Gear ratio change

[express6.0]

Hi.

I plan to change the gear ratio on my Chevrolet Express 3500 2011 from 3.42 to 3.73 to haul my trailer. Does the stabilitrak and abs will still work, or will it need a new programming?

Thanks.

[Jsdirt]

At the very least you'll need a handheld tuner to make the correct changes to the ECU.

 

I have a Hypertech Power Programmer III for my Silverado that has this option. If you don't do this, the cluster will light up like a Christmas tree, and the transmission will slam shifts, all at the incorrect time. A total cluster****. 

[Doug_Scott]

I went from 3.23 to 4.10.  Only issue was speedometer and odometer.  This was 11 years ago on my 2010.  Jason at Blackbear fixed my speedo via the tune.  Drove it for a couple of months before the tune and had zero issues with drivability. 

[Jsdirt]

Interesting. I inputted the incorrect gear ratio in that Hypertech programmer, and my truck wigged out big time. It must change a bunch of stuff in addition to the speedo/odo calibration. I only went 2 miles, and I thought my driveline was going to snap! Friggin thing was shifting at the wrong time, and literally every single light in the cluster was on.

 

Never know how these friggin computers will react. They belong in a desktop or laptop - NOT in automobiles! 

Edited July 29, 2021 by Jsdirt

[Grumpy Bear]

2 hours ago, Jsdirt said:

Interesting. I inputted the incorrect gear ratio in that Hypertech programmer, and my truck wigged out big time. It must change a bunch of stuff in addition to the speedo/odo calibration. I only went 2 miles, and I thought my driveline was going to snap! Friggin thing was shifting at the wrong time, and literally every single light in the cluster was on.

 

Never know how these friggin computers will react. They belong in a desktop or laptop - NOT in automobiles! 

 

They get to cute with them. Kids that can't keep their mitts out of the cookie jar. 

[JimV]

2011 Avalanche

I went from 3:08 to 4:10. Huge Improvement in drive ability and towing. I changed the speedo with Hyper tech and was ok but trans shifting was off and soft. I tuned with Black Bear and now is great. Shifts great and much more power Now I drive in D instead of manually holding in gears to stop the constant shifting up and down. Tow  mode better too. I tow a 7000 trailer and in 5th at 60 is about 2200 RPM.

I would definitely change the gears and tune again.

2200 RPM at 70 in 6th with 17 inch tires

Also installed Derale trans cooler with fan cause the trans runs hot in these even with no load in the mountains etc. Put it between the grill and radiator tight fit but works good.