06 Ram 3500 Gear Ratio Changes?

[DTucker]

Anyone know the difference in mpg when pulling hard with 4.10 vs. 3.73?
I just finished a trip through the Rocky Mountains and the truck struggled up the 6-7% grades; as well, the transmission kicked down often so I figured I should change to 4.10s.
We have a 06 Ram 3500 4x4 dually, 5.9, Smarty Jr. programmer set on 60 hp, K&N filter, and 2012 Grand Canyon. I recently had it weighed at 24,200 lbs. GCWR. The last trip it was about 24,700 GCWR.
Some say there is little difference because the engine w/3.73s is working so hard and that the 4.10 eases the load and you come out about the same mpg when towing heavy.
Any thoughts? Any suggestions for upgrades?

Does anyone know if the new 68RE, or better yet, the Aisin transmission will bolt up to the 06 5.9 engine?
Love the simplicity of the 5.9 and it's paid for.

 

[TandT]

I love my '06 5.9 Cummins. Great engine (only 60K miles) and also paid for.
But, I have the same problem. The 48RE (4 speed) experiences a 700 RPM drop between 3rd and 4th.
If I can't pull at 62+ MPH, my rpm's drop too low in 4th. I then end up running in 3rd with a top speed of about 55MPH. Between 55 and about 62 becomes a no-mans land for towing purposes with that transmission.

I also have 3.73's in the rear. I considered going to a 4.10 or 4.30 rear end. Problem is if you are in a position where you can't pull in 4th, you will now drop to an even slower speed if you must down shift to 3rd. Plus your top speed and mileage when empty will suffer.

That transmission needs one more gear between third and fourth.
I have considered getting a Gear Vendors. http://www.gearvendors.com/index.html
I have talked to several friends over the years who have had one and they could not say one bad thing about them. They are a little pricey however at around $4K. They are also rated to 30,000 lbs.

I believe Sun Coast is now making a 5.9 to 68re (6 speed) setup at a total cost of around $10K for the transmission and adapters. Just not worth it IMHO.

Trace

 

[Bob&Patty]

Trace knows from where he speaks. We have traveled with him quite a few times. His 5.9 pulls real well BUT dies on long grades. A 10K upgrade.....not me. I would sell my current truck and take the 10K and get a newer truck with the better trans. If you spent the 4K or 10K you would never get that back on a sale or trade-in. JMHO

 

[JWalker]

I know that there is a big difference between the 4:10 and the 3:73. 2k-3k more in tow capacity. We are going to look at the change in our 07, when we move into our next 5er. I believe the 6.7 in the Rams has a different transmission than the 5.9. Not sure if it is any stronger or not. No problems so far.

Jamie

 

[Bob&Patty]

Both Ford and Dodge had Allison get involved with their new transmissions a few years back. No worries now with either trans.

 

[ramdually4100king]

I have the new transmission (68rfe) with the 3.73 gears. On steep grades it shifts to 4th and I do 55 mph max if I am lucky. I plan on upgrading to the 4.10 in the near future to help with the go part of California's stop & go traffic and pulling up hills.

On a side note I had no problems with my 11000 lbs sob. My cyclone tops out at 19000 lbs. A little bit of a weight difference between the two.

 

[TandT]

I don't want to give up my 5.9 and my tranny is plenty strong.
I wouldn't say it "dies", it pulls strong, but at a steady speed of only about 55 on hills, if I stay in 3rd.

The design flaw in these 48re's is the RPM drop between third and fourth. A mind boggling 700+ rpms.
Most other trannys are ( I think) in the 300-400 rpm range between upper gears.
The Gear Vendors overdrive would give another gear half way between third and fourth and a taller top gear when running empty. Effectively it would be a shift on the fly, 8 speed. Trace

 

[MCTalley]

Us older Ford owners agree with these statements. The 4R100 is geared almost the same in 3rd and 4th. I run into the same situation on long grades. I just go with whatever it'll pull - sometimes that ends up being 48 mph in 2nd at almost redline.

I considered a Gear Vendors, as well, but decided the few times I've had to pull long grades that the investment wasn't really worth it. As long as I'm still passing a couple 18-wheelers on the grades, I'm happy.

 

[Gaffer]

Love my 4.10's The Dodge 6 speed is direct in 4th and 5th and 6th are over driven and not spaced far apart. In stock form I still know a 7 % grade when I hit one. On a 6%, I just shift to 4th (direct) and pull it at 55 mph (2500 rpm) easy pull at that rpm.

 

[Bob&Patty]

Trace, "it dies" is the speed not the engine power cause of the trans.