Brake issues
 

I run my Roadrunner in a Pure Stock / Factory Stock series in my area. The rules state that you must run factory brakes (11" manual drums in my case). Currently I have organic lined shoes front and rear. The rules state no line lock allowed (so I run the rears loose). The problem I'm having is I'm pushing through the lights. Also, I would like better stopping at the other end. I'd like to try a set of semi-metallic brake shoes on the front. Does anyone know of a source for these? I'm open to any and all other suggestions.

Thanks in advance.

Re: Brake issues
 

Tighten the rears.....

Re: Brake issues
 

Organic shoes hold better on the starting line. Metallic shoes don't fade (after 2 or 3 hard stops) as much as organic shoes but don't hold on the line as well when cold. You could use 1 organic and 1 metallic per wheel as a compromise. In your situation, I don't think you can have your cake and eat it, too. I would err on the side of safety and use metallics myself. Ron.

Re: Brake issues
 

You have a few choices:

Porterfield Brakes
http://porterfield-brakes.com/catego...Full+Race.html
http://porterfield-brakes.com/images...8_02_22_17.pdf

CarboTech - They will reline your shoes with a racing compound
http://www.ctbrakes.com/

Re: Brake issues
 

I have a 1969 Roadrunner that I bought brand new. I was thinking that disc brakes were an option on the 1969 and 1969 1/2.

I just checked Hemmings. It WAS an option that required a 727 transmission, sure grip, and a slightly smaller rear brake drum??????

Look it up yourself....Google search 1969 Roadrunner disc brakes Hemmings.

Problem solved. Good luck.

Re: Brake issues
 

Over time, shoes develop a "glaze" which can reduce holding power. I touch them up a bit with sandpaper when I periodically swap the rear slicks. Personally, I think that rear brakes are more important to hold the car on the line, especially if the car has narrow front tires. If you can't harness the torque at the rear drive tires, it can slide the fronts.


There is also a trick that I've never tried. But I've heard that buying 2 sets of shoes and using the ones with more surface area on both sides of the brake assembly for more surface contact helps.

Re: Brake issues
 

When we ran drum brake we used 10" drums without the self-adjust parts. We would adjust the rear brakes about every ten or so runs. Every time we would change tires side to side we would adjust the brakes. For me proper adjustment was when the drum would slide on and of the shoes without dragging against the shoes. If it drug against the shoes it was a little tight. All adjustments were made with my fingers turning the adjustment wheel, with drum off. Brake shoes were parts store's cheep brand.

I want to say we used two sets of shoes. I cant remember, but I believe we used the two rear shoes (the long ones) per wheel.

Some things to look for that will cause a few problems. Cracked drums, it will happen after the drum is turned to reduce weight. Also have the drums turned so pilot turn and drum turn are concentric. With the torque that a six-pack makes the backing plate life is about two to three seasons, the five mounting holes elongate.

Install a brake pressure gauge on the rear system, it will let you know where you are. As you know the front stop you but will not hold the car in the lights, the back brakes do that.

I think the master cylinder bore was 1"

Good luck

Re: Brake issues
 

I'm confused about the linelock issue and why you would run the rears loose.
Drum brakes are self energizing, the frt shoe contacts the drum and as it is forced to rotate it applies increased pressure to the rear shoe. This is why they work well to stage a car.
On my rear drums I use 2 secondary shoes on each side, you buy 2 sets of shoes so you can only use the long lining ones. Go to a real parts store and try and cross reference wheel cylinders. The larger the bore wheel cylinder the more pressure will be applied. Basic hydraulics, the surface area of the wheel cyl piston multiplies the force.

Re: Brake issues
 

Be careful when you mix or match hydraulic parts.If you substitute larger rear wheel cylinders for your standard units, you increase the surface area on the wheel cylinder pistons,thereby increasing the application pressure to the rear shoes. This could have the effect of causing the rear wheels to lock up easier at the finish line(not nice,especially if the track has rules about excessive braking),and it could result in a real scary situation. If you increase the size of the fronts and not the rears, it would possibly make it harder to hold the car on the line without sliding through.Also, manual brakes have a smaller bore master cylinder that do most power brake master cylinders. We did a master cylinder replacement on an early 70's Dodge van one time and wound up with a van that would just about put you through the windshield when you went to stop because the brakes applied so hard. Come to find out,the parts store sent us a manual master cylinder instead of the power unit. Now, we all know, parts stores never send out the wrong part, do they?

Re: Brake issues
 

First of all...Thanks for all the reply's. You've all given me some great suggestions and things to try.

Mr Derby...I purposely run the rears loose to put less strain on the drive-train while doing a burnout and to avoid overheating the rear brakes. The rules state no line-locks allowed.

R.Thorne / SSDiv6...Thanks for the links. This is what I was looking for. I will be contacting both companies on Monday and see what they suggest as far as material and shoe sizes.

SStockDart...From what I've read you're correct on standard Roadrunners, but in my case (440 6BBL A12 option) was only available with manual 11" drums or power assist 11" manual drums.

Myron...I think no matter what path I take (as far as material), I will try running the large shoes front and rear.

Larry Hill...There are no self adjusters in the rear and I do re-adjust after every race. They're adjusted so that I can slide the drums on and off with no noticeable drag. I will get a brake pressure gauge and see where I'm at.

Eman...Regarding the line-lock issue - the series that I run in is for restored factory muscle cars. Stock cam, exhaust, factory size tires (G70 15's in my case), etc. The organizers specifically say no line-locks...I don't agree, but that's the rule. I think I will pursue the brake shoe size/material first before changing the wheel cylinders.

Greg R...I'll leave the wheel cylinders/master cylinder option as a last resort.

My reply is a little long winded, but I wanted to address all that took the time to answer.

I realize I may be fighting a loosing battle by running the rears loose, but was hoping to find out if a better shoe material would offer better stopping distances and holding power at the line.

Thanks again for all that replied.