[Judd]

I know this is a autoX/road course site but I though some of you might have some insight on this question so I decided to throw this out. I'm thinking about running my car at Maxton N.C. at the E.C.T.A. 1 mile event. I'm putting down around 540RWHP and right now I'm running a 4.10 gear which should max out somewhere around 165 or so. I should get to that which is cool by me since my tech speed should be 175mph. To go over that, I will need a real cage which I'm not willing to do right now.

Later, I would like to replace the gear so I can get some more mph but I'm a bit confused. I've heard that you really should do your best to run 4th gear {1:1} for top speed events because that is the most efficient but my my set-up would really be doggy with something like a 2.73 in the rear. I'm really thinking of running a good dose of nitrous in an effort to get to 200mph {one of my goals} and I think I should have the power to do it but just how much will running 5th gear hurt me? Sure would like to run a 3.42 or 3.73 so I wouldn't have to swap out axles all the time.

Also, I will be carrying a trailer with extra wheels, tools and possibly a bike so I really would like to keep a low gear.

[v7guy]

Are there any driveshafts other than the carbon units you guys would recommend. I know the LT1 shaft isn't good for those speeds but isn't there a cheaper option while still being safe?

[StanIROCZ]

Are there any driveshafts other than the carbon units you guys would recommend. I know the LT1 shaft isn't good for those speeds but isn't there a cheaper option while still being safe?

Has anyone really had critical speed problems with a stock 3" Al driveshaft? Theoretical critical speed 11,600 rpm. From my experience you should feel comfortable with a 30% margin, so that brings it down to 8,118. With a .7 overdrive engine speed would be 5,683. That's pretty damn fast no matter what rear gear you have. If you had problems I would suspect they are for other reasons like a bad balance or loose bushings in the tailhousing.

Do the same math on a 3.5x.125" Al shaft. Theoretical critical speed 13,423 rpm. 9,396 rpm with 30% margin, 6,577 rpm engine speed. You should be able to get a custom 3.5" shaft for about $4-500 or so from a DS shop.

I have a 4" Al shaft because that's what was "available" wink wink. It wasn't easy to fit in the tunnel but can be made to fit.