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| | | | Joined: Nov 2005 Posts: 266 Shop Shark | | Shop Shark Joined: Nov 2005 Posts: 266 | I have a 3.07 ring and pinion gears and was considering swapping those with the 3.73 that I have now to increase gas mileage. I have a 250 and a column shift 3-spd. I was wondering if going to a 3.07 would bog the engine down too much while crusing? I know that 3.07 was offered as an option from Chevy. Also, is it easier to do the work myself, or to have a shop do it for me? From the looks of the 1963 Shop Manual and Supplement, it doesn't look to be that hard of a job to do. Thanks for your help.
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Drew
'66 C-10 stepside | | | | | Joined: Jun 2005 Posts: 1,756 Shop Shark | | Shop Shark Joined: Jun 2005 Posts: 1,756 | Instalation is not much of a problem but read up on setting the backlash. has to be perfect. | | | | | Joined: Jul 2005 Posts: 1,158 Shop Shark | | Shop Shark Joined: Jul 2005 Posts: 1,158 | 3.07 gears would get you better gas mileage than a 3.73...
Just sayin'. | | | | | Joined: Feb 2006 Posts: 395 Shop Shark | | Shop Shark Joined: Feb 2006 Posts: 395 | you are shooting in the dark here..1st if your 3.0 gears are used you will most likely have a noisey diff..2 the setting and preloads are not that easy...3 if you go over the top on gearing you will lose preformance and fuel milage...with a 250 look at a 3.55 doc | | | | | Joined: Jun 2004 Posts: 8,597 Riding in the Passing Lane | | Riding in the Passing Lane Joined: Jun 2004 Posts: 8,597 | I think Doc is right unless you have very small dia. tires. That rear end is a lot harder to set up than the 62 on back. The side bearings do not have screw adjustments. You have to juggle shims to get it right.
They say money can't buy happiness. It can buy old Chevy trucks though. Same thing. 1972 Chevy c10 Cheyenne SuperIn the Gallery Forum | | | | | Joined: Nov 2005 Posts: 266 Shop Shark | | Shop Shark Joined: Nov 2005 Posts: 266 | Thanks guys. Wrenchbender, I'm currently running 235/75-R15 tires in all four corners.
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Drew
'66 C-10 stepside | | | | | Joined: Jun 2004 Posts: 8,597 Riding in the Passing Lane | | Riding in the Passing Lane Joined: Jun 2004 Posts: 8,597 | I don,t think it would drive good with 3:07. Like Doc posted, 3:55 or keep the 3:73 & add o-drive.
They say money can't buy happiness. It can buy old Chevy trucks though. Same thing. 1972 Chevy c10 Cheyenne SuperIn the Gallery Forum | | | | | Joined: Feb 2006 Posts: 395 Shop Shark | | Shop Shark Joined: Feb 2006 Posts: 395 | I think the 3.7 should do you nicely for what you would gain changing,,if you have fuel problem try to correct it first...doc | | | | | Joined: Oct 2003 Posts: 5,152 Cruising in the Passing Lane | | Cruising in the Passing Lane Joined: Oct 2003 Posts: 5,152 | I can't speak to how hard the swap would be, I just don't know. But I'm running similar size tires, a 3.08 geared rear, an SM420 and a GMC 270.
This is in my '55 1st Suburban and as long as I don't put a trailer behind it I think it drives fine. I get 14 running around town and maybe 17 on the highway.
1955 1st GMC Suburban | 1954 GMC 250 trailer puller project | 1954 GMC 250 Hydra-Matic | 1954 Chevy 3100 . 1947 Chevy COE | and more...
It's true. I really don't do anything but browse the Internet looking for trouble... | | |
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