M1028/1008 Ring and Pinion Gears

[seabeeElf]

Has anyone changed out the ring and pinion gears in the front and rear differentials? I am looking into this in order to achieve highway speeds in my M1028. Right now I can only go about 35 MPH before it sounds like I am over-revving.

 

[randyw69]

Has anyone changed out the ring and pinion gears in the front and rear differentials? I am looking into this in order to achieve highway speeds in my M1028. Right now I can only go about 35 MPH before it sounds like I am over-revving.

What gear you chose will depend on what tire size you will run. Shorter tires,lower gears{higher numerical} taller tires, higher gears. What size tire will you run?? There are numerous gear ratio calculators on the web. Just do a google search of "gear ratio calculator" and it will tell you tire height and axle ratio to give you desired R.P.M. at whatever speed you want to run.

 

[Crash_AF]

Are you sure you're in 2wd high not 4wd low? The 1008 should get to at least 50 before sounding like it was going to snap the rubber band...

Later,
Joe

 

[AJMBLAZER]

Before you do a R&P swap consider posting about this on some of your local 4x4 forums. I'd bet you'd have people lining up to buy your complete axles from you and swap their civilian axles in. 3.73, 4.10, 3.55, 3.42, and even higher are out there under civilian trucks.

 

[m38inmaine]

I swapped mine out several years ago to 3:73 using stock tires it was perfect. It was pricy though, around $700 for all new stuff in the rear, the front I found used. Stock I only drive mine at 50mph, otherwise I think the engine won't last long.

 

[seabeeElf]

Joe,
I'm sure it's in 2wd, at least thats where the shifter is positioned.

All:

I guess what in was wanting to know is; how difficult is it to change the gears? Is it feasible to do this instead if swapping the entire axles?

I looked at the Intermediate maint. manual and it appeared somewhat complicated (to an electrician).

M38inmaine,
I was thinking I should change the gears to the same as the M1009, 3.08-1 I believe. I was wondering why you went with 3.73?

 

[AJMBLAZER]

3.08 is rather high geared. You loose a lot of the low end grunt in favor of highway cruising ability. GM was searching for the much vaunted high mpg back then and went higher than they probably should have.
Not to mention I think 3.42 is as high as they went with the 14FF rear axle.


I don't do gears myself. It's fairly complicated and requires specific tools. Folks have taught themselves to do it and had good results...but in my case, and most others, the answer is, "if you have to ask, you shouldn't attempt it."

 

[EO2NMCB]

Ajmblazer is right on the money. If you don't get the backlash, preload and such set correct. Your new gears will make nice paper weights. Best bet is to swap out the axels.

 

[hobie237]

Is your truck shifting into third gear?

 

[1956_4x4]

I've also changed my gears to 3.73. I went with the 3.73 gears because I still needed some bottom-end torque to get the truck going with the heavy load it is always carrying. The 3.73 gears are combined with some 33" tires and it is a decent compromise between getting usable power while lowering engine RPMs at highway speed. It also helped that I had the parts on hand from another gear swap...

If you don't have the proper tools to set up the gears and don't plan on doing more than one gear swap, I'd recommend having it done at a reputable shop.

The best way to go would be the installation of another transmission with an overdrive. It would help to keep the 6.2 within it's powerband while giving you the lower RPMs for highway operation.

Smitty

 

[kennyw]

I have some good used 3.73 gears for the rear axle that i would trade you for your 4.56 set. It is a good compromise between towing and highway gearing. 3.07's are not available for a 14FF though. The rare 3.23 gears are highest you will find. 3.73, 4.10 and 4.56 are the most common ratios from the factory (4.88, 5.13 and I think 5.86 are all now available from aftermarket sources).

 

[seabeeElf]

Hobie,
It is definately shifting into third.

Kenny,
I think I need to change both axles. Do you only have one set?

 

[hobie237]

If it's shifting into third, with stock gears, transmission and tire size, you will hit top gear redline at 71 or 72mph (I don't remember the calculations exactly). 35mph should find you at relatively low RPM in third, or pretty maxed out in second, which is why I asked.

 

[kennyw]

Kenny,
I think I need to change both axles. Do you only have one set?

Yes, you need to change both axles. I only have the one set, but that is $200+ less you would have to spend on gears if you re-gear. My set is loose already so I'd be willing to ship it down to you, have you re-gear, then ship back your old gears when your done.

Although I just remembered your carrier won't work with 3.73 gears either... I have an open carrier as well. You would want to swap the Detroit out of your axle into this carrier. Then I would need your old carrier with the gears.

I could probably come up with 3.73 gears for a Dana 60 as well. I know a few friends who have re-geared their 60's for wheeling.

 

[83k30]

yeah a tranny swap is much easier, look for a 700r4, should bolt to the 208

 

[hobie237]

Anybody who wants to do the trans swap let me know, I've got a 700, with torque converter, (from a diesel application, I believe a 3/4 ton Suburban, so all ready to bolt in) matched NP241 t-case and a couple other parts sitting in a buddy's shed that I need to get rid of.