Help - J4500 Drum Brake Fade?

[WillysWorks]

I have a '72 J4500 Truck with 11" drum brakes all around. I have added the power booster, etc. from another '72. I notice that when pulling my camper (which weighs ~2500 lb and has surge brakes) the truck brakes don't last long before no matter how hard you push the pedal, the thing won't stop on a hill. The master cylinder is new, all the wheel cylinders move freely and the drums and shoes are ok. The pedal feels great and the brakes work well in every day driving, but occaisonally I notice increased pedal pressure required after going down a hill. I am very careful not to stay on the brakes for too long to heat them up. They come back after driving for about 5 minutes. They get a little scary when going down a hill towing something. Is this amount performance normal for these brakes, or is there something that I can do other than convert to disk? I appreciate any wisdom the group may have.

Thanks

[joe]

Just a couple of points here Matt. For one thing the 11" brakes aren't the best in the first place but adequate for their intended loads. The 12" on J-4600's and up do work better.
Two, you're well over recommended GVWR for a J-4500(GVWR of 5000 lb). Your truck with fuel, driver etc is at or more than 4000 lb alone and then add a 2500 lb camper to boot puts you about 1500 lb over whats recommended(and what's legal) :(
Safely hauling a 2500 lb camper around is a job for a 3/4 ton truck or at least the heavy half ton model(6000 GVWR) with at least larger brakes/springs/rear axle.
Other possibilties which may help is make sure the shoes are adjusted correctly and the push rod for the booster is correctly adjusted(0.980"-0.995"). If either aren't in spec you may not be getting full benifit/use of the brakes.
Personally I think your main problem is too much camper for too little truck. You're trying to put 10 lb of Great Googley MoogleyGreat Googley MoogleyGreat Googley MoogleyGreat Googley MoogleyGreat Googley Moogley in a 5 lb bag ;)

[WillysWorks]

Thanks for the reply Joe.

Is yours a 4500? I do see the problem to a small degree when I am not towing the camper - do you ever experience this? The camper that I am using is a tow-behind that has surge brakes that help slow it down. I don't think that the weight of the trailer being towed applies to the GVWR, does it?

Thanks

[joe]

Matt, towing a 2500lb trailer should be no prob. I thought you had a slip-on camper.
One of my trucks is a 4600 and one's a 4500. The 4600 I've had loaded w/firewoood and the the brakes do heat up coming down a logging road winding down a mountain etc but no more than any rigs with a *#%@^ auto tranny.
The J-4500 with the smaller brakes/T-18 works just fine so far but I haven't had a heavy load in it yet. Other than the adjustments I mentioned above...FWIW I've never had much luck with metalic brakes linings either. They seem to fade more than the standard?
Well off to the airport...good luck smile.gif

[WillysWorks]

Thanks again, Joe.

My J4500 does have the Turbo400 Auto Tranny. This is the first of 28 vehicles that I have owned that has an automatic. Maybe that's part of the problem. I downshift on big hills now just to be safe. When your brakes heat up do they behave like mine? My pedal doesn't drop that much when they really heat up, but it gets so that no matter how hard I push the pedal it won't stop the rig on a steep hill.