Gear Ratio Question

TheUnforgotten06 · October 18, 2008

I was just wondering if someone would know how big of a difference in 0-60mph it makes in having a 3.73 axle over a 3.42 axle. I have the 3.42 and even with my mods Im not happy at all with my acceleration...so I was wondering if it was my gear ratio thats holding me back. I contacted GMC and they said that the difference in the two as far as gas mileage goes is less than 1 mpg, so i think id take the acceleration and pulling power over the 1 mpg. GMC could not answer me as far as 0-60. So if it makes that big of a difference should I take the chance in possibly voiding my warranty and getting a differential change???

thecraft · October 18, 2008

What size are your tires?

TheUnforgotten06 · October 18, 2008

275/55/20....

thecraft · October 18, 2008

It's the gears, those tires are just too big for 3.42s in a fullsize truck, IMO.

If I were you, I'd seriously consider 4.10 gears as well.

TheUnforgotten06 · October 18, 2008

Well I just tested my 0-60 and its a 8.90. I think with what I have on it so far it could be somewhat better. I talked to my service dept. and they were gonna charge me $400 (labor). And they said if something should fail on my drivetrain it wouldnt be covered under my warranty which is still very young...I only have 1898 miles on my truck. I found another place that will probably be cheaper and I want that extra get up and go! I have no clue what to do.

jbannick18 · October 18, 2008

Well I just tested my 0-60 and its a 8.90. I think with what I have on it so far it could be somewhat better. I talked to my service dept. and they were gonna charge me $400 (labor). And they said if something should fail on my drivetrain it wouldnt be covered under my warranty which is still very young...I only have 1898 miles on my truck. I found another place that will probably be cheaper and I want that extra get up and go! I have no clue what to do.

I've been looking into getting he 3.73 gears as well. As far as them saying it wouldn't be covered by your warranty they are bullshitting you. As long as its gm parts and done at a gm dealer it will be covered, I would go ahead and talk to them again. I haven't found out what it would cost me but I was hoping it wouldn't be 400 lol

TheUnforgotten06 · October 18, 2008

I just need to know if it would make a big enough of a difference for the pros and cons I will have....

Pros: Finding the powerband easier, better towing, and increased acceleration.

Cons: No warranty coverage if drivetrain fails, slightly less gas mileage, spending alot of money on something that is a $100 factory option, spending additional money on a tune to tell my computer i changed my gear ratio.

Any comments will be appreciated!

TheUnforgotten06 · October 18, 2008

Well I just tested my 0-60 and its a 8.90. I think with what I have on it so far it could be somewhat better. I talked to my service dept. and they were gonna charge me $400 (labor). And they said if something should fail on my drivetrain it wouldnt be covered under my warranty which is still very young...I only have 1898 miles on my truck. I found another place that will probably be cheaper and I want that extra get up and go! I have no clue what to do.

I've been looking into getting he 3.73 gears as well. As far as them saying it wouldn't be covered by your warranty they are bullshitting you. As long as its gm parts and done at a gm dealer it will be covered, I would go ahead and talk to them again. I haven't found out what it would cost me but I was hoping it wouldn't be 400 lol

Yeah i found some 3.73's that came out of 2008 Denali and they were dirt cheap. So i called my service dept. and asked them what the labor would be and they stated $400...thats why i was considering a different shop. He also stated it wouldnt make a big difference....I think that is . He also stated that if something on my drivetrain would fail it wouldnt be covered by warranty because my VIN states I have a 3.42 and Id have a 3.73. They are so strict on those warranties.

jbannick18 · October 18, 2008

Well I just tested my 0-60 and its a 8.90. I think with what I have on it so far it could be somewhat better. I talked to my service dept. and they were gonna charge me $400 (labor). And they said if something should fail on my drivetrain it wouldnt be covered under my warranty which is still very young...I only have 1898 miles on my truck. I found another place that will probably be cheaper and I want that extra get up and go! I have no clue what to do.

I've been looking into getting he 3.73 gears as well. As far as them saying it wouldn't be covered by your warranty they are bullshitting you. As long as its gm parts and done at a gm dealer it will be covered, I would go ahead and talk to them again. I haven't found out what it would cost me but I was hoping it wouldn't be 400 lol

Yeah i found some 3.73's that came out of 2008 Denali and they were dirt cheap. So i called my service dept. and asked them what the labor would be and they stated $400...thats why i was considering a different shop. He also stated it wouldnt make a big difference....I think that is . He also stated that if something on my drivetrain would fail it wouldnt be covered by warranty because my VIN states I have a 3.42 and Id have a 3.73. They are so strict on those warranties.

Hmmmm, I would call up GMC and ask them directly might be the dealer just bs'ing. I have 3.23's right now >< so I figure the 3.73's would make a big difference in mine. Also from reading this boards you should look into a custom tune, heard alot of good things about blackbear

TheUnforgotten06 · October 18, 2008

Well I just tested my 0-60 and its a 8.90. I think with what I have on it so far it could be somewhat better. I talked to my service dept. and they were gonna charge me $400 (labor). And they said if something should fail on my drivetrain it wouldnt be covered under my warranty which is still very young...I only have 1898 miles on my truck. I found another place that will probably be cheaper and I want that extra get up and go! I have no clue what to do.

I've been looking into getting he 3.73 gears as well. As far as them saying it wouldn't be covered by your warranty they are bullshitting you. As long as its gm parts and done at a gm dealer it will be covered, I would go ahead and talk to them again. I haven't found out what it would cost me but I was hoping it wouldn't be 400 lol

Yeah i found some 3.73's that came out of 2008 Denali and they were dirt cheap. So i called my service dept. and asked them what the labor would be and they stated $400...thats why i was considering a different shop. He also stated it wouldnt make a big difference....I think that is . He also stated that if something on my drivetrain would fail it wouldnt be covered by warranty because my VIN states I have a 3.42 and Id have a 3.73. They are so strict on those warranties.

Hmmmm, I would call up GMC and ask them directly might be the dealer just bs'ing. I have 3.23's right now >< so I figure the 3.73's would make a big difference in mine. Also from reading this boards you should look into a custom tune, heard alot of good things about blackbear

See thats the bad thing, I spoke to the manager of the service dept. Yeah i was signed up for the Dallas Blackbear tune in December but because of my job I cant make it unfortunately...I sent my deposit and everything I was ready to go! But now its the damn gear ratio Im contemplating over.

jbannick18 · October 18, 2008

Well I just tested my 0-60 and its a 8.90. I think with what I have on it so far it could be somewhat better. I talked to my service dept. and they were gonna charge me $400 (labor). And they said if something should fail on my drivetrain it wouldnt be covered under my warranty which is still very young...I only have 1898 miles on my truck. I found another place that will probably be cheaper and I want that extra get up and go! I have no clue what to do.

I've been looking into getting he 3.73 gears as well. As far as them saying it wouldn't be covered by your warranty they are bullshitting you. As long as its gm parts and done at a gm dealer it will be covered, I would go ahead and talk to them again. I haven't found out what it would cost me but I was hoping it wouldn't be 400 lol

Yeah i found some 3.73's that came out of 2008 Denali and they were dirt cheap. So i called my service dept. and asked them what the labor would be and they stated $400...thats why i was considering a different shop. He also stated it wouldnt make a big difference....I think that is . He also stated that if something on my drivetrain would fail it wouldnt be covered by warranty because my VIN states I have a 3.42 and Id have a 3.73. They are so strict on those warranties.

Hmmmm, I would call up GMC and ask them directly might be the dealer just bs'ing. I have 3.23's right now >< so I figure the 3.73's would make a big difference in mine. Also from reading this boards you should look into a custom tune, heard alot of good things about blackbear

See thats the bad thing, I spoke to the manager of the service dept. Yeah i was signed up for the Dallas Blackbear tune in December but because of my job I cant make it unfortunately...I sent my deposit and everything I was ready to go! But now its the damn gear ratio Im contemplating over.

Damn, well maybe someone who works with gm or knows more about it can chime in, I know the first time I called the person I talked to didn't even know they could change the gear ratio's lol.

TheUnforgotten06 · October 18, 2008

Well I just tested my 0-60 and its a 8.90. I think with what I have on it so far it could be somewhat better. I talked to my service dept. and they were gonna charge me $400 (labor). And they said if something should fail on my drivetrain it wouldnt be covered under my warranty which is still very young...I only have 1898 miles on my truck. I found another place that will probably be cheaper and I want that extra get up and go! I have no clue what to do.

I've been looking into getting he 3.73 gears as well. As far as them saying it wouldn't be covered by your warranty they are bullshitting you. As long as its gm parts and done at a gm dealer it will be covered, I would go ahead and talk to them again. I haven't found out what it would cost me but I was hoping it wouldn't be 400 lol

Yeah i found some 3.73's that came out of 2008 Denali and they were dirt cheap. So i called my service dept. and asked them what the labor would be and they stated $400...thats why i was considering a different shop. He also stated it wouldnt make a big difference....I think that is . He also stated that if something on my drivetrain would fail it wouldnt be covered by warranty because my VIN states I have a 3.42 and Id have a 3.73. They are so strict on those warranties.

Hmmmm, I would call up GMC and ask them directly might be the dealer just bs'ing. I have 3.23's right now >< so I figure the 3.73's would make a big difference in mine. Also from reading this boards you should look into a custom tune, heard alot of good things about blackbear

See thats the bad thing, I spoke to the manager of the service dept. Yeah i was signed up for the Dallas Blackbear tune in December but because of my job I cant make it unfortunately...I sent my deposit and everything I was ready to go! But now its the damn gear ratio Im contemplating over.

Damn, well maybe someone who works with gm or knows more about it can chime in, I know the first time I called the person I talked to didn't even know they could change the gear ratio's lol.

Wow!

What I would like to know first of all is if it will be like a .1 second change on 0-60 or something like .8 seconds. If its just a fraction of a increase I probably wont even bother...Technically its a one tooth change on the smaller gear, the 3.73 consists of a 41 tooth and a 11 tooth, the 3.42 consists of a 41 tooth and a 12 tooth.

jrrod2004 · October 18, 2008

Wow!
What I would like to know first of all is if it will be like a .1 second change on 0-60 or something like .8 seconds. If its just a fraction of a increase I probably wont even bother...Technically its a one tooth change on the smaller gear, the 3.73 consists of a 41 tooth and a 11 tooth, the 3.42 consists of a 41 tooth and a 12 tooth.

Damn all the replys to the replys!!!!

go to 4.10s instead of the 3.73s (unless you really do a lot of highway driving)

Outbacker · October 18, 2008

Damn all the replys to the replys!!!!

go to 4.10s instead of the 3.73s (unless you really do a lot of highway driving)

I agree. Look to the 4.10 as opposed to the 3.73. A lot better towing power and torque, and if you are going to spend the $$ to get it done, may as well go one step farther. And I agree that if a GM shop is going to supply the material and install it, how can it void a warranty? Does not make sense.

TheUnforgotten06 · October 18, 2008

Wow!
What I would like to know first of all is if it will be like a .1 second change on 0-60 or something like .8 seconds. If its just a fraction of a increase I probably wont even bother...Technically its a one tooth change on the smaller gear, the 3.73 consists of a 41 tooth and a 11 tooth, the 3.42 consists of a 41 tooth and a 12 tooth.

Damn all the replys to the replys!!!!

go to 4.10s instead of the 3.73s (unless you really do a lot of highway driving)

...Yeah i noticed they were getting kinda long...thanks for breaking them up! lol Yeah i do a bit of highway driving getting to and from my air base, 3 hours straight to get there one week and 3 hours straight the next week to get back.