Got a street/perf alignment & corner weighting

[No Doubt]

Got a street/performance alignment and had it corner weighted yesterday as i'm going to be running it on a track this Wednesday. Hopefully these specs will work well for street driving as well.

LF 913 lbs (with driver weight )
RF 849 lbs
LR 822 lbs
RR 753 lbs

Total weight with driver + ~1/2 tank fuel = 3337

Alignment specs:

LF Camber = -1.3 RF Camber = -1.3
LF Caster = 7.0 RF Caster = 7.3
LF Toe = 0.04 RF Toe = 0.04

LR Camber = -0.9 RR Camber = -1.0
LR Toe = 0.05 RR Toe = 0.05

Front Cross Camber = 0.1
Front Cross Caster = -0.3
Total Toe (front) = 0.08


Rear Total Toe = 0.09
Rear Thrust Angle = 0.00

Car was initially lowered 5 turns at each corner a couple weeks prior to this alignment and weighing.

He told me he used a bit less Caster in the LF for straighter tracking on our crowned roads. The shop I had this done at is familiar with the Z. They only work on race cars and high performance street cars.

[quikdoc]

No doubt
I hope those weight values were BEFORE the corner weighting!!! You should be within 1 to 5#'s at each corner when done!!! The whole purpose is to equalize the weight at each corner to keep the car flat in the turns so the shocks can do their best job...
FWIW
Doc

[DJWorm]

It looks like you had the car corner WEIGHED but not corner WEIGHTED.

I would run a touch TOE IN on the rear for the track. And either neutral (for the track) or 1/16" Toe OUT each in the front for AutoX.

[CRUZMISL]

Someone please elaborate on this corner weighting thing and who has the capability to do it. It sounds intriguing.

Joe

[ZeeOhSix]

Originally posted by quikdoc
No doubt
I hope those weight values were BEFORE the corner weighting!!! You should be within 1 to 5#'s at each corner when done!!! The whole purpose is to equalize the weight at each corner to keep the car flat in the turns so the shocks can do their best job...
FWIW
Doc

Is it even possible on these cars with the transverse leaf springs? I thought you could only adjust the corner weight bias with adjustable coil-over shocks.

[DJWorm]

The corners can be weighted on a stock C5 by adjusting the spring bolts. When I lowered my car I also corner weighted it to correct the slight imbalance as it comes from the factory

It is easier with coil overs but the principal is the same. Coil overs do enable you to adjust corner weight, ride height and thus side to side bias, front to rear bias and rake all in one or two quick adjustments.

Static corner weights can also be adjusted by weight in the car such as driver, fuel and ballast. That is why it is important to do competition alignments and weighting with the driver (or comparable weight) in the car and usually 1/2 full tank to get a "Neutral" condition. Other methods include moving componants such as battery relocation. Lighter componants and also preload (ballast) to reduce unwanted adverse torque effects.

The dynamic corner weighting is adjusted using bump and rebound of adjustable shocks. You can also effect the front to rear bias by using different composite leaf springs with different spring rates and different tapers. You can see why this would be a very labor intensive and expensive process of changing composite leaf springs, testing and tuning and then changing again. Again that's why coil overs just make it easier.

In classes where you must run the stock springs or spring type (ie. no coil overs) it is some times wise and cheaper to seek out an expert. 3 of the best suspension tuners with a wealth of knowledge and secrets are Chuck and Lance Mallett at Mallett Cars, Ltd. in Berea, Ohio and Danny Popp at McCluskey Chevrolet in Cincinnatti.

www.mallettcars.com

Danny Popp
ASE Cert. Corvette Specialist
McCluskey Chevrolet
www.mccluskey.com
513-679-9470

Interesting story here. I have seen many race cars that add ballast and preload the right rear wheel to deminish unwanted adverse torque by cutting off a third of a weight lifting bar and welding it verticlely over the right rear axel. They can quickly add or remove weight and ballast by using, yes you quessed it, weight lifting weights and the bar lock.

The driver radio's in "I need more weight on my Hard ON!!"

I don't think many F1 teams use this method but I have seen it in NASCAR, ARCA, Trans AM, World Challenge and others.

[quikdoc]

DJW
Good answer, I could not have said it better myself.
Doc

[CRUZMISL]

SO would corner weighting make a difference if I wanted to keep the stock leafs and use the car on the street? I can get pretty crazy in the corners sometimes.

Joe

[mgarfias]

Originally posted by CRUZMISL
SO would corner weighting make a difference if I wanted to keep the stock leafs and use the car on the street? I can get pretty crazy in the corners sometimes.

Joe

Yeah, it keeps the car turning equally left and right. Its definitely a good idea.

[BAD 06]

Would corner weighting actually keep the car off-level in order to generate the required downward force? Example, with the car perfectly level (according to the wheel lips left to right) and say a 1/2" difference between front and rear, the corner weights will be off due to the car not weighing exactly the same amount on all 4 corners (not to mention the CG of the weight). If you were to adjust the springs so that there was equal distribution at all 4 corners, it only makes sense that the car is not going to be level. Does this actually produce better results?

Thanks,

Chad

[alextz]

Guys, Hellooooo?


Your corner weights are :

LF 913 lbs (with driver weight )
RF 849 lbs
LR 822 lbs
RR 753 lbs


so total weight is 3337
total front weight is 1762

front to rear % is 1762/3337=52.08% front to rear.

To corner weight properly, you want the front to rear weight ratio on each side of the car to be the same as the overall front to rear ratio. Doing this will also get you a 50/50 cross weight (note that it is possible to get a 50/50 crossweight but have incorrect side front to rear weight ratios).

so, the total left side weight is 1735
x 52.08%= 916 lbs is whats needed on the left front,
therefore 819 is required on the left rear (you are 3 lbs off, pretty close!)

now the right side total weight is 1602
x 52.08% yields 846 lbs is what you *should* have on the right front, while 756 is what you should have on the right rear

So..... you are only 3 lbs off of being cornerweighted correctly.
The trick is to raise/lower the corners that need it the most. For example, if I wanted more cross weight in the left rear to right front direction, I could raise either the right front or left rear ride height (you actually have a choice.)

Anyway,

so his car is indeed cornerweighted correctly.,


As for alignment,

a positive toe value indicates toe in.
I would not have any toe in on the front,
and would have a fair amount of toe in on the rear.

The Z06's have horrible bump steer in the rear with the crappy suspension geometry (.564 motion ratio in the back). So I would run at least .2 total toe in on the rear (for a racing only vehicle, 3/8 to 1/2" total toe in is appropriate).

Alex

[No Doubt]

Wow, great information! I don't understand a lot of it but it is very informative nonetheless.

I took it to a shop (Speedware Motorsports in Redmond) that specializes in race cars and high performance street cars. They do a lot of SCCA Porsches as well as others and they said they have worked on quite a few Z's too. They only have one tech who works there and I was the only car in the shop at the time. They seemed very knowledgeable and friendly.

You may be interested in knowing that while I was waiting I was checking out a 68 Camaro Z28 in their showroom that is absolutely MINT!, with 13,000 unrestored original miles. Sea Foam green with the black Z28 stripes. They want $40K firm for it. It has all of the original paperwork and receipts, etc. It was gorgeous. Very

In addition I ended up getting one of their harness bars with fire extinguisher mount built in. It's all stainless steel and is very similar to the Brey-Krause but without the truss. Got the Sparco 6 point harnesses with clip-in ends from them as well as a camera mount (Ioport Racing) I did end up having to order the Brey-Krause clip in attachment stuff from LAPD, however.

[quikdoc]

alextz

I'm not convinced you are using the correct front to rear ratio which would invalidate the corner weights as set up.
Unless I'm mistaken the factory spec on the front to rear ratio is 51% front and 49% rear
which would be for his car:
1701 front 1635 rear for a total of 3337

Then use the equation you outlined,,but I could be wrong...lol if I am I'm sure I'll hear about it soon enough...lol
Doc

[No Doubt]

When we hear something good, and that is positive we tend to listen to it and give credence to it. When we hear what we don't want to we tend not to. I like what Alex said Now I am all confused again, Doc.

[quikdoc]

No Doubt

No doubt you are ...pun intended. Sorry IF I'm adding to the confusion...but I've read in more than one source that the F to R ratio is 51 / 49

as you can see it makes a big difference(that 1 %)

I need to know as well as I will be making the same corner wt adjustments to mine in a week or so
BTW if you don't mind saying what did they charge you for the corner weighting?
Doc