Re: Brake drum removal 1948 22nd Series

Posted by Scott On 2014/7/13 18:38:14

1. Movement does occur when the drum expands due to the high heat from the brakes. The drum will creep onto the tapered shaft. This high pressure movement can result in some galling. It doesn't take much to form a bond.

2. MoM is a dry and very thin film like a powder. It's not a lubricant but inhibits metal transfer and is tolerant of high heat. The problem with commercial antisieze is that it is heavy bodied -- basically a light grease with metal powder. Use MoM and the drums won't be so hard to remove when the next brake job comes around. I've not used commercial antisieze on brake drums but did try it for a short while on small engine flywheels that can also be very difficult to remove down the road when assembled clean. That resulted in flywheels shearing the key during use so I abandoned that product and went back to the MoM. No more problems.

3. Lubricant on the shaft or nut will not give what I would call a false torque reading. General torque tables publish two torque values, dry and lubricated, which are slightly different. They are equally valid. As for the specific application under discussion, the torque value is not precise but is a pretty wide range. It's a castellated nut that must be aligned for the cotter key. Assuming undamaged threads the difference between dry and lubed is less than the published range. BTW, who said anything about lubricating the threads? I must have missed that.

4. Did someone say rust holds the joint together? I stated it didn't. Someone suggested that MoM, if not dried first, could contribute to rust. I stated it's not an issue.

5. It doesn't take 40 years for creep to occur. A few heating/cooling cycles under pressure will bond them quite well. After that, on a clean joint absent a barrier, bonding on the molecular scale will continue slowly over time. So even if the car sits and does not undergo additional heating cycles the parts will continue to increase their bond.

6. I have a very heavy duty drum puller that has a handle designed to accept the blows of a sledgehammer (and it has received many). I've removed lots of drums from cars that have not been serviced for many years and they can be a bear. Rosebud acetyl/O2 heating torch and hammer blows and patience will eventually get them to part company but in these difficult cases I find the surfaces are no longer smooth but are roughened due to some metal transfer. As an aside, in one strange case a pea-sized lump of metal came off the shaft with the drum about a half inch from the end of the taper. That's the only time I've seen two parts weld together so strongly in one spot.