VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1929-1932 29 emergency brake drag excessive?

I'm working on the rear brakes on a LQ 1.5 ton truck. In an effort to prevent a reoccurrence of 'oily brakes', I replaced the original axle bearings with double sealed bearings and I replaced the prop shaft's cork seal with a new single lip, nitrile oil seal. I then had the emergency brake bands relined with 3/16" thick, woven lining from Gary Wallace. (According to previous forums, 5/32" was the original lining thickness, but based on material availability, expected drum wear and riveting considerations, 3/16" seemed to be the correct thickness.)

The problem is that after installing the emergency brakes, and with them in their fully retracted position, there is more drag on the drums than I would have expected. Normally I would have retracted the brakes until there was no drag, and then adjusted them until slight dragging was felt.

In an earlier forum, someone suggested judging the drag with the tires installed (not just the drums). So, with the tires installed, I give each a single pull with the most effort I can muster. From stand-still, to final movement, the Passenger tire rotates 1.75 revolutions and the Driver tire rotates 2.25 revs. Is this acceptable?

I considered having the drums machined (if even possible), but according to earlier forums the drums when none too thick when they were new!

Comments? Thanks!

Easy the 3/16" is too thick. Install correct 5/32" thick lining as per original spec.

Is there a shop near you that still has the equipment to “arc” brake shoes? That process will reduce the thickness of the linings.

The handbrake "shoes" are actually semi flexible bands that can't be radius ground Rusty 37 Master,but the lining must be riveted on correctly or the bands will not conform to the bore of the bores of the pressed steel drums

Cabboy, any suggestions on 5/32" liner suppliers? Someone suggested McMaster-Carr but 3/16" is their thinnest. Another company was suggested but they were bought out by FleetPride. I called the local FleetPride and they recommended the same shop that installed my 3/16" material. I explained the problem to my installer and he promised to see if they could find 5/32". I also called Gary Wallace. He said he's only sold 3/16 for 10-15 yrs, for cars and trucks.

CJP, my installer seems to be the only game in town for this work. Not only were they recommended by FleetPride and other shops, but also by another vintage car restorer. However, I was not impressed by their riveting (different counter sinks depths and inconsistent 'rolling'). I will re-examine then for gaps between the lining and band. Other than that, what else should I be looking for?

I've now read different opinions about machining the drums. To do my due diligence, I've spoken to my machine shop about this and he needs see them before committing. Does anyone know the minimum acceptable drum wall thickness?

Thanks.

Hi CJP’S 29,

Thanks for the clarification about the construction of the parking brake bands.

I juts monitored E-bay until a seller had some original 5/32" for sale. And the pressed steel drums should not be turned. There is no minimum spec as they are already pretty thin as is. Nobody should be selling 3/16" as a replacement for 5/32" in my opinion.

if you search on this forum 1929-1932 you will find many discussions on brake linings

most common source is McMaster-Carr and yes 3/16" thick as it is what is readily available today, you can scour and find some old 5/32" just be cautious if they are asbestos or not.

figure 3/16 vs 5/32 is approx .03125" and probably have that much wear on the drums over 90 years if they were used. if not you can probably thin the linings down some considering they are friction wear material. a little friction equals a little wear.

no one recommends turning or machining the drums. i just cleaned mine up.

Since they are semiflexable bands it is likely.that they wear laid fairly flat to rivet on the linings.I would check the amount of concentricity of those bands. I copied an article from the HCCA newsletter that gave a description of how to arc the bands that were used on these cars "in the day".

One of the other members on here made a gauge out of wood to check his brake linings and mounted/slid it onto the axle shaft. 1/16 difference in overall diameter of that band may be a make or break distinction.

Art

I took the drums to my machinist and he thought it best not to do anything with them. That's that.
I'm waiting to hear from my installer on the availabilty of 5/32" material, but he's out until next week. Thanks for the suggestions to check out ebay and the asbestos caution.
In the meantime, I pulled the wheels and drums off and now (after my spin testing) I see some localized areas of wear, which I'm investigating.
Thanks all.