STX build for 2014
 

I am really enjoying the local autocross season this year. Before the season started I attended an Evolution school Phase 1 event. I am doing well so far. I have been out PAXing everyone the last two events placing first in PAX at the last two, and second in PAX the first autocross. There are only a few cars that run in my current class (D stock). I have been running faster raw times than most of the cars, even cars in C stock, B stock, STR, STS and STX. There is a porsche turbo in SSM that runs a few seconds faster but still not faster in PAX and he is on fricken huge race slicks. I am running Dunlop ZII street tires. One of the B-stock drivers has a national championship so the club has some good drivers.

Possibly I am having a good case of beginners luck but the Evo school has helped A LOT.

I am looking for advice on modifications to make a quick STX car. Currently I am running the full JCW suspension with the exception of the rear swaybar is the H-sport competition bar. What I am thinking for my STX car.

Current Enkei RPF1 wheels and Dunlop ZII tires
Current JCW Red Springs
Current H-sport competition bar
Koni Sport shocks
Vorshlag camber plates (running -2.5 camber unless I should go more?)

What input do others have? Should I go with a stiffer spring than the JCW springs, or consider going with a good coilover like KW V2 or V3's? It seems like a good shock like the Koni is more important than getting a coilover to lower the car...

Welcome to the STX club!

First you need to decide how serious you want to get with the whole auto-x thing. If you're planning on doing Match Tours, ProSolos, Nationals, etc you're pretty much going to have to ditch everything except for the camber plates and start over. If you're just looking for a fun auto-x setup then you're headed in the right direction.

Just for reference a full-on national level STX build for a mini is about $12k unless you have things you can use from past projects (like seats). So it's not a cheap proposition (like any sport if you want to run at the front).

Did your car come with the e-diff?

Our setup is still pretty basic but does OK regionally. The DC region is a pretty tough place to auto-x. I placed 6th out of 13 at the DC ProSolo and I'm not a particularly talented driver. :lol:

Our Setup:
-TC Kline Double Adjustable Coilovers (basically custom valved Konis) with 350 in/lb spring rates front and rear
-Vorshlag front camber plates
-Alta adjustable endlinks
-H-Sport rear control arms
-Powerflex Control Arm Bushings
-7 lb battery
-235 Star Specs

If you have any questions just ask. We did a lot of testing. Everything from tire pressures to probably 10 different alignments and different ride heights. I think the next step for us is to try and get some more power out of the car.

Thanks for the information. For a serious STX build how important is stripping weight from the car? I mean I know that stripping weight will make big improvements but is everyone else doing it? Do I need to take out the rear seats, switch the front seats to light racing seats. What about power upgrades? I would think that weight and handling is the most important.

It sounds like what needs to be on my list is a good coilover, good camber plates, my current rear swaybar, rear adjustable endlinks and potentially new control arm bushings as well as stripping weight were possible.

You can't remove rear seats in STX. I suggest you get very familiar with the SCCA rulebook. I'll make a few points...

How Important is Stripping Weight:
Very. The mini can't fit as much tire as the other cars in STX. We run a 235 and it pretty much rubs everywhere... or did until everything self-clearanced :lol: Maybe if you got everything perfect and trimmed your plastic arches you could run a 245 but I don't think you'd really gain much.

Is Everyone Else Doing It?
Considering a lot of the cars running at the top of STX are fairly affordable (RX-8, E36 325 and 328, FRS/BRZ) then yeah a lot of them are fairly built to the limit of the rules. And at the national level all of them are pretty well developed. Some cars don't gain much from certain modifications so people don't bother with them. Like aftermarket seats in the S2000. The S2000 seats are already pretty light so people don't bother replacing them.

Power upgrades:
All of the other competitive cars in the class can generate more lateral grip than the mini. They can just fit bigger tires. So the mini needs to out-accelerate them. Fortunately this isn't much of a problem as the typical STX car doesn't make very much power. The exception to this is the 5.0 mustang but on 265s (max tire width in STX) the car is far too heavy. The mini pulls significantly harder out of corners than any of the other STX cars (except for the WRX) and you need to use that to your advantage. When we run smaller courses I'll beat the local competition but when we switch to larger lots I'm a few tenths behind. So yes power matters. It's possibly the one advantage in the mini so you need to use it. Keep in mind your tune can't alter the factory boost tables so you'll have to run a custom tune.

Your future upgrades:
I would just start with getting the suspension sorted. Get some good coils under you with the supporting endlinks/control arms/bushings and get the suspension good and sorted. The car will be an absolute blast to drive and relatively competitive with a good driver.

A quick and dirty list of STX allowed modifications:
--Coilovers/camber plates (note you cannot cut into the sheet metal to get to the adjuster at the top of the rear shock)
--rear control arms. Only one of the two on each side may be replaced. We replaced the lower arm.
--swaybars/endlinks are unrestricted
--wheels/tires. Fenders can be rolled but the outer contour may not be changed. This basically just means you can trim the lip of the plastic fender flare. We haven't done this and can fit a 235 no problems
--Exhaust. Full exhaust including turbo manifold can be replaced. It just has to exit "behind the driver" so if you're making a lightweight exhaust it can dump under the car. This is your opportunity to make more power and shed weight.
--Intake. Intake is unrestricted up until the turbo inlet
--Custom tuning can be done provided it doens't alter the factory boost tables. There are some funny rules around this but I'm too lazy to type it all out. Basically if any allowed modifications happen to increase the boost levels then that's ok. For example what people can do is block off part of the wastegate when installing a downpipe and therefore the ECU can't properly control boost and you get an overboost situation.
--seats. Front seats may be replaced with race seats provided the seat/bracket assembly weighs 25lbs minimum
--differential. You can add a diff
--Lightweight battery may be used. We use a 7lb Deka. Starts with no issues and can sit for a few days
--Lightweight brake rotors/replacement pads. Not sure anybody makes lightweight 2-pc rotors for the JCW brakes. You'd have to get something custom made.

That's most of what I can think of at the moment. Any questions just let me know :thumbsup:

But again... all of this isn't that important as the most critical thing at auto-x is the driver. If anyone can get in your car and drive it faster than you then you still have some work to do. So my recommendation would be to get some good suspension under it and tires and then just drive drive drive.

v10climber - your remarks in this thread are very good and obviously very knowledgeable advice on STX - I'd nominate this thread for a sticky.

My own journey through STX is documented here, for the dining and dancing pleasure of the OP.

Although I did well regionally, my driving was not (and may still not be) of National caliber, although we shall see in September out at the National Finals.

I owned STX in the NER for a couple of years, until Dave Thomas took Jeff Anderson as a co-driver (Jeff is definitely National caliber, and Dave is now getting very close) in the RX8. My other nemesis in the 2012 season was the BMW330ci driven by Derek Sivret and Dave Gott who are also very quick.

Running the fully prepped Works R53 against those two RWD cars left me driving my heart out for 2nds and 3rds, and needing only tenths of a second to break out which did happen once in a while. Ultimately I determined that the time I lost in the first 60' really mattered, as my acceleration off the line would peak at about .45 g and the Mazda and BMW could launch at .7g all damned day and take 3-4 tenths by the time we were all in 2nd gear and on the power band.

It takes a quaife (or equivalent) and a damned good driver to make the Mini a winner in STX, but I think it can be done. I just wasn't quite up to the challenge and so the HS "Justa" is what I am campaigning this year (we're undefeated so far, which is a nice change).

v10climber I dunno how the heck you fit those 235s mate -- I was running an asymmetrical setup with 225 out front and 205 in the rear, which worked quite well. Kudos to you and I wish you all the best in your efforts!


Kind regards,

Charlie

Thanks for the kind words Charlie. The wife and I are hoping to make Solo Nationals this year although it wasn't initially in the plans. We won't be driving the mini unfortunately as STX is running Thursday/Friday and we have to be in Florida for a wedding Thursday night (since we're in the wedding party). The wife has a ride in a BSP M3 and I'm trying to scrounge up a Tues/Wed ride. I have a few friends who are going. I just have to decide of those who don't have a co-driver which car is less likely to be broken right before nats :lol:

Jeff did a good job of stomping everyone at the DC Prosolo this year. I wish I could track down the 60' times from the DC Pro but they don't seem to have them anywhere. I had a best of 2.35 which was possibly the best STX 60' all day. Most of my times were in the low 2.4s which was right up there with the other STX cars. Not bad considering all of them were RWD. The announcers sure get a kick out of someone running a mini in STX. Unfortunately the tires were heat cycled out by the Pro and pretty dead. We did a test n tune the week before and they were scorching hot for a few hours while we did back to back runs on them. We used 7 gallons of water spraying them down. I think that killed them. We didn't even notice till at the pro when we were getting inside wheelspin for the first time ever. That's what I get for bringing 150 run tires to a Pro Solo :razz:

We've been kind of wishy washy on going full tilt into an STX mini build because of all the engine problems we've been having. The dealer has been fantastic to us and never gives us a hard time (even with all the vinyls) but I just don't want to keep having to deal with the timing chain and carbon buildup out of warranty. We've finally got the suspension relatively sorted so I think the next thing will be an OS Giken diff. It's just a lot of money to spend that I can't really sell off if we get rid of the car :confused: I'm trying to find someone to get into the car who can drive it better than I can to see what the car is really capable of in current form. Fortunately the DC region has a pretty stacked talent pool so I can see where I fall compared to everyone else. I'm not sure the car will ever be a winner in STX but it should definitely be up there. I mean hey if an ITR can place 3rd the mini should be able to do better than that. :thumbsup:

That's a darned good 60' time, but I also wish we could find the actual numbers.

Conventional wisdom (here is a sample) suggests that the RWD folks should stomp us FWD folks...

Cheers,

Charlie

Now that may not have been actually 60' in distance but I'm sure it was close. You would think the RWD guys would stomp the mini off the line but it just doesn't really seem to turn out that way. I found the RT/60' for the 2012 DC Pro when Dave Ogburn was running his mini.
http://scca.cdn.racersites.com/prod/...%20RT-60ft.pdf

He and his co-driver were right in the thick of it with regards to 60' times. I mean hey Courtney even won the DC Pro in 2004 against a bunch of WRXs.

I think the light weight really helps the mini get off the line and the low end torque helps it pull through the midrange really well. The mini runs out of steam in the higher RPMs but by then you're done with the straight part of the prosolo course.

So much for my lame rationalizations then! :razz:

Cheers,

Charlie

Hello all, I have a 2007 MCS with the factory LSD, Alta 19mm rear sway, end links, lower control arms. IE fixed camber plates up front. I am looking to run STX in 2015 and want to get coil overs and more camber. I am think KW variant 2's with vorschlag camber plates. Any suggestions on which coil overs I should run.

I have been doing autocross with BMWCCA and HPDE's for 7 years. I hope to do well next at Chicago Regionals.

What's your budget?

HVTs, KW v3s, TC Kline, and ASTs are all good choices depending on your budget and valving desires. Then there is always the spendier stuff like JRZ, Moton, and MCS.

We have the TC Kline doubles although we're no longer running TCK shock valving or spring rates. Depending on the spring rates you want an OTS shock might not even work adequately.

Sent from my Nexus 10 using NAMotoring

I was looking at the KW v3's from WMW are they a lot stiffer than V2's or is it just the amount of adjustability?

The V3s are 2-way adjustable (compression and rebound) while the V2s are single adjustable (primarily rebound). WMW tosses the progressive springs the KWs come with in favor of linear 60mm coilover springs. This is a good thing. Unfortunately Way doesn't publish the spring rates he includes in the setups so I can't say whether they are any good for auto-x or not. I can't imagine they'd be terrible but I'm guessing they are not what I would recommend for auto-x spring rates. You might call him and see if he can sell you just the KW V3s with rates that you want instead of what he normally includes. KW does make the clubsport for the mini which is just a KW v3 with more aggressive valving and stiffer spring rates. Looks like they spec 450lb/in front and rear for the mini which would be a good start and would work very well with a larger RSB. Unfortunately the ride is going to be a little stiff.

Some of this depends on how serious you're going to get with auto-x. If a podium finish at Nationals is your goal then the KWs would not be at the top of my list for multiple reasons.

It is not a DD so I can go stiff.

My goal is to be competitive at regionals and eventually go to nats.

What do ppl run at nationals MOTON? Thats way out of my price range. Thanks for all the help!:thumbsup:

The TC Klines look like a good alternative. I can pick the spring rates as well, but the rear spring rate doesn't go real high. 300-500 up front and 171 or 229 in back. Is this similar to what you ran? They appear to only offer one style of coil overs now. They say they are modified Konis.

HVT's sound amazing, but it doesn't seem like you can buy them.

If the goal is a dedicated Auto-x car than I doubt any of the off the shelf spring rates are going to work out.

Nationals has a variety of shock setups. Mostly depending on how much shock the car needs. Some cars have good geometry and your shocks don't have to generate huge shock forces. If that's the case then stuff like the KW V3s are fine. The FRS that won STX at nats this year was on KW V3s. However there are a lot of high dollar ($1000 per shock!) setups that show up at nationals.


I personally think the TC Kline spring choices are retarded. I run 450f and 600r with the factory sway bars. Craig Wilcox runs the same spring rates but with a rear bar. He's also using 15" wheels which I can't because of the JCW brakes. If I was doing it all again I wouldn't get TC Klines. Wilcox is on the HVTs and he really likes them. Brian Hanchey is no slouch when it comes to shock development. They're not hard to get you just have to pick up a phone and call them. You'll find that's the case with a lot of Auto-x parts. The "good stuff" you get by calling the right people.

I think if I were doing it again I'd go with HVTs with custom spring rates and valving. If that's out of your budget try calling someone like TrueChoice or ProParts USA and talk to them about getting a custom valved set of Koni doubles which is essentially what we have. The TC Kline stuff is just Konis with special TCK valving.

Sent from my Nexus 10 using NAMotoring

Subscribing to this just for reference. :)

V10climber, I think I'm going to be seriously outgunned against you this coming season... lol

What's everybody running for sway bars? I'm running a 22mm rear bar, and stock up front, but it feels like the car would use some more help settling during corner braking....

STX build for 2014
 

On my R56 I run 25.5 hollow bar in the stiffest setting

Well you lucked out. We sold the car (and moved to FL). Mark Drew bought our coilovers/wheels. I took a stab at spring rates when setting his car up because he already had a larger rear bar.

We used to run stock swaybars. Wilcox runs a larger rear bar and the same spring rates we used to run. I really don't know how he keeps that thing pointed in the right direction...

Adding a little bit of toe-in in the rear should help stabilize it under braking.

Pics pics pics! :thumbsup: