3.91 rear end question - Camaro5 Chevy Camaro Forum / Camaro ZL1, SS and V6 Forums

arussh · 10-28-2013, 07:27 PM

Is anyone aware if GM has a ECM reprogram for the speedo error after this install? 6 auto trans
Local dealer will not install gear set without a bulletin from GM.
Does not want to take chance to void the car warranty.

DaFisch · 10-28-2013, 08:02 PM

yes.. the dealers should have the reprogramming tools..

Mr_Draco · 10-28-2013, 08:12 PM

Last time I checked, they can only do the speedo recalibration for a manual. The auto also requires a tranny retune to adjust the shift points and GM didn't have that ready yet.

Sandor · 10-28-2013, 08:47 PM

The speedo cal is going to be released very soon, once that happens the 3.91 can be installed by Chevrolet Dealers and your vehicle warranty will be preserved.

camguynj · 10-28-2013, 09:47 PM

Quote:

Originally Posted by Sandor

The speedo cal is going to be released very soon, once that happens the 3.91 can be installed by Chevrolet Dealers and your vehicle warranty will be preserved.

Where are you getting your info from that the speedo recalibration is going to be released very soon?

arussh · 10-29-2013, 02:04 AM

I have had the 3.91 gear set sitting in my basement since august waiting for GM to get this solved for me. I'm headed to SEMA next week and plan on talking to somebody @ GM to get this resolved.

stevey_frac · 11-01-2013, 12:02 AM

Quote:

Originally Posted by Sandor

The speedo cal is going to be released very soon, once that happens the 3.91 can be installed by Chevrolet Dealers and your vehicle warranty will be preserved.

Is it going to be released for the V6 as well? Only thing stopping me from jumping on a set of those 3.91's is that my speedo would be quite out..

Arbgast · 11-01-2013, 12:43 AM

How much would a L99 speedo be off with 3.91 gears?

Mr_Draco · 11-01-2013, 05:41 AM

Quote:

Originally Posted by Arbgast

How much would a L99 speedo be off with 3.91 gears?

The gearing change is a percentage so how much off depends on how fast you are going. I think the L99 is 20%. This can be accommodated by the driver, you just have to remember that you are going 20% slower than what the speedo says.

The big thing about gears is that you will be putting on 20% more miles then you really are and the shift points must be adjusted as well. The miles and the shift points is what most people worry about.

Sandor · 11-09-2013, 09:09 AM

Quote:

Originally Posted by camguynj

Where are you getting your info from that the speedo recalibration is going to be released very soon?

Camguynj,

I am with Chevrolet Performance. California is issuing an E.O. and that is now in the final stages. We expect the cal to be in dealer hands within the next few weeks, stay tuned.

camguynj · 11-09-2013, 09:40 AM

Quote:

Originally Posted by Sandor

Camguynj,

I am with Chevrolet Performance. California is issuing an E.O. and that is now in the final stages. We expect the cal to be in dealer hands within the next few weeks, stay tuned.

GREAT NEWS !!! Please keep me updated

stevey_frac · 11-09-2013, 11:10 AM

Quote:

Originally Posted by Sandor

Camguynj,

I am with Chevrolet Performance. California is issuing an E.O. and that is now in the final stages. We expect the cal to be in dealer hands within the next few weeks, stay tuned.

Is there a calibration for the v6 coming?

Sandor · 11-09-2013, 11:32 AM

Quote:

Originally Posted by stevey_frac

Is there a calibration for the v6 coming?

That is not currently offered.

wwoody · 11-09-2013, 12:03 PM

There are a lot of us 2010-2011 LLT guys / gals interested in this idea.
Come on GM, please help us out to with this programing issue will ya.

10-28-2013, 07:27 PM	#1
arussh Drives: 2011 2ss/rs, 1990 iroc-z Join Date: Jul 2011 Location: Ottawa Ontario Posts: 197	3.91 rear end question Is anyone aware if GM has a ECM reprogram for the speedo error after this install? 6 auto trans Local dealer will not install gear set without a bulletin from GM. Does not want to take chance to void the car warranty.

10-28-2013, 08:02 PM	#2
DaFisch Master Amateur Mechanic Drives: Victory Red 2011 2SS/RS Join Date: Jan 2013 Location: South Barrington, IL Posts: 1,719	yes.. the dealers should have the reprogramming tools..

10-28-2013, 08:12 PM	#3
Mr_Draco Drives: 2SS/RS Join Date: Sep 2008 Location: Western North Carolina Posts: 7,369	Last time I checked, they can only do the speedo recalibration for a manual. The auto also requires a tranny retune to adjust the shift points and GM didn't have that ready yet.

10-28-2013, 08:47 PM	#4
Sandor Chevrolet Performance Drives: Camaro Chroma Join Date: Jul 2010 Location: The Motor City Posts: 409	The speedo cal is going to be released very soon, once that happens the 3.91 can be installed by Chevrolet Dealers and your vehicle warranty will be preserved.

10-29-2013, 02:04 AM	#6
arussh Drives: 2011 2ss/rs, 1990 iroc-z Join Date: Jul 2011 Location: Ottawa Ontario Posts: 197	I have had the 3.91 gear set sitting in my basement since august waiting for GM to get this solved for me. I'm headed to SEMA next week and plan on talking to somebody @ GM to get this resolved.

11-01-2013, 12:43 AM	#8
Arbgast Drives: DRIVES 2014 2SS RS convertible Join Date: May 2012 Location: Eugene Posts: 144 View My Garage	How much would a L99 speedo be off with 3.91 gears?

11-09-2013, 12:03 PM	#14
wwoody wwoody Drives: 2011 Vert Join Date: Mar 2012 Location: Oshawa Posts: 36	There are a lot of us 2010-2011 LLT guys / gals interested in this idea. Come on GM, please help us out to with this programing issue will ya.