Swapping from 3.73 to 3.42 Gears

[MR.K]

Front gears ...

I have a 4x4... . can you get the 3. 4 gears for the front too? Any #'s ...

 

[Morse]

Try giving Greensburg Machine a call. Their number is 724-837-8233. I first called Randy's Ring and Pinion. They told me they didn't make a 3. 42 until I gave him the part number. He said he would call me back with a price and never did. Greensburg took my number, and promptly called me back. He then knocked the price down for me. Very easy to deal with.

 

[VanOverbeke]

I am interested in the results too. If I did not like what you were doing or was not interested I would not read the post or take the time to reply. If you want to see people wasting money on things that are not cost effective or they do not use, go to the conversion site on TDR, you will find plenty. One is in my sig, it was not cost effective and I will never recoupe the money, but damn it was fun and you only live once so do as you like.



when wind speed goes up 2x the effect on the truck is 4x. I found that in one of my crane operating books here at work. Good luck with the swap.



Bryce

 

[MPerez]

MPH RPM 3. 73 gears RPM 3. 42 gears

60 1650 1500

65 1800 1650

70 1950 1800



Man I would give an arm and a leg for those RPM's!!!



2100 @ 65 #@$%!

Me too. When I test drove the truck I swore they must have mistakenly put a 4. 11 in it. I am torn between a GV overdrive, new 3. 42 gears or 19. 5's - Though I may do the GV and the 19. 5's



1900 at 60... But it'd probably move the moon if I could hook a line to it...

 

[DHerbeck]

I look at it this way, if I spend 600 bucks and do get 2 MPG increase, it pays for itself in 25,000 miles. I will put 10 times that number of miles on my truck, so I could net $6,000. 00 savings over the life of the truck. Show me another mod that pays like this, I am not seeing them on this board.



And it just can't take 325 HP to move this truck along the highway at speed. I have seen numbers before about the amount of HP it takes to move a car down the road. I can't believe it takes more the 75 HP to move this truck at highway speed. If I cant run the engine at the RPM that is where max. torque comes in, there is something wrong. I am not talking about straining it at 1100 RPM or something ridiculous like that.



If it suffers too much while towing, I can go to a smaller tire just for towing, it wouldnt take much to get my 150 RPM's back. I would have to hand calculate the speed difference with the smaller tires, just like the guys do with larger tires, but as little and light as I tow, that will not be a problem.



Speaking of wind resistance, I was driving home last night and observed something I have observed before, a 20 MPH sustained headwind with 40 MPH gusts... I sometimes feel what I will call buffeting, like I am driving on a washboard with high wind. I drove a few weeks ago at 70 MPH, 25 MPH headwind and it was a constant buffeting, vibration caused by dirty wind breaking away from the truck somewhere? Anybody ever experienced this? It would be nice to know where it is coming from and clean the truck up a little.

 

[MSLiechty]

In response to why people buy a Diesel if they don't pull heavy. How about this one? My employer gives me free fuel, as long as I own a diesel. No free fuel for a gasser. That made the offset in cost a wash from what I was driving and have 3 times the truck of the Nissan I did have.

FWIW: I will never own another gasser if I can help it.

Michael

 

[opjohnny]

Dave when its time for tires you could always go to the 245/70-17 , it came on the st. Less weight and smaller diameter. If you found you lost to much snap from going 3. 42. With the 4x2 truck I would bet you will like the 3. 42s. . My not work as well on a 4x4 since the difference in frontal area.

 

[DHerbeck]

A few interested folks have asked for info about 4x4 and gears for the front diff, here is the info from AAM:



To convert Chrysler (Dodge Ram) to 3. 42 ratio:



Rear



11. 5" Gear Set - 40045439 (New) - (Fits both GM and Chrysler 11. 5 Rears)



Front - A Diff Case and Diff Kit change is necessary for 2003 to 2006 models - use the following parts...



9. 25" Gear Set (New) - 40045288 - (used in 2007 and up)



9. 25" Diff Case (New) - 40028204 - (used in 2007 and up)



9. 25" Diff Kit (New) - 74042462 - (used in 2007 and up)

 

[jmccart]

I tow like only 10 times a year. But even if it was like once a year, I would still want a Diesel because a 4x4 megacab with the hemi is really slow, especially with some bigger tires.





If I did not plan on putting on a bigger tire, I would totally want another gear option (OD's are big bucks). At time I like to drive pretty fast on the fwy where the tach is sitting at like 2600. I wish the G56 had a better OD. This is a cool experiment.

 

[AKaiser]

Plus you could always tow in 5th if turns out to be an issue. I agree that the G56 trucks are probably geared too low when running empty. I don't know how many times I started looking for another gear. Looking forward to your results.

They flat-out scream above 70 MPH. Mine is dead quiet at 65MPH, when it's running 2000RPM. I'm gonna have to check that again. I'm pretty sure it's 2000RPM, but the speed, not so sure.

 

[DGoyer]

I just changed my 410 to 373, took a 400 mile trip no load. at 2000 I see 69mph. just filled up, overhead red 19. 6 real calc. was 18. 5 guess I cant trust the overhead.

 

[BHaden]

I just changed my 410 to 373, took a 400 mile trip no load. at 2000 I see 69mph. just filled up, overhead red 19. 6 real calc. was 18. 5 guess I cant trust the overhead.

Your is pretty accurate. Mine has been reading high by at least 2 mpg since new. Now has 18k. Last week I filled up and it read 20. 0, hand calc was 17. 6.

That's typical.

 

[CookD]

My overhead always reads low by 2-4 mpg. I just filled up overhead read 16. 4 hand calc. was 18. 3. I think the gear swap will be be great! I have been waiting to hear more on this, my freeway rpm's are just to high. Anything over about 65mph and I really take a hit in mpg. In fact I get better mpg around town that when I drive 70 to 75 on freeway. I think you WILL see the two mpg increase! At 63 to 65 I can usually get 18 to just over 19. But last nov. on I-90 going 75-77 I only got 14. 47! I can hear the talk about wind resistance, but a four mpg decrease. Anyway the noise at those rpm's are very anoying. Good luck with the swap and keep us posted, if it goes well I will do the same.

Dale:-laf

 

[Rotty]

DHerbeck:

I am watching this thread also like many others. I support you and go ahead with the gear swap and all of the information. I am an engineer but still believe in real tests with good data collection. I have the NV5600 but am still interested. Yes, wind resistance maybe a considerable factor, but I believe most are running empty at about 80-95% of the time. You gave the perfect example of running 100 miles in two different gears but do not change speed. This takes out the wind speed change out of the equation. Bigger tires does give some direction but now you are introducing another variable of raising the truck and changeing the wind loading at speed. If you need to tow heavy just drop into 5th (straight 1:1) which is supposed to be stronger gear anyways.

I have 4x4, so it is good to know the front end PN also. It figures that a carrier/differential is needed to be changed on the front end.

Good luck...

 

[DPKetchum]

Most posting on this site running empty(hot rodding)MOST I know and see with Diesel trucks are working them almost daily.

 

[AKaiser]

Daily driver, bone stock. Only vehicle I own, or need. If I was going to do any serious towing, I would've bought a 3500. This thing is hard enough to find a parking space as is, and it's a short bed quad cab. Better MPG than any gasser in it's class, even at 17 MPG.

 

[DBusch]

i have done the same type of experiment with my G56 4X4 2006 truck. towing 18000 gross at 2200 rpm and 69 mph, it would get 10. 5 mpg. I slowed down to 2000 rpm and 64mph and picked up 2. 5 mpg. i cant imagine the difference was only wind related. pulling hills was just as good at 2000 rpm as it was at 2200 rpm. the extra rpm does nothing good for this truck.



its a shame, because the G56 is otherwise a great transmission that shifts significantly better than the older NV transmission.



i like the gear change idea, but has anyone with a G56 considered changing just the 6th gears in the transmission? does anyone know if the small gear on the mainshaft is removable?

 

[AKaiser]

Your is pretty accurate. Mine has been reading high by at least 2 mpg since new. Now has 18k. Last week I filled up and it read 20. 0, hand calc was 17. 6.

That's typical.

Pretty much in line with what mine reads.

 

[Hercules130]

i like the gear change idea, but has anyone with a G56 considered changing just the 6th gears in the transmission? does anyone know if the small gear on the mainshaft is removable?

I am definately looking into this. One of my freinds is the head cummins service tech at a dodge dealer here. I have asked him about swapping the taller overdrive from the 4500/5500 G56, but he hasn't been to any class on it yet. I will follow up with him in a few weeks.



It would be nice if DC replaced my transmission under warranty(5th and 6th gear buzz) with a G56 for the 4500. Unfortunatley they say the gear buzz is normal.

 

[DBusch]

what is the overdrive on the 4500/5500 G56? the 3500 is . 79 as far as i know...