If it doesn't turn out to be cold tires, I guess I could try some alignment changes or may just some R compound tires.

 

I just did the whiteline rear bumpsteer kit (helps eliminate dynamic toe slop changes) and Agency Power rear control arms with hard bushings and my rear is planted like a rock under any track condition.

-Kyle

 

145mph into turn 1 at Summit Point - solid as a rock!
(-1.5 & 0 toe in the rear)

 

you guys dont think that the ABC or brake controller is doing that? I have the same problem sometimes, and thought it may be taking away too much rear bias.

 

I've had it do the dance plenty of times when not in the ABS. I really think it's just a combo of unloading the rear end on cold tires.

 

I agree... now that I think about it, every brake zone is different and I bet some of us are used to the car dancing around and forget how un-nerving it is the first few times.

-Kyle

 

I'm not sure if cold tires have anything to do with it, I kept getting rear squirm on a 25 minute SCCA race session using Goodyear GS-CS tires. I assure you that my tires were very warmed up

I did NOT have this issue when using Carbotech XP12 Fronts, Project Mu Titan Kai rears, but have it with XP12 fronts, XP10 rears.

 

Maybe the track surface is playing a roll as well. I know it's a long shot, but it could be the case. It's really hard to tell. The best way to figure it out is to see if its happening on different tracks.

Also I'm not sure if you have mentioned this, but what do you have your tire pressures set at?

 

Well there you go. It sounds like the XP10's might be too aggressive as rear pads.

 

I have some Porterfield R4S pads that I will swap in midway through the next event to see if it changes anything. I would suspect they are less aggressive than XP10s.

 

I had high speed brake squirm when I had PF95.7 (the one RRE sells) front pads and Hawk HP+ rears. I when switched to Hawk DTC60/70s front and rear and it went away. I recently used Project Mu Level Max 900s in front w/ the DTC60 rears and I didn't get it. I now use PF97 fronts and DTC60 rears and the squirm came back.

 

Jeff wrote: <<I have some Porterfield R4S pads that I will swap in midway through the next event to see if it changes anything. I would suspect they are less aggressive than XP10s. >>

Jeff, I do know the Porterfield R4S Pads are fairly low in the pad torque "spectrum" if ya kow what I mean. However, I don't have any experience with the other pad compound you are running as a point of reference. I assume you will install these in the rear only? I believe it would be worth a shot to make that one change between sessions and see what you think after they "bed in" a bit.

I've run the DTC 70's F and DTC 60 R and found it to be just about perfect. I have run and still like the PFC 01 F and PFC 97R combination too. I believe each of those combinations has a less agressive "torque" pad in the rear, combined with a torquier pad in the front. I believe that the heavier front torque bias of these (and similar) combinations makes for an easier to modulate braking/trailbraking setup. When its "right "you can trailbrake the bejezus out of the car with confidence. you'll be sure to get the rear tires hot & sticky doing that..

Have fun at the next outing!

'Rat

 

To add to the brake pad discussion I was using Ferodo 2500's on the rear. Hawk Blues up front.

 

Yes.... rear only on the R4S....

I'll do a little more testing next Friday hopefully its something easy like pads or cold tires. I had my alignment checked this morning and its pretty much dead on the nuts with zero toe at all four corners.

 

What are your tire pressures? Are you setting it higher in the rear in relation to the front?