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05-20-2016, 06:15 PM
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#1 |
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Registered User
 Join Date: May 2009
Location: Longmont, Colorado
Posts: 84
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3.42 to 3.73 swap
I have a nice set of 1/2 ton axles that have 3.73 gears in them. I currently have 3.42s in the truck now. I have 33" tall tires and the 3.42s seem to be a good fit. Is there going to be much of a difference going to the 3.73s? I do plan on going to a 35" tire once I get around to installing my lift. I need to do some front end work to the truck but dont want to do it if im going to do this swap.
Any opinions? |
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05-20-2016, 06:23 PM
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#2 |
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Registered User
Join Date: Nov 2015
Location: Ionia Michigan
Posts: 336
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Re: 3.42 to 3.73 swap
I wouldn't bother. Escpecially with a 35. IMO, i'd run 4.56's with 35's. If you're going to do it, do it, otherwise, do nothing, it's free lol.
= ( | 3.42 - 3.73 | / ((3.42 + 3.73)/2) ) * 100 = ( | -0.31 | / (7.15/2) ) * 100 = ( 0.31 / 3.575 ) * 100 = 0.086713 * 100 = 8.6713% difference
__________________
J.R. Link to Daryl's build, http://67-72chevytrucks.com/vboard/s...10#post8443010 Link to my Youtube channel with build info, https://www.youtube.com/thedrivewayengineer |
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05-20-2016, 07:15 PM
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#3 |
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Registered User
Join Date: Aug 2005
Location: Louisiana
Posts: 711
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Re: 3.42 to 3.73 swap
You have the differentials. All it will cost you is time.
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05-23-2016, 03:08 PM
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#4 | |
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Senior Member
Join Date: Jul 2000
Location: North Texas
Posts: 3,599
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Re: 3.42 to 3.73 swap
Quote:
 Another way to look at it 3.73 is 9.1% more than 3.42, so RPMs at any given road speed will be 9.1% higher with the 3.73 gears.
__________________
Mike 1969 C10 LWB -- owned for 35 years. 350/TH350, 3.08 posi, 1st Gen Vintage Air, recent AAW wiring harness, 5-lug conversion, 1985 spindles and brakes. 1982 C10 SWB -- sold 1981 C10 Silverado LWB -- sold, but wish I still had it! 1969 C10 (not the current one) that I bought in the early 1980s. Paid $1200; sold for $1500 a few years later. Just a hint at the appreciation that was coming. Retired as a factory automation products salesman. Worked part-time over the years for an engine builder and a classic car repair shop. Member here for 24 years! This is the very first car/truck Internet forum I joined. I still used a dial-up modem back then! |
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05-20-2016, 10:32 PM
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#5 |
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Registered User
Join Date: Nov 2008
Location: Gwinnett GA
Posts: 1,803
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Re: 3.42 to 3.73 swap
200 RPM difference at speed. It's up to you. I'd keep em on the shelf as "spares"
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1982 K10 SWB 1987 V20 - Sold - Doh! |
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05-21-2016, 04:12 PM
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#6 |
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I know the pieces fit
Join Date: Nov 2007
Location: MONTGOMERY, AL
Posts: 5,523
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Re: 3.42 to 3.73 swap
I did this swap and it made more difference than you would think. I went from 3.40's in my 79 to 3.73's. Mine's a 2wd on 28" tires. If you are going to 35's I would for sure since you already have them.
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