M 1028 gear ratio

[PETE BALLARD]

I am looking to make my new M1028 more driveable for expressway driving. I looked into changeing the gear ratios but availble combonations are not attractive, so moving on to other options would be either changeing wheels and tires and or upgradeing to an overdrive transmission. Has anyone gone down this path? if so what components were used? I want to keep the rpm's in the respective sweet spot and get where I want to go a little faster. Any thoughts? All are welcome.

 

[doghead]

May I ask, just how long did you search before posting this?

 

[sandcobra164]

He searched long enough for me to ask this question. Why are you in a hurry? It'll go 50 all day long and loves it. Doghead, good work as usual.

 

[MarcusOReallyus]

Any particular reason this is in the "Conversations" forum, instead of the CUCV forum?

To answer your question, yes, others have been down this road. There are at least dozens of threads around here discussing exactly that.

 

[K9Vic]

Any particular reason this is in the "Conversations" forum, instead of the CUCV forum?

To answer your question, yes, others have been down this road. There are at least dozens of threads around here discussing exactly that.

Technically it should be in the "CUCV Hot Rodding and Modification" section as it is a non-stock modification. Just looking in there I see multiple posts on the subject of gears/axle and transmission mods.

 

[Speddmon]

Any particular reason this is in the "Conversations" forum, instead of the CUCV forum?

To answer your question, yes, others have been down this road. There are at least dozens of threads around here discussing exactly that.

Technically it should be in the "CUCV Hot Rodding and Modification" section as it is a non-stock modification. Just looking in there I see multiple posts on the subject of gears/axle and transmission mods.

Good points....moved thread

 

[martindc1]

I'll bite, because I have been reading and reading threads and researching this very topic. You pretty much have 6 options, and all have their pros and cons:

A. Deal with it
B. 700R4
C. 4L80E with standalone controller
D. 3.73s
E. NV4500
F. HMMWV tires

There are tons of threads on here that you can search through. The cheapest route would probably be to find a civi 3.73 14BFF, a used D60 4.10 and down carrier, and a used D60 3.73 gear-set and swap all that in. Unless you think you can live without the D60 then you could swap in a D44 or other civi front axle. Or keep your eyes out for a 3.73 D60 front axle.

All your options for better highway RPMs will most likely be pushing $2000 or more by the time it is all said and done unless you can play your cards right on the gear swap option I presented.

Heres a hint though, you will get more search results with the term "3.73s" than 3.73 etc.

 

[PETE BALLARD]

thanks for the tips

 

[Sharecropper]

Tall skinny tires are the way to go. My M1028 cruises at 55 mph turning slightly over 2000 rpm with surprising power.

 

[PETE BALLARD]

Nice truck - looks like it should

 

[PETE BALLARD]

Are those tires and wheels from a mnnvvv?

 

[Recovry4x4]

I am looking to make my new M1028 more driveable for expressway driving. I looked into changeing the gear ratios but availble combonations are not attractive, so moving on to other options would be either changeing wheels and tires and or upgradeing to an overdrive transmission. Has anyone gone down this path? if so what components were used? I want to keep the rpm's in the respective sweet spot and get where I want to go a little faster. Any thoughts? All are welcome.

I am befuddled here. What exactly wasn't attractive? You can select ratios between 5.13 and 3.31. The combination you wanted wasn't within that?

 

[PETE BALLARD]

From what my supplier has told me the highest ratio common to both the 14 bolt and the dana 60 is 3.73. I will have to check other places to see if they are in error. Currently i am leaning towards a 700r4 trans. I would like to cruise at 2000-2300 rpm at 65 mph

 

[Tplane37]

I have a 2wd civvy dually that runs 4.10s and is running the TH400 behind the 6.2L J code. Tires are 245/80R16s. She cruises comfortably at 62 MPH down the highway, but I can hear the RPMs are up over 2500, and fuel consumption is pathetic (7 MPG). I want to get that down around the 1800-1850 "sweet spot."

I am looking to go with the 3.73s I have laying around and I am trading the TH400 for a built 700R4 soon. I have had good experience with the 3.73s, they are a good all around gear. Then after installing a tach, I'll find tune the cruising RPM band with the tires after I wear out the set I am currently running.

Just have to remember that for everything you gain, you are giving up a prior benefit. The 3.73s will lower my RPMs at highway speed, but I lose some torque off the line when towing or pulling grades. The 700R4 gearing will help make up for some of the loss of the line and adds another gear, but is a little weaker than the TH400. Larger tires usually cost more and may require chassis modifications depending on the size you go with. The Turbo Upgrade option is still there to help out too.

But stating that a gear change isn't and acceptable option is a little hard to understand. The only time I have ever heard of that was when I started looking for new gears for my XM211, and I just haven't found something acceptable yet, but I am still playing with numbers to get my ideal final drive ratio, so even with the 211, changing the gears is still an option...

 

[martindc1]

Does your Civy have a 14BFF or a Dana 70? If it has a Dana 70 you could go with a 3.54, which shouldn't be too hard to find a gear-set as they were common Dodges.

Another thing to keep in mind with the TH400 is that even though it has a relatively high first gear at 2.48, when you consider the torque amplification of the TC off stall of around 2.5, you are looking at a torque advantage of around 6.2:1 which is close to creeper gear in a sm465. So what I'm getting at is that the gear change is less significant off stall than it seems at first glance.

But yes I totally agree with your point of all the options have compromise. A gear change to 3.73 wouldn't give you quite as good highway RPMs and not quite as good gearing out of the hole but it is simple. I suppose the ultimate combination would be a 4L80E or NV4500 but your concession is higher cost.

 

[Tplane37]

I have the corporate 14FF in my civvy 85 with the 4.10s in it now. I also have a corporate 14FF from a 2002 GMC 2500HD with low miles and 3.73s sitting in the barn, left over from the axle upgrades I did on my 2000 Silverado half ton last year (package deals come in handy sometimes). I now have 4.10s and 35s on my 2000, which works very well with the 4L60E that came in it... actually, the 4.10-35s combo ended up keeping my speedo correct when the truck came with 3.73-265/75R16s combo. So I didn't use the 3.73 14 bolt FF rear end I bought for the conversion on the 2000.

Upgrading the gears and transmission in the civvy 85 dually without spending much cash sure is a nice thought!

 

[PETE BALLARD]

UPDATE - i have been lucky to find a 4l80e trans with 50 miles on a fresh rebuild from a 1 ton chevy that had a 6.5 powering it at a price i couldn't pass up. Will be picking it up this week and install should happen within the month. Will keep you all updated on the fnal outcome, mph + mpg vs rpm. I want to thank everyone for their input - Pete

 

[Cucvnut]

Don't forget the transmission control module and wiring harness

 

[Tplane37]

Don't forget the transmission control module and wiring harness

I know its been referenced somewhere on this site, but can you refresh our memories as to what aftermarket module and harness is required for the 4L80E and where we could acquire such a contraption? I am considering a 4L80E for my XM211.

 

[PETE BALLARD]

There are several manufactures that offer the controller, just google 4l80e controller and see what comes up or i hear you can search the bone yards for the wirning harness and ecu out of a 93' chevy pu/sub or gmc simlilar model. The later is a bit risky if proper operation is unknown. Another ss member just did one of these conversions and i think he is happy with the outcome. Using this trans you can re-use the same transfer case without modifiying the input shaft on the t/c . From what i have read it is a tossup on costs depending on what you have to work with. As they say there is a up and down side for every action or modification and what your expectations are. I got my trans dirt cheap with a warentee so i can afford a little more in other areas. The other member is "richingalvaston" he has helped me decide on my current plan of action