Drum Brake Friction Material Choices - Who - What?

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C J Murray
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Drum Brake Friction Material Choices - Who - What?

#1 Post by C J Murray »

Has anybody found a supplier with choices of friction material to suit different uses? The material on the shoes that I sourced from a popular supplier seems too hard and requires too much pedal pressure. Maybe the material is race oriented? Possibly they are glazed but I don't think so. I need a material that is more responsive when cool during street use. Suggestions?
'57 Speedster
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Re: Drum Brake Friction Material Choices - Who - What?

#2 Post by David Jones »

Have you tried Porterfield CJ?
If I had known I would live this long I would have pushed the envelope a little harder.
Cymru am byth
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Mike Wilson
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Re: Drum Brake Friction Material Choices - Who - What?

#3 Post by Mike Wilson »

Maybe a call to C.H. Topping in Long Beach, CA. They do a lot of Porsche brakes and drums.

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Re: Drum Brake Friction Material Choices - Who - What?

#4 Post by C J Murray »

Thanks guys.
'57 Speedster
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Re: Drum Brake Friction Material Choices - Who - What?

#5 Post by Mike Wilson »

As always, glad to be of help.

Mike
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Re: Drum Brake Friction Material Choices - Who - What?

#6 Post by Bob Forman »

Same with my 62. So, using Vic's kit, I converted the fronts to disk. The stopping power is amazing. Like having power brakes. The process is easily done and gives you the reassurance of a dual system.
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Re: Drum Brake Friction Material Choices - Who - What?

#7 Post by Al Zim »

The first thing I would do is to look through the brake adjusting hole and see which way the front wheel cylinders are facing they should be facing the rotation of the wheel as the car is moving forward. Otherwise they will not stop the car. Second: adjust each brake shoe by adjusting the shoe so that it stops the wheel from turning then back off the adjuster 7 clicks so the wheel turns the brake pedal will be low and usually in line with the accelerator pedal so that you can heal-toe when driving. If possible (but usually not probably) is to have someone arc the brake shoes to the drums. You will have to find an older shop that has managed to keep their equipment operational. Zim's can do that for you. We use a softer brake lining because that is readily available and this usually will list the lifetime of the owner and probably the vehicle. al zim 800.356.2964
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Re: Drum Brake Friction Material Choices - Who - What?

#8 Post by Craig Richter »

Arcing brake shoes to fit the drums usually doesn't work anymore. The drum liners have gotten so big from use and prior turning, that by the time the shoe fits, it"s totally ground away in the middle. There is a way to get things to fit, certainly NOT authorized by Porsche, NOT by the Registry, and I'll deny anything you think you read here. The procedure involves a big rubber mallet and the floor. Now play like a teenager...

1/2 the problem is solved by using one of the great front disk brake kits available, like Bob and I have done.
 

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Re: Drum Brake Friction Material Choices - Who - What?

#9 Post by Al Zim »

Arching brake shoes works for us and has worked for us since we acquired two machines 11 years ago. Brake drums can be resized to standard. Brake drums that are slightly oversize and are not to be stressed in a racing situation can be fitted with oversize brake shoes (.5 MM thicker lining) to restore their stopping power at a very reasonable cost. Zim's has these shoes in stock for immediate shipping. One distinguishing characteristic of Porsche is that they had superior engineering on the 356 vehicles. This is why the cars were durable and responsive. LONG AFTER the British race cars had disc brake Porsche race cars still ran major races with drum brakes. One of the advantages of drum brakes is less unsprung weight which makes the car handle better. When you are using a car in a normal course of operation the drum brakes are plenty adequate when operating properly. In extreme situations disc brakes allow more high speed stops without brake fade. Craig: If you would like to fly into D/FW airport I will be glad to pick you up and you can watch us arc brake shoes. al zim 800.356.2964
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Re: Drum Brake Friction Material Choices - Who - What?

#10 Post by Harlan Halsey »

Of course shoe arcing works!!! Back in the old days, I used to let the shoes arc themselves, just living with the brakes for a while, but one way or he other, they are going to make full contact. Now that I have more patience, (and a bit more cash) I always have the linings arc'd. When I used to use Carbotech linings on the Carrera, They asked and I told them the drum diameters.

Drum brakes are really a deceptively complicated system. Porsche brakes have a lot of self servo action. That is why if you install the front cylinders backward, the loss of braking power is so dramatic. The angles of the ends of the brake shoes, and the adjuster slots, play into it. As does the coefficient of friction of the brake lining. It is important to get the bearing ends of the newly relined brake shoes right, back to factory, as part of the relining job.

Several years ago, Chuck Forge, did a detailed analysis of the servo action of the Porsche drum brake system. He determined that the friction coeficent of the Carbotech linings we were using was higher than optimal. He had Carbotech find a better match-I think it was a forklift material. We used that spec lining on my Carrera and on the Red Von Neuman car for many years.

I am glad to hear that Al can still arc brake shoes. My local guy has retired. Next time I need shoes I will ask him for shoes arc'd to the drum diameters I give him. Assuming he can do that.

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