Been thinking about portal axles recently, ever since someone I know started playing with Mog axles a while back.

Question: Since Hummers drive forwards, either their portal hubs must have three gears in them, or the model-20 diffs they run must be flipped so they run in reverse. Which is it?

I'm guessing door #2, but flipping a diff is no simple matter. The diff castings would pretty much have to be customized for proper oiling, no?

Chris

Hummer grear reduction hubs have 2 gears in them. The diffs run backwards.

Tim.

It is option two the diff housings are totally custom for the IFS/irs I believe they are aluminum. They use normal model 20 gears upside down pinion comes out super high. I keep toying with the idea of a 44 with hummer portals, they have a 2:1 gear reduction so you could run a 3.54 or lower gearset and never break a ring and pinion. The u joints see half the stress assuming that torque is limited by the traction available at the tire etc.

The biggest problems I see are brakes and oiling. I was gonna solve the oiling by running an upside down high pinion 44. or maybe just raising the fill plug and checking it regularly. The brakes aren't so easy ( hummers use inboard brakes mounted right at the diff) You could use a pinion mounted brake, or try to squeeze them inbetween the rim and the geared hub ur try to squeeze them inbetween the axle u joint and the geared hub. The input spline is 1 3/16 27 spline same as a CJ dana 30 outer stub or scout 30/44 outer stub.

There are a couple people building/running the entire hummer setup diff/ brakes/ cv's/ geared hubs and wheels, all mounted in a assembly htat is mounted to the vehicle like a solid axle. They manage to get the diferential a little higher that way but it is so heavy and expensive that a complete mog axle seems like a better route to me.

Cool - thanks, guys.

Gordon, do you happen to know what the input drive connection to the hub box looks like? How does that 27-spline stub shaft connect to the upper gear in the box?

Interesting idea about running a HP D44 upside-down. With enough oil in the case, that would probably work pretty well. Attaching the portal ends to it would probably just be a matter of custom-machined housing end yokes. Pretty wierd-looking ones, I'd imagine.

Brakes are indeed the biggest challenge, but there's probably a way to make it work that's street legal (definitely a requirement for me).

Thanks again,
Chris

actually gordon 4:10 gears are arguably the strongest gearsets of all the ratios.
also i think it would be a bit more difficult working with hummer portals because they are made for the IFS/IRS setup.
by that i mean they arent made to be bolted to a round axle tube like mog prtals. but i havent really studied them so i dont know. anything is possible thats for sure.

Look at the portals in the post titled 2002 Bronco project pics. They are 9" centers flipped. They are mog outers with a 2.1 gear reduction. Contact CTM racing for more info on how he built these.

I have exploded views of the hummer parts that should answer those questions. Can't find em at work so maybe they are at home. I agree the mog parts would be a bit easier to make work. but the hummer parts are way way cheaper and if you are hooked up with the right people in the military you might be able to get them free.

Oh yeah? why would you argue that 4.10's would be stronger than 3.54 3.07 or 2.75's I mean they are pretty strong. and it isn't really an issue because they are stronger than the stock axle shafts but I just don't see it.

I can't imagine wanting to run 4.10 gears in a portal hybrid anyway. With the hub reduction, you'd be looking at 8.2:1 in the axles. Even on 44s you'd prolly top out at 40mph on the highway! <IMG SRC="smilies/biggrin.gif" border="0">

OTOH there's gotta be tons of used 2.73 D44 gearsets out there from guys who've upgraded. Doubled, that's 5.5:1, not a bad ratio for 38s, though even then you'd prolly want an OD tranny.

Chris

yep that's what I was thinking only reason I could think to run 4.10's is if you already own the low ratio locker. But with no way to unlock a hub you are kinda stuck with a switchable locker in the front in my opinion. Although aparently there are TJ guys daily drivin with detroits in front and no hubs or CAD.

hold on guys, i wasnt meaning to say you would want to run 4:10 gears. just makin a comment on 4:10 bein probly the strongest gearset. and that was only in reference to the "run 3:54 or lower and never break a gearset". seems to me the 4:10 has the biggest pinion and thickest ring. when you go lower the pinion gets smaller and when you go higher the ring gets thinner. thats all i was sayin, i completely agree on the high 3:50'ish final ratio with portals. hell i might even go higher say aroung 2:50. <IMG SRC="smilies/beer.gif" border="0">