Mick McCrudden

IF YOUíRE a home mechanic who likes to fix your car, letís talk about the job of changing your brake pads. On a modern car, when you go to release the caliper, youíll notice itís sitting on a bolt with a mount system and the assembly is known as a caliper pin or caliper slide.

Now what a lot of people forget to do when theyíre changing the pads is to remove the pins completely and clean them Ė free them up of all the road grime. Then apply a little rubber grease or anti-seize.

In fact hereís a tip: when youíre buying the pads, see if you can also source a new set of the rubber boots that go on the pins. What happens is they perish, the road grime gets in, attaches itself to the grease thatís in there and turns it into grinding paste. The down side is that, because itís a single-acting caliper in most cases Ė so only one side is applying the pressure via pistons Ė it requires very good free movement for both sides to disengage properly once you take your foot off the pedal.

Now the problem becomes two-fold: first the pins themselves get worn probably faster than they should; And the brakes tend not to fully release. With the pads staying engaged, you get over-heating, which in turn warps the discs. The whole system ends up unhappy, as youíre applying more pressure to get the brakes functioning properly and in turn thatís piling on extra wear and tear.

Now we had exactly this happen to Ed Guidoís E39 BMW 540 Sport. The workshop that last changed the pads and discs didnít go to the extra trouble of refreshing the pins. So the inevitable happened. The pads werenít getting the usual knock-off or suck back, and therefore were contacting the disc more than they should. Then the disc overheats and warps. The car developed brake shudder and the discs had to be machined far sooner than you would normally expect.

Thatís not the end of the world, but itís a nuisance and an unnecessary expense. The moral to the story? Do the whole job and not just a quick pad shuffle. It may take a little longer, but the brakes will work a little better, plus it saves time and hassle in the long run. Good luckÖ

Note: Mick runs Glenlyon Motors in Brunswick, Vic. T el (03) 9380 5082.