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Old 12-16-2006, 12:51 AM   #1
Boise69
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Another gear ?

How do you tell what gears you have without taking off the cover? I run 3300 rpms going 80 and she feels good, i get 16mph and I think she's quick off the light. But i would like to know the numbers i have.
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Old 12-16-2006, 12:56 AM   #2
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Re: Another gear ?

sounds like 3.73 what size tires are you running?
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Old 12-16-2006, 01:06 AM   #3
al's71gmc
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Re: Another gear ?

If you have an non posi rear, jack up 1 back wheel, mark your driveline and tire with a piece of chalk, rotate your tire 2 revolutions and count the number of revolutions on your driveline. A little over 4 revs=411s, 3 3/4 revs=373s, 3 1/2= 342s.....you'll be able to tell what gears if you know which ones are available.
If you have a posi, you have to lift both rear tires, and then one rev on the tire and count the revs on the driveline IIRC.
I wish I was getting 16 mpg!
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Old 12-16-2006, 01:07 AM   #4
Boise69
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Re: Another gear ?

Tires: 275/60/15.
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1969 Chevy C-10 SWB 350/400 - drivable project

www.americanhammer.com

2013 MBZ Sprinter customized
2005 MBZ Sprinter Van
2004 Land Rover Discovery
2001 Yamaha Road Star
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Old 12-16-2006, 01:12 AM   #5
Boise69
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Re: Another gear ?

If i have 3.73, and i like the way it is all over town and the highway, but i want posi, what will it effect in the way it drives? Will i notice a difference? will it take away from the easy feel i have no on the highway? Just because i want to smoke both my tires for blocks is not a good enough reason to ruin the quiet and smooth way it handles now.
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1969 Chevy C-10 SWB 350/400 - drivable project

www.americanhammer.com

2013 MBZ Sprinter customized
2005 MBZ Sprinter Van
2004 Land Rover Discovery
2001 Yamaha Road Star
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Old 12-16-2006, 01:12 AM   #6
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Re: Another gear ?

Well according to here
http://www.1010tires.com/TireSizeCal...?action=submit Your tires are 27.99 make it 28
and go here http://www.angelfire.com/fl/procrastination/rear.html
Looks like 3.07 according to this. I am assuming that you have a 350 or 400 turbo tranny.
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Old 12-16-2006, 01:14 AM   #7
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Re: Another gear ?

YES, TH400 tranny
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1969 Chevy C-10 SWB 350/400 - drivable project

www.americanhammer.com

2013 MBZ Sprinter customized
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Old 12-16-2006, 01:17 AM   #8
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Re: Another gear ?

I cant answer your question on how it would feel since I have never had a posi. All I know is that you will smoke both tires when you stomp on it
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Old 12-16-2006, 01:25 AM   #9
rwgregory
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Re: Another gear ?

It will not be a true "locked" posi. It will be a limited-slip, meaning there are clutches in the assembly that lock both wheels under load, but allow one wheel to slip slightly when turning corners. Under normal driving you will not notice any difference from a "one-legged" non posi rear end.
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Old 12-16-2006, 02:48 AM   #10
BarryB
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Re: Another gear ?

HAd a Limited slip in a Nova I USED to own. I really couldn't tell a difference from an open diff. to a "posi" diff. but When I dumped the clutch I left two black liiiiiiiine's instead of one.

Last edited by BarryB; 12-16-2006 at 02:49 AM.
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Old 12-16-2006, 10:21 PM   #11
Boog
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Re: Another gear ?

Using the Richmond gear calculator with the given 80 mph and 3300 rpms and 28" tall tire it comes up with a 3.44 gear which would actually be a 3.42. A good all around ratio in a non OD application. 16 mpg is nothing to fret about.
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Old 12-16-2006, 11:10 PM   #12
blacktruck
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Re: Another gear ?

i'm turning 3k at 65 with a 28" tall tire. according that i have 3.73's thanks i was curious what my gearing was, i was starting to think i had 4.11's those things are DEEP. well, to me anyway.
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Last edited by blacktruck; 12-16-2006 at 11:14 PM.
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Old 12-16-2006, 11:18 PM   #13
bad_turbo
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Re: Another gear ?

is there a link to that richmond gear calculator?
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Old 12-16-2006, 11:22 PM   #14
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Re: Another gear ?

Sure. Try this. http://www.richmondgear.com/101032.html It's pretty handy. You can adjust tire size, gear ratio, o/drive or not to come up with a suitable gear.
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