Rocky Mountain Brake Adjustment

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Model T Ford Forum: Forum 2013: Rocky Mountain Brake Adjustment
Top of pagePrevious messageNext messageBottom of page Link to this message  By Bob Coiro on Saturday, August 03, 2013 - 09:02 pm:

I seem to be doing something wrong. Back when I first got my Model T, the brakes stopped the car surprisingly well—for a Model T, that is. The Rockies required no more than moderate pressure on the pedal and if I wanted to, I could lock them up without a lot of effort.

Three years later, for the sake of safety, I decided to replace this ordinary type of nut on the Rocky Mountain brakes with castle-nuts.



Well, the bolt was short, so I cut a couple of castle nuts in half and even dremeled down the appropriate castellation, but couldn’t get the nut to fit tight with the hole and castellation lined up for a cotterpin.



I tried to shim it by filing washers down to just the right thickness and when that didn’t work, cut a locknut down, but that didn’t work either.


Eventually, I decided that the brakes had worked just fine for three years the way they had originally been set up, so I screwed the old nuts back on and leaned on blue Loc-Tite for insurance.

By the time I’d finished messing around with that, everything seemed to be out of adjustment, so I had to start from scratch.

I isolated the parking brakes by disconnecting Rocky Mountain pull-rods and adjusting the parking brake rods one at a time. In so doing, I discovered that my parking brakes had not been working effectively because the actuating rods were too long. When adjusted to a useful length, the clevis pins wouldn’t clear the threaded ends of the rods. I pulled the rods out of the car, sawed about 3/8ths of an inch off the threaded ends and hooked them back up to the parking brake system. Then, the rods were adjusted to the point where the parking brakes would lock two clicks before the floor-lever was pulled as far aft as it would go.

Next, I pulled the clevis pins to deactivate the now-correctly-adjusted parking brakes and independently adjusted the brake bands on the Rocky Mountain drums so they’d lock up on the last click before the floor-lever was pulled as far aft as it would go. Then, with both systems hooked back up, I could park on the incline of my driveway and not have to chock the wheels to keep the car from creeping backwards. Okay, good.

Unfortunately, whereas previously the pedal-operated brakes felt like they were indeed “self-energizing,” now it takes a good deal of foot pressure to stop the car from, say, 30 mph and I get the impression that the transmission brake is doing most of the work. I don’t think the problem lies with the way the “hanger tabs” are arranged around the RM drums because the Rockies work just great when operated from the parking brake handle.

I’m thinking that maybe now it’s time to pull the floorboards and shorten the adjustment on the little clevis-rod directly attached to the brake pedal. I figure that should actuate the RM brakes in advance of the transmission brake.

Comments? Tips? Photos?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Norman T. Kling on Saturday, August 03, 2013 - 09:30 pm:

Actually you should lengthen the rod between the pedal and the equalizer. The RM is applied when you push down on the pedal and the bell crank action pushes on the equalizer. First adjust the transmission brake to operate with the pedal about 1 inch above the floorboard, then adjust the RM to operate about 1 1/2 to 2 inches above the floorboard and you should be just fine. Trick is to be able to stop in reverse by pushing down hard on the brake. The reverse brake will be the transmission brake operating. You also need the rockies adjusted so that the lever at the back is the same distance forward on each side when the brake is applied.
Norm


Top of pagePrevious messageNext messageBottom of page Link to this message  By Andy Clary on Sunday, August 04, 2013 - 09:41 pm:

It looks like you're lower guide is misadjusted and could keep the band from rotating. the guide should be in the center of slot so band can move.

Andy


Top of pagePrevious messageNext messageBottom of page Link to this message  By Larry Smith on Sunday, August 04, 2013 - 10:27 pm:

I use original Rocky Moutain Brakes, and the bolt you pictured needs to be longer to accomodate the Rocky Mountain Brake band support. I take a standard grade 5 bolt, and machine it down so it doesn't rub on the brake drum.


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