Many caliper designs use an insulating rubber bush on one of the guide pins. This is to stop caliper knock or rattle. These rubber guide pin bushes are manufactured from EPDM rubber. It is very important to use lubricant that is compatible with EPDM rubber. Using any petroleum based product such as grease will cause EPDM rubber to swell and the pin will seize in the bore. On the other hand rubber grease which is compatible with EPDM does not withstand the temperatures that are reached in normal braking. The best product to use is a silicone lubricant as used by O.E manufacturers. This is compatible with EPDM and is rated to high temperatures. Introducing Silicone Coolube…..PW33001
Why is keeping pins lubricated so important?
Should I lubricate the guide pins when I am doing a brake pad change? The answer is yes. On a sliding caliper the guide pins are crucial to the efficient operation and retraction of the outside brake pad.
Hot Tip
A caliper with seized or tight guide pins will wear the inner brake pad prematurely.
Can a guide pin have too much grease?
When servicing the guide pins it is important to clean out any old, contaminated grease and replace with new grease. Caliper guide pin to bore clearance is about .2mm which means that there isn’t much room for grease. Less is better…it literally only needs a smear of grease around the guide pin.
I have greased the guide pin and now the caliper bracket is springing back.
This has occurred because there is too much grease and there is air trapped in the guide pin bore as the boot is sealing it in. To rectify this, use a blunt spike to release the air from the boot whilst moving the caliper bracket back and forth the on the guide pin.
Hot Tip
Air trapped in the guide pin bore will cause premature outer pad wear.