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      03-26-2009, 11:30 PM   #17
FlyFish
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Quote:
Originally Posted by dcstep View Post
Lucid and that video beat me to it.

I think that the SAs are referring to road tracks, not drag strips.


Here's kind of a hierarchy of stress vs. the design parameters:
  • Rolling starts on the street produce stresses well within design limits
  • Standing starts, with street tires and stock gears, on "normal" pavement, are generally within limits, unless you repeat too much, too quick & build heat
  • Drag strips with clean, concrete launch pads and stock tires, start to put you at the limits of the design
  • Add slicks or R-compound tires and your on borrowed time
  • Drag strips with traction goo, stay away without modded axles. The issue becomes "when", not "if"
I'm guessing that the stress on the axle with slicks and a gooy launch pad is probably triple that of a standing street start. If you can spin the wheels between 2000 and 4000 rpm (typical street conditions) then you're probabably ok. OTOH, if you need 5-grand to spin the wheels at a strip, then cross your fingers and pray.

I was big into Mustangs at one time. ALL of those guys that got serious about dragging ended up with 32-spline axles and Tremec transmissions. The stock parts in the 'stangs are massive vs. the M3 and yet they routinely broke after a few runs. Watch "Pinks" for a while. You'll see 500 hp cars twisting off drive shafts and parts flying like shrapnel. Because our drive train parts are even lighter, we run those kinds of risks, when we run one too many runs at the drag strip. Have your wallet at the ready and the phone number of a good tow truck driver.

Dave
Great information, thank you. I have to tell you though; I am kind of disappointed--not that I was planning on going to 1/4 mile track every weekend. But it sure was fun the one opportunity I had last summer with the 135i, I couldn't wait to do it again with the M3. But now--I don't think I want to risk it. Even if it's just a few times in it's life time. Only $30 bucks to drag race and $250 for the road track--ouch.

Dang it!
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