Rear end gear swap

[Meltdown]

I did a search on this before posting and didn't see exactly what I was looking for so...

 

I have an '05 Yukon XL with the 4.11 gears (2WD). This is my wife's truck and we'll never tow anything with it. We needed it for the space.

 

In any case, I'd like to have the 3.42 gears instead for the more relaxed highway RPM and better fuel economy. The bulk of our driving in on the interstate.

 

1) What would it cost to have a dealer do this?

2) Would this throw the speedo off?

3) Would this cause any other issues that would have to be addressed after the swap?

 

Thanks in advance.

[2004GMC1500CC]

I did a search on this before posting and didn't see exactly what I was looking for so...

 

I have an '05 Yukon XL with the 4.11 gears (2WD). This is my wife's truck and we'll never tow anything with it. We needed it for the space.

 

In any case, I'd like to have the 3.42 gears instead for the more relaxed highway RPM and better fuel economy. The bulk of our driving in on the interstate.

 

1) What would it cost to have a dealer do this?

2) Would this throw the speedo off?

3) Would this cause any other issues that would have to be addressed after the swap?

 

Thanks in advance.

 

<{POST_SNAPBACK}>

 

 

 

I bet you can find a dozen volunteers on this board who would gladely swap out the entire rear end with you. This would be the cheap and (relatively) easy solution.

[700cc]

I did a search on this before posting and didn't see exactly what I was looking for so...

 

I have an '05 Yukon XL with the 4.11 gears (2WD). This is my wife's truck and we'll never tow anything with it. We needed it for the space.

 

In any case, I'd like to have the 3.42 gears instead for the more relaxed highway RPM and better fuel economy. The bulk of our driving in on the interstate.

 

1) What would it cost to have a dealer do this?

2) Would this throw the speedo off?

3) Would this cause any other issues that would have to be addressed after the swap?

 

Thanks in advance.

 

<{POST_SNAPBACK}>

 

 

 

I bet you can find a dozen volunteers on this board who would gladely swap out the entire rear end with you. This would be the cheap and (relatively) easy solution.

 

<{POST_SNAPBACK}>

 

 

 

 

 

I have the 3.42 rear end with only 1500 miles. I would gladly swap you, as I tow routinely. Are the rear ends compatible on the Yukons and Silverados? Any difference between 2wd and 4wd?

[Meltdown]

I have the 3.42 rear end with only 1500 miles.  I would gladly swap you, as I tow routinely.  Are the rear ends compatible on the Yukons and Silverados?  Any difference between 2wd and 4wd?

 

<{POST_SNAPBACK}>

 

 

 

I would suspect that the rear ends are the same for the Silverado and the Yukon. However, IIRC you would also need to do something with the gears in the front of your truck as well. As I understand it, the gears in the front and back on 4WD trucks have to be the same or unpleasant things can happen to your truck.

 

As an aside, I hadn't thought about a swap. I wasn't aware that it was an option. My original plan was to have the different gears installed and then either sell (just to try to offset the cost of the swap) or give away the 4.11's that I currently have. From reading the posts here and on FSC, I know that most folks prefer the shorter gears for improved acceleration and towing capability. It is just that my needs for the Yukon are different that most.

 

In any case, thanks for the info. In addition, if someone does know what it would cost to have the dealer or other competent technician perform the swap and if it would cause speedo or other issues, it would be gretaly appreciated.

 

Thanks again!

 

[dewfpo]

Yes the speedo, odo and trans shifting will be off. A simple recalibration can be done to the PCM to take care of it.

 

DEWFPO

[Green_Monster]

I did a search on this before posting and didn't see exactly what I was looking for so...

 

I have an '05 Yukon XL with the 4.11 gears (2WD). This is my wife's truck and we'll never tow anything with it. We needed it for the space.

 

In any case, I'd like to have the 3.42 gears instead for the more relaxed highway RPM and better fuel economy. The bulk of our driving in on the interstate.

 

1) What would it cost to have a dealer do this?

2) Would this throw the speedo off?

3) Would this cause any other issues that would have to be addressed after the swap?

 

Thanks in advance.

 

<{POST_SNAPBACK}>

 

 

 

When I was first waiting for my truck (GM company vehicle program) all of them were coming with 4.10 gears, and at the time I wanted better mileage (eventully just went with a 4.10 rearend) and call the dealership to ask what it would cost for an entire gear swap. He said he would have to replace both front and rear ends along with reprogramming the tranny. They tech said to make the truck run better, he suggested a transmission re-gear, but it wasn't required. The quoted cost on my truck would have been a total of labor and all was about $4,000. Keep in mind that my truck is 4wd which is more complicated and expensive to replace compared to a 2wd. Hope this helps. Good Luck!

 

Ben

[Ape0r]

The axles are different from pickups to SUVs. Pickups use leaf springs and the SUVs use a five link setup.

 

While the axles can be swapped, this will require some welding.

 

The pickups will have leaf spring perches, whereas the SUVs will have bolt holes for the traction bars to fit in, and differnet spring mounts for the coils. Can't say if the shocks will bolt up in the same spot.

 

Another option is to find a qualified mechanic to swap out the internals of your axles. This will likely require new shims for both trucks, a LOT of time, and at least one professional mechanic.

 

If you want a direct swap with no welding/cutting, it will have to be with someone who has a Tahoe/Sub/Yuk/Escalade.

 

 

 

If you can find someone else with an SUV that wants to swap, all you need is a jack, two pairs of jackstands, an impact wrench, and a Saturday afternoon. All you gotta do is unbolt one and bolt the other back up, very straightforward if you have an impact wrench.

[Meltdown]

Thanks for all of the information everyone...

 

DEWFPO - What you described can be done by a GM dealer?

 

Green Monster - $4000...wow. I'm not very mechanically inclined but even to someone like myself who needs a manual to change the oil this seems like quite a lot of money. I was under the impression that the swap would work like this:

 

1) Get new gears

2) Open the differential (rear end), take out the old gears, put in the new gears, put differential back together OR replace old 4.11 differential with a new one.

3) Reprogram the apporpriate on-board computer to recgonize new gear ratio and / or change a part in the transmission to make speedo accurate.

 

I take it that it isn't this simple? If so, can you please tell me where I have it wrong? I figured that a 4WD would be more expensive but not that much more.

 

From reading the posts here and on FCS about folks swapping gears I thought it would be a simpler process. However, I freely admit that my knowledge is limited and that I'm probably overlooking something.

 

Ape0r - Thanks for the info. Yeah...if I go the swap route I'd really prefer to do something that was a direct swap as opposed to having to modify psrts to make them fit.

 

Thanks again for the responses, everyone.

[Ape0r]

1) Get new gears

2) Open the differential (rear end), take out the old gears, put in the new gears, put differential back together OR replace old 4.11 differential with a new one.

3) Reprogram the apporpriate on-board computer to recgonize new gear ratio and / or change a part in the transmission to make speedo accurate.

 

I take it that it isn't this simple? If so, can you please tell me where I have it wrong? I figured that a 4WD would be more expensive but not that much more.

 

It is just that simple, its just that step 2 is a six or eight hour process that requires a lot of very precise measurement =). Used to be a great article on FSC, doesn't appear to be up anymore. Did find this, but pics are missing:

 

http://fullsizechevy.com/forums/showthread.php?t=41808

[ZZebes]

Once you get the gears out i will GLADLY buy the gears off you, BTW i have 3.23 rear gear ratio.

[dewfpo]

Thanks for all of the information everyone... 

 

DEWFPO - What you described can be done by a GM dealer?

<{POST_SNAPBACK}>

 

 

 

The dealer can only adjust up to a certain point (stock sizes that are/were available). But any aftermarket tuner can pretty much adjust for any tire size you can fit under your rig.

 

DEWFPO

[Meltdown]

Thanks again for all of the information everyone. I'll be sure to let everyone know how it turns out and what it is going to cost me.

 

Ape0r - Thanks for the link. I did read it over. I guess I grossly underestimated the complexity of the swap. There's no doubt in my mind now that a good tech deserves every penny he earns. When I have it done I'll leave it to the pros. The thought of trying to tackle something like that makes my head spin.

 

ZZebes - I've written down your handle. When I have it done I'll send you a PM.

 

DEWFPO - Good to know. I plan on using the stock 3.42 gears which were a factory option and the tire size is stock. Hopefully that part of the change will go smoothly.

 

[Ape0r]

Before you buy the gears and pay for a mechanic to swap them, cruise a few junk yards or look for someone with an SUV that will swap complete axles, would likely be the cheapest (free if you can find a trade!) and quickest way to get it done.

 

Shoot, if I had a 2wd SUV I'd trade ya my 3.73's!

[srlbotanical]

One more thing to keep in mind.

 

The dealership is going to be the absolutely highest priced place you could ever do a gear swap...

 

 

A good reputable tranny shop will do the gear swap front and back on a 4x4 for about $1200. My local tranny shop can even reset the computer as part of that deal, and include a 3/36 warranty nationwide on the work.

 

The only thing I would ever go back to a dealer for is factory warranty work. Never "new" stuff. Just my opinion...

 

Steve

[Meltdown]

One more thing to keep in mind.

 

The dealership is going to be the absolutely highest priced place you could ever do a gear swap...

 

 

A good reputable tranny shop will do the gear swap front and back on a 4x4 for about $1200. My local tranny shop can even reset the computer as part of that deal, and include a 3/36 warranty nationwide on the work.

 

The only thing I would ever go back to a dealer for is factory warranty work. Never "new" stuff. Just my opinion...

 

Steve

 

<{POST_SNAPBACK}>

 

 

 

Thanks for the tip. I'll be calling around in the next few days to get some prices.