portal axles

[haven]

Here's an introduction to portal axles I posted at www.expeditioncampers.com

Chip Haven

-----------

Portal axles provide a lot of ground clearance without a big modification to the stock suspension. This also keeps the vehicle's center of gravity lower than it would be if using a conventional approach (big tires, big body lift) to achieve the same clearance.

Portal axles increase a vehicle's ground clearance by changing the location where the drive axle connects to the wheel. Sitting on level ground, a standard axle extends straight from the differential to the center of the wheel. A portal axle, in contrast, extends straight from the differential to a point near the top of the wheel. A gear case extends down to the hub of the wheel, where it is attached.

Here's an example:

http://www.portal-tek.com/images/GalleryImage_017.jpg

The portal axle adds an extra 6 to 8 inches of ground clearance without making any other modifications to the vehicle. Combine a portal axle with other modifications like taller tires (and suspension changes so the taller tires will fit) and you add as much as 15 inches to the stock ground clearance.

http://www.portal-tek.com/images/GalleryImage_026.jpg

These images are from Portal-Tek, a new company manufacturing custom axles for a wide range of vehicles. See www.portal-tek.com for more information.

Several manufacturers of military vehicles employ portal axles. Best known are Unimog, Pinzgauer, and AM General's HMMWV.

Volvo built a millitary vehicle called the C303 in the 1970's and 1980's. Axles from C303s happen to be the right length to fit Land Rover Defenders and Toyota Land Cruisers. Here's a photo of a Cruiser with C303 axles and a 2 inch OME suspension lift:

http://www.4x4grace.com/Coppermine/albums/userpics/10001/normal_Evarts040106_61.jpg

The result: 17 inches of clearance under the front differential! This lets you glide over obstacles that others have to work hard to surmount.

http://tired-iron.mounet.com/Grace4x4/Bays111905/Bays_111905_05.jpg

You can see more photos of the build-up of this vehicle at
http://tired-iron.mounet.com/Grace4x4/GRBTLC/default.htm

Let's see...portal axles, a central tire inflation system, hydraulic steering at both ends..it's an extreme rock crawler for overland use!

[Scott Brady]

I really like that white 80 with portals. An incredible machine IMO

[haven]

The fellow who modified the Volvo C303 axles to work on his 80 series Cruiser posted recently that he can provide a similar set for $4,000. That's before the modifications needed to make them work with the Cruiser. Upgrading the brakes to more powerful discs costs around $1500 per axle. The tires are 38.5" Interco TSL Boggers, 4 for $900. Add OME 2" Heavy springs and shocks, $800.

So for a mere $8700 plus several days labor, you can have a portal axle Cruiser, too.

The result, however, is stunning: 17" of ground clearance under the front axle, and 41 degree approach angle.

http://tired-iron.mounet.com/grace4x4/GRBTLC/TLC_112.jpg

[The BN Guy]

Droool!

[TiredIronGRB]

Hey that's me:exclaim:

[photoleif]

that is awesome! given that mogs are tough beasts, the answer this question may be obvious.... but are these as strong as regular axles? that's a lot of weight on a gearcase. and yeah i know that good hyploid oil is rated in the tens of thousands of psi, but still...

[TiredIronGRB]

These are Volvo portals, they are rated 1.5 ton so I would say about the same as a Dana 60.

Detailed build thread on Pirate...

http://www.pirate4x4.com/forum/showthread.php?t=398873

[Scenic WonderRunner]

SO.........!

Can I get those to fit on a 1st Generation 4Runner.....?!!!!:ylsmoke:

....and who would like to install them for all the beer you can drink in two days!........:wavey: ..........:elkgrin:


.....um....maybe the beer should come after!:rolleyes:



I call those......."pucker factor eliminators"............!

[TiredIronGRB]

It would be pretty easy if it's not IFS.

[Scenic WonderRunner]

My 1988 Toyota 4Runner...........is IFS................


I'm DOOMED!!!!!!!!!!!!!!!!!!! ..............LOL:rolleyes: .......:elkgrin: ...........:wavey:

[Coachgeo]

Hardcore offroaders mount these things up under all kinds of shiat all the time. To them putting them in your Yota would be easy. But that's them. Hunt around Pirate4x4.com.

[haven]

Portal Tek is a company in Salt Lake City that specializes in portal axles. Here's a photo of a rear-steer axle they built for a rock buggy:

http://i188.photobucket.com/albums/z241/expeditioncampers/portal-tek-rear-steer.jpg

This illustrates how the axle connects to the top of a gear-reduction box, rather than directly to the wheel hub.

Portal Tek axle sets add 4.5 inches of ground clearance without modification to the stock suspension. If you want to run larger than stock tires, a relatively small suspension lift of two or three inches will add enough clearance for most tires.

The Portal Tek web site is http://www.portal-tek.com

Chip Haven

[cruiseroutfit]

Mud thread on a portal 80 buildup:
http://forum.ih8mud.com/hardcore-corner/84611-cummins-6bt-install-fzj80.html

[boblynch]

I know nothing about portals other than they are used on Mogs and offer great clearance with little lift. Pardon the novice questions.

Would portals be a good fit for long term overland trips? What are the down sides (higher CG, poor highway ride, less reliable, max speed limits, hard to find parts, etc.)? What type of rigs would the portal-tex parts fit on? Would they work on a larger rig (e.g., Fuso-based or Earthroamer-type camper)?

[haven]

Weird story -- Portal Tek took the guy's money, kept the truck for months, and didn't install the axles. Last post is in Spring 2007. I wonder how the story ends?

[cruiseroutfit]

Weird story -- Portal Tek took the guy's money, kept the truck for months, and didn't install the axles. Last post is in Spring 2007. I wonder how the story ends?

There are posts up to last week... still no notable progress :(


Its of my personal opinion that such axles would NOT be suitable for an overland build. There are absolutely exceptions to this rule, some of the OE portal units (Volvo and Benz) could be extremely suitable. However considering the failures and spare parts replacements... I wouldn't think extremely deep about it for my personal uses.

[seve7]

I know nothing about portals other than they are used on Mogs and offer great clearance with little lift. Pardon the novice questions.

Would portals be a good fit for long term overland trips? What are the down sides (higher CG, poor highway ride, less reliable, max speed limits, hard to find parts, etc.)? What type of rigs would the portal-tex parts fit on? Would they work on a larger rig (e.g., Fuso-based or Earthroamer-type camper)?

They are sweet for getting extra ground clearance, but in some cases need a torque arm attached to the axle because of the lever action of the wheel center compared the axle center (wicked axle wrap). specifically on vehicles with leaf springs. also the seals on the portals themself are prone to leaking... but if you can get past these things the extra gear multiplication, the extra ground clearance, and the cost its a pretty cool concept. but i think it would be cheaper to go with bigger tires and get heavier duty axles.

[Martinjmpr]

Here's an introduction to portal axles I posted at www.expeditioncampers.com

Chip Haven

....

Several manufacturers of military vehicles employ portal axles. Best known are Unimog, Pinzgauer, and AM General's HMMWV

The HMMWV and the Pinz have 4 wheel independent suspension. AFAIK They do not have portal axles (on military HMMWVS the axle goes straight into the center of the hub.)

[Best4x4xfar]

The HMMWV and the Pinz have 4 wheel independent suspension. AFAIK They do not have portal axles (on military HMMWVS the axle goes straight into the center of the hub.)
Both the Pinzgauer and the Hummer (H1/ Military) use gear reduction hubs, and have the drive axle coming into the drive wheel above the centerline. Just because they do not use solid axles, does not mean they cannot use the geared hub design, which affords both additional gear reduction at the wheel, as well as improved ground clearance from the elevated (relative to the wheel centerline) position of the drive axle. Now in the case of an Independent suspension design, it doesn't necessarily gain you ground clearance (Hummer H1 & HMMWV), but it can, as in the Pinzgauer's case. I'll see if I can round up a couple of photos if you are still in doubt..

Here is a WIKI link on Portal axles (http://en.wikipedia.org/wiki/Portal_axle), that refernces vechicle that use Portals, and list both vehicles as well..

[SAR_Squid79]

I still don't understand why somebody hasn't built an IFS portal kit (based on the HMMWV design) for a Tacoma. I would MUCH RATHER have that than SAS.

[Best4x4xfar]

I still don't understand why somebody hasn't built an IFS portal kit (based on the HMMWV design) for a Tacoma. I would MUCH RATHER have that than SAS.
What is the perceived advantage? The only one I can imagine is improved CV angles with severe lift, but I wouldn't expect increases in ground clearance (still need the bottom suspension arm) and the gearing advantage is pretty much offset by having to run considerably steeper gears in the rear axle, isn't it?

A SAS has many advantages over IFS off-road, including much greater articulation, stronger components, more available differential and gearing options, etc..

This is a photo of a FJ Cruiser front suspension for reference, but I’m fairly certain it is nearly identical to the Taco’s, no?

[cruiseroutfit]

What is the perceived advantage? The only one I can imagine is improved CV angles with severe lift, but I wouldn't expect increases in ground clearance (still need the bottom suspension arm) and the gearing advantage is pretty much offset by having to run considerably steeper gears in the rear axle, isn't it?...

While you wouldn't necessarily gain any across the board ground clearance, as you noted your lowest point will still be the bottom suspension connection at the spindle. However it does offer the opportunity to gain addition clearance in the middle of the vehicle, all while retaining a lower CV angle. With this lower CV angle comes the opportunity for increased suspension travel.

Why hasn't anyone done it in mass scale? Market doesn't demand it IMO. There have been a handful of companies toying with portal technology (Portal Tek for example), none have really hit a home run yet as to a product that really sells. Time will tell...

[Best4x4xfar]

While you wouldn't necessarily gain any across the board ground clearance, as you noted your lowest point will still be the bottom suspension connection at the spindle. However it does offer the opportunity to gain addition clearance in the middle of the vehicle, all while retaining a lower CV angle.

We are kind of going off topic a bit, but I’m still not sure it would be a worthwhile project. I mean yes, you could theoretically increase the central ground clearance by tucking the center driveline components up higher, but how practical is that? I mean if you were the manufacturer doing the whole thing as an integrated design (like AM General) sure, but from the standpoint of fitting an aftermarket portal box? And if you tuck the center driveline gear higher, you are negating the advantage of the lower CV angle.


With this lower CV angle comes the opportunity for increased suspension travel.

Again, I see the theory, but without considerable changes to the mounting point for the lower and upper suspension arms (allowing lengthening of them), or wide fiberglass fenders to clear lengthened arms, I think there is a very real limitation to the stock design that would make additional gains from the alleviated CV angles minimal next to what is achievable without the ‘portal boxes’?

[cruiseroutfit]

We are kind of going off topic a bit, but I’m still not sure it would be a worthwhile project...

Agreed, thats why I said the market doesn't call for it. ;)

On that note one could be designed to use OE suspension mount locations at the frame, and simultaneously provide more clearance at the spindle by designing the lower control arm to intercept the spindle/upright at a mid-point rather than the bottom such as is currently designed. The added moment would require some extra consideration when designing the control arms, but its nothing that couldn't be done. The end product would be extremely vehicle specific thus further limiting the market for said product... in a market that already doesn't exist :D

[Martinjmpr]

Both the Pinzgauer and the Hummer (H1/ Military) use gear reduction hubs, and have the drive axle coming into the drive wheel above the centerline. Just because they do not use solid axles, does not mean they cannot use the geared hub design, which affords both additional gear reduction at the wheel, as well as improved ground clearance from the elevated (relative to the wheel centerline) position of the drive axle. Now in the case of an Independent suspension design, it doesn't necessarily gain you ground clearance (Hummer H1 & HMMWV), but it can, as in the Pinzgauer's case. I'll see if I can round up a couple of photos if you are still in doubt..


Ah, I stand corrected then. :o

As for why this isn't more common, my guess would be cost/complexity.

Sure, you're gaining ground clearance and/or lessening drive angles, but it seems to me you're also introducing a bunch of moving parts where before you just had a relatively simple hub and U-joint. More parts = more weight, more cost and more chances of something going wrong.

For a very few people, the cost might be worth it but for most consumers the marginal advantages wouldn't justify the significant costs.

[Ron B]

your lowest point will still be the bottom suspension connection at the spindle. However it does offer the opportunity to gain addition clearance in the middle of the vehicle.

I was curious so I just measured my hummer and from the lowest point on the a-arm to the ground, 9.5' to 10' at stock height on 37's. My friend's truck was 10.5' on 38'5 pro comps. It's about 17' to the crossmember, 15.5' to the ucp (you can see it hanging down an inch or so under the winch plate).

rb

[rickc]

Hi all:

I just read this thread. I think there is only one mention of the gear reduction advantage of portal hubs. In the Hummer (real one) it's 1.92:1 so there is a power/torque multiplier through the portal hub to each wheel. For those of you with IFS, you know that one wheel is often off the ground on gnarly trails. Without lockers, H1 owners (pre '99), learn to use brake throttle modulation to prevent the free wheel from spinning and transmit all the torque to the wheel that is gripping. A better description here:http://www.off-road.com/trucks4x4/article/articleDetail.jsp?id=263805

Of course a lot of serious offroad H1 owners instal lockers anyhow but this does not detract from the gear reduction and extra power at the wheels. It does make H1's slower on the highway!

[michaelgroves]

I think there is only one mention of the gear reduction advantage of portal hubs. In the Hummer (real one) it's 1.92:1 so there is a power/torque multiplier through the portal hub to each wheel.

Well, of course the only inherent advantage of the hub reduction gearing is that it takes place further "downstream" than if you set up the same overall ratios in the gearbox, transfer box or differentials. And even then, it's a slightly mixed blessing: on the plus side, there is less torque being put through the diffs and halfshafts, but on the minus side, they all turn that much faster.

That was an interesting article on the Hummer - but they weren't explicit about what kind of LSD (limited slip diff) there is in the "BTM" version. If I recall, the Hummer uses some version of a Torsen diff, which allows "x" times as much torque on one shaft as there is on the other. I vaguely remember that in the Hummer, "x"=6, but I might be wrong.

A normal open differential always maintains the same torque on each side ("x"=1), so if one wheel reaches a patch of ice and only supports (say) 1000N.m of torque, then the other wheel will also only be able to apply 1000N.m of torque, which might not be enough. With "x"=6, the Torsen allows the other wheel to apply 6000N.m of torque, which probably will be enough.

But if you lift a wheel, then the torque at that wheel is zero, and so the torque at the other wheel is still zero (6x0). That's where the Brake/Throttle Modulation comes in: when you apply the brake, the wheel in the air comes under significant torque. Even though that torque is useless on its own, the opposite wheel now gets six times that braking torque. The only penalty (traction-wise) is that all the wheels on firm ground also get braked, which offsets some of the benefit.

On thinking about it, I would have thought that such a torque-sensing LSD system would be an ideal complement for the TorqTrac system, because any computerised braking on the spinning wheel would add six times that torque to the opposite wheel, without any penalty. Still not as effective as a full locker, but it seems to me it would be much more effective than a standard electronic traction control system working through open diffs.

[Ron B]

the stock torsen diffs in the hummer were about a 4.5:1 ratio until '99, when they had to go to a 2:1 bias ratio to allow for abs. And I think because of the 2:1 ratio in the geared/portal hubs everything (driveshafts, halfshafts, t-case, diffs) is actually turning slower, not faster?

btm works extremely well, but I went ahead and changed them out for lockers (auburn elec up front, detroit in the rear) to ease some strain on the drivetrain with the crazy stuff. The '99 and later tt4 system is not very popular with most hummer owners who wheel, it's a re-active system instead of being pro-active like btm.

http://www.flashoffroad.com/features/Torsen/torsen_differential.htm

rb

[michaelgroves]

And I think because of the 2:1 ratio in the geared/portal hubs everything (driveshafts, halfshafts, t-case, diffs) is actually turning slower, not faster?


For any given road speed, a vehicle with 2:1 hub reduction gear will have its diffs and shafts spinning twice as fast as a similar vehicle in which the same overall gearing is built into the transfer box (or the diffs). The 2:1 hub reduction then slows the wheels down to the designated speed.



the stock torsen diffs in the hummer were about a 4.5:1 ratio until '99, when they had to go to a 2:1 bias ratio to allow for abs.


Ah, ok, I've read up on this a bit now, and apparently a high bias ratio would interefere with the ABS calculations. So that seems to rule out my thought that it would be ideal to use high bias Torsen diffs in conjunction with electronic traction control!

(Also, just to clarify in case anyone misunderstands, the diff ratio itself remains unchanged (it's 2.53:1), it's the bias ratio that they changed from 4.5:1 down to less than 2:1.)


The '99 and later tt4 system is not very popular with most hummer owners who wheel, it's a re-active system instead of being pro-active like btm.


I can understand that now, because they reduced the bias ratio. If they'd been able to keep the original 4.5:1 bias ratio, then the addition of traction control would have introduced no disadvantages, since BTM would work just as before, when needed.


Your vehicle must be impressive with the lockers fitted!

[Guinness44]

During the Chile Challenge, the portals definitely were an advantage. Diffs on regulars hung up left and right in those extreme trails. Extreme buggies seem to often go that route nowadays. They are hardly expedition vehicles. :).
The groundclearance gained on the H1, and the gearreduction, is what makes it the H1, with the lowrpm torque of a diesel. Like the climb to Grey Mesa on the Hole in the Rock trail: Its 7 feet wide, so there is only one line. The couple H2s that were along had some trouble clearing the diffs at that one spot, while the 1s, just went over. Even so the independant suspension is not favored by most, we have learned to drive "all over again". Coming from a TJ, where air under a tire is gonna be a unstable moment....

[Antichrist]

This also keeps the vehicle's center of gravity lower than it would be if using a conventional approach (big tires, big body lift) to achieve the same clearance.I question how significant this difference really is. All the heavy stuff, diff, axle housing, frame, engine, gearbox, etc. are sill at the same height relative to the ground.

[Ron B]

For any given road speed, a vehicle with 2:1 hub reduction gear will have its diffs and shafts spinning twice as fast as a similar vehicle in which the same overall gearing is built into the transfer box (or the diffs). The 2:1 hub reduction then slows the wheels down to the designated speed.

Now I'm all confused (easy to do)! It just seems the halfshafts spin so slow when compared to the tires when I see videos of my truck climbing but your explanation makes sense, thanks.

here's a mid '90's dealer video that is fun to watch which talks a bit about what you have said:
http://www.youtube.com/watch?v=Yf9FPs40VUM

rb

[Guinness44]

I question how significant this difference really is. All the heavy stuff, diff, axle housing, frame, engine, gearbox, etc. are sill at the same height relative to the ground.

It makes a big difference in stability. Look at a Hummer with the 37 inch tires stock. Then look at a lifted Powerstroke (my friends), with 37 inch tires. To fit those, that lift is 6, 8, inches, not sure. The truck looks very nice, but bet on offcamber sections it will be a trip. And the diffs are still hanging low, so lines will be limitied by that.

[Antichrist]

It makes a big difference in stability. Look at a Hummer with the 37 inch tires stock. Then look at a lifted Powerstroke (my friends), with 37 inch tires.You're comparing two entirely different vehicles. You have to compare the same vehicle, a Ford on portals with 37" tires and a Ford on stock axles with 37" tires.

[Guinness44]

True, then I guess you gain the clearance under the diff. Wouldnt you have less lengthy liftsprings/shoks with the axle higher than stock. When we lifted the TJ, it got very squirly....compared to stock. (it was the 90 inch WB that also didnt help there)

[michaelgroves]

True, then I guess you gain the clearance under the diff.

Yes, as I see it, portals have only one major benefit - increased ground clearance under the axles. It's an extremely formidable advantage off-road, but comes with some significant downside: raised C.o.G. (the axle and diffs are higher than an otherwise identical vehicle with conventional axles), complexity, and more complicated suspension and axle mounting to avoid severe axle-tramp.

The other advantages, such as hub gear reduction, can be achieved without portals, or they are necessary because of the increased ground clearance (e.g. more manageable axle-shaft angles).

[madizell]

Portals are also, as a rule, heavier than a straight axle. Controlling unsprung weight then becomes an issue if the vehicle is used on roads and trails as opposed to hard core off road. There is also a leverage issue because the effective axle line and the weight of the tires is so far removed from the suspension contact plane. Retro-fit portals are not suitable for higher speed vehicles because of the design compromises. Rock buggies and competition vehicles don't usually need to think about highway travel issues.

[Portal-Tek Axles]

We just joined Expeditionportal.com

I have to say that it is neat to see a great site dedicated to expedition vehicles. The staff at Portal-Tek has a tremendous affinity toward the expedition and overland style vehicle travel. The concept of self supported vehicle travel is definitely at the roots of where almost every member of our team comes from.

Since this is a portal axle based discussion we would like to contribute to the conversation. The last seven years of portal testing has provided us with some very interesting data and test results that we would like to make available to this community.

I have noticed a few times that 'center of gravity' has come up in this thread. To be honest before we finalized our prototype design we assumed that the COG on any vehicle equipped with our axles would be higher. One of the silver linings of our testing stage was that we found this to be grossly inaccurate. After some serious rough and angry testing we found that our design was EXTREMELY balanced and stable. We concluded that this happens because more mass is located in the center of each wheel (low and wide) with less relative mass in the center of the housing. This is one of the reasons that a Unimog, which is tall and relatively narrow, is able to be so stable in off camber situations. In comparison a similar vehicle with straight axles, running 39" tires would have to have such a tremendous amount of spring lift to clear this size of tire that the COG would definitely cause the vehicle to be very 'tippy'. In our experience a portal equipped vehicle with less spring lift will allow for more clearance and bigger tires (both positive) while providing a very stable COG. For more info on spring lift vs. true lift please visit- http://www.portal-tek.com/faq.html

-Jim Jackson

[Antichrist]

For more info on spring lift vs. true lift please visit- http://www.portal-tek.com/faq.htmlHmmm..I read Why are Portal-Tek Axles advantageous to a suspension lift?
While some of the information in that section is indeed factual (what would be in a FAQ), other information/terminology is vague and misleading.
You mention 10" suspension lift, but don't mention what vehicle, what size tires you'd fit with that much, what size tire you could fit with a combination suspension/body lift.
You state portals with 33" tires gives a 4.5" "TRUE LIFT" over straight axles with 33" tires. In my years of off-roading true lift (related to true ground clearance) has always been defined as the distance from the ground to the lowest point, which in the case would be the same pretty much for portals on 33" or straight on 33". True lift will always be the difference in radius for one tire to a larrger one.
Portals will get your diffs higher, true, but that's different.

[michaelgroves]

You state portals with 33" tires gives a 4.5" "TRUE LIFT" over straight axles with 33" tires. In my years of off-roading true lift (related to true ground clearance) has always been defined as the distance from the ground to the lowest point, which in the case would be the same pretty much for portals on 33" or straight on 33". True lift will always be the difference in radius for one tire to a larrger one.
Portals will get your diffs higher, true, but that's different.

Am I missing something? Isn't the diff usually the lowest point, in which case a portal axle's raised axle tube and diff translates into more (true) ground clearance?

[Antichrist]

Am I missing something? Isn't the diff usually the lowest point,Depends on the axle/suspension design.

[michaelgroves]

I have noticed a few times that 'center of gravity' has come up in this thread. To be honest before we finalized our prototype design we assumed that the COG on any vehicle equipped with our axles would be higher. One of the silver linings of our testing stage was that we found this to be grossly inaccurate. After some serious rough and angry testing we found that our design was EXTREMELY balanced and stable. We concluded that this happens because more mass is located in the center of each wheel (low and wide) with less relative mass in the center of the housing. This is one of the reasons that a Unimog, which is tall and relatively narrow, is able to be so stable in off camber situations. In comparison a similar vehicle with straight axles, running 39" tires would have to have such a tremendous amount of spring lift to clear this size of tire that the COG would definitely cause the vehicle to be very 'tippy'. In our experience a portal equipped vehicle with less spring lift will allow for more clearance and bigger tires (both positive) while providing a very stable COG. For more info on spring lift vs. true lift please visit- http://www.portal-tek.com/faq.html

-Jim Jackson

It's hard to meaningfully compare portal-axle trucks with standard-axled trucks, because portal axles allow bigger wheels with less suspension lift. However, I don't really see why you'd have a lower COG with a portal vehicle, even if you raised the suspension of the other truck. Comparing them, in both cases, the body, chassis, engine, gearbox, wheels, hubs, brakes etc. all sit at the same height... The springs are longer on the non-portal truck, but other than that, the only difference is that axle tube and diff are a few inches higher on the portal truck. Not a very significant difference, perhaps, but a slightly higher COG.

The "tippiness" of the non-portal truck is perhaps due to the much longer springs, rather than a raised COG?

[michaelgroves]

Depends on the axle/suspension design.

Well, I asked the question specifically in connection with your objection. For normal 4x4 trucks, the differential is usually the lowest point, and is therefore the measure of "true" ground clearance.

If you raise the diffs by fitting portals, then you raise the true g/c, unless the portals introduce a new low point (which, glancing at Portal-tek's design, they don't).

[KevinNY]

Mog on 39s, not tippy.

http://picasaweb.google.com/VTXSVP/RokCut/photo#5240902432709821202

[Ron B]

maybe what Antichrist is referring to is the independent suspension/portals of the hummer -- the a-arms are the lowest points (about 10.5" with stock tires).

rb

[michaelgroves]

maybe what Antichrist is referring to is the independent suspension/portals of the hummer -- the a-arms are the lowest points (about 10.5" with stock tires).

rb

Yes, maybe. But if so, I don't think it fairly applies to portal axles in general. All that means is that if a particular vehicle happens to have something other than the diff that hangs really low, (an exhaust, a towbar, an A-arm or whatever), then a portal axle won't lift it up higher. But no-one's going to retrofit a Portal-tek axle to an IFS vehicle and keep the A-arms etc.!

[michaelgroves]

Mog on 39s, not tippy.

http://picasaweb.google.com/VTXSVP/RokCut/photo#5240902432709821202

All Unimogs are tippy - except that one! Wow, that is impressive!

[Antichrist]

It's hard to tell for sure due to the angle of the photo, but it doesn't look like the diff is the lowest point in this case.
http://expeditionportal.com/forum/showpost.php?p=237371&postcount=12

Don't get me wrong, I'm not saying portals are a bad thing, I just don't like generalizations or vague data about things like this.

[rickc]

Hi all:

Stating the obvious; when discussing COG it's entirely vehicle specific. The Hummer/HMMWV has a relatively low COG despite high clearance afforded by portal hubs because the body is about a foot wider than most trucks and it is more squat - my roof line with stock 37" tires is only about 73". Most stock trucks are about the same or higher.

This has been a great discussion - I have learned a lot. Many thanks to all contributors.

[DenCo40]

Mog on 39s, not tippy.

http://picasaweb.google.com/VTXSVP/RokCut/photo#5240902432709821202


Nothing left on that one to be tippy about!!!

[dieselcruiserhead]

Somehow I missed this thread. Jim from Portal Tek, nice to meet you. I don't know you but I know all the other gentleman that have been associated with your company and I even bought some axles from I think it was Russ once upon a time. I have also evaluated the Portal Tek axles in person and they look pretty good and I really like the design.

I spent some time in this FJ55 that had Volvo C303 axles in it. Fit great, sprung under with no or a moderate lift. This truck belonged to my good friend Brian Steen who is in the Peace Corps in Kygistan currently, really good guy, hell of a cruiser head. Once he built it up he took the ultimate cruiser trip through the desert in early winter if I remeber correctly, hundreds of miles. Unfortunately the gearing situation was a little off and something you very much have to compensate for. Too low, not too high. I drove his 55 all over the place, it was a hell of a truck but top speed was 55. Again, this gets real old real quick. In the end he went back to a FJ55 sprung under 2-3" lift and about 33's or 34's, more of a typical setup. Brian is also a real expeditioner, not a lot of unneccessary gadgets, epic traveller, down to earth and basic, heck of a guy. This was nice but was too "big" for him. If he had a 5 speed and the overdrive unit he had I think he might have done a little better, I dunno. The Portal Tek setup is nice because you can choose your gearing and use really fast Ford car gearing so you can still get reasonable street gearing. I like the Portal concept a lot, the axle nice and high, 4" lift is actually great IMO, and you can drive right over a 5 gallon bucket.

I also drove Unimogs quite a bit when I worked for a company in '02 that sold them, mostly 406/416 diesel models with the 6 speed. Contrary to popular belief, they are not tippy and designed to not be tippy with low engines and low weight (and a lot of it). We tested the tippyness of them repeatedly and never managed to put one over but came close, so we know their limites. Same deal though, 55 mph and engine screaming unless you purchase fast axles.

Hope it helps. When the site's photo database is back up and running I'll post up pics again.

[Portal-Tek Axles]

Somehow I missed this thread. Jim from Portal Tek, nice to meet you. I don't know you but I know all the other gentleman that have been associated with your company and I even bought some axles from I think it was Russ once upon a time.


Andre,

It's nice to bump in to you. You actually have met me before. I took you and Kurt to dinner at Goodwood BBQ in Sandy. I think that had to be a couple of years ago by now. We were talking about roof racks. I was not with Portal-Tek at the time. Thanks for posting on this thread. It is neat to hear input from someone who has had seat time on a vehicle equipped with portal axles. It really is amazing how stable Unimogs really are. You and Kurt have always been great for objective feedback. Feel free to swing by the shop and check out some of the projects that we are working on. One of the projects that we are working on now is the build of two late model FJ40 Land Cruisers. Both of these vehicles will see a lot mini-expedition trips in the upcoming year. One will be built with Portal-Tek G3 axles (sprung-under) and the other will be sprung-over on FJ60 axles similar to Kurt's at Cruiser Outfitters. We will be using them for side by side axle comparison testing. We are really looking for an 'apples to apples' type of vehicle comparison. It would be great to have you come along for some of the test runs. That invitation is also extended to Kurt. I would be great to have some unbiased opinion that would be willing to report on the outcome of the tests that we are planning. We really want to run a large gamut of testing. Freeway, dirt roads, mud, rock crawling, etc. This will probably take place in late winter or early spring. Let me know if you are interested. I am open to suggestions as I would like this to have a scientific basis. That invitation goes for anyone that is nearby or willing to travel to Utah.

Jim

Here is a link to some video that was short last year at the KOH event in Johnson Valley, CA. This was our Portal-Tek sponsored race truck. Look at time 1:35 to 2:20. That would be Number 127, on G3 Axles. Front and rear steer, 600+hp. 104 mph tops speed in the desert. Running on 42" Interco Irok tires. http://www.youtube.com/watch?v=C2Bva3XlEno

[Antichrist]

I also drove Unimogs quite a bit when I worked for a company in '02 that sold them, mostly 406/416 diesel models with the 6 speed. Contrary to popular belief, they are not tippy and designed to not be tippy with low engines and low weight (and a lot of it).I never realized people thought they were tippy, but I knew they weren't so I guess I didn't really think about it. (sorta like people assuming Series Land Rovers are tippy).
I fell in love with Unimogs when I used to spend a lot of time at the local Mercedes dealer in the late 60's.
To this day I still kick myself for not buying a "cheap" pristine 406 with the cascade 20 speed gearing and full PTO and hydraulics and dump bed, back in '79. It looked showroom new and the guy used it to haul new tires from his warehouse a couple times a month so some insanely low mileage that I forget.

[michaelgroves]

Tippy is a relative term, of course. Actually a Unimog does badly in roll-over angle tests compared to other trucks of similar size and track width. Firstly, it does have a high COG - big diameter wheels and portals make for a high chassis and load platform, and also, the engine is mounted high partly because of the portal axles. Secondly, it has long-travel coil springs and lots of axle articulation, so the whole weight of vehicle and payload can lean over a long way. (Anyone who has driven a fully laden Unimog will attest to how even slow negotiation of an uneven side slope will get the whole body rocking quite alarmly!).

[haven]

Here's a set of Unimog 404 portal axles,
reconditioned by the Swiss army, $2950

http://cgi.ebay.com/ebaymotors/Unimog-404-Axles-Reconditioned-by-the-Swiss-Army_W0QQitemZ260283949883QQcmdZViewItem?hash=item 260283949883&_trkparms=39%3A1|65%3A1|240%3A1318&_trksid=p4506.c0.m245

Or buy a set of used 404 portal axles for $1900

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=260283950471&ssPageName=MERC_VI_RSCC_Pr4_PcY_BID_Stores_IT&refitem=260283949883&itemcount=4&refwidgetloc=active_view_item&usedrule1=StoreCatToStoreCat&refwidgettype=cross_promot_widget&_trksid=p284.m184&_trkparms=algo%3DDR%26its%3DS%252BI%252BSS%26itu%3 DISS%252BUCI%252BSI%26otn%3D4

[4Rescue]

The fellow who modified the Volvo C303 axles to work on his 80 series Cruiser posted recently that he can provide a similar set for $4,000. That's before the modifications needed to make them work with the Cruiser. Upgrading the brakes to more powerful discs costs around $1500 per axle. The tires are 38.5" Interco TSL Boggers, 4 for $900. Add OME 2" Heavy springs and shocks, $800.

So for a mere $8700 plus several days labor, you can have a portal axle Cruiser, too.

The result, however, is stunning: 17" of ground clearance under the front axle, and 41 degree approach angle.

http://tired-iron.mounet.com/grace4x4/GRBTLC/TLC_112.jpg
There are some pretty amazing vids floating about of him schooling a whole bunch of "built" jeeps in the rocks. He's "Tirediron" over on Yota-tech and I belive he's a member here as well. I LOVE THAT TRUCK!!!

Cheers

Dave

EDIT: DUH!!! He's posted in this thread, guess I should read all the way through.

[flighht2k5]

All Unimogs are tippy - except that one! Wow, that is impressive!
WWWHHOOOAA there little buddy, where do you get the idea that unimogs are tippy? Im in the Ary guard and I guarantee my mog could sidehill as well as a hmmwv.

[Ron B]

WWWHHOOOAA there little buddy, where do you get the idea that unimogs are tippy? Im in the Ary guard and I guarantee my mog could sidehill as well as a hmmwv.


I don't know too much about Mogs (except that I love them) but the seemingly unimpressive factory specs of a hummvee (60% incline, 40% sideslope) is at continuous operation at full gvw without oil starvation in any gear box, and without fuel starvation or overheating.

Curiosity just got the best of an HML member in Germany and he put his hummer on a sideways lift. It's too bad the truck wasn't stock (it was a standard 4dr hard top, but with a 3" body lift and 42" Irok tires). It started lifting a rear tire at 41 and would've gone over at 45. I know a flat surface is nothing like a trail but it's still interesting. A stock humvee is theoretically supposed to roll somewhere in the 'hood of 53 degrees in a controlled environment such as this guy used.

[charlieaarons]

My "Unimog Resources CD" gives a side angle rating of 35 degrees for the U500. That's with the pickup bed installed; I don't know whether it is with the bed loaded to a GVW of 26000 lb or not. They give a hill angle rating of only 38.66 degrees; obviously if has traction it has power to go up 90 degrees so that might be a continous no oil starvation rating.

Charlie

[Ron B]

My "Unimog Resources CD" gives a side angle rating of 35 degrees for the U500. That's with the pickup bed installed; I don't know whether it is with the bed loaded to a GVW of 26000 lb or not. They give a hill angle rating of only 38.66 degrees; obviously if has traction it has power to go up 90 degrees so that might be a continous no oil starvation rating.

Charlie

35 deg is very impressive for a truck that big. Being at 35+ deg brings the pucker!

[Chas Stricker]

I've been on the dunes at Pismo with the pucker guage reading 40 degrees. Pucker yes...tipped....no. I was ready to put the truck into hyper-speed into the roll if it happened. Well Mog hyper-speed...8-10 mph. The rig does sway back and forth like a boat through the tipping. I only had a spare and a small crane for cargo. I wanted to check it in a somewhat "safe" environment. They will do higher side loads than you'd think. Charlie could really tell you about high bed load and capabilities.
Chas

[RMP&O]

Old thread but I am going to bump it....

I have a set of G3 Portal-Tek axles under my 83 Nissan Patrol. I bought the axles in late 2007. Portal-Tek went belly up in early 2010 not long after introducing the Super 14.

Torq Axle in SLC, Utah has bought the rights, designs and all that jazz from Portal-Tek. It is looking like they will be putting the Super 14 back into production in early 2012. I don't know if they will be producing the G3s, however I think that is their plan. They will be supporting past purchasers of the Portal-Teks which makes me happy!

I have RCV CV axles in the front steering axle under my Patrol. This is a very nice axle with a 45 degree turning radius. I have had next to no issues with my axles and if you want the best ground clearance out there plus extremely strong axles, the G3s and Super 14s are going to be very hard to beat. Not to mention you can order them at any specs since they are not an old axle built for a military truck. That means off set, axle tube size, axle grade (4340 or 300m), width, gear set and more can be had since these are built to order.

A very nice product and I for one am stoked Torq will be moving forward with this.

cheers

[The BN Guy]

I'd love to put a set under Stormtrooper but on a teachers budget...yeah, ain't gonna happen. :drool:

[TACODOC]

I still don't understand why somebody hasn't built an IFS portal kit (based on the HMMWV design) for a Tacoma. I would MUCH RATHER have that than SAS.

X2

[The BN Guy]

X3!!

[762X39]

I still don't understand why somebody hasn't built an IFS portal kit (based on the HMMWV design) for a Tacoma. I would MUCH RATHER have that than SAS.
Part of the reason no one has tried to use the HMMWV portals may be because the disc brakes are inboard.