turbotrks

As I twiddle my thumbs this winter waiting for the good tracks to open, I am thinking about swapping the ring and pinion in my Mustang (see sig) to improve my 60' times. I don't want to go through the trouble if it's not going reach my goal though.

Here's the details: Currently have 8.8 with 3.27 gears and the best 60' I've done is 1.36. That's leaving on 8psi with 2 step. Without loosening the converter I can't seem to make over 8 psi on the line. With a 3.73 the car was good for 1.2x 60' times, but that was in 1/8th mile. I am running 1/4mi and based on my calculations, I would need to go with a 3.55 to theoretically cross the finish line at the ideal RPM (around 6700-6800)

Sooooo, do you think going from 3.27 to 3.55 would get me back under 1.30?

Or, let me know if you see another way to reduce my 60 foot without swapping gears or tranny. Btw, I'm already running a sae 10wt transmission fluid, so I don't know of anything thinner to increase my stall.

Thanks for any advice!

madmike9396

iTrader: (29)

In for proven track results

turbotrks

Anyone out there changed the gear ratio and compared the before and after 60'? Doesn't even have to be a remotely similar set up. Just looking for any information to work with. Really don't want to go through the trouble if the general consensus says I'm only going to drop a few .01

01ssreda4

iTrader: (96)

I increased mine and saw no difference.

turbotrks

OK, thanks for the input. What ratio did you change to and from?

zzracer

iTrader: (33)

I had 3.08 gears and have just put in 3.73s. I have not tried the new gears out yet put plan on going to the track soon . I will post my results.

turbotrks

Ok, good deal.

01ssreda4

iTrader: (96)

3.73 to 4.10

turbotrks

New question. I am currently seeing approx 8% converter slip at 6400 rpm as I cross the line.

If I change to a 3.55 gear, and my finish line rpm is around 6900 rpm, what percentage of slip do think I'd see?

01ssreda4

iTrader: (96)

Slip would go up that's for sure.

turbotrks

Up? Wouldn't the converter slip less at a higher RPM?

01ssreda4

iTrader: (96)

Sorry I misread what gears you had. Going from 3.2x to 3.5x would DECREASE slip.

jblankenship

iTrader: (5)

If you increase rear gear the converter tightens up, this is why the 60' won't change much or at all. The car needs the correct gear for the rpm you wish to finish at. Then you need the converter spec'd for the entire combo.

turbotrks

In a typical or ideal scenario (for a non-lockup TC), what percentage of slip should I be expecting at redline?
That % of slip needs to be in my calculation to determine the best gear ratio.

zzracer

iTrader: (33)

I went to the track yesterday to try my 3.73 gears. I did notpick my 60ft up. With the 3.08 gears my 60s averaged 1.51-1.52 . My best 60 with the 3.73s is a 1.44 so far. I think I can get it a little better with some suspension tuning.

turbotrks

Thanks for the info.

01ssreda4

iTrader: (96)

6-8% I would think.