Posted by David Sherman on Sunday, October 14, 2007 at 19:20:43 :
In Reply to: M-37 Brakes posted by Jerome on Sunday, October 14, 2007 at 15:17:15 :
I think a lot of guys do the conversion because their drum brakes aren't working right, or they grew up on disk brakes and find the feel of even good drum brakes to be unnerving. The original M37 brakes are more than adequate for any grade and load you'd even haul. The drums have lots of area compared to most pickups of similar size. They probably have a bad reputation because guys some old truck where the brakes haven't been adjusted for ages or the hubs leak and the shoes are soaked with oil, and they think that's as good as those brakes work. Every old Dodge I've acquired had bad brakes. They always need to be gone through completely with the wheel cylinders and master cylinder honed and rebuilt, and hoses replaced. If the shoes are oil-soaked they can be cleaned well enough to work (for my taste) by using lots of gasoline and then brake cleaner, and fixing the cause of the oil, but I suspect it's that kind of half-assed "fix" that makes a lot of people think drum brakes are no good. Then there's the matter of adjustment. The adjustment nuts are usually stuck, and it's a pain to break them loose, so it's tempting to just leave them, but that gives you too much pedal play. Lastly, the relief port in the master cylinder is almost always clogged, and if you don't clean it out, the brakes will bind up. It's a very tiny hole (#72 drill) and is easy to miss. These trucks were meant to go anywhere, up or down hill, often carrying a substantial load, and the brake design is perfectly good if everything is working like it did when the truck was in service. I suspect a lot of guys who went to the trouble of converting to disks wouldn't have done so if they'd had the chance to experience a properly working stock brake system.
The one thing I don't like about the stock design is the single circuit. One blown hose, or a line snagged on a rock or stump, and you have no brakes. The hand-brake is meant for holding, not stopping, and will quickly overheat, but it's all you've got so make sure it works. Lots of times they're soaked with oil or worn down the metal too. On my latest truck, the hand-brake drum has a big 1/4" wide crack in it. Beyond that, there's a real stout home-made bumper on my "backwoods" M37, and there are lots of trees along side the roads here. That's "plan C" for brake failure.
Follow Ups: