? FD alignment specs for 2.5-mile road course on slicks with manual rack ?
 

At the PCA Citrus Feb event at Roebling Road, I ran the Koni Challenge Hoosiers (full racing slicks) in 275/40R18 on all four corners, and I love them.

However, with an AtomicRx manual rack, the steering effort is considerable, but I'm only running negative (-) 1.2-degrees front camber.

I'm thinking about running negative (-) 2 degrees instead up front (currently -1.2), for more grip and easier turn-in.

Does that make sense ?

This is a 90% track car, 10% street use, but she is driven to the track (about 200-300 miles away, with my slicks in my buddies trailer.

Mods below.

:-) neil

Advance Design Coilovers (475 / 265 springs)
Tri-Point front sway Bar
Stock rear sway bar
AtomicRx manual rack
18x10 wheels w/ 275/40R18 Koni Challenge Hoosiers
Racing Brake BBK and rear oversized rotors

You might want to check with Hoosier's recs for that tire.

Seems like alot of times, race tires are built for alot of camber relative to something like a DOT R6 that they know will be going on a street car.

if you're aligning the car to be easier to drive, maybe its worth looking at power steering....

the driver has to last also

I'm running Hoosier R6's (285/30/18) on 18x10.5 CCW's. I have -2.2 camber up front and rear, zero toe and 7 degrees caster. I run a manual rack as well (poor man flavor, pump delete). This is a track only car and the steering input is pretty mellow at speed.

How's the effort in high-speed sweepers ?

In my setup, it is considerable!

:-) neil

How about a larger diameter steering wheel? I don't know what increasing the camber will do to the steering effort, but it will make you faster if you are only at -1.2 now.

Neil,

All joking aside, the steering input is very light once the speed is above 10-15 MPH. Feel free to send me a PM or email if you would like more info.

Guy

i run 3.5 degree with offset top bushings in front, 320 race slicks, power steering highly recommmended. i run a coleman quickener in the shaft which gives a 1.9 lock to lock with easy effort. you are fooling yourself with out powersteering. any pro will tell you that !

i run 2.2 in rear with a 330 slick

wb

The steering effort is fine at normal driving speed, but when going 100+ MPH and pulling 1.2g's in a corner, it requires some medium-heavy effort. In short, the car feels like it just wants to stay going straight (it is not understeering), due to the larger rotational mass (gyroscopic effect?).

Is that just normal with wide sticky slicks on a manual rack car ?

I noticed even the Porsche GT3 cup-cars with similar rubber, although wider in the rear, does have a power-steering pump.

:-) neil

Which ratio did you use, and what's the spline ?

Also, can you post pics ?

Thanks,
:-) neil

FWIW: here's how a BMW did it:

http://www.redpepperracing.com/forum...ded&pid=434157

Neil, How much caster are you running? I noticed that steering felt a bit lighter with less caster. I went from almost 7* to about 5.8*-6*.

Funny. I keep telling people that... :)

One reason the car won't turn may be your spring rates. Your pretty soft in the back. My street/track set up was 550/450. Now full race running 750/650. A stiffer rear will help rotate the rear. ie Make the car more loose. I run 2.25 camber , 5 castor, slight toe out.

Another issue could be a warn out shock. I struggled with steering effort on my car. Once the shocks were rebuilt the improvment was huge.

A larger diamter steering wheel is another good idea.

Interesting thoughts on the castor and spring rates.

I do have a 625/475 pair of springs as well, and I went to the softer setup for more road compliance.

To clarify, it's not that the car won't turn-in, it just takes A LOT of effort to turn the steering wheel during a high-G sweeper, and I think it's due to the HEAVY rotating mass of CCW wheels and Hoosier slicks, and having to fight the gyroscopic effect.

Since I need to control one variable at a time, I'll work with caster and camber first.

Shocks were recently rebuilt, but always worth checking . . .

:-) neil

its 1.5 to 1, 3/4 gm spline. you buy ends and weld them to you steering clolumn, which you cut out the space of the reducer. there are pics on the net on a honda, i have no pics right now

M104-AMG - I have been following this thread for a couple of weeks and thought I would provide my input and experience. I've been using the Hoosier Koni series tires for the past couple of years. Great tire for HDEs and I used to be able to pick them up for $75 a piece. As of late it appears that the supply has diminished and I can't seem to get them anywhere. FYI, the Koni series tire is not a full slick. Its a treaded radial which has been shaved. The compound is similar the Hoosier R6 but possibly a little harder. I cannot compare the R6 apples to apples because I have never owned a set of new Koni series tires, so I am not certain how they perform with no heat cycles.

As for your steering problems... I have used a variety of alignment settings up to 2.5 degrees neg camber in the front and 2.2 degrees in the rear. Approximately 5.5 degrees caster with a little toe-in (0.1 degree) in the front, zero toe in the rear. I am currently running Hoosier R6 295/35/17's in all four corners on CCW 17X10s. Even with the larger tires in the front I am currently running with no power steering and find it to work very well. As a matter of fact, when I connect the power steering I find that I tend to over steer the car in turns due to a lack of proper feel. Keep in mind I only run 20-30 min sessions so fatigue is never really an issue. In a perfect world I would like a little power assist but not as much as the stock power steering system delivers. I have toyed with the idea of utilizing a power steering restrictor valve to dial down the power steering assist but didn't want to open up a new set of problems associated with this modification.

If your vehicle is extremely difficult to steer while your car is moving around a track then it sounds like there could be other problems as mentioned in this thread. I've tried different camber settings and I don't seem to feel much of a difference in steering feel other than more or less grip in the front or rear. Steering input tends to remain fairly constant. Since caster tends to have a larger effect on front end stability then maybe you should start there.

Is there anything special required for installing the Atomic Rex rack?

The only difference between your setup and the other reporting on here is the rack

Do you feel any bind in the rack with the front in the air?

We should begin by asking how much you bench press. I had to run back to my trailer and ice my hand after we shook at VIR jk :lol:

Seriously if you want to go as fast as possible you'll have much better car control with power steering in place. If you'd like to argue that then take your car to a skid pad w/o power steering and then try it with ps and you'll find the ps car will be twice as easy to control. If your upper body is relaxed, your hands at 9 3 or 8 4 as as they should be this car offers tons of steering feel with or w/o power steering only with power steering your inputs will be much faster. I don't use power steering on my current car but I'd be faster if I did.

Our setups are about the same but I use a little less camber 2 front and 1.5 rear. I'm amazed by the camber numbers I'm seeing. Someone mentioned 3 plus with 315s or so. That car must feel like it's turning over at the apex. Typically the wider your tire the less camber required.

Regarding springs I firmly believe you need atleast 600 rear and 700 front springs when running a wide sticky tire and driving the car hard (sliding the car using the whole track and creating slip angles) or you'll eat fenders and wobble around the track. I know I'll get some shit for saying that but I've driven atleast 10 different susp setups under various condition for many laps so my opinion is atleast a strong one. I also like even spring rates front and rear.

I've never had an issue with my Maval 285/30 Hoosier R6 combo. If my arms get tired, it's because I'm death-gripping and need to relax, not because of steering effort. I've driven up to 45 min sessions at Watkins Glen, and I ran out of fuel and brakes before I ran out of arm!

I think ideally, yes, power steering would be better, but it's a trade-off—I thought the stock system was too much assist (maybe I'd feel differently if I autocrossed), and I like the weight loss and simplicity to boot.

i agree about the PS, i did a back to back test with mine way way back when, and it was a trade off between having overboosted steering and concentrating on driving the line. concentrating on turning the wheel and being slow

plus when you hit a bump, the PS setup wont pull your thumbs off!

the springs are a bit of a taste issue, but give or take i think

+1 ......Fritz is right on the money!
 

Regarding springs I firmly believe you need atleast 600 rear and 700 front springs when running a wide sticky tire and driving the car hard (sliding the car using the whole track and creating slip angles) or you'll eat fenders and wobble around the track. I know I'll get some shit for saying that but I've driven atleast 10 different susp setups under various condition for many laps so my opinion is atleast a strong one. .[/QUOTE]

I agree with Niles. I'm running in the 750 -1100 lb range for springs. Tire temps show about -3 camber to be correct as well. This is a track only car though with 450 RWHP and is about as extreme as RacingDrivers.

I'm old school and just look at tire wear, I still don't own a torque wrench :lol:

what size tires are you running?

I've been happy with the Tein Super Rs with the lower spring rates 780 on all four corners.

PS congrats on the wins last Sunday :icon_tup: I have to cheer for the rotaries so go get em Shpnout and Fingerlock :egrin:

Fritz - at our last VIR event I was running 2 degrees on all four corners and at the end of the weekend the tires were showing signs of overheating on the outer shoulder. I will definitley be increasing the neg camber for next event.

For those of you running less than 2 degrees of camber, have you checked tire temps? There are a lot of track rx7s running "pettit" alignment recommendations then there are others who are running more extreme settings (over 2 degrees front and rear). I have just purchased a pyrometer and will be checking my temps during next event. If others have info on tire temps and would like to share, it would be greatly appreciated. If I get good data with mine I would be happy to share my results.

I'm in the process of moving currently. Once I get situated and have a chance to dig my pyrometer out of storage somewhere, I too will be collecting data. I'm -2.5 camber all around currently and I suspect I need to pull a little out in the rear and add a little more to the front. All speculation though, as I don't have any data yet :)

Eventually the goal is to go 11 to 12in wide all around on my car. I already have the wheels, pettit flares, and wide front fenders... now I just need the extra 130rwhp so I can max out the next class up... that should be cheap to do, right? :D