Tight brake pad

once a pad has seriously overheated it is best to replace it, just in case. What may have happened is that rust has built up beneath the springy bits that the pad fits between, you need to get those off and clean below them. I wouldn't worry about the bare bits rusting though.

Thanks for that. It's not rust under the shims as I serviced it earlier this year and always remove the shims and clean it all up plus a good wash around with brake cleaner. It's a little odd, because as I say, the pads aren't new. I will do what you suggest though and stick a new set on the front.

Cheers

Bit late but had a holiday in the sun.

these have a single piston calliper?

If either the piston is sticky or the sliding bolts are sticking the pad will bind. Have a look which pad has the most wear as to the one working the hardest to discover whats happening.

Have the callipers been serviced and re lubricated ?? these all have to float and centre over the rotor. The piston needs to be free and the alignment bolts need lubrication.

Replacing the pads may loosen the floating mechanism and place the piston in a different position, But its not the answer just to replace the pads as it will happen again.

Hi

Thanks for that. I understand what you are saying about the caliper being free to move back and forth but I have never greased the pins and there is no mention of doing so in the overhaul manual. The caliper lifted away perfectly freely i.e. there was no sign of jamming apart from when I tried to removed the pads. One came out as expected, the other was really tight. Although I've got the replacement set of pads, so far all's been well and I'm inclined to see how things go. I might though just pop off the wheel again and see how the caliper feels.

Cheers

I don't think sliding calipers should be greased. Just clean, and the seals in good condition.

How long since the pads were changed? Some makers reckon they should be cleaned at each oil service. Whether they are or not is debatable.

I overhauled them in about March but the pads weren't renewed. There's plenty of material on both. It passed the MOT in July no problems. It's been OK for about a fortnight now.

Yes they should, the location/alignment pins need greasing they have a dirt/dust cover to stop the dirt entering, the lubrication does dry inside these, also the covers do pop off or get damaged. I use a copper based graphite grease -(never seize?). Other parts don't as grease picks up dirt and grime and lubricant (grease) may contaminate the pad.

pad life can range heaps I would not like to front up with changing the pads every 20000k. Our modern car had the pads and rotors changed at

55000k with about 30% pads left. 30% is a good change point as with decreasing thickness the heat is not dissipated as well and the pad looses its efficiency as it becomes hotter.

Well that's in TOTAL contrast to the manual.

what does the manual say then?

It says to use Molykote M77 on both sides of the shims, also the piston shim with no mention of the pins, which presumably it would if necessary. Having said that I can see that ensuring there is free movement is important.

Due to use of rubber bits in brakes mineral grease should be avoided. It's not just the bellows that seal piston and sliding pin. To damp vibration they often have a rubber liner in the pin guide or a rubber tube on the pin. Mineral grease will make these expand and bind.

The oil resistant "rubber" they make oil seals out of is too rigid for flexible extending seals.

Mintex CeraTec is correct rubber friendly lube for brakes. Use on shims, pad ends etc as well.

Bosch do one too.

The lubrication wouldn't 'dry' if there is none. And of course the seals should be replaced if damaged. There is no need for lubrication on a bearing like this that doesn't move much. If the materials it is made of are designed to work without. You don't, for example, lubricate a handbrake cable.

Copper grease is used as an anti-seize compound. That wouldn't be needed if the seals are good. If it were designed to be greased, a proper lubricant would be specified.

I've had this type of sliding caliper on my BMWs for 20 years or so. And have never done anything other than clean the slides at pad change time.

Yes you can lubricate a hand brake cable - my MG has a grease nipple for such purpose.

needed when you overhaul callipers

Were talking about the locating pins which do need lubrication not the general slide tracks of the pad.

This is a modern MG? Some old MGs had dozens of grease nipples, but that's beside the point.

I was talking about the slides for the caliper. If it is a single piston type, the caliper itself must move. Either pivot (old idea) or slide on rods. They're not what I'd call pins.

That's only true if it's Teflon lined, or the inner is Teflon coated.

You cannot generalise from a single example. I could say, on the basis of my experience, that all sliding calipers should be greased. I'd probably be wrong.

Well. I've had three assorted BMWs with this type of brakes, my brother four. Neither of us lubricate the slide - just make sure it is clean.

I don't thing your are wrong. If I were doing a calliper overhaul then the the guide pins would be greased with a graphite/copper base grease, even if they maybe Teflon coated, Teflon coatings do wear. The piston and seal are assembled with a silicon compound.

Interesting. What make of calliper says to use a silicone compound for assembly of the piston and seal? And how does it survive the life of the caliper?