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06-12-2010, 10:10 PM | #1 |
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What to do on Z4M for AutoX
Hey everyone,
I just purchase a 2007 Z4M roadster today and will pick it up Monday. Long story short, I thought I was going to buy one last year but talked myself into the cheaper 2006 350Z roadster, but I have been missing the M engine ever since so I fixed that today. I have been AutoXing the 350 quite a bit, with some time trials also. Just for some background - it has a little understeer from the factory with staggered setup 225/245. Only thing I did was go square 245x4 and it took some out but still has a little, nothing the throttle will not fit. I also ran on Z1 star specs and really liked them. Now I am getting this Z4M and I understand it has quite a bit of understeer stock. What do you suggest to get the car somewhat competitive (the 350Z was really not that competitive but I was generally 2 seconds away from really fast cars (except Z06). I plan to get a second set of wheels to run star specs on for events on the Z4M. What size tire setup will dial out the understeer to make it more neutral. Also I understand I can take out the alignment pins to get a little negative camber in front, but will that be enough? I am not really worried about SCCA classing because I usually run with PCA, BMW, S2000 group, so they have their own classing. I don't want to go too crazy because I really want to do this on the cheap and in a year buy a cheap miata to make as a pure track/autoX only car. I want to keep the Z4M as a comfy daily driver. But I don't think I can stay away from racing for that long so I better run the Z4M. Let me know what you guys think. |
06-13-2010, 02:44 AM | #2 |
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Hey jbh, congrats on the new purchase. I just autox'd mine today for the first time, had a blast, but yes a lot of understeer. Here is a paragraph finnegan email me a few days ago. there is a great link in there that talks about tire set up, etc.
Hopefully this will be a good jumping off point for you: this is the link to the thread mentioned below: http://www.zpost.com/forums/showthread.php?t=367909 Have you seen our "dead tires thread"?It's a pretty good primer on our journeyaround tires, alignment, understeer, etc. The stock setup of the car is way too oriented to understeer due to insufficient front end negative camber. Max you can go, with the pins pulled, is about -1.0. Then it's camber plates or some E36 washer/bolt combos that can dial in more in .5 degree increments. Have the washers on order from Turner (want about -1.5% to balance the -2.0 in the rear), and the CDV (clutch delay valve) delete on the way from Zechausen Racing. (Car, used, had +.01 on the passenger front, damn it sucked at speed....) Hate that CDV--makes me look like I can't drive stick worth a damn every now and then. |
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06-13-2010, 07:59 AM | #3 |
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jdl1pt,
Thanks for the reply, lot of good info but no definitive tire stagger setup. Sounds like the 245/265 would get me close. I am new to the M so what is the CDV? |
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06-13-2010, 10:25 AM | #4 |
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The CDV is a clutch delay valve. Sometime when shifting hard 1st to 2nd it wont allow you into gear and makes a grinding noise. http://www.zpost.com/forums/showthre...&highlight=cdv
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06-13-2010, 11:32 AM | #5 |
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Sorry, wish I could give you more insight. I will tell you that many on here run 255/275's. At the even yesterday, one of the instructors, who was driving a caymman, also has a z4m. He has tracked his z4m a few times. I told him I had 235/265's ready, and his comment was, "next time go with the 245/275 set up, they'll fit." Ultimately, he thought that was a better set up for autox. The other big issue is the camber both front and rear. I understand pulling the pins will only get you so far. to get 1.5 - 2+ you'll need to go with washers or plates. You could probably also get more if you dropped the car a bit, but that's getting pricy.
Lastly, from what I've read here, a strut bar will greatly help turn in. This is probably going to be my first addition. You can pick one up from tischer for about 300. I'm gonna take me car out to a highly respected tire/race shop here in the next few weeks to have the new tires installed and start working on a camber setup. Once I do, I'll report back with their recommendations at that time and let you know what transpired. |
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06-13-2010, 03:30 PM | #6 | ||
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My wife's car (the ///M), stock, before tires/alignment was running close to zero both sides front and plowed for days. With the Star Specs and -1 front, it's much better. But remember stock is much less than -1 front and probably around -1.5 rear if I recall. Car, stock, with pins out in front is now -2 rear, -1 front. Pretty decent for street driving, not aggressive enough for anything else. Quote:
I think pins, washers, plates would be where I'd start. I just ordered the washers (cheap) and we'll see. But, tell you what, if you start with the strut bar, I can start with washers, and we can compare notes! I just wish we could find a nice big open parking lot and set up a mini course with some chalk and have at it! We could so use that kind of practice. I'm glad you autoxd it yesterday rather than doing that drive with us. The drive, while fun, was super challenging and not one where you'd want to discover the unique handling characteristics of this car for the first time. I would not have been happy if I had done that drive without the car control clinic first and a good amount of seat time first. See my PM. Here's a good thread on suspension Rick Hunter pointed me to. I understand that the GC camber plates are a PITA to adjust on the fly, and adjustments are opposite of other plates. An option, to the GCs (which are very good mind you, just have those two things about them we should know about) are the Vorschlag Camber/Caster Plates per Rick, they're just as good or better than GCs at a similar price too. Last edited by Finnegan; 06-13-2010 at 09:08 PM.. |
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06-13-2010, 05:23 PM | #7 |
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As others have said... CAMBER CAMBER CAMBER.
Sucks for autox because you are restricted to A stock IIRC, and thus can't run camber plates which is what the car really needs. Best bet is pulling the pins and shimming the lower bolts. You can also run something like I used to run on my e46 m3 which was 245/255 tire setup to minimize the understeer, and get closer to a square setup.
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06-13-2010, 09:26 PM | #8 | |
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Really though I am not running SCCA events generally at all so it probably does not matter, I was just wondering if the bolts and washers would put me out of A stock. 245/255 sounds interesting, did the car feel pretty neutral or did it turn into more oversteer than understeer? I am looking for pretty neutral, understeer is not as fun. This would just be my event setup, I would go back to the stock understeer tires for daily driving 225/255. Thanks for all the replys - I don't even have the car yet. I pick the car up tomorrow assuming nothing is wrong that I did not see yesterday. It has been a long 2 days waiting. |
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06-13-2010, 10:01 PM | #9 | |
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06-13-2010, 10:30 PM | #10 |
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I ran last autox season with stock conti's add they were pretty miserable and greasy... compared to my previous E36 M3 which had goodyear eagle F1 D3-GS's.
Star Specs on our lemons car seem really grippy thus far and I've enjoyed them in the testing we've done. I'll let you know how they hold up after this weekend and thrashing on them for almost 24 hours In terms of tire widths and playing around with that... I haven't had time to experiment with that on the Z4. But you can certainly induce some idiotic power oversteer if all else fails... LOL. Just watch what tires you chose in terms of the rules and class you are running in (e.g. width's, treadwear, etc)
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06-14-2010, 09:06 PM | #11 | |
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At my current -2.5 I am able to fit 255/35/18 R888s in the front on the stock 18s but It does require a spacer. I use a 15mm spacer because its what I have for my ZCPs but you could really get away with a 10mm or less. The 15mm does look bad ass though and I actually have less rubbing with 15mm spacer and the 255s then I did with the 245 and no spacer. In fact I actually have no rubbing at all with the 255 set up... most likely due to the slightly shorter 255/35/18 tire
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06-15-2010, 01:23 AM | #12 |
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Good to know. Any kind of lowering spring is going to give more negative camber, so like you said, that helped get you to -2.
"Glorified washer set" But yeah, that's what it is alright! I'm shooting for -1.5 or a tad more since this us primarily a street car. We'll see how that runs (and wears on the tires) and continue to adjust from there. |
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06-15-2010, 06:46 AM | #13 |
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Just got the car yesterday, what a huge improvement over the 350Z. So much more refined of a car. It will take me a little bit to get familiar with the car but hopefully I will take it to an event sometime within the next month or so. Lets keep this thread going for you guys who are making adjustments - report back on how it works for track and also how it effects daily street driving.
I will be looking out for some wheels now to use. Anyone need a set of wheels with star specs mounted for a 350Z/Infinity G35 coupe? I noticed in my manual some cars have a data logger, so BMW is watching us and recording data? Any chance it could be used against us for warranty claims if they said it was used for track/autoX. Probably not what they intended. |
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06-15-2010, 06:48 AM | #14 |
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They just had the lemons race by me at Eagles Canyon 2 weeks ago, that looks like a good time.
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06-15-2010, 07:31 AM | #15 |
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Good to hear you got your car and like it. I've had mine for about 2 1/2 months and I feel very comfortable driving it but I refine driving it everyday. This car is a little tricky to get the hang of, between the touchy clutch and the very direct steering, it takes so fine tuning of your driving skill to make it behave exactly how you want it to. I was planning on hitting some local tracks this summer but have been hella busy trying to find a new place on the weekends. There are lots of good track events coming up in our area. Check DFWautoclub.com events section for local DFW action. Hope to see ya around!
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06-16-2010, 12:22 AM | #16 |
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06-16-2010, 07:34 PM | #17 | |
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I have no need for my kit any more so if you want it you are more then welcome to have it for free... you just gotta pay for shipping which shouldn't be much. I would say it was about 0.8-1.0 inch
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06-27-2010, 03:11 PM | #18 |
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Holy understeer!!
I just got back from my first AutoX with my local PCA club. Car is totally stock with stock tires as well. Next event I am putting on my 4 245/45 R18 2/3 used up star specs on my second set of M wheels and then try that out. I could definately tell the stock tires are not as sticky as the star specs. I really thought my braking sucked but I think it was just the low grip of the tires. I am probably going to go from understeer to oversteer but thats ok, I already own the tires so its not like its costing me anything to try it out. I then need to get some negative camber by pullin the pins and getting an alignment, maybe using the washer kit. I did feel like the back end stuck pretty good coming out of corners with throttle. I guess the M differential is a good one. If I had to guage it I would say I was 1.5 to 2 seconds slower on a 45 second course vs the 350Z with the square star specs setup. Hopefully the different tires will bring my times down. Anyone else had a chance to try out any of their changes? |
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06-27-2010, 08:38 PM | #19 |
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Def do the washers. Pulling the pin may not gain you anything as it's very car dependent. Some (including me) could only get about -1 with pulling the pin, but using a washer helped a lot. I'm not sure I'd like a 245 square setup as the rear can get loose with my 275 Star Specs, so 245's would be worse.
Switching out the Conti's for Star Spec's improved my time about 1.3sec on a 60ish second course relative to my class competition, so I really am not a fan of the Conti for trying to be competitive. They help you learn car control as you try to manage your tires, but your not fast.
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06-27-2010, 09:20 PM | #20 | |
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Yes the 245 square setup may be a little overboard but after today I will take loose over tight. I assume your running 245/275 setup? Thanks. |
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06-28-2010, 12:50 AM | #21 | ||
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Just had Skelekitty's ///M aligned and used the Turner bolt kit, and they put the washer kit on before alignment. The prior alignment, barely got to -1.0, with just the washers and before they dialed in changes the camber in front was -1.9. I had them dial things in front to -1.5, and went -1.8 rear. -1.5 compared to -1.0 is very noticeable--the turn-in is so much crisper and sharper it's not even the same car! We'll see how SK likes this, and if she wants more we'll go -2.0. That's as far as I really think we want to go with street settings--but I can see where you'd easily want more (like maybe even -3.0) for autox. I'm pretty sure you can't get that w/o plates though, which would put the car in another class. But I'm impressed with how the .5 change up front really makes a difference! It's so much sharper and responsive! The "stock" setup when we got the car was -.1 up front--which was understeer/plow city. Damn it was bad; going to -1.0 with pins pulled was better; -1.5 is better yet. Alignment: Oh, also had the CDV deleted...wonderful mod. Much easier to modulate and control the clutch and drive smoothly! I highly recommend both mods (Turner washer kit and CDV delete). Quote:
Last edited by Finnegan; 06-28-2010 at 01:50 AM.. |
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06-28-2010, 01:04 AM | #22 | |
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