Road Racing and Autocross check list??

[ElusiveIS]

For those who have gone road racing and/or autocross, please share your knowledge with us. A check list.. tips.. anything you can think of.

[ElusiveIS]

Found a few good reads

- http://www.supraforums.com/forum/showthread.php?t=162783

- http://www.supraforums.com/forum/showthread.php?t=169965

[D-cell]

My $.02.....


weight is the enemy, lose as much of it as you can.

the weight you do have, put it as low, as close to the centerline and between the wheelbase as you can.

Move your seat as close to the trans tunnel and as far back as you feel comfortable. Your body is a large chunk of ballast. Extend the steering wheel, move the pedals, whatever it takes.

Safety is paramount, invest in quality SFI or FIA rated products. Not all JDM seats, harnesses, etc carry any third party safety rating, i.e. junk.

Buy some stainless brake lines, Hawk or Carbotech pads, and some good brake fluid. ATE superblue is NOT good brake fluid, it has a low wet boiling point, it stains the master cylinder reservoir, and is nothing more than overpriced piss water. Ford super duty, Valvoline synthetic and Castrol are far superior and cheaper. If you want to lighten your wallet more, Castrol SRF and Motul are excellent as well. Buy small containers of brake fluid. Brake fluid is hydroscopic (absorbs moisture), the moment you break the seal on the container, it begins to absorb moisture from the air (lowers boiling point/wet boiling point). Reduce this risk by buying the smaller containers, they tend to not hang around open, as they get consumed quickly.


Wheels...... something wide, something light, with the correct offset. Sorry, I have no recommendations, I don't race an IS300, but I do work on them extensively. Try to match widths, front to rear. 245 front with a 285 rear is a great recipe for an understeering pig, reguardless of rear roll stiffness. 275 on all four corners would be great for a car that weighs as much as the IS. I like the Toyo RA-1 and the Nitto NT-01's. Great bargain tires that can survive and consistently perform after multiple heat cycles. MOST IMPORTANTLY, get the car corner weighted (requires coilovers), get a proper alignment. Pep Boys is NOT the place, go to a performance shop that has the correct equiptment and understands that factory specs are not what you need. -2 to -2.8 degrees camber on the front, -0.5 to -1.5 in the rear. 0 toe to 1/4" toe out in the front, 1/8" toe IN in the rear. Rear toe is far more crucial than front toe. Toe out in the rear= offtrack excursions. Caster should be +3.5 or more, whatever you can get.
Corner weighting is NOT the equalizing of front to rear weight distribution. It is the equalizing of the crossweights of the car, i.e. LF+RR=x, RF+LR=y, x+y=total vehicle weight, the goal is to have x=1/2 total vehicle weight. This allows for consistent performance in both left and right hand turns, the car behaves the same.

Suspension.... The rear control arms are stamped steel garbage, get them boxed in. The rear subframe is very flexible, stiffen it with braces and good bushings. The rear swaybar is too small, find the largest aftermarket one available. Most front and rear swaybar combo's are designed with understeer in mind. I doubt Hotchkis wants a lawsuit because their swaybars caused your car to severly oversteer due to their design.
As for dampers and springs, do your homework. Eibach, QA1 and Hypercoil make suspension springs, the rest are junk. As for dampers (shocks, struts), Koni makes some mediocre ones, they also make some very nice ones. Truechoice is a company that specializes in properly valved Koni's for racing applications, if you want to spend the coin, they're the way to go. Just because a coilover system is anodized purple, green and has cute Anime characters doesn't make them quality. Buyer beware, do your homework, research and find out about the spring rates offered from these companies, the longevity of the product, and any other information before making a purchase.

I've excluded engine/transmission performance for a reason, the car has enough power to get you around the track. Sign up for a driver school, go learn to drive your car, then worry about making 900 rwhp and bragging about your turbo size and engine management.

['03IntensaBlueBeast]

My $.02.....


weight is the enemy, lose as much of it as you can.

the weight you do have, put it as low, as close to the centerline and between the wheelbase as you can.

Move your seat as close to the trans tunnel and as far back as you feel comfortable. Your body is a large chunk of ballast. Extend the steering wheel, move the pedals, whatever it takes.

Safety is paramount, invest in quality SFI or FIA rated products. Not all JDM seats, harnesses, etc carry any third party safety rating, i.e. junk.

Buy some stainless brake lines, Hawk or Carbotech pads, and some good brake fluid. ATE superblue is NOT good brake fluid, it has a low wet boiling point, it stains the master cylinder reservoir, and is nothing more than overpriced piss water. Ford super duty, Valvoline synthetic and Castrol are far superior and cheaper. If you want to lighten your wallet more, Castrol SRF and Motul are excellent as well. Buy small containers of brake fluid. Brake fluid is hydroscopic (absorbs moisture), the moment you break the seal on the container, it begins to absorb moisture from the air (lowers boiling point/wet boiling point). Reduce this risk by buying the smaller containers, they tend to not hang around open, as they get consumed quickly.


Wheels...... something wide, something light, with the correct offset. Sorry, I have no recommendations, I don't race an IS300, but I do work on them extensively. Try to match widths, front to rear. 245 front with a 285 rear is a great recipe for an understeering pig, reguardless of rear roll stiffness. 275 on all four corners would be great for a car that weighs as much as the IS. I like the Toyo RA-1 and the Nitto NT-01's. Great bargain tires that can survive and consistently perform after multiple heat cycles. MOST IMPORTANTLY, get the car corner weighted (requires coilovers), get a proper alignment. Pep Boys is NOT the place, go to a performance shop that has the correct equiptment and understands that factory specs are not what you need. -2 to -2.8 degrees camber on the front, -0.5 to -1.5 in the rear. 0 toe to 1/4" toe out in the front, 1/8" toe IN in the rear. Rear toe is far more crucial than front toe. Toe out in the rear= offtrack excursions. Caster should be +3.5 or more, whatever you can get.
Corner weighting is NOT the equalizing of front to rear weight distribution. It is the equalizing of the crossweights of the car, i.e. LF+RR=x, RF+LR=y, x+y=total vehicle weight, the goal is to have x=1/2 total vehicle weight. This allows for consistent performance in both left and right hand turns, the car behaves the same.

Suspension.... The rear control arms are stamped steel garbage, get them boxed in. The rear subframe is very flexible, stiffen it with braces and good bushings. The rear swaybar is too small, find the largest aftermarket one available. Most front and rear swaybar combo's are designed with understeer in mind. I doubt Hotchkis wants a lawsuit because their swaybars caused your car to severly oversteer due to their design.
As for dampers and springs, do your homework. Eibach, QA1 and Hypercoil make suspension springs, the rest are junk. As for dampers (shocks, struts), Koni makes some mediocre ones, they also make some very nice ones. Truechoice is a company that specializes in properly valved Koni's for racing applications, if you want to spend the coin, they're the way to go. Just because a coilover system is anodized purple, green and has cute Anime characters doesn't make them quality. Buyer beware, do your homework, research and find out about the spring rates offered from these companies, the longevity of the product, and any other information before making a purchase.

I've excluded engine/transmission performance for a reason, the car has enough power to get you around the track. Sign up for a driver school, go learn to drive your car, then worry about making 900 rwhp and bragging about your turbo size and engine management.

Good info, I definitely have been researching alot of the companies as far as suspension goes.

[ElusiveIS]

Good info, I definitely have been researching alot of the companies as far as suspension goes.

Care to share some of your research? What is available for the IS?

[D-cell]

An addendum on suspension. The rear subframe bushings are very flexible, filling them in or having a shop fill them in with 3M window weld is a must. While the subframe is down, have some small gussetts welded in places where suspension pick-up points exceed 75-80 degrees. The rear diff bushings, either have them filled in with window weld or you could go as far as press the bushings out and replace them with solid billet aluminum. Noise, harness and vibration will result, there is no free lunch. Be weary of homemade heim joints and tubular suspension components. QA1 makes the best heim joints, they will not pound out. Circle dirt late models and outlaws use them exclusively. Tubular suspension components should at the very least be made from a reputable fabrication shop and even then be magnafluxed for integrity. A broken suspension arm can result in death, see Renntech Mercedes for more on that scenario. The front and rear swaybar endlinks are hardly up to the task of increased torsional resistance that a larger bar provides. Upgrade those with QA1 joints or ask a shop like to make some. They need to be high offset chromoly heim joints.
Upgrade to at least the LSD from Lexus, or a TRD unit. Viscous couplings are fine, torsion and helical are great as well, the 2 way units are noisy and clunky. 1.5 way is my recommendation for the clutch-pack style LSD.
Lightweight wheels, lightweight flywheels, and one piece aluminum driveshafts all provide better response and acceleration. Contact your IS tuners for details on these components. Remember, 1 lb saved off rotational mass generally equates to the same as shaving 20 lbs from the car, dependent upon gear ratio. Therefore a lightweight flywheel that saves you 5 lbs is the same as dumping 100 lbs of chassis weight. A wheel that's 6 pounds lighter is the same as 480 lbs weight reduction (6X20X4 wheels), not to mention the added benifit of improved braking, i.e. less weight to stop (lower inertia).

[mikefate]

turboeast does custom rear subframe work. they did custom bushings on my car and bgwillz car. boxed control arms and a few other goodies also help with the cars hiney.