jerry gollnick

My RPO 684 car has eccentric anchor pins( the pin in the center of the top of the backing plate that the shoe ends sit in) . Is there a procedure for adjusting these. When I rotate them I can increase or decrease drag. This isn't covered in ST-12.
second question, I'm not sure I understand how to tell lead shoe from lagging shoe. They are the fronts and have the same length.

62corvette

Jerry,
The one with less braking surface is the front (primary) shoe. On my RPO687 car, I just loosened the big nut on the back of the eccentric, and just slowly rotated the drum and adjusted the star wheel. I then turned the eccentric pin from the back until it created the most drag. There was a fair amount of trial and error, as I recall. Have fun!
Mike

jerry gollnick

Not sure I understand. Do you first center the eccentric and then adjust drag using the star wheel? Do you do a "normal" star wheel adjustment? ie expand until you get drag and then back-off a preset amount?
I thought the purpose of the eccentric was to better balance the shoe contact between leading and trailing shoe.ie Center them in the drum. Not sure how adjusting to drag does that? I'm not saying it doesn't I just am having difficulty understanding physically whats happening. Theres a lot I don't know about drum brakes.

K2

Jerry;
you are correct that the eccentric anchor is for the purpose of centralizing the shoes in the drum. The proper procedure for adjusting is to expand the shoes first with the star wheel till you feel a two handed drag, then loosen the nut on the anchor stud 3/4 turn, and rotate it till shoes are centralized. You should feel less drag as the shoes are centralized. If all drag disappears then snug up the anchor nut and repeat the process. The shoes are centralized when you feel the least drag. Then tighten anchor stud nut and adjust star wheel for final shoe adjustment. Hope that helps you.

63Corvette

Jerry, Klaus (K2) knows his stuff on the C1 Corvettes.
I would also suggest that you hand fit or radius the new shoes to your drums.
Klaus, you might want to exchange phone numbers with Jerry for the purpose of info exchange on this brake issue. I race with Jerry

jerry gollnick

Whats the procedure to hand fit or radius shoes to the drums. Is this done by machine?

DZAUTO

Yes, shoes are arched on a machine.
MANY years agio, shops that turned drums also had a machine to arch the shoes to fit the newly turned drums. Today VERY few places have the machine to arch shoes (WISH I HAD ONE!!!!!). I have my own brake lathe (bought it 6mo before a friend passed away) which I got for a song.
It has been at least 30yrs since I've seen a shop with the machine for arching shoes. All I know to do now is just let them "wear in" with time and use. The home made HD brakes that are on the 56 still are not fully seated into the drums, but they work great (for drum brakes).

K2

Jerry:
In the old days they used a brake shoe grinder like this.





Sent you a PM
Arcing shoes



Shows how shoes index on anchor pin jig



Properly fitted shoes

K2

PM sent.

K2

Thanks for the kind words Garrett and glad to hear you're still racing. I've been away from the forum for awhile so out of touch.
Keep that purdy car running.
Klaus