drum brake question

Ron Gusack · 06-05-2014, 06:09 PM

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.

Jim B · 06-06-2014, 07:44 AM

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?

ss3011 · 06-06-2014, 08:09 AM

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 ?

Ron Gusack · 06-06-2014, 09:36 AM

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.

Jim B · 06-06-2014, 10:26 AM

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

ss3011 · 06-06-2014, 11:26 AM

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.

Run to Rund · 06-06-2014, 11:29 AM

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.

Eman · 06-06-2014, 04:30 PM

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.

fordteacherguy · 06-06-2014, 08:21 PM

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.

Ron Gusack · 06-06-2014, 09:55 PM

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?

06-05-2014, 06:09 PM	#1
Ron Gusack Member Join Date: Feb 2009 Posts: 243 Likes: 1 Liked 7 Times in 6 Posts	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.

06-06-2014, 07:44 AM	#2
Jim B Member Join Date: Dec 2008 Posts: 100 Likes: 0 Liked 1 Time in 1 Post	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?

06-06-2014, 08:09 AM	#3
ss3011 Senior Member Join Date: Feb 2002 Location: Southeast Michigan Posts: 885 Likes: 63 Liked 221 Times in 102 Posts	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 ?

06-06-2014, 09:36 AM	#4
Ron Gusack Member Join Date: Feb 2009 Posts: 243 Likes: 1 Liked 7 Times in 6 Posts	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.

06-06-2014, 10:26 AM	#5
Jim B Member Join Date: Dec 2008 Posts: 100 Likes: 0 Liked 1 Time in 1 Post	Re: drum brake question Experience always trumps opinions and theory....listen to the guys who have done it.....

06-06-2014, 11:26 AM	#6
ss3011 Senior Member Join Date: Feb 2002 Location: Southeast Michigan Posts: 885 Likes: 63 Liked 221 Times in 102 Posts	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.

06-06-2014, 11:29 AM	#7
Run to Rund Senior Member Join Date: Sep 2007 Posts: 574 Likes: 6 Liked 44 Times in 22 Posts	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.

06-06-2014, 04:30 PM	#8
Eman Member Join Date: May 2014 Location: E TN Posts: 441 Likes: 14 Liked 105 Times in 60 Posts	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.

06-06-2014, 08:21 PM	#9
fordteacherguy Member Join Date: Jun 2007 Location: Federal Way, WA Posts: 233 Likes: 24 Liked 147 Times in 47 Posts	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. __________________ Brian Thompson NHRA Stock / Super Stock Class P/SA 6665 SS/MA 6665

06-06-2014, 09:55 PM	#10
Ron Gusack Member Join Date: Feb 2009 Posts: 243 Likes: 1 Liked 7 Times in 6 Posts	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?