Last work session, I was trying to remove the back drums on my 51 Packard Mayfair 2 door hard top. They are tapered fit and have not been off during the 20+ years that Ive owned the car. I rebuilt the front brakes, put on a new master cylinder and bled the lines. The rear wheel cylinder would bleed, but the wheels would barely turn by hand and with the car in the air, running and in drive, the drivewheel (no posi) would turn at engine speed and not stop when the foot brake was applied, but the emergency brake would stop it. Another problem was there were no adjustments on either wheel from the adjusters. I could see with my scope they were all the way in, but the drums were 95% locked up! The drums had to come off!
Using the special three finger heavy duty puller, with the wheel removed, I put the three fingers on the drum by putting one lug bolt in every other hole in the drum (the drum has threaded lug bolt holes and comes off as a unit). In other words, the drum is self contained and does not slip over a hub with lug bolt holes. I always back the axle nut off until it almost flushes with the axle. This keeps the drum from flying off under tremendous pressure from the puller. The axle has a center drilled hole (dimple) that allows the pullers threaded tightening bar to fit its pointed end into. This keeps the bar from slipping off when tightened. I tightened down on the puller a little each day for 7 days, but no luck. I would have to use heat.
Getting an oxygen/acetylene torch set up, I heated the area around the hub of the drum while tapping with a hammer. The best tip for this is a rosebud(fan tip) but I didnt have one, so I used a regular tip and turned the flame up. It had been several years since I had used an oxy/acetylene set up, but I remembered that the acetylene should be around 5-7 lbs and just enough oxy not to blow out the flame. Also, never use an oxy/acetylene set up unless it has a spark arrestor on each hose at the gauges, (some have them at the torch). If a spark blows back, it can blow you up! But the purpose of this article is to fix the 51s rear brakes, so I would say read instructions before using any welding outfits.
I never heat the axleit has already been heat treated and I believe it weakens the metal to re-heat it. I knew of a man who heated the axle until it was cherry red, got the drum off, and when he went for a test drive, the axle broke. This was on a 48 Packard Custom 8. He survived, but the car didnt do so well. Before I started using the torch, I put a welders blanket around the inner fender well to keep any sparks away from my gas tank and, of course, goggles and gloves. As I heated and tapped, I opened the bleeder valve on the wheel cylinder and heard a solid popand the drum came off!. Same thing on the other side. What I found was amazing. Both sides were rusty, but the left side actually had mold growing on everything. The star wheel adjuster was all the way in, and the brake linings were too thick. They were 1/4thick instead of the 3/16that the manual calls for. Thats why they wouldnt adjust. I took a picture and removed everything down to the brake plate, cleaned the plate with a wire wheel and primed and painted it. Last, I bought all new parts and had the drums turned. It is important when having drums turned to have them cut all the way in and not just where the shoes hit. The linings float and will grab when they hit a drum that has an edge. The 51 has just over 36,000 miles and I had intended to replace the inner and outer seals, but there was no sign of leakage, so I decided to leave them alone. To replace the inner seal would require pulling the oil guard, oil seal retainer, outer seal and shims, then pulling the axle with a slide hammer. This will allow you to get to the inner seal. Since the factory tool no longer exists, you must make your own to pull the axle and seal.
With the axle out, grease it, then put the new seal in (if its leather, soak it overnight in oil). To put the inner seal in, take a metal rod and weld a freeze plug to the end and push this against the seal to install. Install the shims on each side the way they came out. As a starting point, to set end playyou have to have one side the way it came out, and in place, as the block in the center of the differential (where the spider gears are) is what you are making sure to keep centered when setting the end play. Once you have the end play finished, you can completely reassemble everything. There is a lot more to this and is under Axle Repairin the 51-54 Factory Shop Manual (Max Merritt* has them).
ORDER OF AXLE SEAL ASSEMBLY: (Inside to Out) Inner seal (in differential housing, then axle goes in, bearing is on axle and the race goes in, then shims, backing plate, paper gaskets, outer seal, paper gaskets, retaining plate (retaining plate lets oil flow to outside of backing plate). So, you can see why, with No LeaksI passed on replacing the axle seals!
The rear wheel cylinders are 1in diameter and the front wheel cylinders are 1 1/8 When I put wheels cylinders on, I always leave the bleeder screw loose until the brake shoes are all the way in and the drums are on. The new retraction springs are not color coded like the old ones (which were yellow/red). The yellow ones were a little stronger with more wire turns and go to the secondary shoes. Since the springs are from 1951, I used the new ones.
When removing these drums, it is a good idea not to lose the key ways. They usually stay in the axle, but this time I had the right side to stay in the drum. They just fit right back into the axle slot. With all of the brake parts on the backing plate, I pushed on the drum. It is recommended not to grease the drum taper; push it on dry, then the washer, nut and cotter pin. The recommended torque on the nut is 200-280 ft/lbs. I guess that covers the 200 smaller series to the 400 larger Packard Series. I torqued mine to 225 ft/lbs. Next time, we will bleed and adjust. These 51s have an awkward master cylinder low on the frame. I will show you what I do to make the job a little easier. I also have found a new Bosch brake fluid (not silicone) that I will review for you. Its Summer! Keep the brakes up and keep em driving!
NOTES: 12Brake Drum
1 3/8Axle Nut
200-280 ft/lbs axle nut torque
Brake Hoses: Rear hose must be 17long. Beware of sets that say Alland are based on the shorter front hoses length. Max Merritt* has the proper ones.