That could have left a mark

[helpme]

This past sunday I was at Thunderhill for a normal track day.

During the last session, I had some wierd pull in the brakes while braking on the back straight on my second to last lap (had to go around once more to get off the track)...

Got off the track and heard some nice metal to metal sounds, great... Here's what was left after I pulled the pads out...

http://iidx.smugmug.com/photos/571624062_EPrA6-X2.jpg
http://iidx.smugmug.com/photos/571623712_GGnYi-X2.jpg

Looks like the pad just chunked off (look at the edge of the bad pad), and it was game over from there. The piston is damaged (SRT-4 brakes are single pot), and will need to be rebuilt. The passenger side set looks just fine, as well as the outside pad on the driver's side (pictured).

The pads had 2 track days on them so far, and had great pad left before the event.

These were Hawk HT-10 race pads, meant for the track. It looks like this might have happened due to the single pot calipers flexing the backing plate, in addition to the HT-10 material crumbling once it gets used hard.

http://forums.bimmerforums.com...owthread.php?p=5118834

 

[zerocool84]

:Q

I've never seen that happen before but it makes sense.

 

[StageLeft]

Skimming that other thread it looks like these pads are garbage.

 

[Squisher]

I've lost the friction material on pads before and this didn't involve any racing.

The last time was on a 3 year old SUV.

 

[BW86]

wow

 

[DivideBYZero]

I wouldn't expect any set of pads to survive three serious track days in a row.

 

[helpme]

Originally posted by: DivideBYZero
I wouldn't expect any set of pads to survive three serious track days in a row.

When I used to use HP+ pads, I would get 6 track days out of them before it was time to replace them. This was actually only the second track day I had used these on, and they had plenty of meat on them before, which is why I was suprised. The other pads looked like they had plenty of material left for a couple more days.

 

[alkalinetaupehat]

Looked at the thread and apparently there's a new line of pads from Hawk which will replace the entire HT series and bring it up to date with better feel etc. so perhaps go with those or move to multi-pot calipers? Sounds like an issue when those pads are used hard with single-piston calipers like you said OP. From that thread it looked like HT-14 and HT-15 were less likely to crumble like your HT-10's did.

 

[helpme]

Originally posted by: alkalinetaupehat
Looked at the thread and apparently there's a new line of pads from Hawk which will replace the entire HT series and bring it up to date with better feel etc. so perhaps go with those or move to multi-pot calipers? Sounds like an issue when those pads are used hard with single-piston calipers like you said OP. From that thread it looked like HT-14 and HT-15 were less likely to crumble like your HT-10's did.

Sadly I can't try the new DTC series since they don't seem to be made for the SRT-4 stock calipers yet. I have the caliper rebuild kits already, so I may rebuild the busted caliper and try another brand of pad before I spend 1,300$ on a wilwood kit. I would try the PFC97s, but they don't come in my size either

I may try the HT-14s, but they probably offer too much torque for the RE-01Rs I use.

Appearantly Carbotech offers their XP10 pads with an extra thick backing plate, so I may try those first before spending big $ on replacement calipers.

 

[Greenman]

Am I missing something here? In both pics one pad is destroyed and one looks to be hardly used. I would expect to find ceased components in the caliper assembly, and most likely a badly warped rotor from the uneven heat.

 

[helpme]

Originally posted by: Greenman
Am I missing something here? In both pics one pad is destroyed and one looks to be hardly used. I would expect to find ceased components in the caliper assembly, and most likely a badly warped rotor from the uneven heat.

The inner pad delaminated, causing the backing plate to make contact with the rotor. I don't think it was because of anything dragging, it may have been due to the reasons in the BMW thread (single piston caliper bent the backing plate of the pad, which caused the pad to fall apart).

The inside of the rotor was scored from the backing plate contact, and the piston was chipped up from the vibration that must have occured when the pad failed.

The brake didn't seem to be dragging when did my pre track day checks, and bled the brakes then. Also, the pads are meant to operate up to 1400F, so heat alone probably was not the problem. The slide pins aren't seized, and the piston easly pressed back into the caliper when I took it apart after.

 

[helpme]

Originally posted by: alkalinetaupehat
Looked at the thread and apparently there's a new line of pads from Hawk which will replace the entire HT series and bring it up to date with better feel etc. so perhaps go with those or move to multi-pot calipers? Sounds like an issue when those pads are used hard with single-piston calipers like you said OP. From that thread it looked like HT-14 and HT-15 were less likely to crumble like your HT-10's did.

It sounds like Carbotech has XP10s with extra thick backing plates for the SRT-4, so I may give those a try instead of paying 1,400$ for new wilwoods first. That way I can still keep my stock wheels for street use. I have two stock brake rebuild kits on the shelf that needed to be put to good use anyway ;.

Sooner or later I'll have to bite the bullet, since you have to pay to play... Another reason why I never tried to increase the power .

 

[helpme]

Hawk got back to me about the pads:

t looks to me like the caliper put enough pressure on the pad to cause it to flex in the middle causing the friction material to break in the middle and then come off the backing plate. I have seen this on a couple of different platforms with different materials, Ours and others. Generally the best way to fix it is to move into an upgraded brake system.

Let me know if you have any other questions. Also the pictures helped a lot.