned 35 years ago from an even older time mechanic. Squirt a couple of shots of powdered graphite into the drum of the offending wheel. What it does is it stops the lining from grabbing as much by giving a little slip so it balances more with the other side as all the linings wear in. My friend used to service all the patrol cars for the Palm Springs P.D. when they all still had drums at all four corners. He used the trick when the cops complained of the brakes pulling to one side or the other. He said it worked like a charm and he never had any problems with the shoes wearing in properly.

Vetterodder

Have you made sure that the problem isn't in wheel alignment (or even a tire)? There are alignment conditions that won't show except under certain conditions, such as braking and the subsequent forward weight transfer. If it is in the brakes, consider the possibility that the linings on one side have been damaged by fluids (brake fluid, bearing grease, differential lube). In some cases the fluid will swell the lining and cause it to become "grippier". In other cases it lubricates the lining and it grips less. Either scenario results in a pull, only on in different directions. As they haven't used asbesos in linings for many years, I don't think you'll have a problem having them ground, even in "Kalifornia" .

kenmo

I had a somewhat similar problem with my 1960. It would do it after being laid up for a few weeks. Turned out to be a bad front passender side spindle. It had a bad groove in it...

jimdvan

I did the graphite trick and it worked like a charm! That tells me that the contact area of the two front sets of shoes is inconsistant. Now I will try to find a brake shop that will arc the shoes for me.

Thanks to all.