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03-30-2011, 12:07 AM
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#1 |
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Registered User
Join Date: Feb 2011
Location: desert hot springs
Posts: 27
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gearing advise?!
hey guys,
i was hoping if i could get some help with my gearing on my transmission, i have a TH350.. I plan on running 33" with my current 4 inch lift. Only problem is i don't know how to begin on this as i'm new to messing with trucks.  If anyone could point me in the right direction i'd appreciate it. Thank you 
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03-30-2011, 12:21 AM
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#2 |
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Junior Member
Join Date: Jul 2002
Location: Scottsdale, AZ
Posts: 1,696
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Re: gearing advise?!
Gearing your transmission? I wouldn't mess with that.
Differential gearing is where you want to look. Mine has same lift and tire combination with 3.73 gear diffs. I believe the general consensus is that is just right. Yours is most likely a taller gear than that. Taller meaning a higher ratio giving you lower RPMs at highway speed but it'll be a dog when accelerating. Check the SPID label on the inside of your glovebox door and see if it says anything about gear ratio. The definitive answer however would be to rotate the tire/driveshaft and count revolutions or pull the diff cover and count teeth.
__________________
"I was patina when patina wasn't cool." 1973 Cheyenne SWB Gold White Fleetsides/Saddle |
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03-30-2011, 01:33 AM
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#3 |
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Registered User
Join Date: Aug 2009
Location: Vancouver, WA
Posts: 174
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Re: gearing advise?!
IIRC, at least up until 71 the 350ci came with 3.07 gears, the 307ci came with 3.73, and in pickups the 6cyl came with 4.11 gears. I dont know if the trans made a difference. Majority of the trucks I've encountered of this era were 3.73 geared. But I put 3.07s in when I was in HS to get by while we rebuild the 12bolt that came in my truck, and with the 33" tires it made zero power off the line, and really didnt improve at freeway speeds either. 4.11s would be good around town and wheeling, but not so much on the freeway.
My truck is a 350/th350/np205/3.73 on 33/12.5/15 tires. Erik |
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03-30-2011, 01:53 AM
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#4 |
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Registered User
Join Date: Jul 2010
Location: Carnation Wa
Posts: 199
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Re: gearing advise?!
You could get a 350 with 3.73 gearing right? I'm almost positive it's marked on my spid.
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03-30-2011, 02:07 AM
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#5 | |
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Registered User
Join Date: Aug 2009
Location: Vancouver, WA
Posts: 174
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Re: gearing advise?!
Quote:
For a while we owned a 69 Blazer that had 3.73s on the SPID, 350/350 truck. So I'm sure someone with more knowledge than I have will speak up. I just know that for 71, gearing was the main reason he ended up special ordering my truck. Erik |
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03-30-2011, 02:58 AM
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#6 |
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Registered User
Join Date: Mar 2010
Location: Los Angeles, California
Posts: 226
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Re: gearing advise?!
What if you move from 33" to 35" tires? 3.73 still a good ratio? 350/350/205 etc.
__________________
'71 K/5 CST Work in progress...In Sicily, women are more dangerous than shotguns.
Last edited by bigeasycigars; 03-30-2011 at 02:59 AM. |
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03-30-2011, 07:28 PM
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#7 |
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toys'r'us
Join Date: Nov 2010
Location: Penticton, BC, Canada
Posts: 347
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Re: gearing advise?!
These trucks arent the greatest on the highway to begin with due to the short wheelbase and front straight axel. I have a sm465, 373s and 33-12.5s and its great around town and off road, but im not about to set any land speed records. It gets sketchy with no roll bar. too many what ifs
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71 jimmy bone stock 350 sm465 33x12.5 rallies 79 caprice landau full load crate350 th350 lowered 20"wires 00 f150 reg cab sb 4x4 5.4L |
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03-30-2011, 07:34 PM
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#8 |
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Registered User
Join Date: Feb 2011
Location: desert hot springs
Posts: 27
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Re: gearing advise?!
haha thanks guys i guess i'll be screwed on gas this summer lol least i'll enjoy the ride
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