Gear Ratio Analysis & Discussion -- Manual transmission

[NIsaacs]

I am not sure what 4. 10's have to do with "useable power". I have 3. 55's and can use all my power, plus cruise on the freeway at 75 empty @ about 2100 rpm. As a 30 year veteran of the log woods and hotshot trucks, all in the western states, I know about hauling in the mountains.



Whats wrong with having to go to 4th gear on a 6 percent grade. That's what the transmission is for. The close ratio 6spd is great for towing heavy loads in the mountains. If you don't like to use 4th, add some power.





"NICK"

 

[crobertson1]

Nick,



I must have misunderstood you. Even with a 6 speed and 4. 10s, I do still need to downshift to keep from lugging the engine, which is a lot here in the Rockies. I have read a lot of posts from guys who seem proud to not downshift. So I see what you mean. Heck, 4. 10s help with just my driveway!



If I didn't live here, 3. 73s would have been my choice. By "useable power", I just meant, I wanted to have the maximum pulling power with minimal power loss from gearing. Maybe I should add some power too .

 

[67guzzler]

This is a great discussion. I really appreciate everyone's wisdom. From the hard-core haulers to the highway commuters and everyone in between. What a great mix of people!



For me, I just would like to end up with a final drive ratio that's taller than my 2. 95 (. 79 * 3. 73 rear). It's effectively the same combo as the NV5600 w/the 4. 10 at 2. 993 (. 73 * 4. 10). I'd trade a little greater spacing and maybe a slightly taller 2nd for a . 69 6th gear with the 3. 73 for a final of 2. 57. I can't tell you how many times I enter the interstate, get up to 60 and want to go into a 7th gear that's just not there!

 

[TYCreek]

First drive with the G56 ... I swore it had 4. 10's! Had the salesman stumped as it wasn't marked anywhere! Found another that was marked 3. 73's drove it and what do you know it felt just like the previous one. I wasn't happy ... the next day we found a NV with 3. 73's ... things just felt much more right all the way through and up to highway speed.



I didn't like the freeway feel/experience with the G or even the shifting of it. Sort of thought I lucked out finding a NV set up just like I wanted (whew)! And oh, mine also didn't have a note about cali... emissions like the others?

 

[NIsaacs]

JGann, your best bet cost wise, (after you wear out your originals) is to put bigger tires on. What is the width of your rims? Bigger tires=lower air pressure=ok ride. 33" tires will give you about 6 percent higher gear and 35" tires about 12 percent. 3. 73 x . 79 x . 12=2. 596 close to your 2. 57 final ratio.



The Gear Venders is great for a daily driver, but be carefull if you use your truck hard, as in heavy loads, drag racing or truck pulls. The GV is only supported by the transfer case. It is long and heavy and over time can split the rear case of the transfer case. It becomes the weak link in an other wise bullet proof drive train.





"NICK"

 

[6 2 Carl]

I would be willing to try out the new transmission with the dual mass flywheel, but my biggest problem is that Dodge obviously realized that the overdrive on the G56 is not as deep, and no longer offer the 4. 1 gears because of this. My biggest beef is that they didn't offer a lower gear to satisfy the 3. 73 owners. I see this as a slap in the face and an indication that Dodge doesn't want me as a repeat customer.



I am in agreement with most people in this thread that, a truck should be spec'd out to pull in 5th gear and leave 6th for running empty. With my 3. 73 gears and 315, I am able to cruise in 5th only turning 2350 rpm at 65mph giving me all the pulling power I need, and another gear for some high speed empty driving.



Carl

 

[GWBourne]

i have a NV5600 BUT i have 4. 10's so i am running almost identicle ratios, RPM's and speeds. here is my thougsh on what i PLAN on doing... 35 inchish tires. that would drop me down a lil on the RPM's BUT also keep me in a power range that is acceptable when towing. i will keep my truck stock height and beign that i am 2wd as i dont need 2wd then ill be fine. mileage drop will be minimal and all should be well. if i could do it i would find a 3. 90's area rear ratio. with 3. 90's and 35's it would be like 3. 73 and 33's. that would get RPM into a more acceptable area, keep towing power on the verge of low, but once the truck is no longer stock it wouldne be a factor again and mileage would be improved or remain stock.



on a side note to me my 16 to 22 MPG, depending on how much i am beating on the truck, is not bad at all. my 98 K3500 w. 4l8e and 454 vortec gor 8 unloaded and 3 loaded with a much lighter load than what i pull now. i am VERY happy with 12 pulling twice the load at higher speed uphill. i could even go a bit slower and not mind, so a ratio change or tire change, it if slows me down... no big deal.



Grant

 

[67guzzler]

JGann, your best bet cost wise, (after you wear out your originals) is to put bigger tires on. What is the width of your rims? Bigger tires=lower air pressure=ok ride. 33" tires will give you about 6 percent higher gear and 35" tires about 12 percent. 3. 73 x . 79 x . 12=2. 596 close to your 2. 57 final ratio.

"NICK"

Nod -- 35" tires would accomplish the same thing. I wish they made more options in the 17" (stock) wheel size... I want a quiet highway tread that's thin and tall. I'm thinking about going to 19. 5" wheels and some over the road truck tires but from what I've read and what the guys have told me the offset difference will have the wheels stick out a little bit...

 

[67guzzler]

I would be willing to try out the new transmission with the dual mass flywheel, but my biggest problem is that Dodge obviously realized that the overdrive on the G56 is not as deep, and no longer offer the 4. 1 gears because of this. My biggest beef is that they didn't offer a lower gear to satisfy the 3. 73 owners. I see this as a slap in the face and an indication that Dodge doesn't want me as a repeat customer.

Carl

I'm with you Carl 100%. They changed to the G56 w/o any official notice. This resulted in a bait and switch to a different final drive ratio and thus, a material change to the specifications of the vehicle without prior notice. It's like ordering a CTD and getting a Powerstroke. I just like the truck so much (otherwise) that I'm taking it in the gut and trying to find out the best way to proceed.

 

[Kirwin]

My $0.02

My complaint with the 3. 73-NV 5600 combination is that my truck loaded to 12K GVW, towing my 11K travel trailer resulted in brief unsettling full throttle excursions over small hills with cruise set at 62 MPH. Even highway overpasses could get you to full throttle! I find that my truck is much happier towing at around 2100-2300 RPM which is too fast for my likes when towing in traffic. Since I use the truck predominately for towing I would rather have had the 4. 10s. But then I found the TST box and now thats all history. Although the cruise is even more touchy now, but the truck rarely gets to full throttle. :-laf :-laf Thanks TST! Ken Irwin

 

[kah68]

D. C. Why don't you give us a 7 speed manual. 5th = direct, 6th = O. D. 1 (lets say . 80? ) and 7th = O. D. 2 ( . 71 ) Then to really give your customers what they want offer both 4:10 for the hardcore hauler, and 3:73 for general purpose use. Hey how about a special order 3:42 ??? And if D. C. gets smart do an auto with the same type of double over and axle ratio options. Imagine how happy your Cummins customers would be ???

 

[kah68]

Hey, do you think a guy could sell enough custom build 6 or 7 speed trannies to Cummins owners to justify a high quality aftermarket unit built to each customers specs but based on one or two models ?

 

[APersondek]

I used to use my truck to pull a boat or a snowmobile trailer depending on the season. However I had to relocate from MI to IL this past spring (for work), so now all I have is a daily driver - which is fine by me... . My question is this:



I have the NV5600. Would it be possible to swap out the . 73 OD gear for say . 69 OD gear that is found in the automatic? Or are the tolerances to close to change any of the gearing within the nv5600 itself.



I was thinking if you could get a 3. 73 with say a . 65~. 70 OD gears the RPM would come down and the MPG would go up. Since AAM does not offer anything less then a 3. 73..... Just thinking out loud... . thoughts and opinions welcome..... no flaming please