speedracer33

Okay, let's see if we can work this out so I can figure out what is wrong with my car. Keep in mind that I spun more times this weekend then I have in the last 4 years combined - so the question is - why?

I spun 6 times this weekend. In 5 of the 6 cases, it was while under braking while the car was still relatively cold. In all 5 of those cases, the car suddenly pulled to the left (the rear moving to the right). In that 6th case - My spectacular 360 in turn 9, the car got loose under braking, but I wasn't braking when the rear snapped out. The rear did move in the same direction as the other times though.

Obviously the car being cold was a factor in the spins, in that the lack of grip might have magnified something that would have been a little wiggle, into something big enough to turn the car around. However, something is causing the car to get loose, and I need to figure out what it is.

The car has never done this before, so I'm looking at what is different.

#1) Tires/wheels. New type of tires - Kumho V700s. They seem to be much more temp sensitive than the Toyos that I used to use. They hook up REALLY well when they are hot, but cold - eek! They also are larger than the Toyos, so they might take longer to heat up, especially with a car as light as mine. The new wheels are 14" x 7" Panasports instead of the stock 13" wheels. I guess they could change the turn-in characteristics and in turn have an effect, but I think that's a long shot.

#2) Camber plates and new alignment. I just got adjustable camber plates in the car, but the camber was just set at -2 degree for the rears - hardly an unusual setup. They changed the rear toe set up though, so that could be a part of it.

#3) Rear brake pads. I switched from stock rear brake pads to Carbotechs. I obviously had a lot more rear braking power, and I repeatedly locked up the rears under heavy braking. I don't have a brake bias valve, but I think I should get one - fast!

Could the rears locking up cause the instability that sent me off the track 5 times? Could the left be locking while the right still turns, and as a result, yank me off the track to that side when the tires are cold?

I know I have problems beyond the brakes though, because several drivers who were behind me reported what I felt all weekend - and very nervous car. The rear end was really dancing a lot behind me, not under braking. Both Scott and Karl told me that the rear was all over the place through the uphill esses. Could that be just from the rear toe settings?

One thing I was thinking that could help would be stiffer springs. The ones on their now are really pretty soft. Stiffer springs would reduce the weight transfer to the front under heavy braking, and in turn, keep more weight on the rears to keep them from locking up so easily. It could also reduce the dancing over the bumps, since the springs won't be transferring the weight so much. On the other hand, do I really want stiffer rear springs if I can't keep the rear behind me as it is?

Thoughts?

Matt (or as Corey was calling me, the Tazmanian Devil)

.RJ

#3 Is a contributing factor - carbotechs bite... hard and i like it! But that shouldnt make the car nervous...

#2 Too much rear toe causing the car to become skiddish? My saturn is like that on the highway - its got alot of toe out and it tracks all over the place @ 80mph. Definately both hands on the wheel. A touch of toe in might help stability - seems like that would help more than stiffer springs in the rear, which would increase the car's willingness to rotate around in turns.

-Ryan

4doorH22

Wow you changed wheels, tires, rear suspension geometry and rear braking power while away from the track and only had your instructor sessions to get used to your new setup before the Enduro? Sounds like you make the mistake of adjusting too many variables between track sessions and not having enough seat time to learn the car's new behavior, be it a subtle or drastic change. I thought only I did that.

Ah, that explains my 5 "offs" at VIR in December <--- not driver error, I swear!
(yeah, right)

Warren

I think part of the reason was the cold track. My car was being absolutely evil on sunday. I was sliding all over the place, and scared the crap out of a few people probably. No off course excursions though, and no spins, but my car is really easy to recover from.

I had one totally nutball pass at southbend, that I don't plan on trying again anytime soon. Ever seen the video of the guy driving the yellowbird at the ring? Yeah, I was basically pulling one of those.

One of our drivers in the enduro complained about how his car was handling too. It was also being extremely tail happy (white ITB Golf). Payton's spec miata was all screwed up too, but he took first in class.

I ended up fueling for 3 different cars. Whew. I remember the good ole enduro days when all I had to do was sit in a chair and entertain the driver(s) that were not currently driving.

Warren

Track rat

Check that rear toe first. Then, I'd ditch the aggressive rear brake pads, the rear tires on a FWD car are practically in the air under hard braking anyway. With sticky track tires and aggressive pads up front, the forward weight transfer is even more pronounced. W/O ABS, they're gonna lock real easy. Tire temps are tricky too, FWD cars heat the fronts much more quickly than the rears.

B18CXr

#3 gets my vote

Knestis

The formula is something like...

(polar moment of a CRX * track temp in Feb)/(#2 + #3) = spin factor

Kirk

JeffS

Definitely check the rear toe first.

Dented Rx7

matt i'll go w/ #3, if you remember when we went to cmp last year, i spun off twice having never done that before and i was get rear-lock up all weekend under braking, the difference that weeekend was it was the first time i put hawk blacks in back kinstead of street pads, i took the hawks off for sunday, put the streets back on a presto!! everything was back to normal, i'd say brake bias valve or less aggressive rear pads.

ps. how did you end up, my car broke ,

we lost 4th gear for good 5 laps in, but i still managed to equal my quailyfing times by going 3rd to 5th (although the car would not top 85 mph that way! (normally 100 mph on both straights !

Honda318dx

Rear Toe Dude!! If its toed out, you will be everywhere!!

Hracer

Definitely check the rear toe. It should be close to 0, if not 0. Do not try to run toe out in the rear on a CRX at the track. It could also have been the rears momentarily looking up. A brake bias valve is not a bad idea. I think Scott J. also has rear disks, so he might know a thing or two about that.

Add in the fact that it was cold, and you'll have a few spins in the rex. Since the CRX is so light, it takes a long time to get the rears up to temp. Forcing it by trying to slide the rear around here and there on a warm up lap helps build rear temps faster, but just make sure you don't spin out on the pace lap. (Yup, two years ago I spun out once under yellow going 40 mph in 2nd gear!) My guess is that your stronger rear brakes bias was able to lock up your cold (and not up to maximum grip) rear tires. If I were you, I would give it a try again on a warmer day (after checking the rear toe) and see how the car feels fully warmed up.

The CRX is a tail happy car by nature and those 110 mph esses just make it really obvious (10x more obvious on cold tires). I've made a 360 at my first weekend at VIR at south bend T10 (when someone bet me I couldn't take that flat out.. he was right.) Since then it's been just the usual pick up a few tenths here and there. But the rush you get climbing those esses and flying through south bend is greater than on any other track I've been to. VIR is #1 !


[Modified by Hracer, 11:11 AM 2/18/2002]

speedracer33

Thanks everybody for the replies. Yes, the rear was toed out slightly by my mechanic - something that was never done before. I'm going to have it zeroed out ASAP. I'm also going to try to do the brake bias valve and keep the more aggresive rear pads because for the first time in my life I didn't have any brake fade the entire weekend. Andy from Carbotech could tell you better which pads I'm running in the rear - I don't remember what he sent me, just that they were not supposed to be very aggressive for this very reason. With the stiffer springs to reduce weight transfer, they might be fine. I'll make sure I can get the car back to the way I want it before I think about stiffer springs though. I regress - hopefully I can find a mix with the bias valve so that I don't have fade, yet I'm not locking them up in every braking zone. If not, I'll just go back to the stock pads and deal with the fade. Thanks again guys, I REALLY appreciate it!

Matt

Cementups

I didn't realize you spun that many times. It was nice to see another CRX there especially another DX. I was the guy in your hotel with the blue CRX that had to follow you to get to the track the first day. Good job running in the enduro.

maybe se you next time there.

Ryan

sjasmund

I have rear disks but don't run a bias valve. I talked to Larry at Carbotech a while back and he said it would be useless.

Matt... what were the air and track temps?

Alex is right. It takes a lot of laps or one really hairy warmup lap in a CRX to get any temp at all in the rears. We had a race at Mid-Ohio last year where the track temp was 34 degrees at the start of our race! The race was red flagged on the first lap to clean up all the cars in Turn-1 piloted by drivers who didn't warm up the rears enough. Even in those conditions, once they're warm (at least with Hoosiers), you can push the car enough to keep them that way.

I haven't spun on a warmup lap, but I've come awefully close!

ApexKiller

Matt I ahve not developed the pics yet, but I got the spin in 1 frame by frame. If i remember right, there was slight lock up and it seemd like it was as the car got light over that slight rise in the track in the brake zone at like 200 yards. I will get you some pics ASAP.

speedracer33

Those changes were all done over the winter. I didn't change anything between the practice sessions and the enduro. I had the same problems on Saturday, I just wasn't pushing the car as hard as I was during the race (2:28s on Saturday, 2:27s on Sunday, when it was colder out), so it showed more on Sunday.

Matt

speedracer33

Oh ****. How do I know those are going to end up being a part of the promotional materials for Carlise? Well, just so long as you can see my sponsor's names on the car! LOL!

You remember very right. That is exactly where the car shot off the track. That's why I took out the "100 foot" and the "turn in" markers! I'm actually kind of surprised that VIR hasn't asked me to pay for them. If you hit the ARMCO at the Glen, they not only charge you to fix it, you also have to pay for the paint!!!

Matt

4doorH22

Oh, that was you that took all those down eh?

speedracer33

Yep. Good thing nobody uses those brake markers, huh? I'll tell you though, that felt so..... Gran Turismo! LOL!

Matt

NASACHRIS

Despite your off-road excursions, you still got a trophy!

If someone will tell me how to post a picture, I have a good one of Matt with the trophy girls.......

Laura Cobetto
(Posting under Chris' name!)

MattD@Stoptech

I think Matt almost had one of his eye's popped by the trophy girl...it was a g00d thing he was wearing sunglasses...

grippgoat

I remember someone on the board last year having an incident where they hit the pit wall and cracked. Originally they were told they'd have to pay for it, but the in the end the track's insurance paid for it, or something like that. Maybe VIR has better insurance than the glen.

-Mike

phat-S

I am guessing it is at least in part due to number 3 as well. I just picked up a set of OE rear shoes. I had Carbotech P+ on the rear as well as the front and I felt like I was lighting up a rear tire *every* time I got on the brakes.

T'was good seeing you again Matt - the exhibition (or expedition as I heard a number of times ;-) that's my kinda session) session we got was an absolute blast. Well, until that black teg had to jump in there - j/k - that probably made it more fun :^)

krshultz

Bookler, I'm gonna vote for "the track was ice cold on Sunday." I had a much harder time keeping the car under me on Sunday. Braking for roller coaster was an exercise in "involuntary trailbraking."

ApexKiller

After re-reading my post I must have been stoned earlier with all the misspelling and 200yard not foot marker remark. I will have pics tomorrow for sure I have just been swamped down today.

And to all you ECHC guys. I have pics with all of you and those girls. I also have a crack art dept. at my disposal. What's it worth to each of you to make sure that they stay original? Hmm. who had girl friends other than Corey?