GoldenOne
Junior Member
- Joined
- Dec 18, 2013
- Posts
- 15
- Reaction score
- 24
- Location
- Central Missouri
- Ram Year
- 2012
- Engine
- Hemi 5.7
I wanted to write a little about my experience with swapping gears in my 12. Like a lot of you, I bought a 2012 4X4, lifted it, put 37's on it and then dealt with the power loss as well as fuel mileage. Hopefully, this will help some of you out there with the ZF Differentials and a lift if you decide to swap gears.
I had driven my truck for over 2 years on my 37's. The power was greatly reduced as well as the gas mileage (I didn't buy, or lift, the truck expecting great fuel economy). After the day to day routine for the two years, I pretty much had forgotten how the truck felt with stock tires when it came to performance. The truck still ran well in town, sounded great with my Magnaflow and was looking good on 22's with 37's. The real problem that I had with it was on the highway. It had 3.55 gears in it. At 70 - 75 mph, the truck would barely shift into 6th. If I even saw the slightest incline, it was in 4th hitting 3500-3700 rpms to maintain speed under Cruise Control. At the end of the day, I was averaging about 12mpg Hwy and 10 in town.
I started looking at swapping gears in the Differentials to correct the increase of tire size affecting the transmission and thats where things got a little fuzzy. The only clear answers that I found were; 1) Its expensive 2) You have to swap out the front differential for an older model 3) Its a pain in the ass. I researched the topic for a few months. Pricing out the various things that I would need as well as finding a reputable shop that could perform this magic. What I didn't ever find was a list of what was needed to get the job done, so I am going to do you all a favor right now.
Things you need -
1) Front Differential Housing Assembly from a 2010 1500.
2) Ring and Pinion Sets for the Front and Rear. (Motive makes a 4.56ZF set for the rear and the 2010 front)
3) Rebuild kit (I elected to rebuild with all new bearings etc. on the front due to unknown mileage and condition of the 2010 front Diff)
4) Gear Install Kit
5) *****This is up to you - 2010 Front Drive Shaft and Spacer (I ordered the spacer from Rough Country for the 2010 6" lift) OR Have your existing Spacer machined to accept bolts for the smaller 2010 Diff.
6) ***** This is where I had issues - Brackets for the 2010 Diff. (The 2010 Diff has a different mount then the 2012. I ordered all of the associated brackets from Rough Country when I ordered the Drive Shaft Spacer. *not realizing that where it mounts to the truck is completely different in one location* The 2012 is mounted at an angle, while the 2010 is straight vertical. The solution here was to basically cut both brackets, using the 12 bracket to mount to the 3rd member and the 10 bracket to the Diff.
7) Money - lol.. Actually, I had seen where others had payed around $3,100 and I ended up at $2,750 (including labor, the parts ordered from Rough Country, drive shaft and diff)
Issues -
The big issue was the 3rd member bracket. ***Don't drive without it - the tube on the stub shaft on the 2010 diff will break, lesson learned.
***
Results -
I drove the truck home, about 75 miles, stopping 3 times to let the Diffs cool down (part of the break in period). On the highway, cruise set at 72mph, the truck purred like a kitten at 2000-2100 rpms in 6th gear. I actually had the ECO mode kick on while on even stretches. After the 500 miles, returned to the shop and had the fluid changed, then proceeded to find out what I had payed for.... WOW... The truck feels bad ass again.. with traction control on, it feels like its about to do a wheelie from a stop. The acceleration is what it was stock and sounds amazing! the exhaust tone changed a lot, now that the engine isn't bogged down. A little higher pitched and louder.
MPG -
I haven't calculated the city MPG yet, but after a fill up, with about 30 city miles and 150 Hwy miles, I got 16.5MPG. I am going to check it solely on the Hwy and then again in town and update.
Shop-
I live near the KC area on the Missouri side. I called a few mechanic shops in my town, and I didn't really get that warm and fuzzy that any of them were capable of doing the job. I looked online a bit and found Gears Unlimited in KC. I spoke with Billy (the owner) and told him about the challenges as I mentioned above. He was at a show somewhere when I first spoke with him and actually went around to different booths talking to other people about the 2012's. He called me back and said that he absolutely wanted to do it. I liked how he wanted the challenge and so that where I went. When I arrived to drop off my truck, they had already installed the gears in the 2010 front diff and rebuilt it. I came back the next afternoon and it was done**(with the exception of the bracket issue). When I returned for the 500 mile inspection and diff oil change, we saw that the tube on the stub shaft had cracked all the way around. Billy ordered another Diff, swapped out the internals and fabricated the bracket at no additional charge. (AWESOME)
I am absolutely pleased about how the truck performs! Best thing I have done since the lift.
If anyone has any questions, I will do my best to help you out to keep your troubles to a minimum.
I had driven my truck for over 2 years on my 37's. The power was greatly reduced as well as the gas mileage (I didn't buy, or lift, the truck expecting great fuel economy). After the day to day routine for the two years, I pretty much had forgotten how the truck felt with stock tires when it came to performance. The truck still ran well in town, sounded great with my Magnaflow and was looking good on 22's with 37's. The real problem that I had with it was on the highway. It had 3.55 gears in it. At 70 - 75 mph, the truck would barely shift into 6th. If I even saw the slightest incline, it was in 4th hitting 3500-3700 rpms to maintain speed under Cruise Control. At the end of the day, I was averaging about 12mpg Hwy and 10 in town.
I started looking at swapping gears in the Differentials to correct the increase of tire size affecting the transmission and thats where things got a little fuzzy. The only clear answers that I found were; 1) Its expensive 2) You have to swap out the front differential for an older model 3) Its a pain in the ass. I researched the topic for a few months. Pricing out the various things that I would need as well as finding a reputable shop that could perform this magic. What I didn't ever find was a list of what was needed to get the job done, so I am going to do you all a favor right now.
Things you need -
1) Front Differential Housing Assembly from a 2010 1500.
2) Ring and Pinion Sets for the Front and Rear. (Motive makes a 4.56ZF set for the rear and the 2010 front)
3) Rebuild kit (I elected to rebuild with all new bearings etc. on the front due to unknown mileage and condition of the 2010 front Diff)
4) Gear Install Kit
5) *****This is up to you - 2010 Front Drive Shaft and Spacer (I ordered the spacer from Rough Country for the 2010 6" lift) OR Have your existing Spacer machined to accept bolts for the smaller 2010 Diff.
6) ***** This is where I had issues - Brackets for the 2010 Diff. (The 2010 Diff has a different mount then the 2012. I ordered all of the associated brackets from Rough Country when I ordered the Drive Shaft Spacer. *not realizing that where it mounts to the truck is completely different in one location* The 2012 is mounted at an angle, while the 2010 is straight vertical. The solution here was to basically cut both brackets, using the 12 bracket to mount to the 3rd member and the 10 bracket to the Diff.
7) Money - lol.. Actually, I had seen where others had payed around $3,100 and I ended up at $2,750 (including labor, the parts ordered from Rough Country, drive shaft and diff)
Issues -
The big issue was the 3rd member bracket. ***Don't drive without it - the tube on the stub shaft on the 2010 diff will break, lesson learned.
***Results -
I drove the truck home, about 75 miles, stopping 3 times to let the Diffs cool down (part of the break in period). On the highway, cruise set at 72mph, the truck purred like a kitten at 2000-2100 rpms in 6th gear. I actually had the ECO mode kick on while on even stretches. After the 500 miles, returned to the shop and had the fluid changed, then proceeded to find out what I had payed for.... WOW... The truck feels bad ass again.. with traction control on, it feels like its about to do a wheelie from a stop. The acceleration is what it was stock and sounds amazing! the exhaust tone changed a lot, now that the engine isn't bogged down. A little higher pitched and louder.
MPG -
I haven't calculated the city MPG yet, but after a fill up, with about 30 city miles and 150 Hwy miles, I got 16.5MPG. I am going to check it solely on the Hwy and then again in town and update.
Shop-
I live near the KC area on the Missouri side. I called a few mechanic shops in my town, and I didn't really get that warm and fuzzy that any of them were capable of doing the job. I looked online a bit and found Gears Unlimited in KC. I spoke with Billy (the owner) and told him about the challenges as I mentioned above. He was at a show somewhere when I first spoke with him and actually went around to different booths talking to other people about the 2012's. He called me back and said that he absolutely wanted to do it. I liked how he wanted the challenge and so that where I went. When I arrived to drop off my truck, they had already installed the gears in the 2010 front diff and rebuilt it. I came back the next afternoon and it was done**(with the exception of the bracket issue). When I returned for the 500 mile inspection and diff oil change, we saw that the tube on the stub shaft had cracked all the way around. Billy ordered another Diff, swapped out the internals and fabricated the bracket at no additional charge. (AWESOME)
I am absolutely pleased about how the truck performs! Best thing I have done since the lift.
If anyone has any questions, I will do my best to help you out to keep your troubles to a minimum.
