Upgrade while maintaining stock class

[z3elda]

Let me start by confessing: I know that experience and sound driving advice will do more to improve my times than car upgrades right now. I do need to plan some maintenance and want to make all the reasonable upgrades I can while staying in stock class. I've been reading the rule book and I think I've got it straight, but thought I'd run it by the experts on the forum.

As I understand it, here's the basics of what is allowed...:
- Any DOT tire that fits on stock size rims without modifying the fenders.
- Any brake pad material, but stock type rotors.
- Basic Tune-up parts are unrestricted.
- Lubricants/fluids are unrestricted
- K&N Stock style Air Filter replacement
- Cat-Back exhaust using stock mountings

Here's where the questions come:

-Shocks: What's allowed? I know the mountings have to stay stock, but what about adjustables?

-Front Sway Bar: I can upgrade the bar and bushings/links, but is this going to help or hurt? One BMW forum
seemed to indicate that upgrading only the front swaybar would actually make understeer WORSE. Thoughts?

-Suspension Bushings: Planning to inspect these during other work, but is it correct that I can only use stock (rubber) replacements?

Anything else worth doing that I should consider?

[cr89x]

You have it all about right. Stock class still allows R-Compound (slicks) as long as you maintain factory wheel specs. This means diameter, width, and offset.
Agree with the front sway bar concern. Sometimes they help, sometimes they don't. Adjustable is the way to go, but do some more research on your particular chassis.
Bushings, correct. Aftermarkets will bump you out of Stock.
Spark plugs are allowed to be changed also. With the Air Filter, you can only change, or I believe remove, the filter. The plumbing must remain factory.

[lancer360]

Shocks may be replaced with single or double adjustable shocks, but they must use the factory mounting points, factory springs, and you can't alter the ride height from factory specs. In stock class, shocks usually provide the best improvement next to tires. Exhaust systems might gain you a little bit of power, but it usually is not enough to worry about. Usually the goal with upgrading the exhaust is to shed as much weight as possible. Power only helps you accelerate, less weight helps you accelerate, brake, and turn.

As far as setup, try asking around on the autocross forums and the Z3 forums and find someone who has a well setup stock class Z3. If you are new to autocross, I would recommend staying away from Hoosiers the first year. Get a really good street tire like the Toyo R1R, Dunlop Star Specs, etc. and come play in tire class if you aren't already running in Novice. Good street tires will have a fairly progressive breakaway and give good feedback compared to Hoosiers.

[SteveCouture]

Eric -

Another thing you can do in stock class (not already mentioned) is add 4-point safety belts. You'd be surprised how much easier (and thus faster) it is to drive when you are firmly connected to the vehicle instead of sliding around/propping yourself up with just stock belts.

[lancer360]

Apr 20, 2011 10:30:25 GMT -5 SteveCouture said:

Eric -

Another thing you can do in stock class (not already mentioned) is add 4-point safety belts. You'd be surprised how much easier (and thus faster) it is to drive when you are firmly connected to the vehicle instead of sliding around/propping yourself up with just stock belts.

Great point Steve. If you drive a vehicle that doesn't have very form fitting seats with good thigh and rib bolsters, a harness will make a great improvement. It makes it easier to interpret what the car is doing if you can make yourself "one" with the seat. Sliding around on the seat makes it much tougher for your body to detect the tail trying to step out etc.
If you do have great stock seats, then you may be able to get by with a CG lock which locks the stock seat belt in place.

[z3elda]

Good point on the belts. Thankfully, I'm pretty TIGHT now. Seats are form fitting, and I'm a big fella, and I'm tight on the door and the console. Definitely not moving around alot during runs.... Now.. If I Loose some weight... I might need 'em

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[infernoz28]

I would say shocks and tires are the biggest for most cars. Do some research and see what people are running for a sway bar and how the car reacts to it. It will increase your roll rate thus decreasing lateral grip. But if the car is rolling to the point it is overloading the outside tire or making the car unstable (such as F stock cars) then a bigger front bar will help.

[z3elda]

Thanks for all the feedback guys.

The problem I'm having with research is that most of the Z3 coupes out there are M Coupes, and while similar, they are not the same setup.

I've got a set of basically new Bridgestone Potenza Pole Positions on the way, courtesy of my friend and sponsor.. It's also time for front brakes. So, the current plan is to change tires and get some more aggressive brake pads before the Memorial day event at CMP.

I'll start researching shock options.. Maybe for later in the year - I don't want to make too many changes at one time.

[jbyrd]

Do not.....REPEAT......DO NOT ASK ANYTHING ON Z3 FORUMS.

I will try to find Mark Sipe's setup he used on his Z3 coupe and pass it along.

REPEAT.....you WILL BE MISLEAD by ANYTHING you read on any of the major Z3 Forums.

[jbyrd]

I can't find the Sipe setup anywhere, but I'll keep looking.

What I do remember is Koni Double Adjustable Struts in front with Double Adjustable shocks on rear. I believe these were from TCKR.

Supertrapp muffler.

Lightweight battery.

Truthfully, once you get a set of Hoosiers and wheels, there's not much more to add. It would be best to do all of that before you consider a front swaybar, because you might not even need it.

The afore mentioned items alone can keep you busy for quite some time working on setup.

I would suggest a Traqmate Data System for anyone before beginning setup.

[stealthgtfour]

spend your money on seat time and instruction ie: solo pro or evolution driving schools.
no mod in the world will make you faster i promise. do it you wont regret it.
the loose nut between the seat and the steering wheel usually needs the most tightening.
and I agree with jb, be weary of what you read on the major car forums. here we have but
one goal and thats having fun while going fast. not too much ego on this forum.

[z3elda]

Apr 20, 2011 21:12:36 GMT -5 jbyrd said:

...you WILL BE MISLEAD by ANYTHING you read on any of the major Z3 Forums.

Darned Z3 Drivers - Can't trust any of 'em.

Thanks John!

[SE3P]

Good luck finding sipe's set up John. He has a habit of deleting his build threads So the general public can't copy him.

[infernoz28]

I do have to agree with Mike. The best thing you can do is get seat time. I have been doing this for about 2 years now and am still learning at every event. I would think a completely stock Z3 with a decent set of tires would drive pretty nice. And I agree with chris. If you can be fast and smooth on street tires you will be even faster on race tires. Save the money on tires and put it into seat time.

[z3elda]

Fast, yes. Smooth, -not consistently. With this loose nut behind the wheel- my completely stock Z3 coupe likes to understeer. I'm still finding the limits of the car.

I would auto-cross every weekend if my marriage and my wallet could stand it. I will try to hit a few other events outside CCR this year. Another school is not in the budget this year, but I'm planning on doing the Triad school next year.

As for upgrades:
-Front brakes need to be replaced anyway, so I'm going to use the opportunity to upgrade the pads.
-The set of Potenzas described above are basically free. They should be stickier than what I have now.
-Good shocks are expensive. Thats not in the budget yet either

[cr89x]

Your on the right track Eric. Read this months SportsCar magazine. Great article in Pobst Position about understeer. I need to practice his tip in tight stuff, like the one turn we had Sunday that was more than likely keeping me away from Walter.