$%*#$ Performance Friction

[Rick Kirchner]

Wrote performance friction's tech support twice with no reply. Does anyone know the minimum acceptable thickness for a set of their FC pads?

[Mike Scanlan]

I've used them on my FF for a while and replace them when they get down to about 1/3 left. That's when they seem to start showing cracks in the material.

[problemchild]

The USF2000 website has a lot of PF info on it and is a good reference.

[tristancliffe]

I run all pads until they don't have enough material for one more session or meeting. They don't "go off" when they get thin.

[Brakeguy1]

Dear Rick Kirchner,

Not sure why your email did not get through our PFC Tech Line as we've been pretty due diligent with responses. For future references for the readership, please feel to contact me on this site or ddong@pfcbrakes.com; direct phone 803.222.0442

The absolute minimum friction thickness is 2.0mm or 7.0mm including the backing plates. Much of the issue when running the pads too thin is the bulk temperatures of the pads. If you see evidence of oxidation as temperature is migrating through the pads and that oxidation of charred discoloration envelopes the backing plates, regardless of overall thickness, the pads are running too hot. You will start to lose brake efficiency and overall stopping power if you observe that evidence.

The other issue is the pad's bulk temperatures can then easily migrate into the calipers unless the calipers are outfitted with proper heat caps. The current crop of LD20 style calipers that I'm aware of, haven't any provisions for heat caps so replacing pads a little more often is prudent to protect seal and brake fluid integrity.

The current crop of Citation and Piper cars are outfitted with PFC calipers and those calipers do have heat caps and rocket nozzle insulators for heat isolation. Calipers fitted with heat caps then has less issues with high operating temperatures.

As a matter of tuning and monitoring, we would highly recommend the use of the 3 color disc temperature paints at all venues to build data points. The use of temperature sensitive caliper stickers is also a good practice.

A bad practice is team's flipping the pad orientation in an effort to chase pad taper. Pad taper has to be addressed at the caliper's force distribution and the dynamic symmetry of the temperature output profile vs. pad material migration. It all has to work together if you expect the consistency in the brake performance. Replacing pads due to pad taper is far more prudent practice than taking the chance of erratic torque variation and the possible consequences of that erratic behavior while the pads are getting reacquainted with the disc's interface.

Hope that helps

Darrick Dong
PFC Brakes
ddong@pfcbrakes.com;
803.222.8128

[brownslane]

Gotta love rocket nozzle insulators......I don't care if they work or anything....just to say I have them.......

[Steve Demeter]

Dave W runs whatever brand of pads down til they are real thin.

Doing this, it would be wise to make spacers out of old backing plates to keep the pistons in the bore as much as possible for stability.

YMMV

[glenn cooper]

That sounds super flashy!

[Rick Kirchner]

Yeah, I have backing plates all around on this set and I'm probably 1 session from needing 2 in the front. bought new pads But I'd like to stretch these if it makes sense.

Don't know what it is with some of these web based submission systems. I guess businesses like them because it makes it tougher to get spammed, but they seem to not work as well as plain old e-mail.

[DaveW]

Dave W runs whatever brand of pads down til they are real thin.

Doing this, it would be wise to make spacers out of old backing plates to keep the pistons in the bore as much as possible for stability.

YMMV

I definitely use old plates as spacers when the pads are worn enough to allow them - works well for me. They not only keep the pistons deeper in their bores, but provide a small amount of insulation (due to the increased heat path length and holes in the plates) to help keep heat out of the pistons.

[JeffW]

I use PFC pads (93 and 01 cpds) on LD 20 calipers and LD 65s as well. When first fitted I noticed an immediate improvement in braking but also boiled the fluid (of many different types) until a very experienced engineer gave me a bottle of Castrol SRF - no problem now.

However, I do have issues with PFC pads and I'd like some feedback on this. On many occasions I find the pads begin to crack and crumble, and literally separate from the plate - very disconcerting. Its not the first time I have finished a session to find the pads in a caliper literally in pieces.

This happens even on rear calipers - with much less braking pressure applied to them. Do PFC pads need special bedding in?

Any thoughts anyone?

JeffW

[Swift17]

Gotta love rocket nozzle insulators......I don't care if they work or anything....just to say I have them.......

Man, ... approaching turn 3 leading to the long straight, HARD on the brakes then off we go -- LOVE those rocket nozzle insulators, (whew) ... got to get them for the "wow" factor ....


and on a serious note .........

http://www.esterline.com/engineeredm...ilesSpace.aspx

[glenn cooper]

I use PFC pads (93 and 01 cpds) on LD 20 calipers and LD 65s as well. When first fitted I noticed an immediate improvement in braking but also boiled the fluid (of many different types) until a very experienced engineer gave me a bottle of Castrol SRF - no problem now.

However, I do have issues with PFC pads and I'd like some feedback on this. On many occasions I find the pads begin to crack and crumble, and literally separate from the plate - very disconcerting. Its not the first time I have finished a session to find the pads in a caliper literally in pieces.

This happens even on rear calipers - with much less braking pressure applied to them. Do PFC pads need special bedding in?

Any thoughts anyone?

JeffW

Demon on the brakes much?
I've never heard of anyone boiling the fluid in FF/FC/FB or whatever you have those LD calipers on - until now, that is.
You sure something's not really wrong on your car/brake system such as massive drag heating every thing to a dull orange?

[JeffW]

This happened on both S2s Glenn, which may go some way to explain the boiling, but that problem is solved - and there are air vents to the calipers.

However, I'd like to know if anyone has experienced this crumbling problem with the pads. It happens well before the pads get very thin. Maybe someone from PFC can provide some insight.

Thanks,

Jeff

[rickb99]

S2's have something of a history of boiling brake fluids in the past. Not enough air flow without ducting and vents.

[DaveW]

This happened on both S2s Glenn, which may go some way to explain the boiling, but that problem is solved - and there are air vents to the calipers.

However, I'd like to know if anyone has experienced this crumbling problem with the pads. It happens well before the pads get very thin. Maybe someone from PFC can provide some insight.

Thanks,

Jeff

Just a guess, but I'm thinking you are operating the pads above the temperature limit for the compounds. Obviously, they are running hot - otherwise you wouldn't have had the fluid-boiling issues that you solved by very high-temperature-resistant fluid.

Have you measured the temperature at the pads during operation (temperature stickers, paint, etc.)?

[EYERACE]

Boiling which fluid? Please be specific.

I've boiled fluid in my Crossle 32F using DOT 3 - switch to AP 551 and had no problem - later went to AP 600 - again, no problem but I doubt I really needed to go to the 600 stuff.