73-87chevytrucks.com
73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: kdime on October 10, 2011, 07:07:26 pm
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i only have three hwy gears and its eating up my fuel regardless of old man shifting/driving. at BEST i get maybe 14mpg @40-45mph. i know the 4.11 gears in frnt and rear dont help but i just want to get a tranny with 5gears (maybe 6? (nv5600?)) has anyone already done this? need help on cost and time spent (im doin this myself if i go that route)
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http://www.rhinoman.com/nv4500%20conversion.htm
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thanks i wasnt planning on spending that much though.. still in high school
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There are some people on here that have done the swap, have you used the search and looked through the threads on here ?
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i did but not thuroghly. not in a big hurry to do it just a future plan. i like to plan a head if you know what i mean..
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If you are getting 14 now, that upgrade may get you to 17 if you are lucky. Our trucks are not known for their aerodynamics. Unless you have a lot of disposable income you will probably spend more than you will ever recoup. You may be better off going numerically lower in gears to get the RPM's down. My $.02
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if and when iget to it im changing gears to 3.73 if not 3.42 (if i dont add a lift). that along with a .75 with o/d tranny gear is (i'm hoping) will get a lil more than 17... aerodynamics ::)? did GM even know what those were in 83? lol
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I'm in the middle of doing it. My truck is a 77 C20 and had the SM465. I wanted that OD for the highway too.
I found a 93-95 GM model with the 10 spline shaft for $500. I got the Advanced Adapters bellhousing for $370. New clutch $180. Crossover U-joint $30.
Now all I need is to get the driveshaft shortened.
I kept the old non-hydraulic linkage. If you allready have hydraulic you can use a GM bellhousing and be $$ ahead.
Good luck, BTW, it is one heavy transmission!!!!
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Thinking out loud through a keyboard (and probably shouldn't be)...
For a lot less than the cost of the transmission swap and gear swap you can put a propane system on your truck and save money on fuel with less engine wear and no cold start engine stumble to boot...
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One thing I've wondered about with this swap, is do you need to go to the 12" Clutch? And are the SM465's 10 Spine? I can't remember from when I had mine out last year.
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pre 85 sm465 are 10 while post 85 are 32. i dont know about the clutch but i would want it to match up as best as possible
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I ask cause my clutch is only about a year and a half old, and the truck barely saw any miles till I rolled my Yukon last year. Even now it doesn't see much. It'd be sweet if I can get the adaptor and trans and just throw it in there.