Brakes: New 2R5 Brake Drums

[Old Radio Tech]

Installing new front brake drums on my 1949 2R5. The new drums won't go on. About 1/2 way is all I get before I can't turn them anymore. I've triple checked my eccentrics, even measured from the backing plate to both the top and bottom of both the front and reverse shoes to make sure the shoes are equal distances from the plate, and the eccentrics are backed off all the way. There is no self adjustment mechanism, just the eccentric. I have 1/8" of shoe all around. The drums measure right at 11". Measurements taken every 45 degrees.
Do new drums need to be machined before use? Should I open the bleeders to get that last little bit. The shoes are not up against the rubber of the wheel cylinders. If I did that I may get them on but I think they will drag even with the eccentrics backed off all the way.

[jackb]

Alas.... no more shoe arcing shops..... You can try to open the cylinder bleed screw, but I'm afraid you'll lock up the brakes once applied maybe not-worth a try

[Robert Crandall]

I also have a 1949 2R5. It appears that mine had oversize pads fitted to the 1/16" oversize turned drums before I bought it in 1980. After 25 years on blocks the rear pads delaminated. I bought new shoes, and the new pads are noticeably thinner than the front pads. If there is a way to measure, it may be that your existing pads were fitted to turned drums, which would make them not fit new ones. New shoes will not be over size. Just a guess based on how mine turned out.

[Old Radio Tech]

the pads are 1/8" thick. It crossed my mind that they weren't the right ones or if I found a set with thinner pads the drums might fit. The existing pads seem to be wearing on the first 1 1/2" of the pad closest to the wheel cylinder, but looking at the design that kind of makes sense. Thanks for the input.

[Lynn]

"Do new drums need to be machined before use?"

Don't know about the drums today, but the thousand or so drums that I installed in the 70's all had to be machined. I never put one on the lathe that was perfectly true before machining. Just getting banged around in shipping, they are much more susceptible to being knocked out of round than a disc brake rotor is to getting warped.

Are the shoes returning all the way in? You should not have to open a bleeder for them to return. Your return springs should be enough to do it. Is the top return spring stretched as it should be? You can push the shoes in and make certain they are going all the way in with just the return springs.