Mon Aug 12, 2019 7:53 pm by mrjim2017
Emergency Brake Relining.
Photo #1 - The 4-speed transmission, like many older units, has the round drum brake on the back end of it. The locking button on top of the handle was a little stuck and when I checked the brake lining, it was pretty worn down. Got the locking button working real well with a little WD-40 shot down the stick, so the brake lever works as it should.
Read several blogs on the internet on how to reline the brake drum as I have never done this. I did not see any need to send it out for relining as I can handle shooting rivets if need be, although there are plenty of the old rivet tools on Ebay if you wanted to go that route. Others talked of bonding the lining with JB Weld, and still others mentioned brass screws and nuts.
I went with a combination of both JB Weld and brass screws and nuts. Keep in mind that the purpose of the hand brake is just that, a hand brake to use once the truck was at rest. I suppose some drivers used the brake as a supplement in stopping, perhaps with the truck loaded to its limits or going up and down mountains. So I figured my approach would be fine.
Photo #2 & #3 is the original brake band with lining and then the lining removed. I simply ground off the rivets on the back of the band and knocked them through. The lining then fell off. I cleaned up the rust with a wire brush - didn't go too crazy on it.
Photo #4 shows the new brake lining material. The lining came from McMaster-Carr online. The lining can be purchased by the foot, so I measured the old lining and ordered 4 feet of 3/16" thick x 2 1/2" Wide. I did not need 4 feet, but figured I would CYA in case I screwed up and had to redo the job. Once the lining came in, I cut 2 pieces to match the original lining length.
Photo #5 A pot? That's got to be a mistake, right? Since I was going to use JB Weld to bond the lining on the brake band, I needed a pot the same size as the brake drum to secure the brake band/lining to as it cured. Makes sense, right? Pulled a tape measure on a lot of pans and round objects. Finally got the perfect match at Walmart. Tramontina brand 3 Quart Sauce Pan was exactly the same diameter as the brake drum. I removed the handle.
Photo #6. I coated the brake band with JB Weld MarineWeld after reading about all the different types of JB Weld. I then put my cut brake linings in place, wrapped it around my sauce pan, then used the C-clamp to tighten the band around the pan. This does get messy as the clamp pressure oozes the JB Weld out the sides. The linings may even slip around a bit on the JB and you will have to readjust them to get them in their correct position. I may have used just a little to thick of a coating. LOL Don't worry about the excess too much, as once it is cured, you can trim the excess JB off. I let the stuff cure for the week waiting on the next weekend.
Photo #7 is what the new lining looks like after it has been released from its "mold" and the edges cleaned up of JB Weld. Note the JB filled in the rivet holes, no big deal because you will be drilling through these holes.
Photo #8 shows the right angle air drill I bought at Harbor Freight, the wood bit I bought at Home Depot which you can see has a drill stop from Harbor Freight secured around it so the wood bit will only go about 1/2-3/4 way into the new lining. You want a shoulder for the head of the #8 brass screws to sit down onto and tighten/hold the lining onto the brake band with the use of the nut on the back side.
So I first drilled all my rivet holes from the back side where all the JB Weld plugged holes were using a drill bit matching the #8 screws. Rivets used on brake linings have flat heads. The #8 screws are a round slot head. Each screw head was ground flat on my grinder to take out much of the crown. Gotta leave enough material for strength, so you get an eye for how much to grind.
Next up is the angle drill and wood bit. The wood bit is slightly bigger than the screw head because you want the screw head to pull down into the hole you are about to make. If it seems not to pull in correctly, you can grind a little off the edges of the screw head and try again or wiggle the wood bit around - this is not an exact science. With the stop in place on the wood bit, it keeps you from going to deep. The stop didn't fit as well as I wanted, so you can see the masking tape I built up on top of it to keep it from slipping up on the wood bit. Crude, but it all worked out. I drilled all the holes out on the lining side, taking my time and trying to get them straight. Got a couple holes at the wrong angle so had to work the wood bit around to correct it. The main thing is having that shoulder in the lining hole under the screw head so it has something to tighten down upon and hold it to the brake band.
Photo #9 shows my altered #8 brass screws in place and the brass nuts on the back side to draw the screws tight. The trick here is not to over tighten the screws as brass is a little soft and can snap off. Again, you get a feel for it and know when to stop wrenching. Once all the brass screws are in and snugged down, cut off the excess sticking out past the nut. Don't cut the tails off flush with the nuts, but leave a little stick out. Why? I supported the screw heads with a round flat end punch, and then peened over the slight screw stick-out to prevent the nuts from backing off.
Photo #10 shows the finished brake band. Screws are trimmed, peened over, and everything get a coat of black hi-temp paint used for outside grills. Then sand a bevel on each end of the brake lining just as you would see on any brake shoe lining.
Then it is just a matter of reinstalling the relined brake band and following the adjustment procedure found in the Service Manual. Took a number of photos of the emergency brake linkages on the transmission before pulling all the parts off. This always helps when you don't get back to installing the brake band until 3 weeks later. All adjusted up, the emergency brake & lever work like new.