Tech article - Installing Rocky Mountain Brakes

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Real Rocky Mountain Brakes were made back when Model T’s were new, and are far simpler than the modern replacement. They are cable operated, and stop when backing up too. They require no special brake pedal, or welding on a tab on the bottom, The have a very simple equalizer, and a clamp for the brake pedal.

Hi Royce - According to the instructions, while installing my RM brake shoes, the rear wheel goes on up to the hilt but won’t turn beyond what looks like the spacing of the wheel bolts. There’s probably a 1/4" of bolt exposed after both brake drums are on and the nuts the catalog sends you with the longer wheel bolt nuts are thin. It doesn’t take much backing off the the wheel nut on the axle to get a rotation so I’m pretty close right now. Is the longer bolts a common problem when installing RM brakes? They talk about putting on an axle shim. Is that something I might look into before cutting off twelve wheel bolts?


Yes that is the easiest solution. It probably all works fine if the Model T hubs and axles are in like - new condition.

It’s too bad that when Jack Sunderlin made the first series Rocky Mountain Brakes, he didn’t continue to make them. The current ones are copies of a 26-7 AC Brake. He never did bother to find out what the original pedal clamp looked like, or the equalizer either. Too bad. A lot of grief has been laid upon our members because of a lack of research. If I could do it, so could he. He just didn’t know how! I have three T’s with original R-M Brakes, and I couldn’t be happier.

I lucked out recently, and found a pair of first series Rocky Mountain cast iron brake drums off ebay. A close friend of mine only had to machine the 3/16 radius on them to make them right. The originals were two pieces, riveted together, and don’t work as well as the cast iron drums. I think they would work fine if softer lining was available.

So you’re the one who outbid me on those cast drums! Glad they went to a good home. :slight_smile:

Hi Royce

The axles are new the hubs are not. So I ended up cutting the wheel bolts down to the nuts and I see in your article that I need a shim anyway to accommodate the RM drums. The instructions are a little criptic and your article was a big help. I’m starting off with the everything looking like your pictures. (see below) The parking brake is set when the handle is around 100 - 110 degrees or so versus 90 degrees vertical but the RMs grab at 90. Isn’t neutral supposed to be there? Is the idea for the RMs to bite before the transmission brake or around the same time?

You still need the Ford parking brake and you still need the ability to put the car in neutral without any brake application. So the Rocky Mountain brakes have to work exactly in the same place as both the factory foot brake pedal and the factory parking brake.


I tried to put the wheels on with 0.017 shims and I would have had to tighten the lug nut to get the wheel seated. I suspect the method is to tighten the nut finger tight so there’s not too much friction from the nut rubbing on the wheel and then secure the nut in place with the cotter key so there’s some freedom of movement. I tried it with 0.005 shims and have provided some pictures of that. I can see some daylight around the brake pads and they also drags on the drum in places but I can turn the wheel by hand. The car hasn’t been out yet and I wonder if the pads straighten up over the drums eventually during the breaking in? I guess the whole point of the shims is to keep the brake shoes from getting into the spokes. Is that right? You can see the lip of the pads hang out between 1/8" to 1/2" over the drum toward the inside. The wheels lock up when the lever is a little past 90 degrees.

The axles are new, the wheels are not. Does it look like I need shims at all or should we look again after a few miles?


Looks good but the center nut needs to be tight with no movement on the axle. The shim on each end is needed with stock T axles especially if the axle or the hub has any wear.