drum brake question
 

1970 Nova, trying to put secondary shoes on all the way around. The first corner I do won't allow me to put the drum on. The adjuster is all the way in. Do I have to grind one shoe to allow the adjuster to seat deeper in the shoe? I guess I could take a little off the short end of the adjuster too.

Re: drum brake question
 

Never having done that myself I would start by placing the secondary shoe and lining over the primary on the bench and look for the differences. If the reason for the drum not going over the brakes is the different thickness of the lining you may be in the area that arc grinding the brake shoes may be required for correct lining to drum contact. (am I showing my age??) If the reason is a different shoe and you choose to grind be sure the adjuster end has proper engagement in the finished cutout and be careful not to weaken the adjuster end by excessive material removal. Use of a brake drum gauge will give you an idea of the amount that is necessary to remove. That said why are you going this route anyway? I have no prior experience on your particular combo but increased lining area may result in an unsatisfactory higher pedal effort and improper lining contact will reduce braking performance. Can't source premium/high performance brake shoes to increase your stopping requirements?

Re: drum brake question
 

When I did this to my Firebird stocker it was an easy bolt in, with no modifications required. Are the pistons retracted fully on the wheel cylinder ?

Re: drum brake question
 

I'll check the piston depth first and start measuring stuff. I was pretty sure this would be a bolt on deal. In fact, I think I accidentally put both secondaries on one side when I did my first brake job back in the 60's. It helps to know that this should be a bolt on.

Jim, I'm trying to get all the holding power I can in my foot brake car to allow for higher launch rpm. I know many racers do this and haven't read of any braking problems.

Re: drum brake question
 

Experience always trumps opinions and theory....listen to the guys who have done it.....

Re: drum brake question
 

I also went through the parts books and was able to pick a wheel cylinder with a larger piston diameter. This will increase the force on the shoes.

Re: drum brake question
 

I had John Andreotti at Ott's Friction Supply build me shoes with premium Abex linings. They hold well, and all shoes look pretty much the same, iirc. They aren't prone to fading and yet grip well cold or hot.

Re: drum brake question
 

Shouldn't be a problem. Check to be sure the wheel cylinder pins are engaged properly into the shoe. Make sure the shoes are riding on the pads on the backing plate and not caught on them, if grooved file smooth or replace backing plate. The actual metal shoe is usually the same primary to secondary, they just put the longer lining on the rear one. Remove the shoes and place in the drum to be sure you have the correct shoes and they aren't bent/warped. that's how you check to see if they need arcing back in the day when you arced shoes after you machined the drum.
A crossover to a larger wheel cyl is another trick for more holding power.

Re: drum brake question
 

I also chamfer the leading edge of the secondary shoe (in the primary position) with a hand file (don't breathe the stuff) so there is a clean release of the new longer shoe. A few strokes will do it....put a shallow bevel transitioning the edge to the shoe.

Re: drum brake question
 

Thanks for all the help and tips. I got them on, but had to use one of my old secondary shoes to allow me to get the drum on. The lining was about .050 thinner and the drum went on easy.

The lead edge of the shoe in the primary position would be the edge nearest the top, right?

I put secondaries on the fronts also. The pedal has so little toe play that I feel like I'll have to drive around the pits to get used to it. Is there a spec for free travel on the brake pedal?

Re: drum brake question
 

It's like a different car. Held 3200 easily. If I deep stage and launch in the
3-3200 range my lights are respectable. Thanks for all the helpful tips.

Re: drum brake question
 

Ron:what brand of brake shoes and what type of lining are you using ? Thanks Greg

Re: drum brake question
 

If your using an e-brake make sure the cable is letting the lever return fully.


Hammer

Re: drum brake question
 

I used Bendix shoes, part number 245 and 246 that have organic linings. I talked to Bendix and the lining material varies depending on when the shoes were made. They all have some metal in them according to the tech I talked to. When I got these I stuck a magnet on them and it barely had any pull.

The downside for me was that I had lots of vibration after the finish line if I put a little to much pressure on the pedal. I was advised to run the front brakes the standard way and that fixed the vibration, but now the car creeps through the beams again.

There's no E-brake on the car.

Re: drum brake question
 

Are you using the stock 9 1/2 inch rear brakes?
You can get an 11 inch rear brake set-up off of a Monte Carlo, or a GM mid sized car of the same body designation. I got a set off of a 77 Pontiac LeMans.

Re: drum brake question
 

Try some custom linings with a better coefficient of friction, rather than using standard low quality linings and more lining surface area. See my post about Ott's use of premium Abex linings. Hopefully that will help you. Also, you can't expect optimum performance before the linings are fully seated (worn in) to the drums.

Re: drum brake question
 

I talked to Ott's before getting the Bendix shoes. I can't remember who I talked to, but he wasn't real helpful. He told me I had to send them metal. which I didn't have at the time. Now that I have some, I'll try to call them again.

Re: drum brake question
 

Working on my Camaro rear brakes now---are their any Oversize wheel cylinders that are a bolt in fit (without modifying the cylinders them selves or the backing plates) OEM is 7/8" Thanks Greg :confused:

Re: drum brake question
 

Come on give us a clue, what year, they made that car for 47 yrs.
Maybe someone can help then.:)

Re: drum brake question
 

The leading edge of the primary shoe is top of shoe towards front of the car, you want to be sure master is fully returned, then you should have approx. 1/4" free play,
Ron, what master are you using now do you know what piston size is ?

Re: drum brake question
 

Ron have you ever given thought to running two linelocs, it's
been done with success.

Re: drum brake question
 

I only use the lineloc in the water.

I don't remember what MC is on the car. I think it's the manual cylinder for a 70 Nova as are the wheel cylinders.

Re: drum brake question
 

Oop's !969:o

Re: drum brake question
 

RockAuto shows 69 Caprice uses a 1" rear wheel cyl., be surprised if
that wouldn't swap, a lot the old GM stuff swapped that was nice..

Ron that holds for you too 70 caprice shows a 1" rear that's a 1/8"
jump over the Nova and front shows 1-3/16" over 1-1/8" for the Nova
jumps not that big for the front may not help much.