Turning? new brake linings

[RichardL]

Well, there may have been other threads for this topic, so I guess I'm being a bit greedy in starting this new one.

Now that I've skimmed the brake drum to some approximation of square and concentric, I need to decide what to do about new linings. Measuring as closely as I could without having a long-throat (carefully chosen words) caliper that will measure in excess of 7" diameter, it appears to me that brake linings turned, or sanded, or something, would be an exact fit to the ID of the drum if they were right around 0.150" thick. Of course, this would be 0.025" more than what I believe the standard 1/8"-thick linings are/were, however, my drum is not standard any more because I've skimmed it. My question is, what should be the at-rest clearance for the shoes for proper operation? I did some forum searching on this beforehand and did not see a numerical value. I did read a couple of posts by some guy named "Beezermac,"  which were quite interesting. Bago also had some interesting advice. Anything you two, or anyone else, care to add about the shoe clearance?

Richard L.   

[CheeserBeezer]

We have a guy local to here who skims drums and makes oversize linings to suit. I don't know what clearances he uses but, presumably, if everything is running true and there's no friction you can run a close clearance. I've heard you can have problems with alloy shoes. If they get hot they will expand more than the drum and cause interference so you need a bit of clearance to avoid this happening. Can't remember what I said in my previous post / life but I'm not an expert on brakes. However, setting up cables is an art, along with making sure actuating levers are at the best angle for maximum leverage.

[chaterlea25]

Hi Richard,
Memory tells me that new linings are 5/32in. ?  And that proper linings for an iron rear hub are thicker?
As the Ariel hubs have an adjuster at the fixed end there is scope for adjustment..
When I do this job, I pack the cam 20 thou on each side between shoe and cam.
I wire the shoes together to steady them
I turn a plug in the lathe to fit the axle hole, drill and tap the end for a bolt and washer to lock the brake plate to the stub and chuck.. Then turn  the linings to just fit into the drum.. doing it this way you can remove the plate and re fit It accurately and easily..
The linings will quickly wear tool steel so you need a carbide tool to turn them.
Finish the linings with some merry to remove the hairy bits,
Once it fits the drum removing the shims should give enough clearance !!

John

[RichardL]

Andrew,

Thanks for this additional information. I would have missed the issue of unequal expansion. Regarding the previous post [granted, I was skimming (ha! "reading fast")], there was some discussion of calculating cam action. I'm going to check that out.

Richard L.

[RichardL]

John,

I released my previous post on top of the 'someone else (you) just posted' message. Thanks, kindly, for providing this set of instructions that I think I'll take as marching orders. It seems to me that the 20 thou shims fit the general idea of "close clearance" (as mentioned by Andrew), so I'll take it as concurrence, especially considering the fixed-end adjuster.

Richard L.

[trevinoz]

I take the wheels to the local brake bloke and he bonds new linings to the shoes and machine the linings  to the correct diameter.

[RichardL]

I take the wheels to the local brake bloke and he bonds new linings to the shoes and machine the linings  to the correct diameter.

Way too sensible.

Richard L.