Yes, at NJMP, and it seems to have been on turn 4 where the crash occurred (or between 4 and 5 - not sure yet). It also appears the mistake leading to the incident probably started in turn 2.

Shuttlegoose, the "light rear" was at its worst going into turn 7 (I think that's the hard left after going under the bridge). It was also there at the end of the straight going into turn 1 but not as bad. I also don't think I was ever going under 60 in those turns. The light rear end was occurring at 100+ under very hard braking.

 

^^^i listened to that guy twice since ive known him...hes been right both times, and one of them was when i did exactly what he just said there. i was suffering the "shaking the hips" badly.


so did you drop a wheel on the outside of 2 and then get out of whack into 3 and 4? its not the easiest complex thats for sure...well at least for me.

i dipped a wheel on the inside dirt heading down to 7...that got sketchy real quick.

 

I had this while braking hard for bus stop at Buttonwillow. I'd have to time the wiggle to set me up for the left turn. While it made me feel like Colin F'n McRae, I knew it was bad. I now have Energy/Perrin all the way around. Those large, front control arm bushings are whack.

 

I can't say for sure yet, and I have no memory of it, but this is the prevailing theory at the moment. I plan to get my hands on the in-car video this weekend.

 

If you enter 3-4 wrong, you'll end up in the wall if you try to save it. Its a common place to crash there. I went off at t4 before. Just go easy off and don't try to save it.

From my experience, if you're on stock aero and rcomp tires and the rear gets light and twitchy under hard breaking, its because there's too much rear brake bias and abs is kicking on in the rear. The rcomp provide more grip, so more weight transfer to the front under braking.

I had to use stoptech street pads in the rear on my RS to keep rear from locking up. After doing abs conversion, I'm still using stoptech street pads in rear, have only done 2 events since abs conversion, so didn't have a chance to try more aggressive rear pads yet. But I'm also runing full aero.

 

you sure its the rear's having to much brake and maybe not enough brake?

 

I've driven a few evos where abs would go out while on track and rear would lock up first, so I would think its too rear bias. The abs system control rear brake bias when its functioning. Where as RS have restrictor pills in the master cylinder to control rear bias.

 

Simple way to test, pull the abs fuse and see if front or rear lock up first.

 

The rear locks up first because of how light the back end gets under hard braking. A wheel with less weight on it will stop/lockup faster than a wheel with more weight on it. I think there is not enough rear bias from factory and that's one of the reasons we all get the tail wag under hard braking.

 

So if the rear gets light under hard braking because of weight transfer, why would it need more rear bias.

 

Because the extreme front bias is what is causing so much weight transfer to the front instead of a more distributed bias, which would stop all portions of the car more equally? That's my understanding, but I do not know the mechanics yet.

 

As I said, from my experience, when ASB malfunction on track, its the rear that locks up first.

Its not really that difficult to experiment. Rear pads are cheap and easy to change. I wanted to put on the dtc60 rear pads I have but car has been down.

 

More rear bias would slow the weight transfer to the front under hard breaking and making the car more stable and predictable. Remeber that a quick weight transfer can be both an advantage and a disadvantage depending on the situation.

I am agree that the rears do lock up first, but because of the not enough bias to the rear.

With anything that we do, at a certain point there is no advantage to it. Experimenting with different brake compunds in the rear will certainly help. Also, something that hasn't been mention yet would be adjusting compression and rebound on the shocks to help as well.

Most times like anything it comes down to preference. I for one like the rear compund to be one step less aggressive than the front compound.

 

Maybe I'm misreading this; I'm going to respond to it as written.

The only way to slow weight transfer is to brake less (in total). So, I guess that I'd have to agree with the upshot of the above, because more rear bias would force you to brake less, which would reduce weight transfer. However, most folks like having the option of braking more, so, if the rears are doing too much of the work and making the tail squirrelly, then moving bias to the front is what should be done.

Again, yes, if you make the entire system worse by moving more bias to the rear on a car that locks the rears first, then this might force the driver to brake much less and that might prevent rear lock-up. But most folks, when faced with a car that locks the rears first, move bias to the front so they can continue to brake hard.

 

I agree with the post above. "Adding rear bias" should be labeled "removing front bias". The nature of these cars, due to weight placement, is the front brakes do most of the work. The only correct way to keep the back end in check while utilizing the front brakes to 100% is with suspension settings, alignment settings, and aero. I understand the thought of making the rear do more work to balance the car, but with the amount of weight over the front end you are just wasting brake efficiency by adding to the light rear that already locks up with the minimal amount of bias it already has. As a non-abs car owner I agree with Hondaguy. I solved my problem (rear lock up) by changing compounds. To steady the rear under high speed braking I would look to the alignment, spring rates, and shock settings before chasing my tail with bias.

*hope I can convey my thoughts on the iPhone lol

Cheers

Craig.