Gears & Axles - Ok Why am I going slower with 4.10 gears.

I know it has to be my driving, but don't know why. With the 3.42's I was turning 87mph in the 1/8 mile turning around 8.40's, now with the the 4.10's I am barely turning 84mph but still turning 8.40's in the 1/8 mile because my 60ft times are lower with the gears. In the 1/4 mile my best with the 3.42's was 12.86 at 110.81mph and with the 4.10's my best is 12.89 @ 109.65. It has to be my shifting but I can't figure it out. I am shifting around 5800rpm now. What do you guess think. Another thing is I now have to shift to 4th gear right at the 1/8 mile mark, could that be slowing me down in the 1/8 because I have to do more shifting. I don't know, just confused because the car feels twice as strong but does not show at the track.

i too have to shift 4th b4 the 1/8 th mark which sux. but it would seem as though u should be able to gain some ground by the 1/4. were u still in 3rd gear in the 1/4 b4? dont forget the time it takes to shift 1 more gear and letting off the gas to do so, unless u powershift which i dont.

It's because your not hooking up. Look at the difference in your 60' times.

It's because your not hooking up. Look at the difference in your 60' times.
New best with Cutout with 3.42 gears:
1/4 mile: 12.86 @ 110.81 (2.11 60ft) on street tires
1/8 mile: 8:40 @ 87.58
With 4.10 gears:
1/4 mile: 12.89 @ 109.65 (Spinning 1.95 60ft)


His 60 is better with the 4.10s

Exactly. And he's spinning. When you improve your 60' times you should be considerably faster in the 1/4 unless you are gear bound. We all know a M6 is not gear bound with 4:10's in the 1/4. The fact that he is spinning at the 60' mark means he is not hooking til after that. Thus slowing his times down. I'm sure the fact that he's shifting an extra time in the 1/8 is also not helping his times there.

I added 4.10s and almost have to switch into 4th in the 1/8th. I just ride out 3rd, it's bumping the limiter right as I cross the line.

What is the top speed in 4th at 6k with 4.10s in a M6? Stock height tires of course...I have heard 112mph, is that correct?

Yep. 112.

Reason your times are the same as with the 3.42s is you're spinning off the line. Reason your trap speeds are lower is because you're going quicker from the torque increase from the gear. Say you have two cars that both run say, flat 10-sec 1/4s. One may come out of the hole slower and as high-rpm hp comes on, he'll smoke through the traps at 150. The other(as in your case, now) though, having more torque applied on takeoff, may carry the front wheels through the 60', and hit the traps at 125 and out of steam.

Some brackets to drop your LCAs at the axle will help to wedge the tires under the car under launch, putting more weight on them(and grip), hopefully at least reducing your spin. Unfortunately, unless you're planning on upping the rev limiter soon, you're probably about maxed out on the 4.10s once you start hooking off the line, 'cuz hitting 5th will take up precious time, and cost you more torque being in a higher gear.

Yes, any faster than 112-113 trap speeds and you'll have to go to taller rear tires with 4.10s. I would not reccomend bumping the limiter up at all unless you do some valvetrain improvements (i.e.; at least Comp 917 springs, titanium retainers, better pushrods), unless you want to experience the dreaded valve float and all of it's damage. If you do push the limiter up a couple hundred revs, I would only make a few passes with stock height tires, 4.10s and the stock valvetrain, at 113 mph+ traps.

Yea I have tried holding it thru third in the 1/8 mile and hit the rev and pushed in the clutch and coasted thru and turned my best 1/8 mile time which was 8.35 @ 85.15mph, which is even more wierd. But it still is not turning 87mph in which it use to with the 3.42's. The thing is if I am running the 1/4 mile I can't be leaving the car in third hitting the rev limiter and then shifting to 4th.

If you are still running a 10 bolt with the 4:10's be careful about how hard you launch and how well you hook. Stuff like that can be hard on your wallet. Try coming out of the hole off idle and accelerate only as fast as traction will let you. See what your numbers are after that.

What about your 330' times? That may help you see how much shifting into 4th in the 1/8 is hurting your ET. If that does not show much, think back to what the weather conditions were like. I ran .2 slower when I put underdrive pulley's on and was pretty upset, but the only thing I can think of was the weather.

Yea I have tried holding it thru third in the 1/8 mile and hit the rev and pushed in the clutch and coasted thru and turned my best 1/8 mile time which was 8.35 @ 85.15mph, which is even more wierd. But it still is not turning 87mph in which it use to with the 3.42's. The thing is if I am running the 1/4 mile I can't be leaving the car in third hitting the rev limiter and then shifting to 4th.
In the 1/4 mile, you'll want to hit 4th gear. Not a bad thing at all, since the need to tells you that the engine is building speed quicker(read: making your car move quicker). I hold fast to the idea that 4.10s will make a stock or bolt-on car incredibly wicked in the 1/4... just anything beyond full bolt-ons and mild cam will either need a numerically lower gear ratio or higher redline(and I wouldn't do the higher redline on stock valvetrain, to be honest). Shift into 4th at the same rpm you would into any other gear when you're at the track. It's an easy one to hit that doesn't eat up a whole lot of time since it's straight back.

In the 1/8, just try hitting 4th. I imagine you'll be almost out of room to use it, but hey, it's worth a try to keep power to the pavement. :drive:

Lurk.