G56 AD to AE

[Southbound]

Brethren-



I am hoping to get some feedback for those of you who have switched from the earlier version of the G56 (AD) to an (AE)? I currently have 156K on my stock clutch (I am knocking on wood as I type) and so far no issues. And yes I pull with my truck often!!! I am one of the lucky ones. That being said I would imagine its a matter of time before my clutch goes SO while in the process of replacing the clutch I would love to replace with the "newer" version of the G56. Since I have a dually I am running close to the stock tire size so my only way of bringing down my RPM's ... . is with the newer final drive on the AE version. I understand that my pulling ability may be affected but I am not sure how much? So I am hoping somebody out there who has the same configuration as I have ... can chime in on positive / negative results??? Having a 5. 9 I do believe the 6th gear ratio in the older G56 is good for pulling heavy loads however it is not ideal when running empty down the highway. Case in point... . my gas mileage is better with "in town" driving when compared to that of "highway" driving. Your probably asking why dont I just rebuild my current... ..... thats a thought but I am leaning to the factory AE at this point.



Oh yeah I forgot to mention that my rear-differential has the 3. 73 ratio... ... ... . which I have been told in my current configuration I convert up to a 4. 10 / 4. 11 ratio when in 6th gear. And with that ratio at 70 mph... ... ... it makes my 5. 9 REV!!! :-laf



Let me know if anybody out there has done this swap. And thanks in advance for your time.



Southbound

 

[AH64ID]

It will reduce your rpms by about 6%, or the difference between 3. 73's and 4. 10's on a NV5600. Based on towing I would keep the AD, I am jealous of the rpms in 6th on my dad's 06 when towing. He can far outperform me on the hills in 6th.

In addition all of the gears, except 5th, are taller. They are all about 6% taller.

G56 AD G56 AE
6. 29 5. 94
3. 48 3. 28
2. 10 1. 98
1. 38 1. 30
1. 00 1. 00
0. 79 0. 74

 

[Regcabguy]

My AD version lends itself to taller tires and probably contributed to the fact that my clutch was like new at 37K according to the installer who fixed my rear main. That's with 2000# on my back and Smarty set on #sw3.

However,with 285-70-17,that I initially had rpm's were brutal on the freeway.

 

[seafish]

For the reasons stated above, I would stick with the G56 AD and it's higher gear ratios for better towing and "potential" longevity.
I say potential longevity only because BOTH the AD and AE have the same aluminum case and are connected to the might cummins by the same, or should I say lame, DMF which definitely relate to a tendency for occasional clutch and/or transmission failures on these trucks.

I would simply change to a clutch with a SMF conversion ( like from SBC) and maybe also install the viscous damper off a 6. 7 CTD to help with the NVH which removing the DMF might cause.
If you have NOT already slipped your oem clutch towing the loads you tow and with the power you have, and DON'T plane to add any power or heavier loads, then you might just go with the SBC organic clutch face, as opposed to the SBC Con-OFE. Using the organic only clutch which likely will keep the transmission less grabby and quieter all by itself, then using the con-OFE.

Just my . 02.

 

[Motorhead]

I have the AE ratio in my 5. 9 (came stock as it was built the last week of '06) and it tows just fine. At 61mph I am right at 1800rpm (sweet spot). The other advantage to the AE is at 65mph with stock tires, I am turning 2000rpm. The AD is turning about 60 at 2000rpm. I am going to look into a Gear vendors OD for gear splitting AND to have a taller 6th for empty freeway mileage. Here is the link to the ratios. Scroll down and the AD ratio is the first generation G56 and the AE is the second gen G56.

 

[AH64ID]

I would guess the "sweet spot" for towing depends on the region you are in. In mountainous regions it is about 2,200, as 1,800 won't get up as many hills.

The difference between towing at 1800 and 2000 is huge in the mountainous areas.

 

[Motorhead]

I was refering to the 1800rpm sweet spot for general highway towing. Hills I need 2000-up.

 

[AH64ID]

Okay, that is more inline with what I have noticed.

 

[Motorhead]

Here is the link to gear vendors for all stick transmissions. It shows the overall ratios with and without OD.
http://www.gearvendors.com/4x4dmanual.html

 

[Southbound]

Brethren-



Sorry for the delay... ... . been on the road and just getting back to the forum. That being said I wanted to thank everyone for your responses. All very good points... ... . unfortunately I am still on the fence! ;-) My fear is that if I went with the AE version the difference from 5th to 6th would be enough to create a "boost lag" ... ..... using the 5. 9. I can obviously get around that with a programmer but concerned about damage long term. I have convinced myself that this 06 will be my last truck for a while... ..... so trying to make her last. Back in the day I would opt for "full bombing" but on this truck I have been very conserative. So at this point I am still "undecided" but glad I got some feedback from you guys.



Thanks to all for your opinions... ... ... ... ... they did help!!



Regards, Southbound

 

[cerberusiam]

Boost lag? Not following on that at all.

You should little diference between the 2 transmissions n the shift point. Your biggest difference is likely going to be running at hiway speeds. If you drive it like it is intended there will be no lag on shifting.

Its like a . 05 change in ratio. With 3. 73's the leverage is good enough it should not even be noticeable.

 

[Motorhead]

FWIW, You can't just change the AE 6 th gear into the AD trans. There is other gearing that needs to be changed also.

 

[NIsaacs]

FWIW, You can't just change the AE 6 th gear into the AD trans. There is other gearing that needs to be changed also.

If the G-56 is like most medium/heavy duty truck transmissions, you change the input shaft/drive gear and the matching driven gear on the counter shaft. Like AH said, it changes all the gears, other then direct.



Nick

 

[KBrody]

Best thing I did was add the Gear Vendor to my truck, G-56 AD. When engaged, it drops the rpms by 500. At 80 mph I'm running around 1850 rpms. One time on hy 50 here in NV. , I was passing and looked down I was around 100 mph and about 22 to 2300 rpms. What I've notice is that in 5 gear o/d on, it's like stock 6th gear. Works great when towing my 30' toy hauler.

 

[Regcabguy]

I have the AE ratio in my 5. 9 (came stock as it was built the last week of '06) and it tows just fine. At 61mph I am right at 1800rpm (sweet spot). The other advantage to the AE is at 65mph with stock tires, I am turning 2000rpm. The AD is turning about 60 at 2000rpm. I am going to look into a Gear vendors OD for gear splitting AND to have a taller 6th for empty freeway mileage. Here is the link to the ratios. Scroll down and the AD ratio is the first generation G56 and the AE is the second gen G56.

My friend's got the Gear Vendor with his '07 G-56. He's pleased with the expanded selection of gears but wouldn't do it again. Lots of dough for maybe a 2 mpg gain under optimal conditions. He also runs a Pacbrake which they discourage.

 

[RVTRKN]

I would leave it alone, once you change it out to the newest ratio's, then you will want to change your differential gears to the 4:10. The higher ratio's actually is easier on the clamshell aluminum design. One of the known weaknesses of the G56 is the transmission can flex under heavy load conditions causing the gears not to mesh properly which cause premature failure. The 4:10's only help in final drive RPM's and the transmission will still have more flex with the newest ratio's.

 

[Bendude]

I know I know I'm bringing a 2yr old thread back from the dead. I came across this after googleing the same thing the op was after.

These are the parts needed to update a G56 from AD to AE
http://www.cmgearworks.com/transmis...dodge-diesel-6-speed-manual-transmission-6-7/
http://www.cmgearworks.com/transmis...ar-6th-6-7-dodge-diesel-6-speed-transmission/