sheel

I just threw my ASTs on (4100) but have yet to use them... just checked AST USA's website and looks like their having a nice clearance sale to make way for the new dampers...

sillyboybmxer

nice discount.
now do i sell my brand new clubsports

GT Motoring

That price list is from January. They have very little in stock and have to be ordered from Holland. They are available in both steel and aluminum bodies, the later being about a $200 premium, but surely worth it.

Id recommend looking into the double digressive pistons and valving - they will be much closer to the 4150s in terms of ride and performance and you won't have buyers remorse once the 4150s are released mid year next year.

If we can help, please let us know.

Thanks,

Austin
GT Motoring

ndogg

So you are saying you can get a 4100 with aluminum body and the 4150 internals? How will the 4150 be any different that that?

GT Motoring

So you are saying you can get a 4100 with aluminum body and the 4150 internals? How will the 4150 be any different that that?
[/quote]

Essentially that's what I'm saying. You've been able to order the aluminum bodied 4100s for some time now. The double digressive pistons and valving are available as well. Talking with AST on the phone last week, we identified that we could made a few sets of this set up to hold customers over until the 4150 is released. I can't remember if they said they could use the new low drag seals or not.

The new 4150s will have a different top guide design and will only be available in Aluminum and come standard with double digressive pistons and valving as well as low drag seals.

Let us know if you'd be interested in a set of these upgraded 4100s. Price isn't set, but I'll have a better understanding after I talk to them this afternoon.

sheel

Gotcha. I actually have the aluminum 4100s and they're so freaking light compared to stock...

I could use some help with initial adjustment - this is my first attempt at tuning the suspension. Specifically I'm trying to understand where I should set initial ride height, dampening, and alignment specs. If you have any thoughts let me know, here is the car's current configuration:

• Car: AP1
• Tires & Rims: 255 RA1 all around on 17x9 rims
• Camber Adjustment: SBC Camber Kit
• Aero: GTC-200 installed... front undertray+splitter combo on the way, but not sure if i'll have time to install it
• Weight: ~2650 w/o driver, ~2850 w/ driver
• Suspension: AST 4100, 700# F, 650# R
• Corner Balanced: No
• Brakes: Stock Calipers; Compound changes based on what's available, but generally Carbotech XP12 Front, XP16 Rear... or some staggered variation like that
• Sway Bars: Stock; Refreshed sway bar endlinks

Where I need help...

Ride Height:

• I currently have the car set to 13 & 1/16" in the front and 13 & 1/8" in the rear - measured from hub-center to fender
• The spring is directly up against the top hat with this configuration, which is not what i was expecting - am i too high?

Alignment:
I'm thinking the following:

• Camber: [F] -3.5 [R] -3
• Caster: aiming for 6 but one of my bolts is seized
• Toe: 0

Dampening:

• 4 clicks down from full stiff, all around

GT Motoring

Its hard to tell you what you will like the best. Every driver has their own preference on how they like their car. That being said, I can offer information no how my car and customers and friends cars are set up.

By the looks of things, you're trying to build a NASA TTC car maybe?

Alignment -

Camber looks good, I run -3.4 and -3.1 on my car (with a Voltex Type 1 wing, 255mm stands, no front aero).
As for toe, I like how zero toe feels in the front, but the car (to me) is more stable with a little static toe dialed in in the rear. I suggest .2 to .25 degrees total rear toe in.
Caster is more important than I used to think. I had the caster maxed to 8.0 degree before and that was just too much, the car would push the more steering angle you had. Cuonice suggested backing it down so I did. I put it a 5.4 and man, what a revelation. Now, steering feel was minimized, but I can get on the power so early that I dont even care.

Ride Height -

For ride height, I have always measured from the jacking points and usually start with 3.25" all around and then corner balance from there, so it's hard for me to say if your ride height is a good ride height or not. My car is pretty low, but it's fast and I'm used to driving it. Too many times, people over analyze their set up and think roll centers, etc matter a lot. They do matter, but having perfect roll centers is not going to make your car fast. You make your car fast. I think a good driver is going to be fast no matter their set up is.

Brakes -

Unsure of why you are running a more aggressive compound in the rear - I can see this causing some issues. The s2000 has a decent amount of rear bias to it, so if anything, id run softer pads in the rear, or at least the same pads all around. You might have reasons for going with a more aggressive compound in the rear, but every s2000 ive ever driven, help set up, given advice to has never had more aggressive pads in the rear. I can see the rear end being quite interesting on a car set up like that under braking.

Suspension -

Spring rates look good. I run 700/600 and have thought about running a 650 rear to get a little more rotation. I know a lot of other TT guys that run the same set up. The ASTs work really well with those spring rates too. For your spring perch question - Id have to see a picture of it. What length springs are you using? For the dampening, I really can't say what you should run - only you can decide that. I usually start in the center when testing on street tires and tune according to how the car feels. Depending on where the car understeers/oversteers in a turn, I adjust what I think needs to be adjusted.

It's all about seat time, knowing how to adjust your car to get the most out of it with your driving style.

Feel free to pm, email, or call the shop with any questions. I'm happy to help with anything you may need.

Thanks

Austin

GT Motoring
austin@gtmotoring.com
847-466-7463

ndogg

With 255 square, stock sways, and 700/650 I think you may find your car is loose. I'm sure others will chime in on this.

When you say the spring is against the tophat, do you mean that you are at exactly 0" of preload? I would say you are not too high, though. There are many threads on ride height in this forum.

sheel

Austin,

Thanks for your help and detailed input - definitely understand that every driver/car has it's own configuration, just wanted a sanity check on my initial approach and baseline configuration and your input has helped. My rear pads are currently XP16s because that was all i could source at the track last time when I ran out ... i usually have XP10/8, XP12/10 combo... So i'll have the 16s until I finish the pads. I'm not currently competing so that's not a worry right now to me, however I am looking at getting involved with NASA TT.

• As for ride height, I'll compare my jack points to the number you provided.
• For the spring perch question... basically, i adjusted the perches, and now at "droop" when i jack up one side (e.g. front passenger), the spring is right up against the top hat... i was expecting a gap to be there, where tender springs would be used to hold the main spring in.
• I believe I'm using 5.5" hyperco springs in the rear and 6" in the front

-----
just measured height from jack point... I'm at 3.625" in the front and 3.75" in the rear... so pretty good starting point i guess

sheel

Yeah, I was running 255, stock sways before and felt great... now i threw in the ASTs 700/650 and a wing... and will try to dial out alignment.

And yes, i'm basically at 0" preload.. i've tried reading through information on the forums, doing searches, etc.. but having a difficult time understanding where i should start. Most of the posts about ride height i've come across either don't refer to spring rates, or say things like "2 finger gap", or 1" from stock... From what information I've gathered, I think i'm about 1.5" lower than stock or so (I forgot to measure ride height before starting all my work, oops )... I just wasn't expecting 0" between the main spring and top hat - i'm not using a helper/tender spring...