[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.

[Blainefab]

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.

The late T56 5th gear is .74, at 6600 engine rpm the ds rpm is 8919, well into the 30% margin. My 1LE shaft started making noise about 6500 ds rpm.