Gary R.

Going by what Dan did on my car, in the front... why not give him a call and ask him?

FredC

tough to lock up the fronts on an SC with stock calipers and running R6s....

I also just remembered that one of the very fastest E-class SC racers in the country is running Blacks in the rear...

So who knows...

Sean F

+1 ^^^

Let's hear about your lock up issues

BostonDMD

Sean, if you are referring to me........

At the Glen.... T-1, end of back straight before the Bus Stop and T-8, I have had front lock up in several occasions.......

I am pretty sure it is my driving deficiencies...... but nonetheless........

FredC

Do you have data that shows how you apply the brakes?

BostonDMD

I usually apply the brakes with my right foot.......

Seriuously, I don't have sensors to monitor the brake force applied, but the chart on Traqmate show a quick spike in decelleration in the braking zone......

I might have too much grip on the fronts or I may just go well past the threshold braking limits.....either way, I am tired of occasionally flat spotting my front tires......

Gary R.

With the 930 brakes on your car it's certainly a possibility that you are over-braking and/or not getting off the brakes quickly enough (during the release). If it's happening at the point of release, it's very likely they aren't retracting properly and the 1st thing I would do is rebuild or replace the calipers to be sure it isn't them.. that was the issue with my rear calipers and if this is a new development I would look there.

quickxotica

I'm not familiar with the Glen, but if the lock-up is occuring at the initial braking point, then the track surface may be different in those two locations you mentioned in which case you should try to smooth out the transition from full throttle to full brake. Off throttle, go to 50% braking, let the nose settle, then 100% braking. The delay between 50% & 100% is no more than 1 second in length, but it allows enough weight to transfer to the front tires that lockup is cured. Works for me at a couple of spots on local tracks out here where I would otherwise get lockup (in my old car) or ABS (in my current car).

Good luck.

Sean F

Paolo, it's important to look at your data. When you are locking up tells the story. For example, if you apply an initial pressure level and then actually apply more after the initial pressure it could cause lockup. Or, if you're locking up instantly you probably have gone past threshold. Another thing to check is if it happens when you do your blip for the downshift. It's not uncommon to apply additional brake pressure while doing the blip which can cause lockup.

BostonDMD

Thanks guys, I will have to review my data (with someone that can actually interpret it)......

Lock up never happens when downshifting, but after the initial brake application and instants before releasing completely.......maybe I hold them too long and past threshold......but then again I have to in order to make the turn.......

I will have my front calipers evaluated and then possibly try different pad combinations........ maybe I should start braking sooner?.......

Thanks again for all your inputs.....

FredC

Didn't strike me when i was near you on the track.

tsheehan

You are running sticker /low heat cycle Hoosier tires? and you get front lock up? Tire grip tends to effect front lock up. Old tires will tend to front lock. They have little mechanical grip. This is where fresh tires can change lap times under breaking. If this is happening with new tires both left front and right front sides. I would start with bias if you cant run bias for rules then I would start messing with compounds. But hand of god front initial bite is what you want, Rears is where you tend to get lock up?
Tires can not be taken out of the mix.

Regards
TSheehan

himself

Just an update to this thread. I ran PFC06 with RS-14 this weekend. I had no issues getting the brakes up to temp at close to the same time. The balance in my 996 GT3 was good, but felt a little more front biased as compared to running RS29/RS14, which I prefer anyway. I don't know the stopping power difference between PFC97 and PFC06, but it seems that a little less bite in the front would push the bias to the back-end that some want.

YMMV.

-td

BostonDMD

Thanks for the update, I will try the set up next week.......

Mike Buck

Sorry I am late to respond. This combo let's me run a race pad all 4 corners better. I used to run 97 front and stock rear. Stock pad would burn up too fast I thought, but running 97 all around gave me kinda variable rear lockup. I don't have ABS. 01 appear to wear just as well as 97, just a sharper initial bite.