Oily brake linings

[Tony Smith]

In the continuing quest to re-furbish the Bofors (although this thread will be relevant to a whole range of vehicles), I got around to stripping down the hubs to re-pack the bearings and do a general clean up. The brakes had not been particularly effective, despite nearly binding on the drums. When I opened everything up, it became clear why.

The oil seal for the wheel bearings does not deserve the title of "Seal" as it's actually just a felt pad that catches the w.b. grease and prevents it from slopping out of the bearings. When the vehicle has been standing for some many years, however, all grease becomes fluid to some extent and the grease runs down inside the backing plate and pools at the bottom of the drum. Roll the vehicle any distance and you smear that grease all across the readily absorbent brake linings.

So here's the conundrum. The brake linings and drums are smooth and not scored at all. The linings themselves are full thickness and it would be wasteful to throw them away. Now the surface of the drum can be degreased quite easily, but what about the linings? Can they be cleaned of grease/oil sufficiently to render them serviceable?

I had thought of a couple of ideas:

1. Soak the linings in a solvent like Petrol, Shellite or (if I win the Lottery) Brake Cleaner to dissolve the grease. This might take some time and changes of solvent. Or,
2. Soak the linings in an alkali such as Caustic Soda to chemically degrease the oil out of the linings. Or,
3. Burn the oil out of the linings with a propane torch, as these are old spec linings made from Asbestos. And,
4. All of the above!

If these cunning plans are no good (and feel free to tell me why. I am aware of the dangers of chewing on Asbestos), what would be better; buying NOS old linings or getting new-made bonded linings put on the shoes?

[Alex Blair (RIP)]

Tony..
It is not as if your brakes are on a Formula l racing car...
For the amount of use they will be getting I would suggest a good solvent cleaning and a careful baking with the torch and a good general clean up should suffice for the brake linings...
I would also suggest a change of packing to a teflon based water pump packing material,the rope type would be better than the original packing material used at the time of manufacture..
Any pump supplier will have the right packing material in all shapes and sizes..

[Stewart Loy]

Tony,

I have had similar 'oil migration' issues on my C15a. I was too cheap to reline the brakes, as there was very little use on the friction material - just a bit greasy.

My suggestion is to wipe them many times with a rag doused in acetone. Acetone does not leave any residue, dries very quickly, and is inexpensive and readily availible.

As a warning, this is best done out of doors, as the acetone is explosive when vapours are concentrated. Also, I would limit your tobacco use while doing this to a 'pinch between your cheek and gum'. This does not stop cancer, but is less likely to cause a fire than smoking while degreasing.

The aggressive solvent literally pulls the oil out of the friction material, and after a while they will be good as new.


Stewart

[cliff]

Tony Meths is another to try that does not leave a residue. Also good for wiping over surfaces before adding gaskets. This would be cheaper then acetone, not as hard on your hands and nose and of course far cheaper on the pocket.

[greg anderson (RIP)]

Here in Canada I have found that auto parts stores sell what is claimed to be a solvent specifically for cleaning brakes - I have not had a chance to use it but I would like to hear from any one who has -Greg

[Grant Bowker]

Originally Posted by greg anderson

Here in Canada I have found that auto parts stores sell what is claimed to be a solvent specifically for cleaning brakes - I have not had a chance to use it but I would like to hear from any one who has -Greg

If you are talking about the brake cleaner sold in aerosol form, it is a very good degreaser for surfaces but I don't know how good it would be for oil/grease soaked into brake linings. It also makes a superb wasp killer, but so far hasn't killed any other inhabitants of the Hammond barn. In past, I cleaned a set of M135 brake linings to what I considered an acceptable standard using lacquer thinner followed by alcohol (methyl hydrate). After cleaning, the linings didn't seem oily and were inspected several times after use to see if heat cycling was causing oil to leach out and be cooked to a glaze on the suface of the linings. Since the linings kept looking good, I kept using them. I may have been lucky in having linings that weren't fully soaked in oil. The choice of solvents came from what I had available and what I thought might be agressive enough to do the job without leaving residue.