Thanks for all of the help everyone. I located the problem just today, finally.

It seems that I fried the inner proportioning valve seals for the rear circuit (being that it is located so close to the exhaust pipe) while sitting in stop and go traffic in 90+ degree heat.

What's happening is the fried rear valve circuit keeps residual pressure on the rear brakes due to the inner seals being melted into submission. This residual pressure actuates the rear shoes and keeps them on at all times.

So, time for a new proportioning valve set up and I should be back on the road.

At least I've had plenty of brake dis-assembly and re-assembly practice. I can now do a rear shoe install in under 15 minutes, both sides!

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'68signet

"Living analog in the digital age."

H'mm. The prop valve seals should not melt or fry; they're not made out of plastic. The ambient temperature in the daytime will have no effect on the durability of seals in the brake system. Is your exhaust and/or prop valve location other than stock? If so, and you're cooking seals, then you need to rework the prop valve placement and/or the exhaust routing to separate the two.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Not plastic but rubber, ask me how I know... Valve is in the stock mounting location just four to five inches away from the 2.25 " exhaust pipe on my rig.

Inline tube's prop valve is probably not all it's cracked up to be either. I will be re-routing/mounting an adjustable prop valve for the rear circuit to the D/S inner fender to alleviate the problem.

Let the fun begin!

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'68signet

"Living analog in the digital age."