A few M3 qeustions

markodell · **Joined:** Wed Jul 27, 2005 6:19 pm **Posts:** 65

MikeWhitney wrote:

Hey Mark -

Nah, I use the term "coilover" loosely to mean "adjustable spring perches". I'm still on stock suspension, but when I make the jump I'm planning to go with 400F, 600R +/- 50lb in the factory locations.

Ahh, that makes perfect sense then - thanks for explaining that.

Good Luck with it!

Mark

Todd Breakey · **Posted:** Fri Jul 07, 2006 8:33 am

MarcusMcRae wrote:

The ASC has been on. Doh!! When the light is off, it's on. That's brilliant. The car is much more entertaining now. :woo:

That's the way the traction control button on the Mustang is. Here I thought it was just some stupid Ford thing. Glad to see other companies used the same logic.

MikeWhitney · **Joined:** Wed Aug 20, 2003 9:15 pm **Posts:** 4724

MarcusMcRae wrote:

\I figured out last night while reading the owners manual why I was having so much trouble getting this thing to slide like I wanted. The ASC has been on. Doh!! When the light is off, it's on. That's brilliant. The car is much more entertaining now. :woo:

Highly recommended for 96+ M3 drivers who don't need electronic nannies helping with their throttle pedal:

http://www.jogger-egg.com/kbob/asc+t.html

Once I go to BSP it's all going in the trash can.

DanDurusky · **Joined:** Sun Apr 10, 2005 7:31 pm **Posts:** 686

^can you delete the ASC throttle body in BSP? If so thatd be the best way i think. get some crap out from under the hood and get that second butterfly valve out of the way in the intake path

Graham Jagger · **Joined:** Fri Aug 29, 2003 12:53 am **Posts:** 1718

It's no different on GM cars. TC is engaged by default and it doesn't turn on lights to tell you that. As Mike said, "Nanny Mode". Good for daily driving, not track and definetely not autox.

The nice thing in the C5 is that there are 3 modes of handling. It uses TC and AH. All on by default. Hit the button once and all off. That puts a little picture of a car skidding in the display. And boy will it skid if you aren't smooth. Don't ask... The other option is Competition Mode for track (again no good for autox). That will let you spin the tires and hang the back end out quite a bit. But when the car goes into a heavy slide it jumps in and tries to gain balance again. Another feature I've accidently tested at high speed...

MikeWhitney · **Joined:** Wed Aug 20, 2003 9:15 pm **Posts:** 4724

Graham Jagger wrote:

It's no different on GM cars. TC is engaged by default and it doesn't turn on lights to tell you that. As Mike said, "Nanny Mode". Good for daily driving, not track and definetely not autox.

I prefer mine off all the time. Catching looseness on the street is part of my car control "practice". I want those yaw corrections to be totally reflexive and second nature. Practicing it every time I drive is the best way to stay sharp and safe no matter what I'm driving.

Honest, officer

MarcusMcRae · **Posted:** Sat Jul 08, 2006 3:46 pm

One more question. What speed does second gear top out at? I am going to order some tires and I am trying to decide whether to get 245/40 or 245/45. I have 8x17 rims. The 45's have about an inch greater OD. I do not want to hurt acceleration too much but if second runs out below 60 the extra diameter might help.

I also tried to check the transmission fluid. I could only find two torx bolts on the passenger side of the trans. Where is the fill plug in relation to the drain plug?

EDIT: I looks like it tops out on the limiter right at 59-60. I think I might go with 245/45. Hmmmm, decsions decisions.

MikeWhitney · **Joined:** Wed Aug 20, 2003 9:15 pm **Posts:** 4724

MarcusMcRae wrote:

One more question. What speed does second gear top out at? I am going to order some tires and I am trying to decide whether to get 245/40 or 245/45. I have 8x17 rims. The 45's have about an inch greater OD. I do not want to hurt acceleration too much but if second runs out below 60 the extra diameter might help.

I also tried to check the transmission fluid. I could only find two torx bolts on the passenger side of the trans. Where is the fill plug in relation to the drain plug?

EDIT: I looks like it tops out on the limiter right at 59-60. I think I might go with 245/45. Hmmmm, decsions decisions.

That ain't right. Revlimit in 1st and 2nd is 6800. In 3-5 it is 6500.

245-40-17 max speed in 2nd is 62
245-45-17 max speed in 2nd is 64

This is according to my calcs and confirmed here: http://www.geocities.com/MotorCity/Spee ... shift.html.

My rule of thumb is that at least 60 in 2nd is ideal for an autocross car. If both sizes are available I'd go with the 40's for acceleration, CG height, and rotating mass. I do run 245-45-17 V710s only because they don't come in a 40. Wish they did. My track tires are 245-40-17. So either is fine, but 45s get a little close to things like the fender and the strut.

MarcusMcRae · **Posted:** Sun Jul 09, 2006 9:53 am

I was just going by what I saw on the speedo. The only problem is the only 40 I was looking at was the MX. The 45 is the RT615. I am not going to spend 200+ for the advan's.

DanDurusky · **Joined:** Sun Apr 10, 2005 7:31 pm **Posts:** 686

what do you think about a 255 on a 8" wheel? pushing it?

RT615s in 255/40-17 fit and are closer to the stock 245/40 diameter. thats what i run on my 17x8.5"s. thats that standard STU recipe

MarcusMcRae · **Posted:** Sun Jul 09, 2006 11:51 am

DanDurusky wrote:

what do you think about a 255 on a 8" wheel? pushing it?

RT615s in 255/40-17 fit and are closer to the stock 245/40 diameter. thats what i run on my 17x8.5"s. thats that standard STU recipe

Yeah, they say the smallest rim to use the 255/40 is 8.5.

Rick Butters · **Posted:** Sun Jul 09, 2006 2:14 pm

Different car, different wheel, different tire, but I have 265/45/16 on a 7.5 inch rim.

DickRasmussen · **Posted:** Sun Jul 09, 2006 6:29 pm

I agree with Mike re: the slightly shorter tires, assuming that cornering traction is no worse and that you aren't traction limited under acceleration most of the time. My calculations and experience indicate that a "little bit of rev limiter time" with shorter gearing is usually better, in autocrossing, than a theoretical higher speed if the difference is only a couple of mph. Frequently the taller gear may actually result in a SLOWER top speed in actual competition courses.

62 versus 64 mph is roughly 3 percent. That can make a significant difference exiting slow corners.

Autocrossing is a whole bunch of very short drag strips followed by slow corners. Elapsed time is generally less with shorter gears even if top speed is a "little" slower.

This assumes that the engine and/or budget involved can handle rev limiter time . . . :wink:

FYI my second gear top speed (formula car) is just over 66 mph and an upshift is rarely required in most autocrosses. When it is a slightly taller gear won't be enough anyway so I geared for a 78 mph third.

Keith Quistorff · **Posted:** Mon Jul 10, 2006 9:41 am

MarcusMcRae wrote:

The only problem is the only 40 I was looking at was the MX. The 45 is the RT615. I am not going to spend 200+ for the advan's.

Marcus,

I'll be using 245/45/17 RT-615s for the rest of this season's autocrosses on my E36, size was a no-brainer because I didn't have to buy tires - I took them off my STi. Ideally, I would've liked to run a set of the Yoko Advans in 245/40, but like you, I'm not spending over $200/tire. If you'll be running in STU, the best 'grip for the buck' bet is what Dan's running - 255/40/17 RT-615's, but squeezing those on your 7.5" front wheels isn't ideal. If you can locate a spare pair of rear wheels to run 8.5" all the way around (like Dan) that would be best. However, you'll also need spacers up front to clear your struts, and you'll probably have to roll your rear fenders. Lower offset wheels would be better for the front but won't work in the rear.

Another option you haven't mentioned is the Hankook R-S2/Z212, it is now available in 245/40/17 (from Edge Racing; size NOT shown on Discount Tire Direct's website). The Hankooks get very mixed reviews - some people like them, some hate them, and I seem to recall you might be one of the latter. If not, you might consider them as another option.

MarcusMcRae · **Posted:** Mon Jul 10, 2006 11:15 am

Keith Quistorff wrote:

MarcusMcRae wrote:

The only problem is the only 40 I was looking at was the MX. The 45 is the RT615. I am not going to spend 200+ for the advan's.

Marcus,

I'll be using 245/45/17 RT-615s for the rest of this season's autocrosses on my E36, size was a no-brainer because I didn't have to buy tires - I took them off my STi. Ideally, I would've liked to run a set of the Yoko Advans in 245/40, but like you, I'm not spending over $200/tire. If you'll be running in STU, the best 'grip for the buck' bet is what Dan's running - 255/40/17 RT-615's, but squeezing those on your 7.5" front wheels isn't ideal. If you can locate a spare pair of rear wheels to run 8.5" all the way around (like Dan) that would be best. However, you'll also need spacers up front to clear your struts, and you'll probably have to roll your rear fenders. Lower offset wheels would be better for the front but won't work in the rear.

Another option you haven't mentioned is the Hankook R-S2/Z212, it is now available in 245/40/17 (from Edge Racing; size NOT shown on Discount Tire Direct's website). The Hankooks get very mixed reviews - some people like them, some hate them, and I seem to recall you might be one of the latter. If not, you might consider them as another option.

I went with the RT615 245/45. I have a set of 17x8 rims and the stock rims. I am hoping the fronts will fit without spacers.

I saw the Hankooks and thought about it for about two seconds. I am sure I will enjoy the RT615's more than the MX's.

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A few M3 qeustions

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