2019 Transmission and Axle Ratios

[HondaHawkGT]

2 hours ago, Whiz said:

Been that route with two GM dealers here, and no one can give me the exact part numbers I need.  I've been told 8.25/8.6, and now a few minutes ago 4 Wheel Parts Inc says GM used the 9.5 and 8.25 "since 2006".  

 

Am a bit gun shy to order in a set for ft & rr a=nly to have it on the hoist with incorrect size(s).  

 

I'll keep checking and, if possible, tap a GM tech with GM whose know EXACTLY what is needed.

 

I worked in a GM parts department many years ago my senior year of college,  so I know that one can be wrong particularly with a brand new body style and thre rumors that GM is now using a proprietary front differential.

 

Have you tried talking to a place like East Coast Gear Supply? There's always a chance that they have information on the 2019 axles. Make sure you have a way to take care of the speedometer/ABS issues that will come up after you re-gear.

[Whiz]

Thanks, I will give them a call on Monday.

 

I have programmers for all my Chevy's, so recalibration of speedo is not a problem, but wise words for other who may consider similar options.

 

 

[yankeedoodle86]

Which transmission and axle ratio should I get if I want to lift it and put 35" tires on it (without changing the axle ratio)? I'm assuming these calculations are with standard tire sizes.
 
Thanks

You don’t need the max tow. I have a 2019 RST with a BDS 6” and 35” ATZ and I can still burn em down. Power loss is minimal but I don’t tow with this truck. I have the 8L90 and 3.23 and I have no regrets.


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[AJMBLAZER]

8.25” front diff and 9.5” rear diff. Unless you have the MaxTow then you have the 9.76” rear. 

[flyingfool]

if you want to run a 35 tire, you need 3.73 rear gears at minimum, and 4.10 at best

[Whiz]

Thanks for the info.

[yankeedoodle86]

if you want to run a 35 tire, you need 3.73 rear gears at minimum, and 4.10 at best

You shouldn’t spread misinformation. People get hung up on gear ratios and not the final drive. Yes 3.73 was necessary when we had 6 speed transmissions.

We now have advanced 8 speeds and air conditioning....no need for 3.73 gears. Why do you think the max tow comes with 3.42? Look at the charts.


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[flyingfool]

30 minutes ago, yankeedoodle86 said:

 

You shouldn’t spread misinformation. People get hung up on gear ratios and not the final drive. Yes 3.73 was necessary when we had 6 speed transmissions.

We now have advanced 8 speeds and air conditioning....no need for 3.73 gears. Why do you think the max tow comes with 3.42? Look at the charts.


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well  6spd vs 8 speed 1-2 forward gears... are almost identical 3.72vs 3.42. but still torque gain is far better with a 3.72 in the 8speed , better off the line stop and go city driving with 35" tires 

Edited July 6, 2019 by flyingfool

[yankeedoodle86]

what's the difference in 6spd vs 8 speed 1-2 forward gears... ?

Go to the top of this thread and look at the charts. That information can be and has been confirmed by GM.


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[flyingfool]

i did

[MeBunkerYou]

Is there any way to tell what ratio a truck has besides the build sheet or what salesman says? They don't put the rpo codes in glove box anymore? Or whether it has the max trailing package? Thanks

[yankeedoodle86]

Is there any way to tell what ratio a truck has besides the build sheet or what salesman says? They don't put the rpo codes in glove box anymore? Or whether it has the max trailing package? Thanks

RPO is in the drivers door now


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[Resolved1LE]

Seems like this thread died but I’m trying to revive it, I have a 2020 6.2 with 10 speed but trying to wrap my head because I’m in love with the 37x13.5 wheels and tires and hoping the 10 speed behind the 6.2 will help the 37’s especially since I tow!?!?!?