6.4 Hemi Gear Swap

[RainDesert]

Excellent report. It amazes me how many people don't understand how important gears are for the gasser performance and efficiency. Thank you. Reading through these Ram threads is just like what I read on the Ford side.

 

[schiene102]

So reading through the thread, I see 4.56 work well as do the 4.44. I was quoted $1565 for 4.56 Yukons with install and pinion conversion kits and $1082 for AAM 4.44 with install and pinion conversion kits, both parts only.

So question is, are the 4.56 gears $500 better for towing up to a 10k camper on the factory 33's and possibly 35's when they wear out. From what I can calculate, there will only be roughly 50-60 rpm difference. WI doesn't exactly have big hills like out west. Moving from 3.73's both with be a huge improvement.

 

[LDBagger17]

Those ratio's are so close I honestly don't think you will notice a difference, you will be fine with either towing 10k. With 35's personally I'd want 4.88's but thats just me. Factory gears normally don't make as much noise as aftermarket gears do, I think the 4.44's they priced you are AAM gears? The reason I went with 4.44's was oem gear sets and a lot cheaper. What gear ratio do have now?

 

[Ratket]

If 456 cost 500$ more than 444"s I would just go with 444"s then.

 

[15BlueStreak]

So reading through the thread, I see 4.56 work well as do the 4.44. I was quoted $1565 for 4.56 Yukons with install and pinion conversion kits and $1082 for AAM 4.44 with install and pinion conversion kits, both parts only.

So question is, are the 4.56 gears $500 better for towing up to a 10k camper on the factory 33's and possibly 35's when they wear out. From what I can calculate, there will only be roughly 50-60 rpm difference. WI doesn't exactly have big hills like out west. Moving from 3.73's both with be a huge improvement.

I would go 4.56 either way. Ldbagger did 4.44 and he has 31 or 32 inch tires. With 33s and or bigger in future no doubt 4.56 or 4.88

 

[schiene102]

Correct, AAM gears. Currently have 3.73's

For the $500 difference, I am contemplating putting a true trac in the front.

 

[LDBagger17]

If you have 3.73's I think you would be very happy with 4.44's

 

[BoldAdventure]

4.88's front and rear, especially if you want to run 37's, Nitro and Yukon have sets. I've got a write up on the swap if you want full details.

 

[SETEX 6.4]

4.88's front and rear, especially if you want to run 37's, Nitro and Yukon have sets. I've got a write up on the swap if you want full details.

I agree. I have factory 4:10's with 35's and I could easily see going to 4:88's. Hell 37's with 5:13's would be great but I don't think we can go that low. Not sure.

Sent from my SAMSUNG-SM-G891A using Tapatalk

 

[schiene102]

Thanks for all the input. After looking at some new 5th wheels today, the height of these new trucks is definitely an issue. If we end up getting one, I don't see 37's going under the truck. 35's might be a stretch without lifting the trailer a bunch.

However, I ran a test running around the 200 mile drive today, keeping the truck in 5th gear, which with the 33's and 3.73 ratio, according to my calculations, put my rpms about where 4.88's would be in 6th until I go bigger. It amazes me how well the 6.4 runs when it is hovering on both sides of 2k rpm running 60-75 mph. MPG's were within 1 of my best to date.

Can only imagine what these would do without having to push a button to make the truck act the way it should to begin with. Really want to feel real gearing in the rest of the power band on this truck. Coming from the 1500 with the 3.0 diesel, 3.92 gearing and that smooth 8 speed, there is a lot of room for improvement.

 

[Ratket]

Also mds will activate easier and stay active longer- Yielding better mileage

 

[BoldAdventure]

I agree. I have factory 4:10's with 35's and I could easily see going to 4:88's. Hell 37's with 5:13's would be great but I don't think we can go that low. Not sure.

5.13's are available. And would be great. Not sure I'd want them for daily though.

Thanks for all the input. After looking at some new 5th wheels today, the height of these new trucks is definitely an issue. If we end up getting one, I don't see 37's going under the truck. 35's might be a stretch without lifting the trailer a bunch.

However, I ran a test running around the 200 mile drive today, keeping the truck in 5th gear, which with the 33's and 3.73 ratio, according to my calculations, put my rpms about where 4.88's would be in 6th until I go bigger. It amazes me how well the 6.4 runs when it is hovering on both sides of 2k rpm running 60-75 mph. MPG's were within 1 of my best to date.

Can only imagine what these would do without having to push a button to make the truck act the way it should to begin with. Really want to feel real gearing in the rest of the power band on this truck. Coming from the 1500 with the 3.0 diesel, 3.92 gearing and that smooth 8 speed, there is a lot of room for improvement.

Power Wagon, which is taller than a standard 2500 4x4 on 35's toying a 5th wheel that doesn't have a lift

You got the MPG gearing. It's terrible. I feel bad for you.

-----

 

[BoldAdventure]

Taken from a friend:

Complete Gear change kit PN# NG-GPRAM-4.88

Kit included the following;

Nitro 4,88 R&P Rear PN# AAM 11.5-488-NG
Nitro 4.88 R&P Front PN# GM 9.25-488R-NG

Nitro Master install Kit Rear PN# MKAAM11.8-B *
(Note this kit will include the conversion bearing required to run the aftermarket gears in the new housings)

Nitro Master install kit Front PN# MKAAM9.25
The bearing install kits included new crush sleeves, pinion shims and pinion nuts as well as gear marking compound/brush and a small pouch of assembly lube

Alternate options for the bearings from Yukon Gear are as follows, both of these kits contain the conversion bearing also;
Master install kit Rear PN# YK AAM 11.5-CONV (Complete bearing and seal kit for the 14+ housings)
Pinion only bearing kit Rear PN# PK AAM 11.5_CONV
(Pinion seal and inner/outer bearings only)
If you want to buy the front conversion bearing by itself the Timken part numbers are;
Bearing HM807035
Race/cup HM807010

Misc fluids/chemicals
8 qts of synthetic gear oil. (I chose Royal Purple) Book says 7.2 qts to fully service both differentials.
Brake clean for cleaning the housing and part and to remove the shipping/storage coating (cosmoline) from the new gears.
A good quality silicone sealant for the axle shafts when reassembling. (A thin layer is sufficient to allow the original gaskets to seal) If gaskets tear or are in bad shape replace them.
White Lithium Grease
PTFE Sealant for the splines on the pinion
Red Loctite for the Axle flange bolts, ring gear bolts, pinion nut, and driveshaft flange bolts.

 

[schiene102]

You got the MPG gearing. It's terrible. I feel bad for you.

-----

You're funny, so is Ram with their thinking, but completely agree with you. I read more reports on 4.10 gearing getting better mileage than the supposed MPG gears of the 3.73. With the 2% of the time the mds actually does kick in, its normally while in town. Only time it kicks in on the highway now is when I'm going down a hill. Barely even know the system exists.

I initially wanted 4.10's, but doing a 250 mile search in my area, there were a total of 2 trucks with them. All the dealers I talked to thought I was crazy for wanting them as well. The deal I was able to work the dealer down to on an inventory truck left enough room for me to change the gearing and still be several thousand ahead of ordering a truck with the 4.10's in it.

Gears will be ordered next week, then it will be a couple of weeks before my guy has time to install them.

Any preference between the Yukon and Nitro?

 

[RainDesert]

You're funny, so is Ram with their thinking, but completely agree with you. I read more reports on 4.10 gearing getting better mileage than the supposed MPG gears of the 3.73. With the 2% of the time the mds actually does kick in, its normally while in town. Only time it kicks in on the highway now is when I'm going down a hill. Barely even know the system exists.

I initially wanted 4.10's, but doing a 250 mile search in my area, there were a total of 2 trucks with them. All the dealers I talked to thought I was crazy for wanting them as well. The deal I was able to work the dealer down to on an inventory truck left enough room for me to change the gearing and still be several thousand ahead of ordering a truck with the 4.10's in it.

Gears will be ordered next week, then it will be a couple of weeks before my guy has time to install them.

Any preference between the Yukon and Nitro?

This mpg scenario is no different in the Ford 6.2, and there are no 4.30's on lots, just 3.73. The tall geared HD gassers could be a way to make the diesel more appealing.

 

[15BlueStreak]

This mpg scenario is no different in the Ford 6.2, and there are no 4.30's on lots, just 3.73. The tall geared HD gassers could be a way to make the diesel more appealing.

I think you may be correct. I see plenty of ford diesels on lots with 3.55 gear sets which is the towing gear set. You don't see a lot of the 3.31 gear sets. I know if dealers would order ford or dodge gas trucks with towing gears 95% of people wouldn't even tell the difference and they would sell even more trucks off their lots instead of ordering.

 

[SETEX 6.4]

I don't understand how dealerships pick the guy that orders the trucks. Maybe I'm just the minority and won't everything that the trucks on the lot don't have. Idk shm

Sent from my SAMSUNG-SM-G891A using Tapatalk

 

[SETEX 6.4]

Of you couldn't tell from my last post, I ordered my truck. There were no mega 4x4 6.4 4:10 with ramboxes with the options I wanted

Sent from my SAMSUNG-SM-G891A using Tapatalk

 

[15BlueStreak]

I got lucky I guess with mine. My local dealer found a couple trucks that I liked and the one had every option on it. They drove to Erie pa from nw Ohio to get it and made the deal for me with no extra cost and even threw in a pair of side steps. I don't know if I ever will work a deal like this one again. Lol

 

[BoldAdventure]

Gears will be ordered next week, then it will be a couple of weeks before my guy has time to install them.

Any preference between the Yukon and Nitro?

My friend who installed the Nitro's says they are getting louder and louder. So the Yukon set might be a better bet. But the Nitro's are cheaper.