Axle ratio swap?

Driver72 · December 3, 2016

Just curious has anybody with a 6.2 V8 and a 4x4 with the 3.23's swapped for the max trailer packages 3.42's?

Or if GM offers a lower ratio (like 3.55) swapped to it?

How'd it go?

Cost from GM including labor?

Thanks

07Softail · December 3, 2016

GM offers 3.73's for your axle.

RT

Driver72 · December 3, 2016

GM offers 3.73's for your axle.

RT

Nice, that may be too low though. Anything between the 3.42's and the 3.73's?

If not, I'll have to see what the 3.42 swap would cost. I'm guessing in the $1,000-1,200 range with parts and labor.

But I'm going to go from the 32" stock tires to 33" and wouldn't mind offsetting those taller tires with a lower axle ratio. But 3.42's aren't that much different than 3.23's

If they had something in the 3.55 range that would be ideal.

TJay74 · December 3, 2016

The 8spd auto has a lot lower 1st gear than the 6spd auto. Also I know you know that both diffs will need to be updated, but have you also sorted out the custom programming you will need in order to address the gearing change in the computers? The dealer and GM cant help you at all in this area.

Driver72 · December 3, 2016

The 8spd auto has a lot lower 1st gear than the 6spd auto. Also I know you know that both diffs will need to be updated, but have you also sorted out the custom programming you will need in order to address the gearing change in the computers? The dealer and GM cant help you at all in this area.

Yes, as you mentioned, I was aware both diffs will need swapping. Since my truck is still brand new (340 miles) often they can reuse many of the parts to save money and just swap out the needed parts for the gears.

GM doesn't support the axle ratio swap for reprogramming?

I was going to do this when I found a Ram Laramie 4x4 I wanted but it had the lame 3.21 gears in the 8 speed auto (with it's stock 33" tires, that would be equal to about 3.10 gears in the GM) in favor of the 3.55's or 3.93's.

Ram dealer said they'd do it on a new truck for about $700 parts and $600 labor all in, fully warrantied.

I ended up just ordering the Ram I wanted with the 3.93's instead and waiting the 8-9 weeks.

I figured GM would do the same for similar price. Wouldn't know why they wouldn't be able to reprogram ECU through GM so it had the right gearing/speedo, etc.??

wuznme · December 3, 2016

The dealers don't do that kind of stuff, they have to stick with what the tech line supplies them. If they need a new calibration file it comes from GM and that's not happening for a gear ratio change.

From 3.23 you can go to

3.42

3.73

4.10

You won't be getting it done that cheap from a dealer if they do it at all, parts front and rear from online is $800ish but then you have local shops that won't install parts they didn't supply. So now your parts are $1k-$1100 and about 15hours labor (book anyways)

I've been quoted $2200 by 3 different shops and $3000 from 1 but that was to stuff complete 9.5 in so I could get a TrueTrac since they don't make a G80 replacement for the 9.76 axle (you have this)

Driver72 · December 3, 2016

The dealers don't do that kind of stuff, they have to stick with what the tech line supplies them. If they need a new calibration file it comes from GM and that's not happening for a gear ratio change.

From 3.23 you can go to

3.42

3.73

4.10

You won't be getting it done that cheap from a dealer if they do it at all, parts front and rear from online is $800ish but then you have local shops that won't install parts they didn't supply. So now your parts are $1k-$1100 and about 15hours labor (book anyways)

I've been quoted $2200 by 3 different shops and $3000 from 1 but that was to stuff complete 9.5 in so I could get a TrueTrac since they don't make a G80 replacement for the 9.76 axle (you have this)

Good grief.

Well I guess it's just another thing GM needs to get with the times with. That's ridiculous pricing and totally unneeded hassles for a simple gear swap.

Thanks for the info. though.

Donstar · December 5, 2016

I don't see where GM needs to "get with the times with". My problem is understanding what tasks a 6.2 with a 3.23 (6 or 8 spd.) is unable to accomplish. Maybe enlightening us as to what you wish to accomplish may bring out some other methods of achieving your goal.

Driver72 · December 5, 2016

By get with the times, I meant simply, when I spoke to Ram swapping gears in my 4x4 it was a $1,300 Ram warrantied service, no issues.

From what I received above with GM it's twice that cost and apparently GM doesn't allow the dealer to flash your ECU to reprogram it to the new warrantied GM axle ratio.

I'm adding 1" taller tires on and was inquiring because I was thinking having the 3.42's on the stock truck would of been great but I got a truck without the Max Trailer Tow package, so no 3.42's.

The 3.23's are ok, but adding 1" taller tires will effectively put the rear axle ratio at like 3.10 now.

So the thought was, by going to the 3.42's at least it would offset the 1" taller tires AND be slightly lower overall than the stock 3.23's on stock wheels.

This way effectively with the 3.42 (or if they have 3.5x's gears) and the 1" taller tires I'd have a rear axle ratio of around 3.30:1.

It's not a major issue, the 6.2 with the 3.23's to be honest just feels a bit soft down low at initial throttle tip in and light throttle application.

And I know people may bash me for saying that, but I'm just being honest. Our family hauler is a Honda Odyssey Elite minivan and it has a better throttle tip in and light throttle application feel. Leaving a light under normal throttle application the Honda feels faster than the Sierra. I feel, and know, I have to give the Sierra more throttle to keep up with the Honda in normal "go with the traffic flow" acceleration.

Granted, I'm also coming from a Hellcat, but I also remember my Ram Laramie's having more gusto on light throttle. Both the 3.55 gear one and especially the 3.92 axle. Sure the 6.2 is faster than the Ram's 5.7, but the gearing down low and the torque down low of the Ram feels stronger. The Sierra will walk past the Ram when booting it for sure, that I know. Again, it's just the throttle mapping and gearing of the 6.2 with the 3.23's which are a bit soft down low.

I don't want to spend $2,500 and a whole issue with GM just to get the axle ratio changed.

If they had a 3.5x ratio and it was $1,300 all in at the dealer with warranty and easy ECU reprogramming, I would of probably done it.

I'll just learn to give the Sierra a touch more throttle when leaving from a stop in normal driving. No real biggie.

Thanks

truckguy82 · December 5, 2016

It's mostly the torque management, not the axle ratio giving you that feeling.

A tune, or a throttle controller will likely give you the result your looking for.

1st gear feels like getting rear ended by a train

My 6speed + 3.42's is probably about the same 1st gear net ratio as your 8 speed + 3.23

Driver72 · December 5, 2016

It's mostly the torque management, not the axle ratio giving you that feeling.

A tune, or a throttle controller will likely give you the result your looking for.

1st gear feels like getting rear ended by a train

My 6speed + 3.42's is probably about the same 1st gear net ratio as your 8 speed + 3.23

I have tuned many many of my cars in the past and one of the things they almost all do is adjust throttle mapping.

Sometimes they make them TOO touchy (like stock Infiniti's are....way to touchy car's leap forward with barely resting your foot on it) other times the tunes make them perfect.

This is my very first new GM product, have owned so many others just never a GM before. And from what i'm reading GM has become pretty hard core with finding tunes. So, adding a tuner just for throttle response, if they find it I don't want the powertrain warranty voided.

Does GM offer a dealer installed tune like some other manufacturers do and support them as warrantied?

If they do, I'd gladly have them adjust my throttle mapping so I don't feel like I have to push the throttle down an inch or so of travel just to get moving as fast as I do in my family hauler minivan when I give it 1/2 inch of throttle travel.

I was at a light the other day along side a guy in a 15 year old Chevy Trailblazer. When the light went green, I started pushing the throttle normally and he leaped forward on me with ease. I've notice this on many occasions now with other cars and I'm having to start recalibrating my foot to give more throttle in the Sierra when I leave a light just to stay up with traffic. Then if I jump in the Honda Odyssey and do the same with the throttle I leap forward like I'm trying to race the car next to me. LOL

Again, if they don't no biggie, I'll just have to remember when I'm in the Sierra to use a bit more throttle or risk being the guy holding up traffic as the other cars in the lanes next to me pull away quicker, and I refuse to be that guy, I'm decades away from that.

TJay74 · December 5, 2016

Even if a GM dealer does the work, it will not be a GM factory warrantied part down the road. It will carry the dealers 12 month / 12k mile warranty. GM will only warranty the truck as it was built the day it left the factory, any changes to it other than the factory built will result in those parts not being under warranty any further.

As said, no GM does not offer any type of modification to the factory calibration file thru the dealer, aftermarket only.

truckguy82 · December 6, 2016

I have tuned many many of my cars in the past and one of the things they almost all do is adjust throttle mapping.

Sometimes they make them TOO touchy (like stock Infiniti's are....way to touchy car's leap forward with barely resting your foot on it) other times the tunes make them perfect.

This is my very first new GM product, have owned so many others just never a GM before. And from what i'm reading GM has become pretty hard core with finding tunes. So, adding a tuner just for throttle response, if they find it I don't want the powertrain warranty voided.

Does GM offer a dealer installed tune like some other manufacturers do and support them as warrantied?

If they do, I'd gladly have them adjust my throttle mapping so I don't feel like I have to push the throttle down an inch or so of travel just to get moving as fast as I do in my family hauler minivan when I give it 1/2 inch of throttle travel.

I was at a light the other day along side a guy in a 15 year old Chevy Trailblazer. When the light went green, I started pushing the throttle normally and he leaped forward on me with ease. I've notice this on many occasions now with other cars and I'm having to start recalibrating my foot to give more throttle in the Sierra when I leave a light just to stay up with traffic. Then if I jump in the Honda Odyssey and do the same with the throttle I leap forward like I'm trying to race the car next to me. LOL

Again, if they don't no biggie, I'll just have to remember when I'm in the Sierra to use a bit more throttle or risk being the guy holding up traffic as the other cars in the lanes next to me pull away quicker, and I refuse to be that guy, I'm decades away from that.

Vittesse throttle controller

Not a tune but the vette guys seem to like it

Pretty sure it is completely untraceable and is doesn't change anything, just gives you a "faster" foot

Driver72 · December 6, 2016

Vittesse throttle controller

Not a tune but the vette guys seem to like it

Pretty sure it is completely untraceable and is doesn't change anything, just gives you a "faster" foot

Thanks a bunch, I'll look into it.

**Edit: Checked it out, gonna ask others for review on this for the trucks. Thanks man.**

Driver72 · December 6, 2016

And found this thread. Apparently I'm not the only one who noticed this issue with the GM trucks. LOL

http://www.gm-trucks.com/forums/topic/172206-throttle-response-on-62/page-1?hl=vitesse

As I stated stock my Honda Odyssey feels like it'll beat the 6.2 off the line with just giving it 1" push down on the throttle. Matter of fact, I KNOW the Odyssey minivan would. The 6.2 feels like a slug under mild throttle application. One guy in the above thread says he thinks the 6.2 feels like a 4 cylinder under light throttle.

I thought about it and clearly GM probably does it for MPG's. Figuring if people use light throttle they'll get better gas mileage. But I think it works the opposite. You end up pushing the gas down more, and more often to go quicker when it's so F-in lazy. If GM wants to program their throttle so sluggish, have an "ECO" button on the dash for people who want to drive it like this, otherwise tune it normal for everyone else.

Seems I'm going to have to get one of these Vitesse throttle controllers to make the throttle response be like every other auto I've driven, and i'm not the last person across the intersection under light throttle application.

Thanks again Truckguy for the heads up.