Sun Feb 28, 2021 8:16 pm by mrjim2017
Part 3 - KB5 Rear Brake Drums
Pic #1 & #2 - I cleaned up the inside of the drum by hitting it with my sandblaster to knock off any loose rust and cleaned up the braking surface as well and blew this off with my air gun. I thoroughly cleaned up all the remaining grease in the inner hub using Brake Clean, rags, and air to blow it out & dry. I used high temperature silver to spray paint the inside area.
Pic #3 - From left to right, my home made tool to knock in the bearing races, the inner bearing & race (Timken #395S & 394A), inner steel retaining shim, felt seals, and outer steel retaining shim, and the spring wire snap ring that holds the seal "sandwich" in place within the drum.
Pic #4 - #6 - I inserted the bearing race down into the hub. Then set my race tool on top of it. It locks inside the bearing race and is shaped & clearanced to fit down inside the hub. Next I used a hardened steel pin I got from my workplace, a locking "pull pin" used at the rear axle/tandems on a big truck trailer, and the big hammer to hit the bearing tool and knock the race down into the hub. Took a little force to knock these in, not as easy as doing it on my cars. I made sure the race was being driven in squarely by observing the top of the race tool. If it looks like it is higher in one area (tilted), I would move the pin over to the higher side to favor it when I hit the pin with the hammer. I also moved the race tool around to different positions on the race to get it to sink evenly into the machined hub. DON'T allow the race to go in at an angle which is easier to do when first seating th race, it must be driven in evenly, so take your time and check after each hammer hit and adjust your hits accordingly. If the race appears to have gotten a large uneven slant to it as it is being driven in, knock it back out and start again, don't force it straight by beating hard on the side that is higher to bring it down even again. CAREFUL, as you can only get the tool so far down as it will hit the edge of the hub when the race insert comes level to the machined hub - the race sits deeper within the hub than the tool can knock it down (same as any automobile). So when you hit this point stop. You can see the differences in height of the tool in Pic #4 and the bearing seated down in the hub in Pic #6.
Pic #7 - To get the race completely seated, I do what I do with my cars. I use an old race to knock the new race all the way in. The race has a taper to match the bearing taper, so it has a wide width and narrow width. You want to use the narrow width to be placed on the new race so as to drive it in. The wider section is rolled on the edges and won't seat squarely on the new race and could damage it. The problem will be once you drive the new race in to seat it, you cannot get the old race out because of the tight fit into the hub and you don't have a lip to grab seeing both races are identical in size at the narrower width. First I notch a step, or lip, into the old race. I use my die grinder and cut-off disc to grind a notch into the wider width of the race. I grind it deep enough to be able to catch the end of a flat bladed screw driver, as shown. Then when I am ready to remove the old race from the hub, I can grab the race with my screw driver blade and knock it back out of the hub with a few light hammer taps.
Pic #8 & #9 - Here the old race is installed and you can see the back, the wider width, of the race with its numbers on it. The narrower width is face down on top of the new race. It should lay right on top evenly with the two surfaces butted together. Mine seemed to self locate just a tad, so it stayed in place. But if it slides easily, you could use something like masking tape and tape the 2 together where they butt on the inside of the race to hold them in place. Then I put my race tool on top of the old race and gave it a tap to seat it. Take the tool off to ensure the old race did not slip off. Repeat as needed. The race should be driven until the new race seats into the machined hole of the hub. You can usually tell when it is fully seated, it will have a "solid" sound when you hit the tool with the hammer. Then visually look to see that the new race is fully seated and no gap/space is seen, or felt, between the race and the machined ledge in the hub. Once it looks good, use the flat bladed screw driver and catch the notch in the old race you made earlier and drive the old race out of the hub. The inner race is now ready for the bearing and seals.
Pic #10 & #11 - Next up is the smaller outer bearing, Timken #390 & #394A. Both the inner and outer bearings use the same race, so the race tool and old notched race can be used for both applications. The outer race is done just like the inner. Knock it in with the race tool until it stops, then use the old race with the notch and drive it in until it bottoms. Then remove the old race and it is ready for its bearing. You can see how far down the tool will go in Pic #14 and how tight the tool is within the hub.
Pic #12 - Now that both the inner and outer races are installed, you can install the bearings doing the inner bearing and felt seals first. I pack my wheel bearings with grease the way I was shown, by hand, no special bearing packing tool. So a pair of gloves protects my hands, grab a wad of grease from the can, I used Lucas brand Red "N" Tacky Grease, and then work the bearing into the wad of grease watching to see the grease ooze out from the race and around the bearings. I pack the bearing from one side, the flip it over and pack from the other side. If you can grab the inner race and rotate it, it can work some grease into the bearings - but the grease was too heavy and bearings big, so I was not able to do this as I would have with a smaller car wheel bearing. In any case, I gave then a good going over and the bearings were thoroughly filled with grease. I also put a layer of grease on the outside of the bearing before inserting the bearing into its race in the hub. The felts have to be oil soaked before installation. The factory manual says to dip them in light oil, I used 10W-30.
Pic #13 & #14 - Problem fit. With the drum completed and ready to install, I made an attempt to put it on. The drum won't fit over the new brake shoes as there is not enough clearance. I made sure the brake shoe adjusting cams were at their low spots, and they were. I then usd a thin feeler gaug to make sure there were no "hi/low" gaps between the shoe and drum - which there were not. So the fix, and a common procedure with the older vehicles, is called "arcing" the brake shoes. A grinding machine specific for brake lining "arcing" uses a sanding drum/disc to remove material from the brake lining to match the arc/curve of the brake drum after it has been turned and to get the needed clearances between drum & lining. I don't want to turn the drums and remove any metal, and I don't want to $$send the drum/shoes out to have this done. So I am going to fabricate another "home made" tool that will enable me to take some material off the brake lining to get the drum to fit over the brake shoes. I will most likely have to do the passenger side as well. So that will be my next installment in this story.