AAM 11.5 3.42 now available!!

[Jason Hughes]

Factory AAM 11. 5 3. 42 ring and pinions now available. Front AAM 9. 25 3. 42 also available, but requires a carrier change. Please PM me for more details. I am sure this will make a lot of people happy that have stock size tires and want lower freeway RPM's.

 

[RodMorris]

Heck with that, I want a Detroit Locker! The 3. 73s work fine for me.

 

[Regcabguy]

3.42's

This is a good development for us G-56 guys,you auto owners aren't turning 2100 rpm's @ 65mph. Thanks Jason.

 

[roperteacher]

My new 07 5. 9 came with the new Manual trans serial number AE. It was the new one designed for the 07. 5 6. 7l engines but my truck was made on Dec 31st!! SO I got the new one... Probably one of the few 5. 9 with the new trans. The gearing a quite a bit different. At 70 I am at 1900-2000 RPM's. .

 

[jjack]

You will only see about a 200 rpm drop at 65. At $325 for front and rear set (plus labor if you can't do it yourself and carrier if you are pre '07) I think I am going to pass. It will take a long time to recoup that in fuel savings.

 

[AKaiser]

You will only see about a 200 rpm drop at 65. At $325 for front and rear set (plus labor if you can't do it yourself and carrier if you are pre '07) I think I am going to pass. It will take a long time to recoup that in fuel savings.

True, but the difference is in MPH. By going from 3. 73 to 3. 42 with my tires, it's a 6 MPH increase at 2000 RPM. THAT is a big difference, and it's on a curve, so the faster you go, the bigger the differential, albeit a slight one. :-laf



For example, 6th gear, bottom end torque is at 1600, difference is 4 MPH. At top end torque of 2900ish, it's 9 MPH. At max fuel, 3300 RPMs its 110 MPH versus 120 with the 3. 42s.



Recoupment just depends on how long you keep your truck.

 

[MStrain]

If they are 325 for front and rear set, how much for a 2wd, half that? Where do you get them?

 

[SSwords]

what does the carrier cost ? that is what will prob get me and what will the bearing kit cost. I drove one of the new g56 trans and now I want one I wonder what the swap out on that would cost?

 

[J&LRam]

3. 42 for a truck ?? Sounds like some need a car for all the power 3. 42s will give.

 

[JFaulkner]

3. 42 for a truck ?? Sounds like some need a car for all the power 3. 42s will give.

Gear fast run slow. If you have the HP the gearing doesn't matter, especially with a manual trans. Our semi's used to be geared low (4. 33) then they went to 3. 90, then 3. 70 and the newest one is 3. 36 and it's awesome. Sure it's geared to run ~115mph but in high gear at 55mph it's only turning 1000rpm. I'd like my dodge to stay around 1800 at 65 but it sounds like the 3. 42's are not going to cut it.

 

[AKaiser]

3. 42 for a truck ?? Sounds like some need a car for all the power 3. 42s will give.

Cripes Sakes Batman, we're talking about a fire breathing Cummins HPCR here, not a gasser, or even an older, lower powered rig. Besides, if you done any BoMBing whatsoever, low end should be a non-issue. If, like me, you have a G56, not only do you benefit on the long end, there should be ZERO downside on the low end with the low-hole (see table below) in first gear, if takeoff is a concern. Second gear ratio is only a 3. 48 on the G56, versus 3. 38 on an NV5600. There is less than 1 MPH difference in 1st gear between a 3. 73 an 3. 42 at 1000 RPMs. Same is true in 2d gear at 1600 RPMs. The trend is about 2 MPG more per gear in 3 and 4, and 4 in 5th and 6th at 1600. For cruising at 2000 RPMs it's +5 MPH in 5th and +6 MPH in 6th respectively.



I'm working on cleaning up this table.

Gear Ratios

1 2 3 4 5 6

NV5600 5. 630 3. 380 2. 040 1. 390 1. 000 0. 730

G56 6. 290 3. 480 2. 100 1. 380 1. 000 0. 790

68RFE 3. 231 1. 837 1. 410 1. 000 0. 816 0. 625

AISIN 3. 740 1. 960 1. 340 1. 000 0. 770 0. 630

NV4500 5. 610 3. 040 1. 670 1. 000 0. 750

47/48RE 2. 450 1. 450 1. 000 0. 690

 

[LesStallings]

I believe that it realy comes down to how one uses their truck.



Guys that tow want around 2,000 RPM at cruising speed. Guys that don't, want lower RPM.



Some folks want a diesel - Some folks NEED a diesel. The "want a diesel" guys would be very happy with a Ram 1500, short bed, big diesel, 22" wheels, wide tires, and some chrome bling. Good on them.



I just don't think a HD 3500 was engineered to cater to that group.

 

[AKaiser]

I believe that it realy comes down to how one uses their truck.



Guys that tow want around 2,000 RPM at cruising speed. Guys that don't, want lower RPM.

That depends on load, desired cruising speed, and tire size. For example, my cruise at 2000 RPMs on 33s with 3. 73s is 67 MPH. It goes to 73 with 3. 42s, but is only 70 with 3. 42s and stock 265/70R17s. All tires load range E. This is just me, but were I to tow any heavy load where I thought I needed to raise my RPMs, I could always put the stock tires back on, and reset my ECM to stock settings with the Smarty, which also resets the tire size to standard. If I really felt it was an issue, I could get a set of 245s for the 17 inch rims, which brings the speed at 2000 RPMs down to 62 MPH.



Food for thought: Actually, I think having a daily driver tire at 33-35 inches (like my 33 inch 275/70R18s), and a heavy towing tire at 245/70R17 is a pretty close to perfect setup for 3. 42s, granted you lose 200lbs per tire rated capacity by going to 245s (on a SRW). I'd be curious to see if the shorter tire would increase MPGs by lowering the vehicle, despite the increase in RPMs.

I just don't think a HD 3500 was engineered to cater to that group.

True, which is why I bought a 2500. More versatility.

 

[Bertram65]

I believe that it realy comes down to how one uses their truck.



Guys that tow want around 2,000 RPM at cruising speed. Guys that don't, want lower RPM.



Some folks want a diesel - Some folks NEED a diesel. The "want a diesel" guys would be very happy with a Ram 1500, short bed, big diesel, 22" wheels, wide tires, and some chrome bling. Good on them.



I just don't think a HD 3500 was engineered to cater to that group.

So very true.

 

[JFaulkner]

Alot of you are missing the obvious point. The higher gear ratios are mainly being requested by the G56 croud. And since it is a manual transmission, who cares if your towing? You don't always have to be in high gear. Heck you could use 2. 25 gears and tow in 3rd. And anyone that's drove a G56 knows that low is really low. 3. 42's and/or 3. 36's are a win win, if your heavy or crusing slow just use 5th gear. For higher speeds or lightweight loads use 6th. My semi with the 3. 36's needs to be moving above 65mph in order to efficiently be able to use high gear. However, that in no way means that it's geared too high. Look at the Ford F-450/550's, 5. 33 gears!! Nice unless you actually want to move faster than 60 and get anything better than 5mpg. I learned my lesson a long time ago, NEVER replace HP with gears.

 

[AKaiser]

Alot of you are missing the obvious point. The higher gear ratios are mainly being requested by the G56 croud. And since it is a manual transmission, who cares if your towing? You don't always have to be in high gear. Heck you could use 2. 25 gears and tow in 3rd. And anyone that's drove a G56 knows that low is really low. 3. 42's and/or 3. 36's are a win win, if your heavy or crusing slow just use 5th gear. For higher speeds or lightweight loads use 6th. My semi with the 3. 36's needs to be moving above 65mph in order to efficiently be able to use high gear. However, that in no way means that it's geared too high. Look at the Ford F-450/550's, 5. 33 gears!! Nice unless you actually want to move faster than 60 and get anything better than 5mpg. I learned my lesson a long time ago, NEVER replace HP with gears.

THANK YOU!!! Someone gets it.

 

[raychem]

Alot of you are missing the obvious point. The higher gear ratios are mainly being requested by the G56 croud. And since it is a manual transmission, who cares if your towing? You don't always have to be in high gear. Heck you could use 2. 25 gears and tow in 3rd. And anyone that's drove a G56 knows that low is really low. 3. 42's and/or 3. 36's are a win win, if your heavy or crusing slow just use 5th gear. For higher speeds or lightweight loads use 6th. My semi with the 3. 36's needs to be moving above 65mph in order to efficiently be able to use high gear. However, that in no way means that it's geared too high. Look at the Ford F-450/550's, 5. 33 gears!! Nice unless you actually want to move faster than 60 and get anything better than 5mpg. I learned my lesson a long time ago, NEVER replace HP with gears.

I also agree with what you say... heck I want gears for top end... especially when I start to hit the track since most trucks are hitting a wall at 122 mph w/3. 73. Also... people tend to forget or not know that as HP increases... you can and many times(talking gassers here as well as diesels)should run taller gears, lower numerically since the POWER BAND starts to change on the engines. With the boxes, programmers, dl's that can deliver 100-300 hp on the flip of a switch(s) or touch of a button these lower gears become beneficial.



I don't care about mpg's cause my right foot has lead as part of its make-up... I just want the lower cruising RPM since my truck is on the hwy at 75-90 mph most of the time.





Richard

 

[BHolm]

I believe that it realy comes down to how one uses their truck.



Guys that tow want around 2,000 RPM at cruising speed. Guys that don't, want lower RPM.



Some folks want a diesel - Some folks NEED a diesel. The "want a diesel" guys would be very happy with a Ram 1500, short bed, big diesel, 22" wheels, wide tires, and some chrome bling. Good on them.



I just don't think a HD 3500 was engineered to cater to that group.

Very true but I think you are missing a few key points. Those of us with G56 trucks that live in the west NEED the taller gears to meet your criteria. The highway speed limits out here are commonly 75 mph. If I want to run the speed limit while hauling I am getting close to 2500 rpm, even with taller tires. These new gears will bring that down 2-300 rpm greatly improving economy while still having plenty of pulling power. My '06 Mega 48re 3. 73 would get 20 mpg, my '06 QC LB G56 3. 73 gets 18 in the same driving. The 2 mpg sure would be nice to get back. The question for me would be justifying the initial expense. Any idea on the front carrier cost yet?



Just don't assume everybodys needs are the same as yours I need AND want a truck like this. Changing gearing might make it infinately more practical for me. If I could run 65 mph without being a hazzard, maybe YOUR plan would work. As it stands many of us are in a slightly diferent boat.

 

[LesStallings]

I believe the G56 is the issue. My NV5600, stock tires, and 3. 73 gives me 2,000 RPM right at 70 MPH (give or take a bit).



I really LOVED running I-40 out west at 75 MPH when loaded, but it does not work as well back east with a 65 MPH speed limit.



I hated when I hit Texas...

 

[C. Harlan]

Some folks want a diesel - Some folks NEED a diesel. The "want a diesel" guys would be very happy with a Ram 1500, short bed, big diesel, 22" wheels, wide tires, and some chrome bling. Good on them.

... Don't forget about having the hard top bed cover for bling too. . Definitely a WANT a Diesel item!!



-Chris-