Diff swap and a traction control issue?

[JKaechler]

This weekend i took the G80 locker out from under my 2011 Tahoe LT 4x4! Hooray no more gov-bomb! Now it has an Eaton TrueTrac.

I hit one snag.
When I did my test startup and spin the wheels with the rear end still up on jackstands, I suddenly had a Traction Control light and the system hit the brakes. This happened several times in a row, I switched off the TCS by pressing the button and was able to verify that mechanically everything was ok.

What followed was an hour or so of mild panic, googling TCS issues, and pulling sensors to see if damaged..... . . . . .

Then it hit me: "Traction Control" ... the front tires are on the ground and stationary, the back tires are trying to spin. Of course that would make the TCS go bananas.
After I buttoned everything up I did a brief test drive and all seems to be well.

Am I right on this? Having the rear axle in the air and putting it in drive will make the TCS engage?

 

[wjburken]

This weekend i took the G80 locker out from under my 2011 Tahoe LT 4x4! Hooray no more gov-bomb! Now it has an Eaton TrueTrac.

I hit one snag.
When I did my test startup and spin the wheels with the rear end still up on jackstands, I suddenly had a Traction Control light and the system hit the brakes. This happened several times in a row, I switched off the TCS by pressing the button and was able to verify that mechanically everything was ok.

What followed was an hour or so of mild panic, googling TCS issues, and pulling sensors to see if damaged..... . . . . .

Then it hit me: "Traction Control" ... the front tires are on the ground and stationary, the back tires are trying to spin. Of course that would make the TCS go bananas.
After I buttoned everything up I did a brief test drive and all seems to be well.

Am I right on this? Having the rear axle in the air and putting it in drive will make the TCS engage?

Doesn’t surprise me. Traction control looks at the speed of all the wheels and if one is going faster than the others, I would think it will think there is wheel slippage and engage traction control measures.

 

[iamdub]

This weekend i took the G80 locker out from under my 2011 Tahoe LT 4x4! Hooray no more gov-bomb! Now it has an Eaton TrueTrac.

I hit one snag.
When I did my test startup and spin the wheels with the rear end still up on jackstands, I suddenly had a Traction Control light and the system hit the brakes. This happened several times in a row, I switched off the TCS by pressing the button and was able to verify that mechanically everything was ok.

What followed was an hour or so of mild panic, googling TCS issues, and pulling sensors to see if damaged..... . . . . .

Then it hit me: "Traction Control" ... the front tires are on the ground and stationary, the back tires are trying to spin. Of course that would make the TCS go bananas.
After I buttoned everything up I did a brief test drive and all seems to be well.

Am I right on this? Having the rear axle in the air and putting it in drive will make the TCS engage?

100% was your problem. You didn't break anything but your stride. When I use my Tahoe as a lathe (don't ask), I disable TCS and StabiliTrak as well as unplug the speed sensor.


*EDIT* Hey- this was my 19,000th post!

 

[B-train]

This weekend i took the G80 locker out from under my 2011 Tahoe LT 4x4! Hooray no more gov-bomb! Now it has an Eaton TrueTrac.

I hit one snag.
When I did my test startup and spin the wheels with the rear end still up on jackstands, I suddenly had a Traction Control light and the system hit the brakes. This happened several times in a row, I switched off the TCS by pressing the button and was able to verify that mechanically everything was ok.

What followed was an hour or so of mild panic, googling TCS issues, and pulling sensors to see if damaged..... . . . . .

Then it hit me: "Traction Control" ... the front tires are on the ground and stationary, the back tires are trying to spin. Of course that would make the TCS go bananas.
After I buttoned everything up I did a brief test drive and all seems to be well.

Am I right on this? Having the rear axle in the air and putting it in drive will make the TCS engage?

Yes, totally correct. The system saw no wheel speed from the front.

 

[JKaechler]

100% was your problem. You didn't break anything but your stride. When I use my Tahoe as a lathe (don't ask), I disable TCS and StabiliTrak as well as unplug the speed sensor.


*EDIT* Hey- this was my 19,000th post!

ok. I know you said "dont ask" but I HAVE TO! How can a truck be a lathe?!?!?!?!

 

[wjburken]

EDIT* Hey- this was my 19,000th post!

 

[swathdiver]

This weekend i took the G80 locker out from under my 2011 Tahoe LT 4x4! Hooray no more gov-bomb! Now it has an Eaton TrueTrac.

I hit one snag.
When I did my test startup and spin the wheels with the rear end still up on jackstands, I suddenly had a Traction Control light and the system hit the brakes. This happened several times in a row, I switched off the TCS by pressing the button and was able to verify that mechanically everything was ok.

What followed was an hour or so of mild panic, googling TCS issues, and pulling sensors to see if damaged..... . . . . .

Then it hit me: "Traction Control" ... the front tires are on the ground and stationary, the back tires are trying to spin. Of course that would make the TCS go bananas.
After I buttoned everything up I did a brief test drive and all seems to be well.

Am I right on this? Having the rear axle in the air and putting it in drive will make the TCS engage?

Did you measure for backlash after moving the ring gear to the new center section?

 

[JKaechler]

Did you measure for backlash after moving the ring gear to the new center section?

I did. A teeny bit of adjusting had it at 7 thousandths... Chevy says between 6 and 10 is the acceptable range

 

[iamdub]

ok. I know you said "dont ask" but I HAVE TO! How can a truck be a lathe?!?!?!?!

It's not as extravagant as it sounds. I've had two separate occasions, both involving light machining of the wheels. Set the rear on jack stands and let it run in gear to spin the wheels while I smoothed the lips with a flap disc on a grinder. BTW, if you ever need to do this and idling in gear isn't fast enough to keep the differential locked, use a pipe, stick, piece of lumber, etc. against the seat to push the accelerator pedal and adjust the seat forward or back to adjust the speed. Or use bricks. But, using the power adjust of the seat gives better control.

Pics in build thread: https://www.tahoeyukonforum.com/threads/growing-up-doesnt-have-to-suck.93510/post-1323703

 

[Joseph Garcia]

Congratulations @iamdub. The value that you provide to this Forum is immense!

 

[alpha_omega]

Now it has an Eaton TrueTrac.
Then it hit me: "Traction Control" ... the front tires are on the ground and stationary, the back tires are trying to spin. Of course that would make the TCS go bananas.
After I buttoned everything up I did a brief test drive and all seems to be well.

Am I right on this? Having the rear axle in the air and putting it in drive will make the TCS engage?

Yes, you are absolutely correct on this “issue”. Your lightbulb moment just arrived later than you probably had hoped. Luckily you realized the cause prior to tearing it back apart.

Do you have the specs, link or p/n info on that Eaton TrueTrac? Does that have any form of slip or is that a thing of the past with the TrueTrac?

 

[JKaechler]

I am using

Eaton 913A481​

https://www.amazon.com/gp/product/B001DN44QO/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

its funny that Amazon says it does not fit this vehicle, when it clearly does. Runs good.

The TrueTrac does have slip. Its not a locker, but a limited slip.
The two biggest differences are that it does not require any kind of special friction oil to function. Its just gears.
and that it engages smoothly from open diff, thru tightening up gradually, and finally to completely binding up and causing the axles to be effectively locked.

This unit ran for a number of years in my 2001 Suburban, and many times on muddy roads and other places i experienced it doing that smooth lockup transition. Most especially during the super crazy winter of 2021. With only a 2wd and that truetrac I was able to be out in the area pulling people out of the ditch and delivering supplies to other homes.

During 90% of the time, it acts as a simply open diff. When you need it there is no controls to worry with, and no lurch or clunk as it comes on.

I dont think a TrueTrac would be the right solution for a serious crawler. If one of the back wheels completely unloads, as if it were in free air spinning.... the TrueTrac would unload and you have no traction. If there is any friction at all on the wheel with less traction then you are ok.

So for a mostly on road/occasional mud or field Tahoe it is the right choice.