Track Brake pad wear....

[Mad Hatter]

My Pagid RST-3 pads wore rather irregularly this time round on the 15" S550 6pot kit..



Any ideas what could be the reason for this wedge wear??? Both sides of the car and more on the inside then the outside pad.

 

[Coz]

Is the backing plate warped or is that an optical illusion?

 

[JDee]

My race car from the early 90s used to wear the pads like that as a matter of course. An engineer I knew who used to rent rides with me in endurance races said it was just a matter of brake torque, caliper motion and lack of piston support that did it. It had big brakes but they were single piston so not a lot of support for the pads. They wore opposite as I recall. I don't see anything like that on this car though.

 

[Norm Peterson]

Looks like either a pad installation or caliper issue. Guide pin wear can cause it, and I suspect that a lazy or sticking piston could also be responsible in calipers having more than one piston per side. I know I've seen uneven pad wear and its causes mentioned in Brake & Front End magazine (an independent repair shop periodical). I'll see if I saved one of their online articles to a Word file.

Meanwhile, the following link is at least consistent with what I remember from the B&FE article.

https://www.knowyourparts.com/technical-resources/brakes-and-brake-components/brake-pad-wear-chart/


Norm

 

[JAJ]

My Pagid RST-3 pads wore rather irregularly this time round on the 15" S550 6pot kit..

View attachment 11197

Any ideas what could be the reason for this wedge wear??? Both sides of the car and more on the inside then the outside pad.

Is the thin edge of the pad the leading or trailing edge? Normally, it would be the leading edge, which is why leading pistons are smaller than trailing pistons.

Two possibilities - first, it could be problems, like sticking pistons, although that's unlikely since it's happening on both sides. More likely is that you're generating enough negative G's that you're getting to the limit of the caliper/knuckle/wheel bearing structure and it's bending a bit. Others who've seen this before can add more insight.

 

[Eric62]

I'd suggest the pads you are using are marginal for the brake temps you create. Wear rate skyrockets past the breakdown temp of the friction material binder and the trailing edge of the pad runs hotter than the front. Inside pads usually run hotter than the outside pad as well unless you have a cooling hose pointed at the caliper. I'd guess mid-way between is running right at the max temp the pad wants. Step up to the next higher temp compound OR add cooling and that taper wear should get better.

 

[Mad Hatter]

Is the backing plate warped or is that an optical illusion?

When I have them off will check again, but I think its the cel camaras distortion.

 

[Norm Peterson]

Don't wait too long (after your personal issues have been resolved, anyway - hope you're feeling better).

The thin end is getting a bit marginal as it is.


Norm

 

[Mad Hatter]

Thanks, feeling much better... looks like I will have some time to sort the car out now..... ...... No races till mid March when the season starts up again for us. Pete gave me a good explantion for the brake pads. New pads on well used discs, the lead edge gets more friction which makes sense. Will see with a new set discs and pads that are in the works anyways.