axle gear

The next step down is a 3.73. If you have a CTD this is a viable option (I would not go lower though because it would add a lot more strain to tranny) If it is a gas engiened truck, you will not gain anything with the swap and will likely see performance and MPG suffer. Also if it is a CTD it uses the same rear axle as GM has used in its big block and Dmax powered trucks since 2001 (a 11.5 AAM) so gears are readily availble for it

----------------- The SnoMan

And, since it's a 4X4, you need to change the front axle ratio too. Contrary to what SnoMan says, many CTD's came with 3.55 axles. They seem to do just fine. Changing ring and pinion's is expensive:(

Al

Not for many years have they offered a 3.55 and when they did the engines had a lot lower rated output too. Some the juggler gears and tire sizes give no thought to possible side effects on drive lines because with taller gears and bigger tires besides the engine having to make more torque to put same effort on ground at rear wheels, the drive line has to route it there and carry a higher average torque load too. If you have a CTD and never plan to pull any thing heavy then a 3.42 or even taller could work but towing with those gears will place a big strain on tranny.

----------------- The SnoMan

If by many, you mean since 2003, then yes - that would be correct.

However, 3.54 has been the standard axle ratio for the Dana70/Dana80 axles used behind the CTD as late as 2002, and since at least 1994, if not further back (don't really have a lot of experience with the 1st gen trucks, so I tend not to comment about them... something you should take note of).

My neighbor has a six speed 02 with 3.55 gears. He's burning cooking oil and getting 22 MPG. Hauls a large goose neck horse trailer all over the place. Wish I could have bought my 04 with 3.55's. Mostly I tow an open car trailer, my truck runs away with it. When I do pull my 24' enclosed trailer is the only time I feel 3.73's are about right. With 3.55's I could just drop back to 5th and get by fine. I can't see any reason for 4.11 gears with a new CTD. I've towed a 6 ton trailer with no problems starting on hills are cruising up them.

Al

3.54 was standard with the advent of overdrive automatics. Before that Dodge used as high as 3.07 with the CTD. That's true whether auto or standard transmission. My current '01 has 4.10's with GearVendors, seems an ideal combination.

Robert

Hello all and thanks for the info

What we have is a 2005 3500 4x4 quad cab diesel 6 speed manual with 17" tires. what the trouble is when at speed of 75 the RPMs are at 2.75 and red line is at 4 would like to take this down. we have all kinds of power even when pulling a 40 ft trailer can you guys tell what would be the best size ring and pinion to replace with??

Peter

Ouch! .... that was close to center ring... Mac

Peter... Just for my understanding...

You're making 2,000 to 2,100 rpm in 6th gear at 75 rpm?

Mac

I'm confused a bit, too - seeing as how the redline is at 3,200RPM for a CTD, not 4,000RPM. If he's turning 2750RPMs at 75MPH, then I'm guessing he's got a dually, with the 235/70R17's, a G56 6-speed trans with a .79:1 top gear, and 4.10's in the axles. On my calculator, that works out to

2730RPMs (close enough).

Swapping to 3.73's will bring those RPMs down to just under 2500 (2484 to be exact). A 3.54 will drop it another 100RPM.

Another option, which really gives the best of all worlds, and isn't that much more than re-gearing both axles, is a Gear Vendors overdrive unit. With this, you get an extra overdrive, which will effectively give you a .62:1 top gear, yielding 2130RPM's at 75MPH with the current tire/axle combination. See

for details.

I know well that early ones had 3.54 but they stopped using it when they went to AAM axle in 03 (because it is not supported in the front

9.25 AAM axle either starting in 03 when they dumped the Dana .(You should take note of this). They had to use a taller ratio back then to because the early cummins did not like to rev much at all (dead at around 2300 RPM or so as I recall) because I drove several 93 and 94 models on some steep long mountain passes when I was comparing trucks back then.

----------------- The SnoMan

So 3 years to you is 'many'?

Fascinating. Hey Max... did you know your engine's supposed to fall on it's face at 2300RPM? I bet my buddy, with his '95 12V, sure would find that statement curious - as I'm fairly certain he revs his out to

3200-3300RPM before each shift (the guy drives like a maniac, what can I tell you).

Sure you did...

WTF!! I've been outa here for 10 day's and your BS is worse. Give us a damn break with your never ending phony info.

glad i dont pay his fuel bill!!!

my lead foot is bad enough! *grin*

Give me a break!!!

So, how was Florida, bro? Mac

Bro, it was fantastic!! A bit more crowded than the last time I was there but no big deal. Signed a p&s on a place and will close on it next month. It is in flagler beach, about 15 miles north of daytona and I'd guess 3 miles from the beach, driving. Sue was a bit hesitate but figures as a investment all was cool. She kinda moves at a slower pace than I do (which isn't a bad thing) but is warming to the idea. So this makes up my mind as far as retireing next year. Hell, by then I'll have 35 years in playing with locomotives, it's time. Anyway it is not near as much fun as it used to be. Way too much bs. Sue on the other hand has 5 more years to go to recieve here pension. But she is off all summer and has weeks off throughout the year so she will float back and forth and I'll do the same until she's done with teaching. Then we sell this house here in MA and at her suggestion look at buying a boat. Damn I love that girl!!

Roy

Sounds like some good planning... hope all goes well for ya..

Will one of the places be paid off, or will you have payments on both? Mac

we thought it out as best we could. I'm sure there will be a few surprise's but ya gotta take your shot when it feels good.

The house here has been paid off and we've been getting killed by the taxman. We decided to buy the place in Fl. with a equity line on the house in MA. So actually the house in Fl. will be paid for and a lein on the house in MA. Figure we can write off a piece of the equity line and a trip to Fl. a year. Gotta sit down with the accountant and here what his thoughts are.

Roy