Gears for Suburban 2011

[Suburbanbeast]

Hi Everyone I have a couple of questions about gears on a 2011 Suburban 7.5 rough country lift with 35x12.5.20s and the 5.3. I am having a hard time cruising at 75 on the highway it keeps down shifting to 5th and staying at 3k rpms. So I was thinking of switching gears to a 4.10 to help the trans out currently 3.08s. I got some estimates from some local shops $2900 to $3200 for front and rear with parts.

I found a front dif from a 08 tahoe on ebay with 4.10s but it says it will not fit my 11 suburban is that correct? what changed between 08 and 11? Is it because of the 6 speed trans? If I could get the front dif cheap and just swap it in that could save alot of cash. Also looking at maybe finding a rear axle from a GT5 option and swapping it in also.

Thanks everyone for the help

 

[Suburbanbeast]

Has anyone lifted their rigs and changed gears?

 

[wjburken]

Might check out the chart at the link below to see what you need for a gear ratio based on tire size. My guess is with your larger tires, you need at least 4:10’s, if not taller gears.

https://auto.howstuffworks.com/auto...wing/maneuvers/gear-ratio-tire-size-chart.htm

 

[iamdub]

Hi Everyone I have a couple of questions about gears on a 2011 Suburban 7.5 rough country lift with 35x12.5.20s and the 5.3. I am having a hard time cruising at 75 on the highway it keeps down shifting to 5th and staying at 3k rpms. So I was thinking of switching gears to a 4.10 to help the trans out currently 3.08s. I got some estimates from some local shops $2900 to $3200 for front and rear with parts.

I found a front dif from a 08 tahoe on ebay with 4.10s but it says it will not fit my 11 suburban is that correct? what changed between 08 and 11? Is it because of the 6 speed trans? If I could get the front dif cheap and just swap it in that could save alot of cash. Also looking at maybe finding a rear axle from a GT5 option and swapping it in also.

Thanks everyone for the help

Ouch- 3.08 and 35s

Doing the math, 3.36 gears would put it back to "stock". Since this isn't a stock gear option, 3.42s are the choice for this. For a little extra grunt to help move the weight, the next size up of 3.73 would probably be my choice if I did a lot of highway driving. If you go too high, then you're still spinning higher RPM unnecessarily on the highway, you'll just be doing it in 6th gear. Although, the difference between 3.73 and 4.10 isn't a whole lot. It'll have plenty of snap off the line and be nice around town, but you'll trade a little fuel economy on the highway. If you know for sure that you'll never go smaller than 35s, 4.10s would be nice.

Anyway, I don't know about the front dif differences, if any, between the years. I would assume because of the 6L80, but even that doesn't make much sense.

 

[Suburbanbeast]

Thanks 4.56s probably be the best but trying do this budget/ wife friendly. If I could get away with some parts from a salvage yard I think would be great money saver I don’t think GM ever put 4.56s in a half ton.

 

[Suburbanbeast]

Ouch- 3.08 and 35s

Doing the math, 3.36 gears would put it back to "stock". Since this isn't a stock gear option, 3.42s are the choice for this. For a little extra grunt to help move the weight, the next size up of 3.73 would be my choice if I did a decent amount of highway driving. If you go too high, then you're still spinning higher RPM unnecessarily on the highway, you'll just be doing it in 6th gear. It'd be all low-end power and wind out up top.

let me see what’s out there for 3.73 thanks. If I have to have a shop do this was the price above high or is that the going rates.

 

[George B]

let me see what’s out there for 3.73 thanks. If I have to have a shop do this was the price above high or is that the going rates.

3.73 is a nice ratio and I think it would work well with the 6 speed.

 

[iamdub]

Might check out the chart at the link below to see what you need for a gear ratio based on tire size. My guess is with your larger tires, you need at least 4:10’s, if not taller gears.

https://auto.howstuffworks.com/auto...wing/maneuvers/gear-ratio-tire-size-chart.htm

I almost posted up the same chart. lol

I decided it was kinda irrelevant since it calculates on 1:1 ratio.

 

[iamdub]

Thanks 4.56s probably be the best but trying do this budget/ wife friendly. If I could get away with some parts from a salvage yard I think would be great money saver I don’t think GM ever put 4.56s in a half ton.

I think 4.56 would be too much. In 6th gear at 70MPH, the difference between a 32" tire with 3.08 and a 35" tire with a 4.10 is about 300RPM. 35" with 3.73 is about 150RPM. 35" with 3.42 is about 20RPM.

That 300RPM is probably nothing you'd ever notice. Aside from the numerical sizes, the extra weight of the larger tires (and wheels?) dictates more gearing. So, 4.10s are the better choice unless you do mostly highway driving and you want every last tenth of fuel economy.

 

[Suburbanbeast]

Okay does anyone know if the Silverado front diff is Interchangeable with the suburban?