Has anyone tried this and does anyone have any comments on this conversion. I ordered a complete rear end from a 89 first gen. I know that I will loose abs but I am not sure what else is different. I hope to increase mileage with the decrease in rpm.

thanks
jim

 

3.07?? dang! do you do any towing? remember there is an rpm sweet spot for the 5.9. its between 1500-2000 rpms. if you lower the rpm too much i dont think you will be building enuf boost to be efficient and possibly therefore not really noticing any difference at normal speeds 55-60. my ram has 3.55s and a 47RH and im doing 1500rpm @ 55mph. cruising at 65 i can get 20-22 mpg on interstate. in town forget it..15-17. regardless this is very interesting to see what results youd get from doing this. dont get rid of your other rear end in case you wanna go back to original

 

Zach Hamilton has put 3.07's in his truck in the quest for mileage. Not sure of the results. In a light truck, it could make it a deadly combo.

 

not worried about towing but if I do it will be in 4th

70 mph will be about 1600 rpm

normal speed out here is 70 to 80

you 47rh has a higher overdrive than the nv4500

at 68 I now average about 24 or 750 miles till the light comes on

just trying to beat the high cost of #2

I run about 200miles per day same boring route every day

thanks

jim

 

sounds like you have put some thot into this already. im curious to see how it pans out

 

Just for grins, work on your Aero. Can't remember who, but on the first gen side there was a guy who played with is till he got 33 MPG if I remember correctly.

Aero will help as much as the gear...........

 

agreed
running 235/85's also has seemed to help although they will not carry as much weight as the 265's

 

I've got nothing against upping the fuel mileage on your 5.9, but if you're not towing and you drive that may miles every day, then you really should invest in a Jetta. My 2001 does 62mpg on the highway (125kms round trip to work). That'd be the best way to save on #2 diesel.....

 

He goes by Crabelle, its a 2nd gen 12v.

 

There you go, thanks!

 

It was going to drive me nuts until I found it, for your thought, here is the thread.

https://www.dieseltruckresource.com/...hlight=air+dam

 

I hear what you are saying but with the idiots on the road and the fact that I sometimes carry tools and equipment that is not an option as much as I like the vw diesels I need a truck too often


Patdaly

thanks for posting the link to that other thread

to tell the truth if I could get to 28mpg at 70mph I would be ecstatic

jim

 

After downgradeing from a duramax 6 speed allison to my 1995 12v standard cab in order to pay for the house, man I agree that these trucks need another gear or as you say a much higher rear end... I tired to chase down a theif in my 12v and the pump de-fueled well before 90MPH, thats something that really bugged me as I used to pull my 15k toyhauler down the straits well above 100mph with the max on EFI live.. anyway, thats gone and I still have a home so back to the 12v. Im all for 3.07 or 2.89 rear gears to get some MPG's or in my case some speed!
Oh and what 9812vram said, the VW jetta is a great Idea as I have a mechanical injected IDI 1985 VW golf ( video> http://www.youtube.com/watch?v=yo-YUR1_DaU )
and I have seen 60+ MPG many times and if you can find a VW turbo diesel 1.6L rabbit truck its like a golden egg

 

I've hit 100mph in my 12V.. Not exactly what I would want to do often. Never mind with a trailer in tow, thats just silly..

The engine design has a lot to do with mileage. Lower RPM's don't always get better mileage. Point is my 6.7 at 70 mph is around 1750 Rpm getting around the same mileage as my 97 at 2150 rpm. Getting my RPM lower on my 97 would be detrimental to the mileage IMHO with the turbo size etc. The only reason they had the 3.07 was to make up for the 727 3 speed tranny they had in 89-92.