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02-29-2012, 02:17 AM
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#1 |
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Fabricate till you "puke"
Join Date: Jun 2002
Location: Ill
Posts: 9,402
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3.42-3.73 gear swap?
I have an 02 silverado(2wd), that is running a 3.42 gear. My parts truck is sportin a 3.73 diff, & I know it will "bust" the mileage a tad going 3.73, but be nice behind that 4.8, pullin a stock car trailer
 My ? is how much tune do I need to play, to make it work properly? crazyL
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69 longhorn,4" chop,3/5 drop, 1/2 ton suspension/disc brakes,1 1/2" body drop,steel tilt clip, 5.3/Edelbrock rpm intake/600 carb, Hooker streetrod shorties,2 1/2" exhaust/ H pipe/50's Flows , 6 spd Richmond trans,12 bolt/ 3.40 gears.... |
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02-29-2012, 01:29 PM
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#2 |
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Truck Enthusiast
Join Date: Dec 2006
Location: Arlington, WA
Posts: 1,346
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Re: 3.42-3.73 gear swap?
Just put them in and go, no need to wory about tuning the motor
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'85 swb |
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02-29-2012, 04:31 PM
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#3 |
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Has more rust than truck...
Join Date: Apr 2005
Location: Ivanhoe, MN
Posts: 2,421
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Re: 3.42-3.73 gear swap?
Only thing the PCM would need to be programed for is to correct the speedo.
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02-29-2012, 04:34 PM
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#4 |
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Fabricate till you "puke"
Join Date: Jun 2002
Location: Ill
Posts: 9,402
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Re: 3.42-3.73 gear swap?
Thanks guys
 crazyL
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69 longhorn,4" chop,3/5 drop, 1/2 ton suspension/disc brakes,1 1/2" body drop,steel tilt clip, 5.3/Edelbrock rpm intake/600 carb, Hooker streetrod shorties,2 1/2" exhaust/ H pipe/50's Flows , 6 spd Richmond trans,12 bolt/ 3.40 gears.... |
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03-05-2012, 08:03 PM
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#5 |
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Registered User
Join Date: Dec 2010
Location: Dallas, TX
Posts: 160
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Re: 3.42-3.73 gear swap?
You can do without, but it should really be tuned to fix the shift points also. They will be different.
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2010 Basalt Black Porsche Cayenne GTS - Daily driver 1991 2500 Suburban, Black - 454/80E tow monster, soon to go under the knife... Again.  1979 16' Action Marine/"Johnny Cash" Merc Bridgeport Champ Motor - Metalflake Maniac |
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03-05-2012, 10:24 PM
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#6 |
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Fabricate till you "puke"
Join Date: Jun 2002
Location: Ill
Posts: 9,402
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Re: 3.42-3.73 gear swap?
I had wondered about the shift points.....the old school stuff , always messed with the shift points ,running lower gears. Tiss my 1st rodeo on the 3rd gen , I love my 02 silverado(4.8), & that is what the diff swap is about. I have a 5.3 to roll in my old 69 longhorn/backed with a Richmond 6 spd box, & 3.42 gears. She will be goin "rock stock", with a little tune.....maybe add the cam upgrade& valve springs, next season. The old 383 has showed me all she has.....but fuel mileage was not in the picture. crazyL
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69 longhorn,4" chop,3/5 drop, 1/2 ton suspension/disc brakes,1 1/2" body drop,steel tilt clip, 5.3/Edelbrock rpm intake/600 carb, Hooker streetrod shorties,2 1/2" exhaust/ H pipe/50's Flows , 6 spd Richmond trans,12 bolt/ 3.40 gears.... |
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03-06-2012, 01:25 AM
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#7 |
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Senior Member
Join Date: May 2009
Location: Fort Worth, TX
Posts: 6,370
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Re: 3.42-3.73 gear swap?
Its the same theory as changing speedo gears & calibrating a governor in a older ride, Just its all in the "Flash Memory" in the PCM.
3.42:1 to 3.73:1 isnt a huge change. It would run fine....But better with a good tune. |
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03-06-2012, 01:37 AM
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#8 |
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Fabricate till you "puke"
Join Date: Jun 2002
Location: Ill
Posts: 9,402
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Re: 3.42-3.73 gear swap?
Any betts on mileage difference? My thoughts are probably about nothing in town....but I may need to slow down a tick on the hyway
?
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69 longhorn,4" chop,3/5 drop, 1/2 ton suspension/disc brakes,1 1/2" body drop,steel tilt clip, 5.3/Edelbrock rpm intake/600 carb, Hooker streetrod shorties,2 1/2" exhaust/ H pipe/50's Flows , 6 spd Richmond trans,12 bolt/ 3.40 gears.... |
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03-06-2012, 01:46 AM
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#9 | |
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Senior Member
Join Date: May 2009
Location: Fort Worth, TX
Posts: 6,370
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Re: 3.42-3.73 gear swap?
Quote:
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03-06-2012, 02:25 AM
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#10 |
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Fabricate till you "puke"
Join Date: Jun 2002
Location: Ill
Posts: 9,402
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Re: 3.42-3.73 gear swap?
235/75/16....they are a little shorter than what was on the 4wd parts truck. crazyL
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69 longhorn,4" chop,3/5 drop, 1/2 ton suspension/disc brakes,1 1/2" body drop,steel tilt clip, 5.3/Edelbrock rpm intake/600 carb, Hooker streetrod shorties,2 1/2" exhaust/ H pipe/50's Flows , 6 spd Richmond trans,12 bolt/ 3.40 gears.... |
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03-06-2012, 11:21 AM
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#11 | |
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Registered User
Join Date: Dec 2010
Location: Dallas, TX
Posts: 160
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Re: 3.42-3.73 gear swap?
Quote:
For the size tires that are generally considered truck tires these days, 3.73s are the way to go.
__________________
2010 Basalt Black Porsche Cayenne GTS - Daily driver 1991 2500 Suburban, Black - 454/80E tow monster, soon to go under the knife... Again. 1979 16' Action Marine/"Johnny Cash" Merc Bridgeport Champ Motor - Metalflake Maniac |
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03-06-2012, 04:19 PM
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#12 |
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Registered User
Join Date: Jan 2010
Location: Kansas City, Mo
Posts: 284
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Re: 3.42-3.73 gear swap?
we did a 3.73-4.10 swap in a 2000 Siliverado 5.3L 1/2 ton 2wd years ago without any reprogramming and the speedo was only about 1-2 mph off. no real effect on shift points either. It ran great. so we just left it alone after the install.
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03-06-2012, 09:04 PM
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#13 |
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Fabricate till you "puke"
Join Date: Jun 2002
Location: Ill
Posts: 9,402
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Re: 3.42-3.73 gear swap?
Thanks again, to all for the info....it sounds like I will bolt in & play. I may go with the tune later, but this one is my DD.
Hotrods 1st! I am working on the 5.3 into my old 69.....dam, this old man has refound some sore muscles, tearing the parts truck down if it jacks with me too hard, I just lite the "smoke wrench" tho...thanks again,crazyL
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69 longhorn,4" chop,3/5 drop, 1/2 ton suspension/disc brakes,1 1/2" body drop,steel tilt clip, 5.3/Edelbrock rpm intake/600 carb, Hooker streetrod shorties,2 1/2" exhaust/ H pipe/50's Flows , 6 spd Richmond trans,12 bolt/ 3.40 gears.... |
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03-06-2012, 11:40 PM
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#14 |
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Registered User
Join Date: Mar 2012
Location: Harker Heights, TX
Posts: 23
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Re: 3.42-3.73 gear swap?
Hi, I have a 2008 4.3 2wd reg cab with 3.23's but I'm planning on going from the stock 245 to 285 tires so I want to get 3.73 or 4.10 gears but which one? And what are the pros and cons? I wouldn't mind the better acceleration either!
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