# 3.73 or 3.91



## GTODAVE05 (Apr 29, 2005)

Hey guys just a quick q to throw out at ya? I have an 05 m6 and debating which gear to pick. Heard alot of people with the m6 running 3.91's and the auto guys running the 3.73's. Is this true and how much of a diff is between the 2 gears? Thx for your help and any inputs apprecited. I do run headers, full catback, lpe cai, tune and maybe a cam in the future!!


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## DrFix2Fly (Oct 27, 2004)

I'm not sure you can install either gear in our diffs. 3.91 is a hard ratio to make quiet and 3.73 may not be worth the expense from your current 3.46.


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## SloTymer (Sep 16, 2005)

DrFix2Fly said:


> I'm not sure you can install either gear in our diffs. 3.91 is a hard ratio to make quiet and 3.73 may not be worth the expense from your current 3.46.


Why is there a noise problem with 3.91 (when back lash is set right), I've been in camaros with 4.10 gears and no whine at all.:confused


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## DrFix2Fly (Oct 27, 2004)

4.10 is just fine and is a great truck gear. 3.91 is simply difficult to set up and keep quiet. Perhaps asking the opinion of a reputible shop would be a good idea.


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## gtoster (Jul 13, 2007)

The gear ratio doesn't matter as far as noise! It depends on WHO is doing it & if the Tech can get the correct shims & has patiences to set it up properly. & charge the owner accordingly. An inexpensive gear swap usually will equal noise.


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## koman (Sep 25, 2006)

i've only seen and heard about 3.91's as an upgrade maybe even advertised as the "ultimate gear change for goats" with the m6 i'd go for the 3.91 or so. find a good reputable shop or one the specializes in gears and knows how to read the wear pattern and set backlash for long life of the ring and pinion. i have a drivetrain whine now and everything is as it was straight from the factory....


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## svede1212 (Nov 1, 2005)

i have the 3.91s and they are GREAT. get the spring kit for the posi at the same time. the gears makes the car feel 500# lighter. to be honest my 3.46s were noisier. great for the track or street racing. i only pull 2k @ 70 mph so it's not too much of a hit on mileage. with lean cruise enabled it's the same mileage i got with the old setup


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## baaadgoat (Jul 25, 2007)

*4:10 Gears........*

Whats up guys, i just bought my goat about 3 months ago, and i am loving it. They have told me that Gears would be a great help at the dragstrip. Does anyone know about 4:10 gears ? Where would i be able to find them ? If not ,how about the 3:91? Thank You in advance guys.


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## svede1212 (Nov 1, 2005)

my review can be seen above your post and the only sets available for this rear end are the stock 3.46s or the 3.73s or 3.91s. 3.73s are better for autos and 3.91s are better suited to manuals. the first gear on these cars makes 4.10s pretty unnecessary. you'd have to get out of it before you started . another thing is the strength to hold 4.10s isn't there. i will note again . . . *get the spring upgrade kit if you're going to be putting in gears.* it will prevent the one legged take off. *Diff Technics* in Aussieland is where you get them but be sitting down. the uniqueness of our pig makes gears very expensive.


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## baaadgoat (Jul 25, 2007)

*NOS and Gears*

Hello guys, i have an 04 goat. i want to go with gears, and a shot of nitrous from ZEX ? is it good brand ? Now my question is, Do i need a heavy duty drive shaft and heavy cv joints if i put 3:91 ratio and 100 shot of nitrous ? 

Also how about Cams and Heads or Gears and Shoot ? \

What upgrade would be better ?


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## Monaro6MT (Jul 17, 2007)

svede1212 said:


> my review can be seen above your post and the only sets available for this rear end are the stock 3.46s or the 3.73s or 3.91s. 3.73s are better for autos and 3.91s are better suited to manuals. the first gear on these cars makes 4.10s pretty unnecessary. you'd have to get out of it before you started . another thing is the strength to hold 4.10s isn't there. i will note again . . . *get the spring upgrade kit if you're going to be putting in gears.* it will prevent the one legged take off. *Diff Technics* in Aussieland is where you get them but be sitting down. the uniqueness of our pig makes gears very expensive.


Hey Svede, so with the gears and the spring upgrade...how much would that cost me for that plus the installation? Is that all that needs to be up-graded if i want to swap out the gears? Thanks man, you're great help! :cheers


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