2015 dealership gear swap

robvas · February 1, 2016

If i upgrade I will not use the dealer because they said it will void the warranty.

Getting it done anywhere would void the warranty.

TJay74 · February 1, 2016

Once you switch to 3.42 or 3.73 you will have to update the tune on the truck, which will void your warranty if you still have one.

Just an FYI.

This will be anyones biggest issue. As of now GM does not allow the dealer to flash the ECM/TCM with anything other than the stock calibration that the vehicle was built with along with any updates. The only way currently around this is via custom tuning, which while it wont void your warranty it could put you on the hot seat if anything ever comes up down the road.

You will tuning changes to the gear size, the entire shift calibration in the TCM will need to be tweaked along with some other items. Not hard on the custom side since you can just copy those calibration details from another vehicle with the gear size you are using, otherwise it can be quite tedious to mess with in order to get the shift under part and full throttle correct and then along with the torque converter lock up as well.

2004lebanshee · February 1, 2016

take it somewhere else. Use factory gears. I doubt any dealer would ever know you swapped them. Another option is really small tires.

Dan1220 · February 2, 2016

They may not notice swapped gears but they would/could notice a tune. Maybe an ignorant question, but what would happen if swapped to 3.42s and didn't change the tune?

TJay74 · February 2, 2016

The speedo would be way off, the transmission would not shift correctly either. The calibration uses known RPM and MPH points in order to shift under part throttle and full throttle positions.

So basically it wont work, either do it the right way which is by using a custom tune or else don't touch it at all.

Badass69 · February 2, 2016

It might not be as bad as you think... I had a 6.2 powered F150 that left the factory with 3.55 gears in it. It's speedo was always out. ... more than what I am used to all stock.... a food 5 to 6 % out. Shifted fine and all that. Pulled the oem Ford tune out of it.... they had inputted it as having 3.73 gears.... nice work Ford. Your speedo would be 10% out but it would drive okay.

I drove my 05 around for a while when I went from 3.73 to 4.10... just the speedo was out... drove the same. It's no different than the guys here and in the real world that increase tire size and never fix the speedometer lol. You will be racking up more miles than you are putting on though... 10% more.

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Buckwild27 · February 2, 2016

I have a 2010 and a 2013 sierra 1500 4x4 I had the smaller diffs. With 3.42s and after listening to gm's bull story about blowing up the T-case if I changed gear ratios I just went and bought the 9.5" 14 bolt for both trucks with 3.73's in them with the matching front diffs, tuning is a good idea it will drive fine but the shift times will be a little off and if you don't change the ratios your dash might look a lot like Christmas. Gm won't warranty a gear change because your truck wasn't safety crash tested with the lower gears. Doesn't matter that the same style of truck was tested with lower gears.

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Dan1220 · February 3, 2016

Just an update...I called the dealer to see what it would cost to swap from 3.08 to 3.42, and whether or not gm would void warranty. He said he would have to call his GM rep. After speaking with the rep, he called me back and said it would cost approximately $4200 to do both the front and the rear. He also said GM would cover the warranty as long as the dealer did the swap with OEM parts. I then asked if they would have to re flash the ECM and he said "uhh he didn't say anything about that so I don't think so". After I suggested that they may need to adjust the computer, he said they probably would, and that it would add to the cost.

He didn't seem to be very knowledgable about the subject.

If I decide to swap gears in the future, it will be done at a shop, not a dealership

2004lebanshee · February 4, 2016

I figured the speedo shifted to the RPM not the MPH. Might be wrong.

Badass69 · February 4, 2016

I figured the speedo shifted to the RPM not the MPH. Might be wrong.

It uses both.

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A.J._Langholff · February 4, 2016

I have a 2015 4x4cc 5.3 3.08 gear ratio. I have done plenty of searching on here and can't find an exact answer. Would it be a direct swap to change to 3.73? Is this something the dealer could/would do? Also, if the dealer did it, would it void my warrant at all? I regret buying a truck with 3.08, but you live and learn. Thanks in advance

What problems / issues are you having that you don't like the 3.08?

I have a 2015 4x4cc 5.3 3.08 gear ratio. I have done plenty of searching on here and can't find an exact answer. Would it be a direct swap to change to 3.73? Is this something the dealer could/would do? Also, if the dealer did it, would it void my warrant at all? I regret buying a truck with 3.08, but you live and learn. Thanks in advance

What problems / issues are you having that you don't like the 3.08?

crafferty · February 4, 2016

Just an update...I called the dealer to see what it would cost to swap from 3.08 to 3.42, and whether or not gm would void warranty. He said he would have to call his GM rep. After speaking with the rep, he called me back and said it would cost approximately $4200 to do both the front and the rear. He also said GM would cover the warranty as long as the dealer did the swap with OEM parts. I then asked if they would have to re flash the ECM and he said "uhh he didn't say anything about that so I don't think so". After I suggested that they may need to adjust the computer, he said they probably would, and that it would add to the cost.

He didn't seem to be very knowledgable about the subject.

If I decide to swap gears in the future, it will be done at a shop, not a dealership

You're wasting your money if you pay $4200 for 3.42 gears. I just can't help but to laugh at that price.

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Buckwild27 · February 4, 2016

What problems / issues are you having that you don't like the 3.08?

What problems / issues are you having that you don't like the 3.08?

Simply put some pickups are used as work horses and not for Sunday drives to the mall.

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LongrangeLauber · February 4, 2016

I remember about 3 years ago the rear end blew up in my 02 silverado. Took it to the dealer and asked about getting it repaired. They would regear to the same 3.73 ratio for 5k, yes 5 grand, for the rear only. I told them they can park the truck out in the lot and I'll have a tow truck come get it.

They easily could have gotten a reman through jasper for around 1100 at the time. I picked one up for 400 the next day. Few months later blew that one up so I finally invested money in aftermarket 4.88's a new locker and all the other goodies for the front and rear. Local shop charged me 350 an axle for install, I paid about 1200 for the parts. Basically what I'm saying, the dealer is a rip off for regearing. Obviously that truck was far out of warranty (327k miles at the time lol) but they still tried to take advantage of the customer

Dan1220 · February 4, 2016

AJ- the truck just seems to drive like a slug. Makes me nervous to get heavier tires or to really pull anything. However, It also makes me nervous to re gear and tune a brand new truck with 5k miles and void the entire warranty. Hind sight is a bitch, I should have gotten something else.