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      09-24-2012, 09:23 AM   #1
Kgolf31
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Can the M be competitive in AS

I've been trying to figure out what I want to do with this car.

I really wanted to get coilovers, but for the sake of my bumping classes and having a harsher ride, I think I'm going to steer away from them. In addition, BSP brings a world of modifications I don't think I'd ever do to this car.

If I upgraded to TCK DAs, removed my shims, got an exhaust and A6s, could this car really compete at nationals? I've been looking at the line-up, and been thinking that it seriously might have a chance (neglect the knucklehead behind the wheel for the moment).

I may have a slightly camber challenged car, but with how stiff it is from factory with DAs, I think it wouldn't be too terrible on transitions and it certainly has the power for corvette type courses.

Here is the AS line-up

AS Audi S4 (10-'11)
AS BMW 1 Series M Coupe ('11) Z4 M Coupe & Roadster ('06-'08)
AS Cadillac XLR
AS Chevrolet "Corvette (C5 chassis, non-Z06)('97-'04)"
AS Ford Mustang Boss 302 (12)
AS Lexus IS F ('08-'11)
AS Lotus Esprit Turbo ('96-'04) Evora (n/a)('10-'11)
AS Mazda RX-7 (Turbo) ('93-'95)
AS Mercedes C 63 AMG ('08-'11)
AS Porsche 911 (996 chassis) ('98-'05) Boxster S ('05-'08) Boxster and Cayman (non-S) ('09-11)
AS Cayman S ('06-'08)

Serious opinions needed. I'm thinking come a year or two if I decide to go this route I would be ready for nationals.

If contingency starts for RT classes, do you think there is a chance there?

Main goal - Become a competitive car in Solo while still having a weekend car and a track car I'd enjoy.
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      09-29-2012, 01:16 PM   #2
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I've been thinking about this hard this past year. Yes I think a Z4M could be competitive with a good driver. However it won't do it in stock trim. Your biggest competition is in the Porsche's & RX7.

You'd have to at minimum get the right wheel tire package (18x8 & 18x9 within 6mm from stock offset. Preferably 6mm Wider Front. Maybe 6mm narrower Rear Or stock to combat understeer)

Tires if in AS & not street tire really have to be Hoosier A6's. Figure 2 set for a full season. You can play with widths & profiles. Figure 245/275 with as low a profile as possible in rear to decrease rolling radius thereby shortening gearing (better acceleration)

Adjustable suspension & its setup is the biggest step to tame the roll / pitch of stock suspension. There's nothing stopping you from having coilovers in AS. You just have to mount lower perch in "same" position as stock & use stock springs. Traditionally that "same" measurement is taken from tire to perch. If you reduce the profile of front tire the lower perch can come down.

IMHO forget Koni's at least not the sport or modified sport sets. If you can find their higher end units they are significantly better.
Again IMHO consider Bilstein PSS10's, they do have clunking issues & potentials for blowing seals. But the single adjustment makes for an easy repeatable setup.
If your more suspension savy consider Penske, Moton Or Quantum.

All that being said, even though a Z4 could be competitive in AS, it'll cost more to build a competitive car and it'll be slower than stepping into BSP.

BSP allows for camber plates, Seat swap, sway bars at both ends plus adjustable end links, Whatever springs you want. etc..

If you want to do nationals, then dive in with both feet now. If you wait a year the rules will change which nulls the playing field. DO it now.

On the RTR class, yeah its fun. But without mods as above you'll be 3-4 seconds off top SS cars. Closest i got this year was 1.5 seconds from a national level driver in a Lotus Elise. For ref I needed to be 0.7 sec off his raw time to beat him in PAX.


Lastly i've been lucky enough to run with a co-driver that competes nationally in her Boxster. It's a base 2.7L with suspension & tire outlined above, that car is 1-2 seconds faster than the z4.
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      09-29-2012, 03:44 PM   #3
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Quote:
Originally Posted by Trev View Post
I've been thinking about this hard this past year. Yes I think a Z4M could be competitive with a good driver. However it won't do it in stock trim. Your biggest competition is in the Porsche's & RX7.

You'd have to at minimum get the right wheel tire package (18x8 & 18x9 within 6mm from stock offset. Preferably 6mm Wider Front. Maybe 6mm narrower Rear Or stock to combat understeer)

Tires if in AS & not street tire really have to be Hoosier A6's. Figure 2 set for a full season. You can play with widths & profiles. Figure 245/275 with as low a profile as possible in rear to decrease rolling radius thereby shortening gearing (better acceleration)

Adjustable suspension & its setup is the biggest step to tame the roll / pitch of stock suspension. There's nothing stopping you from having coilovers in AS. You just have to mount lower perch in "same" position as stock & use stock springs. Traditionally that "same" measurement is taken from tire to perch. If you reduce the profile of front tire the lower perch can come down.

IMHO forget Koni's at least not the sport or modified sport sets. If you can find their higher end units they are significantly better.
Again IMHO consider Bilstein PSS10's, they do have clunking issues & potentials for blowing seals. But the single adjustment makes for an easy repeatable setup.
If your more suspension savy consider Penske, Moton Or Quantum.

All that being said, even though a Z4 could be competitive in AS, it'll cost more to build a competitive car and it'll be slower than stepping into BSP.

BSP allows for camber plates, Seat swap, sway bars at both ends plus adjustable end links, Whatever springs you want. etc..

If you want to do nationals, then dive in with both feet now. If you wait a year the rules will change which nulls the playing field. DO it now.

On the RTR class, yeah its fun. But without mods as above you'll be 3-4 seconds off top SS cars. Closest i got this year was 1.5 seconds from a national level driver in a Lotus Elise. For ref I needed to be 0.7 sec off his raw time to beat him in PAX.


Lastly i've been lucky enough to run with a co-driver that competes nationally in her Boxster. It's a base 2.7L with suspension & tire outlined above, that car is 1-2 seconds faster than the z4.
IMO the car to beat is the Vette. The Porsche is up on that list too. IMO the RX7 is the least of my concern.

Ideally, I'd have to run APEX Wheels. As of now I'm running 5mm spacers on all 4 corners to eliminate rubbing in the rear and clearance on the shock tower up front.

For AS I'd have to get massive tire up front, 255 at least. I don't know how that's going to happen.

Trying to get a coilover to accept a OEM spring would be hard IMO. I've been in contact with TCK Racing and for a DA shocks it will be around $2k. They have a coilover kit for our cars that is $2500, but that is with linear springs and different dia. I was able to run a STU E36 M3 (well almost STU, had flywheel) but it was fitted with TCK DA Coilovers. The car is so neutral, and just a couple clicks on suspension completely made the car throttle oversteer happy and no understeer...So sweet. SA shocks are out of the option...they won't do squat.

I don't understand how stepping into AS will cost more than BSP. The level of modifications to become a BSP car is mind blowing. Swaybar is done on my car, I need shocks, and some tires. Ideally, I need to shed weight from the exhaust but it isn't needed.

BSP requires new seats, removal of AC/Heating Cores, cut fenders...etc, etc. It's too much prep for me.

I think the route for me to take is RTR. Some minor alignment changes with DA Shocks will make it a sweet car. If SCCA gets their head together and gets a set PAX multiplier for RT, it will be a competitive class. This year, I was undefeated in RTR in Ohio (Cleveland, Toledo, Columbus). With that, I don't think people know what the RTR car is yet, so it's all experiments.

Thanks for your opinions though, they do help
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      10-03-2012, 08:57 PM   #4
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I bought a set of track rims from a guy this spring who was running 265's square on our cars... I can't fit them up front with my kwv3's, he was on stock suspension.(maybe if I camber it out...)
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      10-03-2012, 09:30 PM   #5
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A few guys tried this past year and may not be continuing their effort while citing they did not feel it was competitive. The same was said by owners of the E36 M3 in STU and BSP until this year when it won one class and nearly won the other. My sense is the right class is BSP but it could mean compromising (removal of AC, exhaust, seats, fender rolling/pulling) your car in ways you may not like.
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      10-03-2012, 09:40 PM   #6
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Quote:
Originally Posted by z3papa View Post
A few guys tried this past year and may not be continuing their effort while citing they did not feel it was competitive. The same was said by owners of the E36 M3 in STU and BSP until this year when it won one class and nearly won the other. My sense is the right class is BSP but it could mean compromising (removal of AC, exhaust, seats, fender rolling/pulling) your car in ways you may not like.
Yea. I may just go a light-BSP prepp'ed car to have fun and enjoy it on the track and never pursue nationals. Who knows.

At least I can run more camber, custom spring rates...etc.

I would like seats and actually running a 5-point
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      10-04-2012, 03:21 PM   #7
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Having just been to nationals with a slightly prepped BSP car I can tell you it could be competitive. But, it will require a significant investment in suspension....motons or equivalent. Fenders do not have to be cut to run 285 hoosiers front and rear. With an extremely good suspension and 900-1000 lb front and 1000-1100 lb rear springs, race seats, light battery and keeping the AC I am sure the Z4M can be nationally competitive in BSP
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      10-04-2012, 10:34 PM   #8
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Quote:
Originally Posted by AUTOX08MC
Having just been to nationals with a slightly prepped BSP car I can tell you it could be competitive. But, it will require a significant investment in suspension....motons or equivalent. Fenders do not have to be cut to run 285 hoosiers front and rear. With an extremely good suspension and 900-1000 lb front and 1000-1100 lb rear springs, race seats, light battery and keeping the AC I am sure the Z4M can be nationally competitive in BSP
What suspension are you running?
I'm looking to build a race car Z4 3.0 coupe.
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      10-05-2012, 05:56 AM   #9
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Quote:
Originally Posted by AUTOX08MC View Post
Having just been to nationals with a slightly prepped BSP car I can tell you it could be competitive. But, it will require a significant investment in suspension....motons or equivalent. Fenders do not have to be cut to run 285 hoosiers front and rear. With an extremely good suspension and 900-1000 lb front and 1000-1100 lb rear springs, race seats, light battery and keeping the AC I am sure the Z4M can be nationally competitive in BSP
Hey Kevin -- didn't see you at Nat's as we ran opposite days. I'm toying with the idea of a jump to BSP with the new 27/35-17 sizing which should fit with a little massage. May be fun to get back on Hoosier crack. Need to come to one of last remaining events in Rantoul.
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      10-05-2012, 06:04 AM   #10
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For anyone interested, these two threads may be of assistance:

http://www.zpost.com/forums/showthre...1#post12791552

http://forums.bimmerforums.com/forum....php?t=1665917
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      01-07-2013, 09:46 PM   #11
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I run my Z4m in AS. I am certainly not a national champion level driver, but the car can be reasonably prepared.

I run Koni DAs from TC Kline, and looked into getting AST 4200s. I eventually did not, but they will happily build you a set for stock springs as long as you're willing to wait for a few months to get them. You need to send them a pair of donor struts so they can cut off the spring perches.

I have run two tire setups: 285-30R18 Hoosier A6 all around, and 245/275 Goodyear Eagle RS. The Hoosiers mount just fine on the stock wheels, and there are no clearance issues at all. In the rear, a 5mm spacer is required to clear the fender liner.

With the Hoosiers, I ran a UUC front bar. With the staggered Goodyears, I use a Ground Control "race" rear bar to bring more weight transfer to the rear to help get rid of understeer. I think I like the second setup the best, but they're not too hugely different. I think turn in was better with the big fronts, but I can get the overall balance much more loose with the rear bar and the staggered tires. I had to have the compression maxed in back and full soft in the front with the hoosiers, and I still got understeer. With the rear bar, I have the rears full soft and the fronts about in the middle of the range. I have no issues with the big rear bar limiting traction. The M LSD is really good.

Now that Goodyear has bailed from autocross, I am pondering what to do next: Go back to the square 285 A6 setup, try a staggered A6 setup (maybe 255/285) or try Kumho 710s (245/285). The Kumhos are obviously worse in the grip department, but they do last a long time. It's a battle of cheap vs. fast .
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      01-07-2013, 10:19 PM   #12
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Based on what you are suggesting, have you considered the BFG R1S in the 265/35-18 front and 285/30-18 rears. I've heard from several Nat'l guys the R1S are just as fast as the A6's but hold that level of grip longer in terms of life. By the way, anyone seriously interested, there is a thread on SCCAforums where a guy in a fully prep'd M Coupe is soliciting co-drivers for Nat'l events.
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      01-08-2013, 07:12 PM   #13
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Quote:
Originally Posted by cgroppi View Post
I run my Z4m in AS. I am certainly not a national champion level driver, but the car can be reasonably prepared.

I run Koni DAs from TC Kline, and looked into getting AST 4200s. I eventually did not, but they will happily build you a set for stock springs as long as you're willing to wait for a few months to get them. You need to send them a pair of donor struts so they can cut off the spring perches.

I have run two tire setups: 285-30R18 Hoosier A6 all around, and 245/275 Goodyear Eagle RS. The Hoosiers mount just fine on the stock wheels, and there are no clearance issues at all. In the rear, a 5mm spacer is required to clear the fender liner.

With the Hoosiers, I ran a UUC front bar. With the staggered Goodyears, I use a Ground Control "race" rear bar to bring more weight transfer to the rear to help get rid of understeer. I think I like the second setup the best, but they're not too hugely different. I think turn in was better with the big fronts, but I can get the overall balance much more loose with the rear bar and the staggered tires. I had to have the compression maxed in back and full soft in the front with the hoosiers, and I still got understeer. With the rear bar, I have the rears full soft and the fronts about in the middle of the range. I have no issues with the big rear bar limiting traction. The M LSD is really good.

Now that Goodyear has bailed from autocross, I am pondering what to do next: Go back to the square 285 A6 setup, try a staggered A6 setup (maybe 255/285) or try Kumho 710s (245/285). The Kumhos are obviously worse in the grip department, but they do last a long time. It's a battle of cheap vs. fast .
Did you just order Koni DAs from TCK or did they do anything special for fitment? I was quoted $2k for DAs from them. I was also told that I cannot transform the DAs to accept linear springs and act as coilovers based on the perch design, right?

Do you have a trailer hitch to transport the tires?


EDIT: Found your thread: http://www.zpost.com/forums/showthread.php?t=574966


Do you have any problems trailering the tires?


Quote:
Originally Posted by z3papa View Post
Based on what you are suggesting, have you considered the BFG R1S in the 265/35-18 front and 285/30-18 rears. I've heard from several Nat'l guys the R1S are just as fast as the A6's but hold that level of grip longer in terms of life. By the way, anyone seriously interested, there is a thread on SCCAforums where a guy in a fully prep'd M Coupe is soliciting co-drivers for Nat'l events.
Any link?
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      01-12-2013, 10:49 PM   #14
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Did you just order Koni DAs from TCK or did they do anything special for fitment? I was quoted $2k for DAs from them. I was also told that I cannot transform the DAs to accept linear springs and act as coilovers based on the perch design, right?

Do you have any problems trailering the tires?
I bought my Koni DAs used here on zpost from a guy in New Jersey. He got them from TC Kline. As far as I know, they are just the standard DA Konis advertised on the website. The perch design for the front struts is only for stock springs. The perches are welded on just like the stock struts, but they're yellow and have two adjusters on them. The rears are just shocks, and use the stock spring setup. I cut an access hole in the trunk trim to get to the driver's side rear rebound adjuster. The passenger side is accessible once you remove the can of fix-a-flat. If you went with AST 4200s, you could get them re-valved and change out the spring perches to convert them to coilovers. The problem is they will run you something like $3300, last I checked.

Never had a bit of trouble trailering the tires. I just wish I could hire someone to change them for me when it's 110F out in the summer...
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      01-12-2013, 10:55 PM   #15
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Quote:
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Based on what you are suggesting, have you considered the BFG R1S in the 265/35-18 front and 285/30-18 rears. I've heard from several Nat'l guys the R1S are just as fast as the A6's but hold that level of grip longer in terms of life. By the way, anyone seriously interested, there is a thread on SCCAforums where a guy in a fully prep'd M Coupe is soliciting co-drivers for Nat'l events.
No, I have not considered them yet. None of our local hotshoes run them, so I haven't gotten any good feedback. We have something like 6 or 8 national champions in Arizona, and they're a good resource for this sort of thing. That's how I ended up on Goodyears. Brian Peters won FS this past year on them. When I ran the 285 A6s, I was buying Doug Rowse's take-offs from his DSP car. Since he had a garage full of tires won on contingency, he'd unload them once he put about 20 runs on them.
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