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View Full Version : Cross balanced the car..



andyrew
02-26-2009, 03:42 PM
So I put it on scales and the damn thing was perfectly cross balanced.. Only off by fractions of a pound.
However 57% front, 43% rear on ratio.

Came out to 3350 w/ 200lbs in the drivers seat. Seams a little light IMHO, conversion factor might not be quite right on the scales... This was with the spare in the trunk and full interior w/ about 1/2 tank (where I run it at for autox)

I threw 30 lbs in the trunk to simulate me putting a solid metal bar behind the rear bumper and it increased my ratio to 56% front 44% rear. Im considering putting 50lbs on the rear to try and get 55 45.

Any of you serious racers do this?

jrock
02-26-2009, 03:49 PM
Why do that for a mere 2%?

njm23
02-26-2009, 03:54 PM
put your battery in your trunk to start if it isnt already.. I definitely would not ADD weight, would try removing weight up front first before anything..

v1nyd
02-26-2009, 03:57 PM
put your battery in your trunk to start if it isnt already.. I definitely would not ADD weight, would try removing weight up front first before anything..

+1
relocating the battery to the trunk is a great way to start.

andyrew
02-26-2009, 04:10 PM
Why do that for a mere 2%?

2% is a Big difference. Do you race?



Relocating the battery is an option, I'll just have to counter balance the weight.

The battery weighs 30 lbs so put it on the pass side and balance the weight with adding weight to the other side.. That should definitely help.

Not much else I can remove from the front, I might be able to go fiberglass on the bumper but I doubt that will do anything more than a pound or two. I had contemplated a fiberglass hood, but I dont know if thats going to take me out of my class.

White98A4
02-26-2009, 06:01 PM
What class do you run in your car? I dont realy know about fiberglass but carbon fiber would bump you to SM.

Kyle H
02-26-2009, 06:18 PM
I thought you had to be in street modified if you swapped turbos... isn't that a high up class where you can do mostly anything?

White98A4
02-26-2009, 06:43 PM
Yeah I run in that class with my 2000 RS with a 2006 WRX swap. It is pritty open for whatever mods you want to do.

andyrew
02-26-2009, 10:26 PM
What class do you run in your car? I dont realy know about fiberglass but carbon fiber would bump you to SM.

Im in SM-ST, but I know some things could bump me into MOD, a class I DONT want to be involved in... I know I have to run certain interior bits and such in SM, and I really shouldnt be in SM, there are a couple other classes I could force myself into... But im fairly competitive in ST-SM, Only the vette guys have a chance, and thats only because they PAX lower than me.

Kyle H
02-26-2009, 11:14 PM
The vettes PAX lower than an A4?! how does that work...?

andyrew
02-27-2009, 09:12 AM
Super stock vettes (Z06's and newer vettes) pax lower than my SM car, however I run in the street tire class as I am running bridgestone RE-O1R's. There is no way I'd be competitive in street mod with other guys running R tires (That being said Im consistently faster than my dads 944 turbo in SM2, I attribute it to quattro)

White98A4
02-27-2009, 02:33 PM
Im in SM-ST, but I know some things could bump me into MOD, a class I DONT want to be involved in... I know I have to run certain interior bits and such in SM, and I really shouldnt be in SM, there are a couple other classes I could force myself into... But im fairly competitive in ST-SM, Only the vette guys have a chance, and thats only because they PAX lower than me.

Ok then yeah a light weight hood would probably do wonders for your weight on the nose of the car. I know with a trunk you would get bumpped to a Mod class.

andyrew
02-27-2009, 02:49 PM
A light weight hood is definitely in the cards.

Flash
02-28-2009, 09:57 PM
Yeah, cf hood would be good, possibly cf fenders if you can. It depends on how far you want to go, but adding weight is definitely not a good thing. Your suspension looks good, but you may want to look into smaller diameter and lighter wheels, but rays/volks/gramlights are going to be expensive, but I know they've got a wheel that 14 lbs in a 17 IIRC.

If you're hardcore you'd put the rad in the back with ducting like time-attack cars ;)

djwimbo
03-01-2009, 06:37 AM
I pulled 15-16lbs out of my front bumper support when I cut it apart for the FMIC mounting. That's another option. I don't know how much you have trimmed or removed now, but I pulled out ~31" of the entire bumper support.

If you need to shed more weight up front after that, you can drain the washer solvent tank, lighter bumper, C/F hood, seats, the couple insanely heavy interior panels up front, there's a couple other things, but it would depend on the rules/regs as to what's kosher or not.

andyrew
03-02-2009, 10:58 AM
Ya I dont have anything in my water tank, and I removed about 5lbs of bumper support. Im not up for the task of removing that safety item in my daily driver right now :)

Interior will need to stay stock for now, but the hood is a definite option, provided funds.

Im currently racing on my stock 16's wrapped with 225/50 RE01-R's, dont want to go any smaller than that. But they are heavy... I am always keeping my eye open for light weight 16's to replace it with.

Next year the car is going on the diet and getting serious in SM. Im going to look at removing about 300-400 lbs.

Then after a couple of years, im going full out :) tube frame, 2200lbs curb weight goal :)

Always wanted a superlight awd high HP monster...

mike-2ptzero
03-02-2009, 12:05 PM
I pulled 15-16lbs out of my front bumper support when I cut it apart for the FMIC mounting. That's another option. I don't know how much you have trimmed or removed now, but I pulled out ~31" of the entire bumper support.

If you need to shed more weight up front after that, you can drain the washer solvent tank, lighter bumper, C/F hood, seats, the couple insanely heavy interior panels up front, there's a couple other things, but it would depend on the rules/regs as to what's kosher or not.

Was your front bumper support made out of lead or did you just remove 95% of it? I just put my stock bumper that has the back cut off and a few 2" holes removed from the front onto scale, it is right at 12 lbs. Stock B6 bumper support which is about the same size(just different shape) is 20 lbs total.

My slightly cut bumper support with the OEM bumper is just over 20 lbs total and thats with the stock lic plate bracket and frame.

I might pull my S4 bumper off but I dont think cutting more of the support is going to lose more then 5 lbs, maybe 10 if I pull all of it out but I dont want to mount the bumper skin by itself.

belinko
03-02-2009, 12:06 PM
I know that in some cases (driver dependent), Audi race teams were adding anywhere from 35-50lbs into the rear for "better" handling characteristics. It would let the car swing around corners better and equal out the weight distribution as well.

andyrew
03-02-2009, 04:05 PM
I know that in some cases (driver dependent), Audi race teams were adding anywhere from 35-50lbs into the rear for "better" handling characteristics. It would let the car swing around corners better and equal out the weight distribution as well.

Being able to get the rear end around is crucial in autox.. There is nothing worse than power understeer in a tight corner....

Im still thinking I might try it. It'll be completely reversible so its not that big of a deal.

djwimbo
03-02-2009, 05:07 PM
Was your front bumper support made out of lead or did you just remove 95% of it?

My slightly cut bumper support with the OEM bumper is just over 20 lbs total and thats with the stock lic plate bracket and frame.


To be entirely honest I didn't weigh the part I removed, but it felt about like a MK4 front rotor, which has a shipping weight of 15-16lbs.
As far as what's left of my front bumper support, I'd say there's ~12" on either side where the bumper shocks are located.

If/when I have it off again I'll weigh it, but it's definitely on a diet.

UCFQuattroguy
03-03-2009, 05:06 AM
2nd on what Belinko said. I believe 034 Motorsports added just shy of 100lbs in the trunk of their A4 Time Attack car for better turn-in. FWIW I leave the spare in the trunk when I auto-x. Every little bit helps.

Andyrew, when are you going to step up to R-Compounds?

gmx
03-03-2009, 06:32 AM
Aluminum uprights conversion?

How much would that save?

mike-2ptzero
03-03-2009, 08:46 AM
2nd on what Belinko said. I believe 034 Motorsports added just shy of 100lbs in the trunk of their A4 Time Attack car for better turn-in. FWIW I leave the spare in the trunk when I auto-x. Every little bit helps.

Andyrew, when are you going to step up to R-Compounds?

IIRC they strap 130-150 lbs under the trunk for road racing events.

andyrew
03-03-2009, 09:17 AM
2nd on what Belinko said. I believe 034 Motorsports added just shy of 100lbs in the trunk of their A4 Time Attack car for better turn-in. FWIW I leave the spare in the trunk when I auto-x. Every little bit helps.

Andyrew, when are you going to step up to R-Compounds?

When I get out of my street tire class. Currently everyone who rides with me thinks Im running on R compound tires, and I can get 10-20k miles on these tires..

My balance #'s were done with the spare in the trunk.

Now I feel a little more confident on strapping some extra weight to my car...

belinko
03-03-2009, 11:56 AM
DO IT.

let us know how it feels, how much weight you added and take some pics of location of the weights and how you stapped them down.

TIA[drive]