Gear swap:how much change in 60'? - LS1TECH



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Gear swap:how much change in 60'?

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Old 01-12-2017, 08:23 PM   #1
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Default Gear swap:how much change in 60'?

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!
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Old 01-12-2017, 08:45 PM   #2
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In for proven track results
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Old 01-13-2017, 07:40 PM   #3
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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
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Old 01-14-2017, 10:16 AM   #4
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I increased mine and saw no difference.
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Old 01-14-2017, 11:22 AM   #5
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Originally Posted by 01ssreda4 View Post
I increased mine and saw no difference.
OK, thanks for the input. What ratio did you change to and from?
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Old 01-15-2017, 03:15 AM   #6
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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.
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Old 01-15-2017, 06:42 AM   #7
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Originally Posted by zzracer View Post
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.
Ok, good deal.
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Old 01-15-2017, 09:47 AM   #8
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Originally Posted by turbotrks View Post
OK, thanks for the input. What ratio did you change to and from?
3.73 to 4.10
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Old 01-24-2017, 07:31 PM   #9
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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?
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Old 01-26-2017, 08:55 AM   #10
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Slip would go up that's for sure.
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Old 01-26-2017, 09:24 PM   #11
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Quote:
Originally Posted by 01ssreda4 View Post
Slip would go up that's for sure.
Up? Wouldn't the converter slip less at a higher RPM?
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Old 01-28-2017, 09:23 AM   #12
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Originally Posted by turbotrks View Post
Up? Wouldn't the converter slip less at a higher RPM?
Sorry I misread what gears you had. Going from 3.2x to 3.5x would DECREASE slip.
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Old 01-30-2017, 05:15 PM   #13
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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.
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Old 01-30-2017, 07:20 PM   #14
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Quote:
Originally Posted by jblankenship View Post
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.
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.
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Old 02-06-2017, 01:45 AM   #15
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Default Gear swap 60ft update

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.
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Old 02-09-2017, 11:00 AM   #16
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Thanks for the info.
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Old 02-11-2017, 08:29 AM   #17
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Quote:
Originally Posted by turbotrks View Post
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.
6-8% I would think.
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