3.91 gear cost - Page 2 - Camaro5 Chevy Camaro Forum / Camaro ZL1, SS and V6 Forums

acammer · 08-23-2018, 04:08 PM

Quote:

Originally Posted by 1JEWLDSSRS

Ok, question for you guys, I am going to do the 3.91 gear swap in my L99 that is stalled and cammed with a custom dyno tune, if I have my dealership does the install our Camaro club gets 15% discount on parts and labor, I can get it done for a good price I think, going with the GM Performance kit that has everything, my question is when they flash my computer to correct the speedo for the gear change, will that interfere with my tune we have on the trans now? For the stall and shift points? Or would I have to drive down to my builder / tuner to have the trans retuned. Just wondering. Thanks guys..

It's a good question. I would guess that they overwrite the entire tune back to an OE calibration. I would think you may want your tuner to handle the change. There's not much to it, shouldn't take them much more than the time it takes to re-write the calibration.

1JEWLDSSRS · 08-23-2018, 05:45 PM

Quote:

Originally Posted by acammer

It's a good question. I would guess that they overwrite the entire tune back to an OE calibration. I would think you may want your tuner to handle the change. There's not much to it, shouldn't take them much more than the time it takes to re-write the calibration.

Thanks sir. So you are saying I should just let my tuner do the gear swap and retune at the same time? Or I can have my dealership do the gear swap and then just drive down to my tune shop and let THEM re calibrate the speedo. Almost forgot, would the gear swap affect my trans tune I have now and would have to have it retuned as well anyway? All this is new to me so pardon my questions as I am learning all I can about these computer controlled cars. Thanks again. Appreciate it much.

acammer · 08-23-2018, 06:13 PM

Quote:

Originally Posted by 1JEWLDSSRS

Thanks sir. So you are saying I should just let my tuner do the gear swap and retune at the same time? Or I can have my dealership do the gear swap and then just drive down to my tune shop and let THEM re calibrate the speedo. Almost forgot, would the gear swap affect my trans tune I have now and would have to have it retuned as well anyway? All this is new to me so pardon my questions as I am learning all I can about these computer controlled cars. Thanks again. Appreciate it much.

I think with an auto car you need to get calibrated right away after changing the rear gear, or it can cause issues. I guess it's up to you, you could ask your tuner what the install would cost there, or you can ask the dealership if they can perform the change without altering the rest of the tune. I would want to be sure I'm not going to lose my tune, and that I'm not going to have any issues driving the car if I don't get the tune changed right when the gears are done, I don't know the answer to either of those questions unfortunately

rontammy0 · 08-23-2018, 06:50 PM

Quote:

Originally Posted by 1JEWLDSSRS

Thanks sir. So you are saying I should just let my tuner do the gear swap and retune at the same time? Or I can have my dealership do the gear swap and then just drive down to my tune shop and let THEM re calibrate the speedo. Almost forgot, would the gear swap affect my trans tune I have now and would have to have it retuned as well anyway? All this is new to me so pardon my questions as I am learning all I can about these computer controlled cars. Thanks again. Appreciate it much.

Yes your gear swap affects your rpms in different gears thus changing your shift points slightly. You trans will need a slight adjustment in its tune. My tuner swapped the diff with one that already had the 391s installed then re calibrated it and adjusted the trans tune.

Baddbird · 08-23-2018, 09:19 PM

Quote:

Originally Posted by acammer

I think with an auto car you need to get calibrated right away after changing the rear gear, or it can cause issues. I guess it's up to you, you could ask your tuner what the install would cost there, or you can ask the dealership if they can perform the change without altering the rest of the tune. I would want to be sure I'm not going to lose my tune, and that I'm not going to have any issues driving the car if I don't get the tune changed right when the gears are done, I don't know the answer to either of those questions unfortunately

A dealership cannot program a module without an entire rewrite of that module. Alot of people have the misconception that we can pick and choose what is written but it doesnt work that way. Its all or nothing. The Op will be better off having the tuner make the adjustments for the gears before the car is driven.

acammer · 08-24-2018, 08:47 AM

Quote:

Originally Posted by Baddbird

A dealership cannot program a module without an entire rewrite of that module. Alot of people have the misconception that we can pick and choose what is written but it doesnt work that way. Its all or nothing. The Op will be better off having the tuner make the adjustments for the gears before the car is driven.

That's kinda what I figured, and it's a good thing for the OP to be aware of. I'm not sure you want to drive it on the old calibration at all with the automatic, I believe I read somewhere this causes some issues. On an M6 car its no problem, I drove for like a week on my 4.10s before I updated the tune, the speedo just read high.

1JEWLDSSRS · 08-24-2018, 10:41 AM

Good morning guys, hey thanks for all the quality information! And I kinda figured that would be the outcome. I am going to let my tuner do it all at once, just waiting for him to return my email with a price for the job. Thanks again, much appreciated.

Netraa · 08-26-2018, 10:55 AM

An auto is *drivable* with a set of 3.91 gears installed and the trans tune not updated. I installed mine and had to reschedule my apt with the tuner a week later. The problem was my car is a daily driver and I had to get to work. It shifts a little funny, but as long as your not on the strip and keeping your toe out of the engine compartment you'll be fine to drive to your tuner. don't forget your speedo is off.

1JEWLDSSRS · 08-29-2018, 06:29 PM

Quote:

Originally Posted by Netraa

An auto is *drivable* with a set of 3.91 gears installed and the trans tune not updated. I installed mine and had to reschedule my apt with the tuner a week later. The problem was my car is a daily driver and I had to get to work. It shifts a little funny, but as long as your not on the strip and keeping your toe out of the engine compartment you'll be fine to drive to your tuner. don't forget your speedo is off.

Thanks sir, I'm just going to wait and let my tuner do everything all at once, just to be safe.

08-24-2018, 10:41 AM	#21
1JEWLDSSRS Drives: 2011 SS-RS Join Date: May 2011 Location: FLORIDA Posts: 11,402	Good morning guys, hey thanks for all the quality information! And I kinda figured that would be the outcome. I am going to let my tuner do it all at once, just waiting for him to return my email with a price for the job. Thanks again, much appreciated. __________________ TSP STAGE 3 CAM,231/246 @112 LSA 614/641 LIFT, CIRCLE D 5C-4200-4500 CONVERTER,LOD INTAKE.CORSA EXHAUST. DSS 1 PC DS. PEGASUS SOLID CRADLE MOUNTS. 486RWHP/475RWTQ.LOTS MORE.

08-26-2018, 10:55 AM	#22
Netraa Drives: 2014 2ss/rs Join Date: May 2012 Location: New Braunfels, Texas Posts: 293	An auto is drivable with a set of 3.91 gears installed and the trans tune not updated. I installed mine and had to reschedule my apt with the tuner a week later. The problem was my car is a daily driver and I had to get to work. It shifts a little funny, but as long as your not on the strip and keeping your toe out of the engine compartment you'll be fine to drive to your tuner. don't forget your speedo is off.