Way back in the seventies, I was employed by P.B.R. at their service division at the top of Swanston Street, Melbourne, for 18 months – a car a day, the experience I gained I will never forget, of course all drum systems. However I would like to pass on some worthwhile tips, to those enthusiastic home mechanics, on the do’s and don’ts.
Lets look initially at the drum shoe situation; the wear that occurs is not only the lining diminishing, but also the drum surface. I have always suggested to people to take both drums and shoes to a reputable brake service organization who is conversant with older vehicles and their needs.
The drums may require machining due to the undulating wear surface (there are limits to the diameter permitted) by increasing the diameter of the drum the shoes may require packing under the new lining to cope with the diameter change. Poor drum surface and new linings is not the way to go, brake efficiency does not occur until the linings have bedded into the undulating surface.
The thing to also bear in mind is with standard linings, the total surface of the shoe must bear in contact with the drum. Currently, brake efficiency has increased very effectively with a softer lining and that is BMJD Mintex. I have used it for several years and it is certainly worthwhile. Lubrication of shoe pivots, contact points and adjusters can be done, but not with standard greases. I have used Castrol zinc oxide grease for years and it maintains lubrication under all conditions, dust and water. There are other available, but I would suggest a brake service centre advice in this regard, but bear in mind that this lubricant is not to be used for any internal hydraulic needs.
The effectiveness of the handbrake can only be checked and effectively adjusted by the raising of the rear of the car until both wheels are clear of the ground. Firstly, ensure both brakes are correctly adjusted at the drums.
Secondly, apply the handbrake until the pawl engages with the fifth notch on the ratchet and adjust the nuts at the handbrake lever until it is just possible to rotate the wheel by hand under heavy pressure. It is important that the road wheels offer equal resistance. With the leaver in the off position check that both wheels are perfectly free.
I sincerely hope that these guidelines are of help. Please contact me should you require some advice.