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Hi All,
I'm trying to go through the exercise of finding various parameters on the IS. The goal is to determine the weight transfer to each wheel at a certain grip level (namely 0.9-1.0G, should be spot on with some 225 Azenis). This is somewhat of an exercise I wanted to go through, but it is also something I wanted to look at to help setup the car, ie. tuning the roll resistance Frt to Rr, wheel rates, suspension frequencies, etc.

What I would love to get my hands on are some of Toyota's drawings...but since that'll never happen I was hoping one of you guys may have taken some relatively accurate measurements.

What I need is:
Front Unsprung Weight
Rear Unsprung Weight
All control arm dimensions and their relative positions to the chassis and wheels..I took these measurements but when I dropped them into AutoCAD they didn't quite look right.

Any help or suggestions would be appreciated.

Thanks,
John
 

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Sorry, I'm not the engineering type that could accurately answer your questions, but I can tell you that each stock 17 x 7 wheel weighs 23 lbs.
 

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Re: Suspension Measurements, Unsprung Weights, Sprung Weight

KekeK said:
Hi All,
I'm trying to go through the exercise of finding various parameters on the IS. The goal is to determine the weight transfer to each wheel at a certain grip level (namely 0.9-1.0G, should be spot on with some 225 Azenis). This is somewhat of an exercise I wanted to go through, but it is also something I wanted to look at to help setup the car, ie. tuning the roll resistance Frt to Rr, wheel rates, suspension frequencies, etc.

What I would love to get my hands on are some of Toyota's drawings...but since that'll never happen I was hoping one of you guys may have taken some relatively accurate measurements.

What I need is:
Front Unsprung Weight
Rear Unsprung Weight
All control arm dimensions and their relative positions to the chassis and wheels..I took these measurements but when I dropped them into AutoCAD they didn't quite look right.

Any help or suggestions would be appreciated.

Thanks,
John
I actually did take some rough measurements (within .25 inch accuracy) of the lower control arms (LCA) (from pivot point to center of wheel) as well as measurements of the shock pivot point to LCA to get the effective spring rate (or wheel rate). I do not have access to those #'s though. I'll post them up later when I get back from vacation.

I guess you checked out the Eibach Site for theWheel Rate Formula

I think offhand, the actual spring rate for our suspension design is a little more than half (50-57 percent +/-) of the published static spring rate by manufacturers. I may be a little off since I assumed the ACF (angle correction factor) = 1 for simplicity sake. FYI, I got those TRD Sportivo springs (492# f/ 442# r). I rode in one of my buddies WRX (~290# springs on struts) and the firmness of the ride is fairly close to his (his being more firm).

Good luck...
 
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