Differential ratio Poll

[4x4 Forever]

If you guys had to change the innards of the front and rear diffs on the M1008, what would you go for?

4.56
4.10
3.73

 

[cpf240]

I'd think you would need to decide what you wanted to use it for first.

 

[panzerwillie]

3.27

 

[richingalveston]

stay with the 4:56 and put an overdrive in it so you have the best of both worlds.

 

[chevyCUCV]

This is only if i HAD to change,

3.73 , stock tire size

Highway would be nice

 

[350TacoZilla]

I have 4.10's 5spd manual and 37's and love the gearing, still has low end grunt in 1st and can run highway speeds no problem. I could actually go with 4.56 with 5spd (and may in future if get a good deal on axles)

 

[11Echo]

If you guys had to change the innards of the front and rear diffs on the M1008, what would you go for?

4.56
4.10
3.73

The original post did not mention wanting to change the transmission or doing a lift for big tires. The poll should reflect what he was asking.

That said I would do the 3.73 swap. Still plenty of power and more highway friendly. I run 255/85's which are taller than my 285/75's on my M1008 and require no modifications to the truck.
I currently run 235/85's on my 3.73 equipped V30.

 

[4x4 Forever]

When I posted the poll, I have all intentions of leaving the TH400 as the tranny guy said the transmission was in excellent shape. I am running 33" tires with the 4.56 and the engine revs pretty high on the highway. I was looking for better highway RPMs but still have good low end power.

I do not want to change the trans at this time or go bigger tires than I have.

 

[350TacoZilla]

I'll stick with 4.10 even with the th400 and stock rubber, I had a 3.73 truck and it was nice for highway but seemed to lose the low end when pulling anything with it. I guess it really depends if truck will ever be used to pull a trailer. If it is mainly going to be a highway commuter I just saw a m1008 on here for sale with 1009 axles in it (3.08 gears) , if you are looking for highway cruising that would be cheap alternative since alot of people with 1009's like to swap in the 1 tons.

 

[twomorestrokes]

Yep too many variables to answer. I kept my 4.56 ratio and turbo 400 so my final ratio is about 3.50 with the bigger tires.

 

[Sharecropper]

The easist and most reversible thing to do is increase tire diameter. If you haven't noticed yet, I really like tall tires.

 

[SouthernSteel]

I personally like my 285 75 16s(biggest size tire that fits on a stock m1008 that you dont have to trim the fenders:]) and the Th400 and 4:56 gears.I can run about 55-60 and it isnt to terribly loud runs like a champ in that speed range and though i have normal exhaust with a set of mufflers for a diesel and it seems to do pretty decent maybe a 700r4 eventually but i like the 4:56 gears its got guts for pulling.I know a couple of guys with the m1008's who are running 3:73s talk about some good highway speed the 4:10s are not bad.I think if i was going to go with the stock configuration i would change to the 4:10 gears but thats me.

 

[Gunfighter1]

I also run 33's and have the stock 3.08 gears, id like to go with 3.73 if i were to change them. Give you a little more bottom end than the 3.08 and stil be able to go decent on the highway. I just rebuilt my Th400 so the overdrive swap is out of the question for now.

 

[bjacobs]

I've got 4.10 in mine with stock transmission running 35's and am quite happy with it. Highway speeds are good,haven't towed much yet, but have every I tension to do so once I install a new receiver hitch.

 

[4x4 Forever]

Thanks for all the replys!

Well, after looking over everything, I bit the bullet and changed out the gears to 4.10. It still has the guts to tow good and seems to have really good RPMs at 60.
Spent about 1800 on all the innards, seals, gears, and such. (The price should be the same for 3.73). I think it is about the same price as a rebuilt 700R4 but just a little stronger...

 

[Keith_J]

The expense of a limited slip front carrier and DL rear is forcing me to go to route of the 4L80e. Yes, it is electronic but that doesn't bother me one bit. These transmissions are bulletproof in this application, the Baumann controller is the major expense here. I plan to keep the driveshafts the same length by moving the engine forward to offset the additional length. The cooling fan will probably go, replaced by electrics for the AC.

The deep axle gearing is kind to the universal joints in the driveshafts and helps in the crawling department since the 205 transfer case is limited. I don't plan on any heavy off-roading, just making it through the farm when it rains.

I cruise at 62 MPH, GPS verified which is a shade under 65 indicated. This is above the resonant range of the intake so the engine doesn't sound like it is grenading. And since the harmonic damper is new, I have little worry about the crankshaft. I've put 5000 miles on it since July of last year without a single drop of oil leaking from the main seals, a problem some have had with high speed operation. The other issue with high speed running is cooling since the combustion chambers will get hotter. And returned fuel will also be warmer so keep the tank over 1/2.

If the noise of 55-60 MPH bothers you, get the intake ducting to help muffle some of it. This can also benefit mileage since cool air makes for better efficiency.

 

[4x4 Forever]

Well, I would have gone the 700R4 or the 4L80e but want NO electronics at all and do not want to move the engine fore or aft. The TH400 and the 4.10 should be as bullet proof as I want it and like I said before, no electronics...

Thanks for the input though.