Brake lining glue

The first brake pads weren't bonded, they were moulded in situ on a shaped steel plate. The connection between the friction material and the steel backing plate is mechanical as much as adhesive.

Why not ?! They have considerably more

Andy Dingley mumbled incoherently to the rest of uk.rec.cars.maintenance:

I wasnt talking about this car specifically :) I'd be amazed actually if they did :) I was just pointing out that parts are very often used for a lot longer than you think. Like peugeot blocks (106) still uses the old

Chris Bartram ( snipped-for-privacy@delete.me.piglet-net.net) gurgled happily, sounding much like they were saying :

I'd be surprised if new sets weren't easy to source for something as relatively common as a Ponton Merc.

Andy Dingley ( snipped-for-privacy@codesmiths.com) gurgled happily, sounding much like they were saying :

Particularly because Merc were still using drums on the '55 Le Mans 300SLRs

- that was the year they thought the airbrake bootlid a great idea...

Merc suffered so badly from Not-Invented-Here syndrome that not even the Gullwing 300SL got disks...

Was for cars too. I remember fitting some to my Bentley S1. Bentley only supplied brand new shoes at vast expense - but the same linings were available from the makers at about 1/10th of the cost.

No - pretty well all pads bear against the side of the caliper, and that takes the shear force. Indeed Dunlop disc brakes had no steel backing at all - they were purely friction material.

In fact, if you think about it, why should brake linings be exceptionally well-secured to the shoe? The frictional force between the lining and the shoe (because the shoe is not polished) is probably a lot greater (even without the help of glue) than that between the lining and the drum. So, apart from holding the lining in place when the brake is not being used, what is the point of the glue? The harder the brake is applied the greater is the frictional force holding the lining to the shoe.

Many items that are bolted together use the friction between the bolted parts to allow a smaller bolt to be used if the parts are subject to a shear force.

Rob

Rob graham ( snipped-for-privacy@btinternet.com) gurgled happily, sounding much like they were saying :

You've never had the shoes stick to the drum, have you?

No. Can't say I have.

BTW, I 'm not arguing in favour of no glue at all. I'm just arguing the point regarding why should the shoes shear off if they are not properly glued.

Partially true, but with a leading shoe type you have the self servo action which pulls the shoe onto the drum.

Indeed. But is that saying that the lining is being pulled away from the shoe? I don't think so. In which case, we are still talking about the relative frictions between shoe and lining and lining and drum - the latter being much the lower even with this self-servo effect, I suggest.

Because shoes are designed to be pulled onto the drum, when travelling forward, to assist braking. If the lining isn't exceptionally well secured, it ends up being pulled off the backing.

Yes. If you have a shoe fitted vertically on the right side as you look at it, the forces exerted on it are trying to pull it downwards.

Rob graham ( snipped-for-privacy@btinternet.com) gurgled happily, sounding much like they were saying :

They often manage to perfectly well with the factory bonding process, let alone with some pikey using araldite...

Yes. But the frictional forces pulling it downwards are less than the frictional forces preventing that from happening. There's more friction between the shoe and the lining than between the lining and the drum.

Rob

FYI, here is the text of a reply from Araldite

a brake shoe is a sensitive part, so I am not sure whether it should be re-bonded.

In principle, products such as Araldite Standard or Araldite 2011 are suitable for these kinds of substrates.

Rob

Whatever the effects of the self-servo action, they don't change the fact that if the lining is held against the drum, you must have equal forces on it from both sides (the drum side and the shoe side). The theory is sound.

My first reaction to that would be WRONG! Based on surface area, there will be a much greater surface area connecting drum and lining than lining and shoe, as the drum will be smooth and the shoe not so. So the greater surface area of contact should ensure greater friction.

However, practical experience would tell me otherwise. Couple of year ago bought an old Micra for my daughter that had been stored outside for 9 months. Did a full service and safety check before I gave it to her. Found the rear linings had virtually come away from the shoes, only glued on by a tiny area. But, the brakes worked perfectly and the linings didn't come away from the shoes when I hammered the brakes. So that would imply that it doesn't need much "glue" to hold them in place, and aralditing them back on may well work.

Having said that, I replaced all four shoes. There was no way I was going to let her loose in the car with them like that or re-glued back on. For the cost, simply not worth the risk. And like most replies, that's what I'd recommend to the OP.

BobC

Wrong.