Rear End Gearing
08-20-2013, 07:42 AM
#1
Rear End Gearing PT7675 turbo, shift points round 6400, 4L80E..
Was thinking a 3.50 gear area, or go lower with a 3.08 maybe?
On a 27inch hoosier, the 3.50s put me round 146mph, which I do not think it has the steam for, but would be nice to have an easy car to launch.
Was thinking a 3.50 gear area, or go lower with a 3.08 maybe?
On a 27inch hoosier, the 3.50s put me round 146mph, which I do not think it has the steam for, but would be nice to have an easy car to launch.
08-20-2013, 07:59 AM
#2
With the 2.48 1st gear in the 4l80 I would not be scared to to with the 3.08 of course a lot of things come into play when choosing a gear ratio that you have left out. Weight of car? What are your goals for the car? Is it a street car or track only car? Converter?
08-20-2013, 08:48 AM
#4
You'd be surprised what your car will do at that weight. That is about what mine weighs and I went almost 137 mph on 10-11 lbs, shifting the 1-2 at 5300 rpm. I am running a 3.23 rear and 27.6 inch tires. I am going back to my 2.73 10 bolt as I killed the posi in this one. I hated the 2.73's with my Mickey's because my converter is way too loose, but I need to swap. I need to get it tightened up this winter.
08-20-2013, 08:54 AM
#5
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I love my 3.73's for street use and my car has no problem pouring on boost with that turbo, however I am hitting the traps on spring pressure(10psi) and hitting the rev limiter at about 135-138mph. I'm on about a 27 inch tire. I'm going to give it a little more rpm and switch to 3.54's which is the lowest I can go with an s60 so I hope that puts me in the mid 140's. at least that is what the calculators put me at.
Edit:my honest recommendation is to run it at the track and evaluate from there. Fwiw when I ran a half mile event I used OD in my 4l80e to hit 165mph(low boost) and it took it like a champ.
Edit:my honest recommendation is to run it at the track and evaluate from there. Fwiw when I ran a half mile event I used OD in my 4l80e to hit 165mph(low boost) and it took it like a champ.
08-20-2013, 08:55 AM
#6
You'd be surprised what your car will do at that weight. That is about what mine weighs and I went almost 137 mph on 10-11 lbs, shifting the 1-2 at 5300 rpm. I am running a 3.23 rear and 27.6 inch tires. I am going back to my 2.73 10 bolt as I killed the posi in this one. I hated the 2.73's with my Mickey's because my converter is way too loose, but I need to swap. I need to get it tightened up this winter.
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08-20-2013, 09:53 AM
#9
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FWIW...
3.50 gear, 28" tire, 6 speed, 6500 RPM shifts
4th gear (1:1) will peg the speedo give or take a few mph actual speed. 5th will cruise 65 @ 2000 RPM and 6th will do over 90 @ 2k.
3.50 gear, 28" tire, 6 speed, 6500 RPM shifts
4th gear (1:1) will peg the speedo give or take a few mph actual speed. 5th will cruise 65 @ 2000 RPM and 6th will do over 90 @ 2k.
08-20-2013, 10:22 AM
#12
if you don't mention you drive a LT1, people won't ruin thread with Lt1 hate. Sadly enough.
Can you go with too much gear, IE 3.08 or is it just gonna be slow off the line and then once it lites off, be fine?
08-20-2013, 10:44 AM
#13
I agree, that is sad. Nothing wrong with LT1's IMO. Your car should run well.
I have not had the opportunity to run my car at the track with anything but the 3.23 rear end. I do know, that I could build more boost on the foot brake without pushing through the tires with the 2.73's. I will hopefully have some times with the 2.73's in the next couple of weeks.
I have not had the opportunity to run my car at the track with anything but the 3.23 rear end. I do know, that I could build more boost on the foot brake without pushing through the tires with the 2.73's. I will hopefully have some times with the 2.73's in the next couple of weeks.
