63 drum brakes pulling

[Boyan B.]

Hi guys, I have a problem with my 63 brakes pulling the front end violently to the driver's side when I apply them. Letting go of the steering wheel during braking, the car turns left violently and spins the steering wheel around. Everything is new, as I am finishing up a full restoration. I checked both sides and verified everything is assembled correctly, I have a generous amount of experience with drum brakes, so its not my first time assembling them.

I checked to make sure the star adjusters are not mixed up (Thanks Duke) and they are not. I put the front end up in the air and applied brake (non power car) and verified both front tires locked up and I could not spin the wheels, so both are getting pressure in the lines.

I think I have a problem with either the left side adjusting too tight or the right side not adjusting enough. I have tried the slide the drum on snug and back off the adjuster method then reverse for final adjustment to no avail.

I also backed the adjusters all the way down and drove up and backward down my steet applying the braks so the automatic adjusters do their thing all the way and the same effect, changes lanes when I apply the brakes.

Both sides are getting wear on all four shoes. I did not do the old school "arching" of the brakes.

The left side seems tighter to me than the right. It feels like it drags in spots as I spin the wheel without the brake applied, but very slightly. The right side seems to spin freely. Drums are new reproductions.

Any thoughts?

Boyan

[Dan H.]

Re: 63 drum brakes pulling

Boyan, I had a similar problem with the 64, check that the adjusters don't rub the lower spring or catch on anything. The adusters need to be equally free etc.
Dan

[Boyan B.]

Re: 63 drum brakes pulling

OK, had a helper hold the pedal down for me while front end was up. I said apply about 1/3 of pressure on the pedal and I checked the wheels and it feels like both wheels had equal drag, but I could force the wheels to turn. There were rough spots, not total even drag on each wheel.

Then we did 1/2 pressure, and both wheels are locked solid and I could not turn them.

Then I said use full force while I spun the wheels freely and both seem to lock up at about the same time.

Not scientific, but only thing I can do right now to diagnose problem.

Any help would be appreciated.
Boyan

[Boyan B.]

Re: 63 drum brakes pulling

Dan, I just checked the adjusters, the spring is really close but does not touch. Just to verify, the star wheel "free wheels" to expand the brakes, doesnt it? If you rotate it one way it clicks against the adjust lever, expanding the brakes, the other way it is pretty much locked until you lift the adjusting lever up, then you can spin the star wheel and it re-tracts the brakes....right?

Boyan

[Tracy C.]

Re: 63 drum brakes pulling

You say the drums are new, it is possible they are not concentric. You might want to pull the drums and take them to a local parts house that can turm drums and see if they need to be trued up.

Following that, I would arch the shoes to match the drums if you have a press in your shop.

tc

[Steve M.]

Re: 63 drum brakes pulling

you Can Swap The Drum To The Other Side To See If The Problem Moves From Left To Right . If The Drum Is A Way Out Of Round You Should Pick It Up Under Light Pedal. The Pedal Will Pulsate.
You Might Have A Tire Issue. Bad Cord In A Tire Will Make It Pull. Did You Change The Master Clynder? Is It A Double Line Master Or A Singale Line? If It Is A Disc , Disc It Will Have A Check Vavle In It. It Will Hold Presure 2 Psi In The Line.it Will Need To Be Taken Out For Drum Brakes. Also I Have Seen The Rubber Brake Line Deteriorate On The Inside And Acted As A Check Valve. Alignment? Good Luck!

[Duke W.]

Re: 63 drum brakes pulling

Try the suggested side to side drum swap - easy and might tell you something.

As long as you have to pull them off a local brake shop should have a drum measuring tool that can tell you if they are in spec and reasonably round.

Duke

[Tom H.]

Re: 63 drum brakes pulling

Your problem may be totally different than mine, but I had the same violent pull and steering wheel turn upon braking on my 63. It was a bad wheel cylinder on the front. Only one side of it was working causing the front shoe to jam into place and locking it up.

[Bob R.]

Re: 63 drum brakes pulling

You say all parts are new burt could there still be some air in the system? It can be very difficult to get all the air out. A litttle air could give you uneven braking.

[Stuart F.]

Re: 63 drum brakes pulling

I did a complete brake re-hab a year and a half or so ago on my 63 which originally had Sintered Metallic brake shoes. I replaced them with Metrix Ceramic and, expecting the worse for wear of my original drums, so I too got some replacement drums. I had a lot of difficulty trying to get them bled and adjusted correctly, and had all kinds of erratic braking. I tried switching the drums around, changed the star wheels (of which there are many different ones both in direction and coarseness of adjustment threads and points on the star wheels), and bled them many times. I finally took my original drums in to mic them and determined they could be reused with a minor cleanup turning. In the coarse of changing them out, I compared them and found there was a major difference between the originals and the replacements. The replacements did not fit all the way back to the backing plate, rather left a gap. It seems that the difference was in the depth of the drums and the relationship between the hub mounting surface and the depth of the braking surface. They are NOT exact replacements, rather some sort of generic "fits all" items that don't fit 63-64 Corvettes. They have a different outer flange and no grooves for the anti-chatter springs.

If I were you, I'd try to save your original drums (if possible) or look for exact replacements - not the generics. If you now have the generics you can try everything, as I did, and you will never get them to work right because they don't fit! Close enough, but no cigar.

Stu Fox

[Boyan B.]

Re: 63 drum brakes pulling

Thanks guys, I will try the side to side swap....good idea. I miked the drums last night and they are consentric +- .001 Also they are the same size 11 in. both although one is about 1/2 thou bigger, but it might be my vernier caliper too. I will pull out the old drums and compare, but the new ones do have anti chatter springs and seem to fit well.

Again, my system is stock 63 no modifications. I did notice that I resused my old star wheel adjusters and auto adjusting levers. Everything is detailed new so I forgot that they were used. I have a feeling my adjuster is not making the right one tight enough. I will put a new one in after the drum swap and see what happens. Thanks.

Boyan

[Stan E.]

Re: 63 drum brakes pulling

Boyan, If the restoration took some time and the wheel cylinders have set awhile I would check the oppisete side from the pull for correct operation. The wheel cylinders can set up even if they have been sleeved with brass or stainless. Usually a fast hard stab on the pedal will free up the stuck cylinder and the car will stop pulling to one side.

[John H.]

Re: 63 drum brakes pulling

If It Is A Disc , Disc It Will Have A Check Vavle In It. It Will Hold Presure 2 Psi In The Line.it Will Need To Be Taken Out For Drum Brakes.

Steve -

Nope on both counts.

Disc/disc master cylinders have NO residual pressure valves of any kind; the springs behind the caliper pistons hold the pads in full-time light contact with the rotors. Use of residual pressure valves with disc brakes will fry the pads in short order.

Drum brakes DO require residual pressure valves - always - and they hold 10 psi in the system. Without them, it will take more than one full pedal stroke to engage the shoes with the drums.

[Tim S.]

Re: 63 drum brakes pulling

Your problem may be totally different than mine, but I had the same violent pull and steering wheel turn upon braking on my 63. It was a bad wheel cylinder on the front. Only one side of it was working causing the front shoe to jam into place and locking it up.

x2. I had a couple of rusted up pistons that did not leak. Shoes had wear on them would would make the same type of major pull. New cylinders, no problem. When you bleed the system, is the pressure and volume of fluid consistent?

[Steve M.]

Re: 63 drum brakes pulling

John Disc Do Require A 2 Psi Check Vavle If The Master Clynder Is Below The Caipers Or Wheel Clynders 2 Psi For Disc 10 For Drum I Have Never Seen A Spring Behind A Caliper Piston? The Square Cut Seal Will Move The Piston Back Some. The Rotor Run Out Also Moves The Pads Back 2 Psi Will Not Burn Up A Set Of Brakes It Will Just Give You A Frim Pedal.