06-23-2018, 05:16 PM
So, I replied to a thread about Bendix/Azusa drum brakes recently. The topic turned to re-lining the shoes yourself, rather than using the newer Azusa shoes. At that time, I had not yet attempted the project, but I did do it this weekend, and I have a few observations on that topic. To be clear: I have not had track time yet to test my work, and the results of my work will be what they'll be. Your results may vary. I am pleased with the results initially, as far as uniformity and structural integrity are concerned, but these are superficial observations. My proof will be at the end of the straight at Avon next month. LOOK OUT!!!! (Just kidding)
Anyway, I'm not going to do a step by step instructional. That's already been done. The process is described in the August 2016 VKA FirsTurn. Others have explained their methods on this and on other forums. I just want to offer some side notes to others who are considering this project.
I used the methods and brake lining material described in the article. I couldn't find the exact rivets described, but when I went to aircraftspruce.com I did find RAPCO RA105- 0020 rivets and the RAPCO RA825 brake rivet tool. I also used JB IndustroWeld epoxy.
I tried to use 1" c-clamps, instead of all those vise-grips: I just don't have 8 pairs of locking pliers, and c-clamps were cheap. I should have saved the money I spent for c-clamps. Too fiddly, and there's so little room to spin their handles. Instead, go to Surplus City, or Harbor Freight, or whatever cheap tool store you have in your town, and get a bunch of 5" or 6" cheap no-name locking pliers. Much easier, and it still ends up looking like medieval torture.
As far as the RAPCO RA825 is concerned: It's a wonderful little tool, but it is not perfect for this job immediately out of the box. Two modifications need to be made.
First, theres no room for the t-handle to swing when the brake shoe is in position in the RA825 press. The t-handle needs to be knocked out of the threaded ram. Mine was only finely knurled, so it was knocked loose by a couple raps with a ball-peen hammer. The end of removed t-handle can then be used to turn the ram. It should have been a sliding t-handle in the first place, probably.
Second, the spine of the brake shoe interferes with the forward edge of the threaded part of the press frame. The nice, new, USA made tool needs to be marred by a grinder before this task can be accomplished. I beveled the frame using my Dremel tool and a grinding stone to make the clearance that was needed. It's still a tight fit! The diameter of the ram is almost too much, but it gets the job done if you line it up with the rivet and rotate the shoe assembly back and forth with each increment of tightening. Be sure to grease the threads of the tool! I used moly disulphide grease from a CVJ driveaxle boot kit. Don't get it all over your linings.
Once modified, the RAPCO tool worked smoothly and formed the rivets beautifully.
For counter-boring the lining, I used a cheap 5/16" drill bit that I ran in my drill press while tediously using the edge of a file to create a flat point with an integral pilot. Drill bits are hard. It took a while, and probably took a few decades off the life of my hand-me-down, family heirloom of a 60 year old Nicholson file. From that perspective, a $20.00 purpose-built bit might be a better choice?
That's about it. I figured that since I had chimed in with "advice" about brake linings, I should have at it myself. I hope these tips help someone out. And now.... Pictures!
Anyway, I'm not going to do a step by step instructional. That's already been done. The process is described in the August 2016 VKA FirsTurn. Others have explained their methods on this and on other forums. I just want to offer some side notes to others who are considering this project.
I used the methods and brake lining material described in the article. I couldn't find the exact rivets described, but when I went to aircraftspruce.com I did find RAPCO RA105- 0020 rivets and the RAPCO RA825 brake rivet tool. I also used JB IndustroWeld epoxy.
I tried to use 1" c-clamps, instead of all those vise-grips: I just don't have 8 pairs of locking pliers, and c-clamps were cheap. I should have saved the money I spent for c-clamps. Too fiddly, and there's so little room to spin their handles. Instead, go to Surplus City, or Harbor Freight, or whatever cheap tool store you have in your town, and get a bunch of 5" or 6" cheap no-name locking pliers. Much easier, and it still ends up looking like medieval torture.
As far as the RAPCO RA825 is concerned: It's a wonderful little tool, but it is not perfect for this job immediately out of the box. Two modifications need to be made.
First, theres no room for the t-handle to swing when the brake shoe is in position in the RA825 press. The t-handle needs to be knocked out of the threaded ram. Mine was only finely knurled, so it was knocked loose by a couple raps with a ball-peen hammer. The end of removed t-handle can then be used to turn the ram. It should have been a sliding t-handle in the first place, probably.
Second, the spine of the brake shoe interferes with the forward edge of the threaded part of the press frame. The nice, new, USA made tool needs to be marred by a grinder before this task can be accomplished. I beveled the frame using my Dremel tool and a grinding stone to make the clearance that was needed. It's still a tight fit! The diameter of the ram is almost too much, but it gets the job done if you line it up with the rivet and rotate the shoe assembly back and forth with each increment of tightening. Be sure to grease the threads of the tool! I used moly disulphide grease from a CVJ driveaxle boot kit. Don't get it all over your linings.
Once modified, the RAPCO tool worked smoothly and formed the rivets beautifully.
For counter-boring the lining, I used a cheap 5/16" drill bit that I ran in my drill press while tediously using the edge of a file to create a flat point with an integral pilot. Drill bits are hard. It took a while, and probably took a few decades off the life of my hand-me-down, family heirloom of a 60 year old Nicholson file. From that perspective, a $20.00 purpose-built bit might be a better choice?
That's about it. I figured that since I had chimed in with "advice" about brake linings, I should have at it myself. I hope these tips help someone out. And now.... Pictures!
