318is autocross : questions within

[captain awesome]

So I've decided to try my hand at autocross. I'm going to get my feet wet with my daily driver Elantra GT for the beginning of this season and in the meantime put together my 91 318is for next season if not sooner.

Here's where I need help. I already bought some parts for the suspension before realizing I'm probably going to push myself into a class my car won't remotely be competitive. I have no grand plans to dominate any class, but it makes sense for a purpose built machine and it has to be on a budget.

So far here's my starting point:

H&R race springs
Bilstein sports all around
Also all new rubber bushings etc. all around.

I figured this was a good place to start and I can always swap poly where needed when my driving deficiencies start to fade. With all that said, I don't mind selling off what I got and starting fresh.

Where do I fit in??? What's a good class I could be competitive in if I were to ever develop any skill? BTW I'll be in the SCCA.

[BlackbirdM3]

I'd guess you would fall in one of the Sports Touring classes, SM, STS, STX or one of those. I think you will be surprised at how well the car does, and how much you learn in doing it. I think tire wise as long as you have a treadwear of 200+ you will be in good shape. Go you your local event and ask what class you should run the car, then read the rules for the class.

Will

[captain awesome]

I was thinking STX or STU due to LSD restrictions on other class rules. I would assume STX would be best due to tire size, but I'm still green on a lot of the info. I'll see if I can get any info on the local club forum to confirm. Thanks for the help.

[Mr. Me]

All E30, except M3, fall into STX. I suppose you could bump into STU, but then you're playing with STI and EVO's in an under-powered and under tire'd car. If the car isn't already modded out of street class, play there for a while. Sticky street tires, good brake pads/fluid, and good struts is about all you can do. more seat time is going to be beneficial up front than throwing money at the car. Figure out what you don't like as you progress as a driver and change those items within class rules. Running Street class is going to be the cheapest way to autox as well.

Just the 0.02 from someone who's been autoxing for a while in a number of cars

[thebutterson]

"What's the best class to run in?" is too subjective of a question. There's pro's and cons about each class and you need to figure out what kind of experience you want. Starting with your stock elantra is a great idea though. Get out there, have fun, and talk to people in different classes you're interested in.

I've ran a 325e in STX, a 318ti w/ an S52 in SM, and a BRZ in C Street.

STX is good because it allows you to do most of the things car people want to do to their cars anyways like lowering it, aftermarket wheels, sway bars, exhaust, tune. Its the standard stuff most people on forums are doing.

SM allows you to do engine swaps, turbo, etc, and lots of other crazy mods to your car. But then you have to compete with modified EVO's and you have a large PAX modifier.

Street allows the least amount of modifications and forces you to take all the blame for the slow times. I found that in other classes I was trying to modify my car in between events and would blame my poor times on not having enough tire, or camber, or something. Street was cheaper and easier to run and forced me to just do the best with what I had.

[captain awesome]

I think if all went according to how I was originally planning things, STX would be a good start. Maybe a season or two dialing/upgrading suspension and tires would be sufficient. Eventually I wanted to turbo the m42 which would put me in SM. It's all talk at this point, but I know gradually escalating in stages as my skill level hopefully improves.

[Digitalwave]

Unless you want to go to the nationals or compete in a points series or something, I wouldn't worry about classing that much. You'll likely be in STX until you turbocharge your car. Just go out there and have fun and improve on your driving skills.

[e30if]

I run my 318is in STX, it's really not a competitive car for the class without some serious work. In general I'm about 4 seconds off pace when compared to a properly STX prepped FRS/BRZ. That said I love driving the car, been autocrossing the 318 since it was stuck with Civic's in ST and STS, the e30 has been bounced around 3 or 4 different classes in the last few years. The SCCA doesn't seem to know what to do with this particular generation.

[c0rbin9]

I don't get the point of building a car to conform to the rules of regional competition where the class winner is more determined by how big the class is and individual driving ability. Building to a class only makes sense if you have designs on Nationals, IMO.

[captain awesome]

I've always read that when doing any form of racing to figure out what class the car belongs in and do modifications within those rules. It appears since I probably won't be too competitive with this car to not sweat those details so much.

[TobyB]

Building to a class only makes sense if you want to go out and race competitively against 'like' cars.

Fixed that for ya.

I've 'built' cars for several classes, and have had the most fun when I was racing
against people my own speed, in the same class. It's a real kick to have competition that's competitive And
constrained by the same limits you are.

And yes, if you think you may wish to pursue this farther, just don't do something
hard to reverse that will bump you up 6 classes- like flares, for example.

t

[c0rbin9]

Fixed that for ya.

But if it's regional, its only a valid comparison if the cars you're running against are also built to the class limit, which very often isn't the case. The ST classes in regional auto-x are for the most part full of cars with an exhaust and an aftermarket steering wheel which bumps them up.

SCCA auto-x has good classing, but it only starts to work as a skills comparison tool at the national level.

[captain awesome]

Okay, I've officially signed up for my first autocross this Sunday. Pretty excited and hopefully I can manage to pull off some runs without plowing over a bunch of cones.

As for the continuing efforts on the e30 I have a couple questions that some may be able to weigh in on.

I'm looking at getting a smallcase lsd. In the not too distant future I have boost planned, so I'm picking a gear ratio with that in mind. Is 4.10 going to be too short for 190-200hp range? I'm afraid 3.64 is going to be too tall. I know there were 3.91 ratios available as well. In fact I have an e21 3.91lsd in the garage, but since they don't have the speedo chopper wheel it just doesn't make since to mess with it.

[BlackbirdM3]

Okay, I've officially signed up for my first autocross this Sunday. Pretty excited and hopefully I can manage to pull off some runs without plowing over a bunch of cones.

As for the continuing efforts on the e30 I have a couple questions that some may be able to weigh in on.

I'm looking at getting a smallcase lsd. In the not too distant future I have boost planned, so I'm picking a gear ratio with that in mind. Is 4.10 going to be too short for 190-200hp range? I'm afraid 3.64 is going to be too tall. I know there were 3.91 ratios available as well. In fact I have an e21 3.91lsd in the garage, but since they don't have the speedo chopper wheel it just doesn't make since to mess with it.

Nice. Good luck. Don't worry about clipping a cone or two, it happenes to the best of us. It won't do any damage (unless its a very solid cone) and don't dwell on hitting one while you are on your run. If you do hit one, try and find out where, but I bet you will already know. Walk the course, but do so with the mind set that you are driving the line you are walking. (Walk so that your line is about where you will be sitting as you go through the section driving) Pay less attention about where you are, and more to where you are going. In other words look down track at where you will be in several seconds. Looking ahead is something many people have a hard time doing. Most of all, have fun. Heck, if they have instructors, ask for one to ride along. Most clubs will have an experienced driver willing to jump in with you.

As for the diff, I think a medium case 4.1 should be fine. The E30 M3 came with the 4.1 in all but the EVO versions (they had the close ratio dog leg box and ran a taller rear end.) The 4.1 seems to be a very flexible ratio. I wouldn't go any taller than that unless you have some serious power in the engine. Quick out of the corners is key. (If you are quick into the corner and don't have to slow down much, you will already be quick out. This is part of the beauty of a momentum car.)

Will

[captain awesome]

I was hoping to stay small case to avoid the weight penalty of the medium case. I need to do some more reading on using e36 diffs, but I recall them being the beefiest version of the smallcase made. At this point though I'm sure a standard e30 will do the trick. There's a couple parts yards nearby I'll check out to see if they have any.