I've seen some threads replacing suspension and chassis parts, but no specific autocrossing threads. Did I miss it?


I'm slowly going through the car making sure everything is tight. From what I have read, the panhard bar and lower control arms seem to be the first things that make a big difference. Correct?

I have a set 17x11s With Hoosier A6 tires that I'm measuring for spacers. Should be finished by the end of next week. Replacing the brake lines on this old TA will be next.

For those that have been where I am going, where were your weak spots...besides the noob behind the wheel

 

First things should be sub frame connectors.

 

Hello
I other than SFC's and LCA's and a Adjustable Pan Hard Bar. I would suggest a set of good springs and shocks. But also a adjustable torque arm to allow you to adjust your pinion angle and giving you better fine tuning compatibility. Other than the springs and shocks below is a link to show you what all UMI Performance has to offer!
http://www.umiperformance.com/catalo...=index&cPath=6
If you have any other questions feel free to ask.
Thanks
Brad

 

I'm looking to go autoX myself and I would decide what class you want to run before you install SFCs.

From my research online, simply adding SFCs will bump you out of F stock, STX/u, and ESP. From what I understand you'll have to run in SM which means you'll get killed by the other cars in that class. Considering that last years national champ in ESP was an 88 t/a, I think you can build a very fast car without SFCs (assuming sfcs were still illegal then)

If you have a hard top I would add the t-top/convertable door strikers and adjust them for an interference fit.That's probably not technically legal but I doubt anyone would notice or care at a local level. If you have a t or convertable I would shim them to be sure they are tight.

My plan of action is to decide the class, and then get the biggest and stickiest tires allowed in the class and then work inward, shocks, struts, alignment, springs depend on class. You also have to be careful about adding small things like different steering wheel, seats, etc. According to the rules I have read, this kind of thing can bump you out of certain classes.

disclaimer: this is all from information I've gained through just research online so this may not be entirely accurate. Maybe someone with real world experience can chime in.

 

What if you dont care about class and just want to do timed runs against yourself? Then its ***** to the walls right?

 

 

If that were the case I'd personally rather set it up for open track events than autocross.

 

.

 

We all ran 5 times through the course. My first was 57 seconds, last was just over 50 seconds. So I guess I didn't do too bad Most of the other cars were running 42-46 seconds mostly with experienced drivers.

I had tons of understeer. Front tires are looking a bit rough, but the scrubbing is even across the tread. There wasn't a single other vehicle in my class. I was basically the only dosmetic V8 rwd car there besides one Mustang and a few Corvettes.

 

Well, did you have fun?

 

Yup. Too bad the only limits were my Trans-Am as I know I am the greatest driver in the world

 

I love it. great attitude

The thing about auto x when comparing your vehicle to othes is a thing call PAX indexing. Cars are classified in catagories becasue of wheelbase and track length. A car 4 feet wide and 8 feet long has to attack the cones at a faster milder angle that a car 6 feet wide and 12 feet long. The larger car will hence be slower due to simple physics. You need to comare to other cars of your type.

 

I think that was my main problem. I was racing with smaller cars with equal or more HP then I had. Another SCCA event is near me (60 miles) races on the Sunday's that my local division doesn't and also has another Solo II school on Saturday. Looks like my tire dealer is going to wonder why my tires don't last very long

 

You gotta trust me when I tell you that often more HP equals more problems in autoX. AutoX is mostly about tire heat management. More HP will just make those greasy street tires overheat that much quicker and go away in grip sooner in the duration of the run lap.

Size and weight of the vehicle is what matters. Its all about how that weight is placed in polar weight transistion as well as how that weight is controlled. Thus a heavier car with better chassis weight control can sometimes outperform a lighter weight car with poor chassis weight control.

Tires have EVERYTHING to do with prefomance. This is where the real money is in ANY racing when it comes to a new day. The guy with the new tires on the new day will always have the advantage.

 

This was the course someone just posted up

http://www.youtube.com/watch?v=UqMU_...layer_embedded

My driving wasn't anywhere near that smooth
Many drivers were spinning the rear tires and getting tail happy doing nothing but losing time.

 

The car in that video is a 240sx Nissan s14.

Lets compare your difference.

I will list you first, then him in values.

Vehicle curb weight
3350/2750....You are 500 lbs heavier Same overall height, but you have much more polar AND roll weight to content with controlling the chassis. Lighter objects change direction faster.

wheelbase- 101"/ 99" You are 2" longer in tracking. This means the rear tires will cut the corner closer so you need to take a slightly wider girth in corner entry.

Vehicle length- (this is major)
195"/ 177" This means you are 1 1/2 feet longer than him. What does this mean? This is a total of 3 feet longer you have to clear cones (before and after the cone) to make the same transition. You have to drive further past the cone before you can angle the car towards the next cone and THEN attack the next cone 1 1/2feet sooner than he so your slip angle is greater and thus transistion speed is greatly reduced.

Track width-
72.5"/68" same principal applies as length only laterally. You are 2.5" wider so you have to travel a total of 5" greater distance left to right to clear a cone and then that same 5 more inches laterally to clear the next cone. Your angle of attack to each cone is steeper thus slower cornering speeds in tansistion of slalom.

You will never phsically have a chance in slalom against that car. Do not let it intimidate you, if he thinks he is mr great driver because he's top time of the day, show him this list or have anyone explain to him national autoX PAX indexing for car classes and then indes his pecentage with yours. Its laws of physics. Road courses are not as critical by any means as little autox cone courses. THe larger tracks are much more forgiving and evening of any use in PAX indexing because the larger nature of the racetracks.

http://www.autox4u.com/pax.htm

 

A quick search to see the 240sx stock is DSP PAX indexing, but that car is easily well into SM if not higher with that Turbo boost you hear.

They may be putting him into a fully modified catagory and not "street Mod" for that dramatc alteration.

anyways, letys take his ninimum bump up to SM PAX index

You are FS (PAX index of .807) and then times that by 50 seconds = 40.35 seconds

The mod 240sx is minimnum PAX indexing of .846 x 42 = 35.53
If he is as high PAX as CM he will be PAX indexed to .924 x 42= 38.80

Instead of an 8 second margin, you are now only a 1.5 to 4.8 second margin of his time

Now you see how much closer you really are to him? Laws of physics!!!

 

Excellent. That's what I had assumed all along. I felt as if I was driving a Lincoln Towncar compared to some of the others

With better driving, I think I could have knocked off 2 more seconds

I'm going to another course after I replace swaybar links and bushings. But they didn't have any cars like mine competing.

 

Thats exactly why you PAX index your times compared to others racing that day so you can compare driver to driver.

 

Here are the results. I didn't do too bad for a old worn out car and a noob behind the wheel

*edit* They seem to thing something is wrong with the values.

Final results http://www.kyscca.com/new/index.php?...=118&Itemid=45

Raw time http://www.kyscca.com/new/index.php?...=120&Itemid=45

Pax http://www.kyscca.com/new/index.php?...=119&Itemid=45

 

I can tell you what i did starting out autocrossing a few years back, i like my cars set up and it competes with many smaller cars in my local street tire class. i first had to upgrade front and rear sway bars because my car is a base model, your car already has the biggest sway bar combo you can get 36mm front/24mm rear. then it was koni yellow front and rear struts. i picked up some hankook RS2 245 45 r16 tires they were the only extreme performance summer tire that i could find in a 245 to fit on my 16" rims. they are very sticky for a street tire. i also put a wonder bar on the front end and swapped brakes fluids etc.... I have run this car hard and it handles very well. you can keep up with much smaller vehicles, it just comes down to course design and driver skill. my set up is to keep me in F stock class. I have run faster raw times than guys in mini coopers, and modified mustangs, but in autocross its more the driver that affects your times than the car. ive been served humble pie by a fast driver in clapped out single cam auto neon.

 

Personally I feel PAX is not a very accurate unless all the cars are fully prepared to the class rules. Course design will also skew the PAX results. IMHO PAX was setup to compare fully prepared competitive cars with competitive drivers on a national style course. If you look at results on the SCCA webpage you will see that they don't even post or recognize PAX times. PAX values are set up by a man named Rick Ruth who is a long time autocrosser who just wanted a way to compare times with different classes of cars and it caught on with many of the regions. There are just to many variables that can effect PAX time and the SCCA knows that. Don't believe me then just go to scca.org and look at the solo results, you will not find PAX results anywhere on the main SCCA site. That tells you how much value the SCCA puts into PAX. Sorry about the rant but just wanted to give the facts about PAX.

BTW, just because a car is in a stock class dosen't mean it's stock. We have one car here that used to run in DS and he has more money in shocks and wheels and tires then I have in my complete car. The car is also never driven on the street and trailered to events. Many serious autocrossers put a lot of money into their so called "stock" cars just to be nationally competitive. BTW, he kicks my **** but he has also trophied at the National finals and drives a much smaller car then mine.

 

I'm getting ready to order a few parts, but the lower control arms are a bit confusing. Too many different ones to choose from
Do I really need offset arms if my plan is to use 315 in the rear? Which ends are best for autocrossing?

Everything else seems pretty straight forward.

2" dropped spindles
Factory height springs in the front
2" lowered springs in the rear
Sub-frame connectors, probably from Spohn. I like tubular
Panhard bar
Steering brace
Solid Caster/camber plates
Torque arms seem a bit expensive and I still don't understand what they are doing

I'm debating the purchase A arms. I still need to get the slop out of my steering. I need to yank the steering shaft and replace the rag joint first.

I may as well order everything at the same time to save myself some work. Seems each part compliments the other.

 

You said earlier you had tons of understeer, with 36mm front and 24mm rear

sway bars, understeer should not be bad at all. id work on figuring out why

you are understeering before buying a bunch of new parts. id get polly

bushings for your rear sway bar and see if that helps. what size/brand tires

did you run for your last event? I had a problem with braking while turning

hard, that would lead to massive understeer, took me a couple events to

figure out i need to get my braking done before i turn the steering wheel.

otherwise i would understeer massivley. but that was with a 30/19mm sway

bar combo.

 

I just have the 215/65 Firestone Indy 500s on it for now.
I don't thinK I ever touched the brake, but I may be wrong.
The rear bar links were severly worn as was front and rear body rubbers. They all hot replaced with Moog poly bushings.
I don't want to make drastic changes as my driving probably sucks monkey nuts.

Missed yesterdays event due to rain

 

Are you sure those 17"x11" wheels will fit front and back after the car is lowered 2" and you still have the stock soft springs up front? Those wheels/tires will stick out a good bit in front and likely get sliced up by the fender under hard braking.

Any plans for the brakes?

Try and save swaybar swaps until after the car is built and then use them to fine tune the car to your liking. Swapping the bars now will mean you will be swapping them again later.

Be careful with what you order if you want to stay in a competitive class. As others have said, the subframe connectors alone will bump you up to at least Street Prepared but I would imagine when all is said and done, you will be in Street Modified. Don't expect to ever win in either of those classes unless you are an unbelievably good driver and everyone else in your class is having major issues with their cars. The solid axle rear end we have is holding us back from the rest of the class. If you want to be competitive and still change some stuff on the car, build it for ESP.

My car is in SM but I don't care much about classing anymore. I do it for the fun which is why I started to begin with.

 

I agree, build it for ESP until you get an idea of what you want to race in. Read the rules carefully before buying subframe connectors because too many connection points can quickly throw you in C-prepared...

You can fit 18x10.5's up front with little work, but anything more than 11" wide up front and smaller than 18" diameter is going to get expensive or time consuming. 17x11's will not fit in the front unless you want to start cutting up the front fenders.

Are you on 15" or 16" rims now? I'd just suggest getting some good street rubber and good alignment then go have fun. Shoot for zero toe up front and run the max camber and caster you can get out of the stock strut plates.

I wouldn't suggest spending or modifying much until you know exactly what you want to do with the car, or you may want to jump ship to a cheaper car/class to run. I hate to say it but there is no cheap place for these cars to run competitively.

 

My thoughts on class preperation-

Just some food for thought for everyone. If you are going to race, it is generally for a thrill of speed. With that said, I don;t care if you are the fastest Hundyai or Yugo in stock class, it still sucks driving one. Get my point? Why build a car just to class restrictions for 3 total minuts of glory in some stock class when you can just build your car the best you can afford and go run it at its best potential regardlass of class restrictions even if there is someone faster. Maybe people wnat the copout of saying." well, they had subframe connectors so they should be faster, thats why they beat me"...

not me. I want to go as fast as I can go, its the thrill. Its like drag racing a 15 second car- you can do that every stoplight on the street and not get a speeding ticket... whats the thrill.

 

^^ Well put. Rules ruin fun! haha

 

Very True. Thats why I run in prepared, so I can build the car the way I want it. We have Good drivers in stock classes with very well prepared cars in this region and they beat me all the time. Now ask who has a car that is more fun to drive or watch(From a spectators standpoint) and I can tell you that I do. Last year I even had a ride in a stock 1989 Trans Am and that also seems like a fun car to autocross. Not as stable as my car and also dosen't have the Horsepower as mine(The torque was pretty impressive though). It really seemed to handle very well and was also very tossable, you could actually steer the car with the throttle. I think one prepped to the limit of stock class rules would be a very very fun and fast car to drive, Dare I say funner and faster then my underprepared prepared class car but it's just not my style, I allways have to fiddle with stuff and the stock or even Street Prepared classes are just to limiting for me.

 

.

 

Sounds like prepared is for you if your willing to take a sawzall to your fenders I'm lacking the ***** to do it myself, but I figure if I've got to trailor a car to events I'd just as soon build a half *** A-Mod at least make it easier to tow...

Just remember, the cheapest way to improve your times is more experience driving, even in the rain which your region most likely ran in

 

Sorry if I am just barging in, but SFC's are now legal in STX for those who don't yet know(only bolt in's though).
As far as they go. I would suggest getting the UMI sfc's since they are, in my opinion, some of the best sfc's out there. (fyi, the spohn's go into CP since they have too many mounting points.)

I personally would set it up as an esp car since as it was said earlier that for the past three years, an 88TA has been the national champion beating those pesky Subaru's.

I'm sure you'll be happy with whatever you choose.

here's the current rulebook.
http://scca.com/documents/Solo_Rules...solo_rules.pdf

I couldn't agree more. There's days that I pray for rain. You can learn even more in the rain due to slippery conditions. so if you learn to be fast and smooth in the rain, you can hopefully be fast almost anywhere.

 

[quote=stevo874;4499245], an 88TA has been the national champion beating those pesky Subaru's.[quote]

While that is true, That car is modified to the full extent of SP rules and would easily trophy in CP at nationals. Probably could win a CP championship with more power. That car and driver have many years of development time and he is still making changes on the car that make it faster. He is also an increadible driver.

 

That's telling you how good these cars can be without having to be converted into purpose built race cars that aren't street legal. although he probably rarely if ever drives his car on the street and probably has an easy 15-$20,000 in his car. C Prerared is even bigger money to be competitive.

But all of this means nothing if you are just out there to have fun, and just go to local events.

 

I am sure that Mark has more money into his ESP TA then a vast majority of the CP guys do but he is also faster then a vast majority of the CP guys. Regardless of class you chose it takes a good deal of $ to be nationally competitive in autocross(Which is where I would like to be), I even priced out building up an FS or ESP third gen and it got expensive very quickly. I guess we are back to the saying, Speed costs money, How fast do you want to go.

As Stevo said, build the car the way you want it and go have fun. that is the most important thing.

 

I have a 1984 Trans Am that I autocross. I am in the STX class. I am running a Hotchkis Sport Supension, Tokico 3 way adj gas shocks, 255/40/17 ZR71 rear tires, 225/40/17 ZR1 fronts on Aluminum Torque Thurzt wheels. Easton exhaust with no mods other than that. Cat handles like it is on rails and will usually be about 2 to 5 tenths of a second behind a Subaru WRX or Mini Cooper S. It is a whole bunch of fun. There are probably some engine mods that would make it quicker. It is a stock 305G engine with Cally smog.

Hope this helps,

AL
Spokane
WA