Mintex F4 pads - Towel rails

I have recently worn down a set of front Mintex F4 pads. At around 6mm of pad wear material left I had brake grinding which turned out to be towel rails in the pad hitting the disc and scoring it. The supplier told me that this sometimes happens to let you know the pads need changing. I have never experienced this on any other pad. I don't want to be checking the pads every five minutes to see if the towel rails are about to bleed through and score my expensive AP discs. Has anyone else come across towel rails (which are like cylindrical bars) embedded in the pad. When you have worn the pad by 50% they show up and score the discs. Cant be right surely?

I haven't heard of "towel rails", not can I find anything about them - if you could provide (a) picture(s), to illustrate?

The only things that come to mind are the spring tabs sometimes used to rub the disc to indicate wear limits, or sometimes an insert is used within the pad material that, when the pad is worn, contacts the disc and earths out an electrical circuit to bring up a warning - this is usually a single wire system, or sometimes a two wire system is used where wear breaks a circuit within the pad and brings up the warning light.

From the description, this is different again.

Oh, I think it unlikely, but it might be a mis-match of pad/disc/caliper, where they just don't play nice.

Dowel or towel?

Looking at the Mintex website I cannot see any information on these. Some pad manufacturers will use short dowel pins, or a serrated pattern on the backing plates to assist in the adherence of the pad material to the backing plate, but I haven't seen any that are 50% of the pad material.

On a racing pad you usually want to avoid going below around 50% wear on the pads, as the reduction in thickness increases the chance of the pads tapering in the caliper as the pistons move further out of the bores and are this less stable, as well as reducing the thermal insulation that the pad material provides to the pistons.

Sorry for delay

That is quite terrible, not something I recall seeing before - the cynic in me wonders if it's a ploy to sell more pads and discs, and it'd be a bit of a nightmare for teams running longer races, where there may be a choice of rolling the dice with wear, or perhaps going to a competitors product.

Beginning to think you are correct about the ploy. Crazy as I have never seen it before.

aren't these rather brass bits?

I've already seen similar things with other pads manufacturer, they use them brass pins as an extra help for pad compound adhesion the the backplate and help against pad sheering and / or delamination.

Yes, Pad manufacturers will use various methods to enhance the retention of the pad material to the backing plate, however, there methods usually only intrude less than 10% into the actual pad material. The pieces being shown in these images are more than 50% (the groove in the material represents a depth of about 60% of the material thickness) into the material, which is not normal.