3.91 gear talk - Page 3 - Camaro5 Chevy Camaro Forum / Camaro ZL1, SS and V6 Forums

judkins75 · 10-13-2019, 11:54 AM

Quote:

Originally Posted by camguynj

I got mine installed at dealer and got 1,000 mile warranty. Also make sure they apply the speedo recalibrate update.

The recalalibrate is included. Thank you.

samman11 · 11-07-2019, 01:47 PM

Finally got what I consider to be a somewhat fair price on having a Chevy dealer install 3.91 gears into my manual Camaro SS convertible. Was quoted with parts and labor a total of $1551. Some local dealers and speed shops were quoting $2100 to $2500. I hope to have this done in the spring.

mbesman · 11-07-2019, 03:15 PM

Quote:

Originally Posted by judkins75

The recalibration is included. Thank you.

I got mine done and had the certificate but my dealer didn't do the recalibration and tune. They said I had to have that done elsewhere. I used my Diablo to calibrate and tune.. all good. Just noting that your dealer may not do the recalibration for you even with the certificate and still warranty the part.

Benman · 11-07-2019, 03:27 PM

I rebuilt my diff replacing all bearings, seals, and went to billet caps. I also added the LPW cover. I went with the 3.91 in my M6 car. I doubt if you would see a nickels worth of difference between the 3.91 and the 4.10 for 95% of the drivers out there, except for all out Drag race performance. My thought is the 3.91 is available from the OEM maker of the differential, whereas the 4.10/4.11 are only available from aftermarket suppliers. Is there a reason the OEM does not offer the 4.10/4.11? I don't know, but I do know the 4.30 was available for a very short period when these cars were first built and there were a multitude of problems trying to run a gear that tall. I daily drive my car, don't go to the track at all, so for me longevity is a more concerning factor than all out performance. Just my .02 cents which is worth maybe less than that.

InFiD3ViL · 11-07-2019, 03:28 PM

The recalibration is done in the tune, correct? So if someone already has their car tuned they just need it updated via their preferred tuner?

I guess what I am asking is, if for instance, if I had the install done at a dealer...I already have my car tuned. For people that already have a tune, the dealer really wouldn't be able to touch a pre-tuned ECU would they? So I would simply have my tuner update the existing tune?

I guess my question is, is the speedo calibration in a separate writable part of the ECU or is it part of the tune? My brain isn't working properly today...

samman11 · 11-07-2019, 05:19 PM

Quote:

Originally Posted by InFiD3ViL

The recalibration is done in the tune, correct? So if someone already has their car tuned they just need it updated via their preferred tuner?

I guess what I am asking is, if for instance, if I had the install done at a dealer...I already have my car tuned. For people that already have a tune, the dealer really wouldn't be able to touch a pre-tuned ECU would they? So I would simply have my tuner update the existing tune?

I guess my question is, is the speedo calibration in a separate writable part of the ECU or is it part of the tune? My brain isn't working properly today...

My understanding is that the recalibrate for speedometer is done with the hand held tuner. If your car was already tuned, they still need to get back in there once you change the differential gears.

mbesman · 11-07-2019, 06:15 PM

I had a tune on my car but took it off before I brought to dealer so there would be no issues with warranty at install. Later may be a different story if Im not able to take the tune out before a repair if necessary. So the car was stock at time of install. They did not want to do a tune or calibrate. I didn't want to wait for my tuner to calibrate if he could. Not sure of that. So I used the Diablo and a mobil gps that indicated my speed. I played around with tire size in my handheld until the speed calibration was correct. Once that was done I finally got around to getting the gears tuned by a tuner through my handheld. He had me run a couple of data logs and he sent a tune. This made a world of difference as far as performance. I probably can get more out of her if I had a tune and dyno but that's another day. Just food for thought.

camguynj · 11-07-2019, 08:08 PM

Quote:

Originally Posted by mbesman

I had a tune on my car but took it off before I brought to dealer so there would be no issues with warranty at install. Later may be a different story if Im not able to take the tune out before a repair if necessary. So the car was stock at time of install. They did not want to do a tune or calibrate. I didn't want to wait for my tuner to calibrate if he could. Not sure of that. So I used the Diablo and a mobil gps that indicated my speed. I played around with tire size in my handheld until the speed calibration was correct. Once that was done I finally got around to getting the gears tuned by a tuner through my handheld. He had me run a couple of data logs and he sent a tune. This made a world of difference as far as performance. I probably can get more out of her if I had a tune and dyno but that's another day. Just food for thought.

fyi... a tune updates the ECU count which CAN NOT EVER be reset even if you reload the stock tune. The count will be checked for a power train warranty claim and if it's more than one your claim will be rejected. When a dealer does a speedo recalibrate they will (and only they can) register the recalibrate/ECU update with GM to preserve your power train warranty

MeanV8 · 11-07-2019, 08:17 PM

Quote:

Originally Posted by camguynj

fyi... a tune updates the ECU count which CAN NOT EVER be reset even if you reload the stock tune. The count will be checked for a power train warranty claim and if it's more than one your claim will be rejected. When a dealer does a speedo recalibrate they will (and only they can) register the recalibrate/ECU update with GM to preserve your power train warranty

I am getting a set of 3.91 gears for my SS and Shop foreman told me they will recalibrate the Speedo.

Dan

11-07-2019, 03:27 PM	#32
Benman Drives: 13 IOM 2ss RS manual Join Date: Jun 2018 Location: Euless,TX Posts: 213	I rebuilt my diff replacing all bearings, seals, and went to billet caps. I also added the LPW cover. I went with the 3.91 in my M6 car. I doubt if you would see a nickels worth of difference between the 3.91 and the 4.10 for 95% of the drivers out there, except for all out Drag race performance. My thought is the 3.91 is available from the OEM maker of the differential, whereas the 4.10/4.11 are only available from aftermarket suppliers. Is there a reason the OEM does not offer the 4.10/4.11? I don't know, but I do know the 4.30 was available for a very short period when these cars were first built and there were a multitude of problems trying to run a gear that tall. I daily drive my car, don't go to the track at all, so for me longevity is a more concerning factor than all out performance. Just my .02 cents which is worth maybe less than that. __________________ Rectangular Dollars will beat Cubic Inches

11-07-2019, 03:28 PM	#33
InFiD3ViL Drives: 2010 CGM 2SS/RS LS3 Swapped A6 Join Date: Sep 2016 Location: Spring Hill, FL Posts: 4,570	The recalibration is done in the tune, correct? So if someone already has their car tuned they just need it updated via their preferred tuner? I guess what I am asking is, if for instance, if I had the install done at a dealer...I already have my car tuned. For people that already have a tune, the dealer really wouldn't be able to touch a pre-tuned ECU would they? So I would simply have my tuner update the existing tune? I guess my question is, is the speedo calibration in a separate writable part of the ECU or is it part of the tune? My brain isn't working properly today... __________________ 2010 CGM Camaro 2SS LS3 Swapped A6 - GPI LS3 SS1 .647/.638, (224/237, 112 +4, 7º overlap) on CamMotion 8620 core, BTR Platinum .660" Dual Spring kit w/titanium retainers, CHE bronze trunnion upgrade, stock heads milled @ .015, Melling HV 10296 oil pump, TSP 1-7/8" long tube headers (W/Catless Off-road Pipes), Corsa Xtreme 3" Catback, GPI Ported/Rod Mod Intake, Stage 2 Ported Throttle Body, Vararam OTR CAI, Mike Norris Gen 2 catch can + GM 1LE clean side separator, 160º thermostat - Megan Racing adjustable coilovers (lowered 1.75"), MRR M017 10/11" wheels-Tuned by Ryan @ GPI

11-07-2019, 06:15 PM	#35
mbesman Great White Drives: 2015 Camaro 2SS Join Date: Jan 2017 Location: Florida Posts: 251 View My Garage	I had a tune on my car but took it off before I brought to dealer so there would be no issues with warranty at install. Later may be a different story if Im not able to take the tune out before a repair if necessary. So the car was stock at time of install. They did not want to do a tune or calibrate. I didn't want to wait for my tuner to calibrate if he could. Not sure of that. So I used the Diablo and a mobil gps that indicated my speed. I played around with tire size in my handheld until the speed calibration was correct. Once that was done I finally got around to getting the gears tuned by a tuner through my handheld. He had me run a couple of data logs and he sent a tune. This made a world of difference as far as performance. I probably can get more out of her if I had a tune and dyno but that's another day. Just food for thought. __________________ [

11-07-2019, 01:47 PM	#30
samman11 Drives: 2011 Camaro SS Convertible Join Date: Nov 2015 Location: Rochester, NY Posts: 671	Finally got what I consider to be a somewhat fair price on having a Chevy dealer install 3.91 gears into my manual Camaro SS convertible. Was quoted with parts and labor a total of $1551. Some local dealers and speed shops were quoting $2100 to $2500. I hope to have this done in the spring.