auto cross suspension

[eclipsegst3131]

i have a problem...i plan to race auto cross next year. but am on a very tight budget. i have a 93 tsi awd. i want to get a good suspension system, so could anyone let me know what i should get that would be get. i plan to the shock/springs, and do strut bars and sway bars. what i need is advice for the shock spring combo. i dont have the money to buy elaborate $1000+ systems, im looking to spend no more than $700 really. any advice or help would be awesome.

 

[GreenGSX]

If I only had a $1000 to spend to go autocrossing here's what I'd do...

H&R springs ($220)
KYB AGX Shocks ($360)
ST rear sway bar ($200)
Skip the strut tower bars
Alignment ($100)

For alignment I would slot the front struts and if there isn't enough adjustment in the rear I would either cut/weld the upper rear control arms or get a set on Engels adjustable ($160).

Front camber -2.0 w/ zero toe.
Rear camber -1.5 w/ just a touch of toe out.

Set the front AGX's on 3 and the rears on 1. Use tire pressure to adjust oversteering. For a bit more money Koni's are night and day better than the AGX's but a bit more of a pain to install.

Or....you could just leave the car stock and have just as much fun but with $1000 in your pocket.

Good luck

 

[bjones18]

i have a problem...i plan to race auto cross next year. but am on a very tight budget. i have a 93 tsi awd. im looking to spend no more than $700

Tires, alignment, weight distribution, and set up for neutral un-ovr steer.

I would recommend starting "bone stock" before adding cash. If you haven't been to a high performance driving school, that might also be worth the $$$.

I've had a tremendous amount of fun in a stock little festiva. It was close to neutral, and very predictable. Seat time up to a Lotus Elise and a Lola Sports 2000 are even more fun, but entering/exiting tight corners on a 1-2 gear course, with side slip & yaw can be had with just about any car

 

[jtmcinder]

What class with you be in? DS, STX, ESP, or SM? Your (best) options depend on this.

- Jtoby

 

[eclipsegst3131]

well im not sure, dont really know much about the classes though so if you wanted to enlighten me on that, it would be aweesome . thanks in advance.

 

[mavisky]

www.scca.com

You can download the latest version of the rulebook under the headings SOLO and then Cars and Rules.

The class structure is kind of strange and you'll find that something as simple as an mbc will put you all the way up into the street modified class with some seriously prepped cars. I'd advise hitting up the first few stock until you figure out whether you like it or not and just what class you want to run in. SM is probably the most fun, but its alot of money to be competitive. My car is just barely competitive on a local level, at the nationals I'd get smoked by stock class mini coopers.

 

[my_precious]

What if one were to just replace all the stock suspension components with new stock replacements. New stock shocks, bushings etc. For bushings, using Polly urethane substitutes of course. What kind of handling performance could one expect from this? This all costs a lot of money, but how much exactly? An educated guess would be that it costs less than aftermarket performance suspensions. If a fully new stock suspension handles similar to performance suspension, but for half the price, it seems that it would be a wise decision to go in that direction. I've been wondering this myself and hopefully it could help with this thread.

 

[mavisky]

I would look into replacing anything you can that pertains to steering/suspension systems as I'm sure the last 10 or so years have been anything but kind to our cars.

 

[bjones18]

I would recommend stock bushings unless you know what kinematic or compliant property you are trying to change.

I will guarantee you that nobody tested throttle-steer or side-force-compliant-steer when they fitted the urethane bushings for your car. Aftermarket is more of the tone..."hey this fits...what is our profit margin?"

I am not saying aftermarket is bad, (although OEMs use natural rubber for improved durability) but swaping parts without reason or direction is expensive and can lead to other problems.

You would not believe what OEMs & suppliers go through for a simple bushing. Use the expertise of the guy who designed that part, until you are confident you know what & how to improve it.

A fool and his money will soon part...(buying parts :^)

 

[jtmcinder]

I would recommend stock bushings unless you know what kinematic or compliant property you are trying to change.

Cars have mass. Kinematics is worthless.

More seriously, what we want are cars that respond quickly and don't lose camber due to bushing squish. We also want to get rid of the non-linear, underdamped effects of OE bushings.

What I find amusing are cars with STBs and stock bushings and crappy street tires.

- Jtoby

ps. the reason the OE bushings are the way they are is to eliminate the need for yearly lubrication; the Great Unwashed can't be trusted to do this

 

[mavisky]

What I find amusing are cars with STBs and stock bushings and crappy street tires.

- Jtoby

I've got stb's, good tires, but stock bushings. Working on that though, even though I don't want to, not much more annoying than removing 14 year old bushings.

 

[zephyr_8]

I used to run a stock 1g n/t fwd and had a ton of fun with it. Then a slightly modified 1g awd and had more fun. Eventually got what i have now(lots and lots of welding later) its a fsp car running crap shocks, crap springs, crap bushings, decent tires....and I am having a ton of fun. Learn to drive first (i used to run 125cc Karts) and no matter what your in you'll have fun. I even ran a Blazer once and had a ball .

For the money, decent tires are the best mod in my opinion. After that, play with tire pressures. Play with them alot. I had a horribly understeering pig one day(on who knows what pressures, i hadn't checked them in a while ), and the next i changed the pressures to 45 front and 47 rear and it was very neutral. I was very happy.

My opinion is if you have 1000 bucks to spend on autocrossing, keep as much as possible of the money in your pocket and run the car as it is. You'll learn alot and when you decide to spend money, you'll know the car and what you want out of it. Different people like different setups.

 

[eclipsegst3131]

well either way i'll be at least getting the kyb agx's and h&r springs with some nice tires by spring time. i want the car to handle more aggressive and better, i like to whip around on backroads and sometimes on the streets. and i dont like the lifted look of dsm's .

 

[speedy13]

yeah thats a good setup for starters.I'm gonna go with teins and agx's next year as well.I can't stand my 4X4 Rubicon Talon.

 

[bjones18]

Cars have mass. Kinematics is worthless.

In 10 years of designing suspensions (two in mass production, another on the way) I have found suspension kinematics to be very important; compliances are not direct functions of mass, but rather forces transimitted to the body from the contact patch; link location bushing stiffness & orientation are more important than vehicle mass. I have driven vehicles back to back with doubled rear lateral bushing stiffness... in one instance, providing little to no effect. Is this always the case? no. BUT double your rear camber gain and you will notice an effect (unless the spring is shorted out).

More seriously, what we want are cars that respond quickly and don't lose camber due to bushing squish. We also want to get rid of the non-linear, underdamped effects of OE bushings.

Camber compliance can be an issue, strut bending will be the largest contributor on 1Gs. 2G long spindles will have good camber stiffness, the bearing will probably be the most compliant member in the stack. The stock bushings will be linear during handling loads. During impact events they will enter the non-linear range. Vehicle Dynamic loads are applied at under 1Hz and therfore dependent on static bushing rates. Noise & vibration at higher frequencies 12-300Hz are more dependent on bushing damping (dynamic rates).

What I find amusing are cars with STBs and stock bushings and crappy street tires.

- Jtoby

ps. the reason the OE bushings are the way they are is to eliminate the need for yearly lubrication; the Great Unwashed can't be trusted to do this

Urethane is not as durable as natural rubber for bushings. I have witnessed tests where bushings were compounded with urethane & rubber (for that snazzy urethane look). Any amount of urethane reduces the durability from natural rubber. The reason our bushings crack is they are too small, leading to tensile stresses in the rubber (rubber preferres compression).

Does anyone have data on camber stiffness before and after bushing substitution?

STB? how about the huge rear-wings on fwd cars?

 

[stirpicult]

save on the suspension. buy a decent helmet so you dont have to borrow or rent, and a decent set of tires.

 

[Zero Bar]

I agree. Tires is one of the most important things on your car for autox. I just finished the season on the Hankook Ventus RS2 and loved them. Lots of lateral grip and they let you know the limits. Excellent in the rain too. Only area I had a complaint was the straight line grip, I easily spun them on launch and from tests I read they're a little lacking in that area, but for the $$$ it's one of the best street tires you can get.
A helmet of your own is a must, on a hot day those loaners are worn by who knows how many sweaty a$$ people.

 

[Nanan]

...

Front camber -2.0 w/ zero toe.
Rear camber -1.5 w/ just a touch of toe out.

---

Toe out on the rear will aid in cornering but it will make your car twitchy as hell in high speeds. If you DD the car then do not go with toe out in the rear unless you never plan on going over 50 mph. I have found that for the rear, 0 to -.05(toe in) toe will give very reactive stearing with out the high speed twitch.

Experiance, tires, and a good alignment will cut your lap times a hell of allot faster then going with $1k suspension mods.

As for strut tower bars, eh the DSM cars are rather solid so they really do not need much for additional bracing but if you really want to get one go ahead. The cheapo $20 Steel bars are just as good for what you need as the 100+ polished aluminum ones.

 

[jtmcinder]

Another reason to avoid toe-out on a daily driver is that it will kill your tires (unless you run very low pressures). But you can probably get away with a sixteenth total out and it will help on 'Honduh courses.'

- Jtoby

 

[my_precious]

what kind of prices could one expect for replacing the FULL stock suspension (maybe not springs, but everything else) vs. a moddified one? My car has been sitting for awhile, i got it over the weekend, but i guess it hasn't been ran for a year. I expect the suspension to be garbage. I have alot of other things I need to replace first, but still, i plan to replace the suspension eventually.

 

[stirpicult]

what kind of prices could one expect for replacing the FULL stock suspension (maybe not springs, but everything else) vs. a moddified one? My car has been sitting for awhile, i got it over the weekend, but i guess it hasn't been ran for a year. I expect the suspension to be garbage. I have alot of other things I need to replace first, but still, i plan to replace the suspension eventually.

what do you mean "FULL" stock suspension? if you don't plan on swapping the springs, then the FULL stock suspension would cost the amount the struts/shocks you get and, if you decide on going with bushing replacements, their price as well.

 

[bjones18]

what kind of prices could one expect for replacing the FULL stock suspension (maybe not springs, but everything else) vs. a moddified one? ..., i plan to replace the suspension eventually.

Too many people want to change everything. Thats how I was when I was 21 yrs old. I wanted to redesign my suspension, change roll center heights, camber gain... etc.

I am now 41 yrs old and have been paid to design chassis for 12 yrs.

If I can teach you anything it is this:

1. learn to drive (Hi perf driving school).
2. Autocross your stock vehicle many times.
3. play with tire pressure, tires, alignment, weight distribution.

After many hours of driving (keep in mind a course is a few minutes) you will gain consistency in your driving skills. THIS IS REQUIRED TO UNDERSTAND THE EFFECTS OF PART SUBSTITUTION.

At this point you may be able to feel how a part substitution has improved or reduced WTF the performance of your car.

Anyway, few people will take this advise; Oh well, the $$$ will help the economy.

 

[eclipsegst3131]

i understand what your saying and everything but theres also my own preference not to have a sky jacked dsm . so im trying to up the performance of my suspension as well as lowering it a bit. i want to take your advise, but i think im just gonna get the kyb agx's and h&r springs only, doubt ill do anything else. well besides tires. how are the bfgoodrich g-force t/a kd tires? heard there pretttty good. any feedback on them?

 

[mavisky]

Are you looking to buy just one set of tires for daily driving and autocrossing? Do you guys ever get really heavy rain or snow where you are? Let me know and I'll help you find a good tire.

 

[my_precious]

OK, when i said "full suspension" i meant everything. I figure springs wont change much over time, but the stock shocks on a 14 year old car are pretty bad i bet, and bushings too. I just want the car to perform like or better than it did from the factory. For now, I'll probably just replace the stock suspension with oem parts from the dealer/ autozone or something. From what i understand from you guys, the stock suspension is plenty efficient for autocross and is better to learn on. I definately want to learn as much as possible. I look at my car as a learning tool. With my lebaron, it was a tool that helped me learn the basics of mechanics. Now i want to get my talon up and running so I can work on my driving skills. I've been thinking I might do ice racing/ rally cross too (money permitting). A buddy of mine, alot better with cars and more knowledgeable about these things than I, told me that I should get the car so it is reliable, and runs right. Something I can trust to drive accross the country. I agree with him. He also told me I should worry about brakes, suspension, etc, rather than the engine first. You can have a powerful engine but when your suspension is crap whats the point? That's what he says and i agree. So, I'm going to fix my engine to get the car running, and then work on brakes and suspension. Then after all that, tires and wheels. I know you guys say tires are probably the most important thing, and I've read that many places, but they cost alot of money, and wear down after awhile (especially at the track). I just want the car in good shape for track use you know? Anyways, I'm sorry if I hijacked this thread, but i think this is a good way to go about things, and as I understand, you guys do too.