THE PORTAL HUB - Pinzgauers, Haflingers, Volvo 303s and more!

IIRC a stock 710M is factory rated at something like 43 degrees (NOT PERCENT grade), and from experience I'd suggest that this number is with a full compliment of passengers. What complicates calculations for a Pinz are the swing axles; at high side grades the low side can go from having all the weight (pushing the wheels UP, increasing stability) to swinging over the half axle (pushing the wheels DOWN and decreasing the stability). The measurements taken from a static, flat surface won't be exactly the same. Accessories - winches, hard tops, etc. generally reduce the stability as they are never low enough to improve it.

But with my tall, relatively top heavy W box I can say that going from the stock rims to 8" wide modified rims (about 3" wider track at the outside, not at the center of the tread) made a HUGE difference in the handling and feel of comfort on sideslopes. I have tried to keep the greatest weight low in the truck and have negotiated 30 degrees sideslope successfully with a 9' tall box. Unless the spacers are significantly less expensive I'd recommend having new, wider rims placed on the stock wheel centers - and you could still increase the offset a bit further out. I think my wheels made the tire sides almost flush with outside edge of the rub rail (here with 295/75R16s, looking good but really too big):


Then again, we've all had various stages of "too much fun":

Luckily I only lost a bit of paint on this one.

Jim,

I too have modified wide 8" rims (Beck), and after these pictures
I have come to appreciate a heck of a lot more

Now that mine is white I am worried
Hopefully will not be adding any pictures to this thread!
A couple years back when we went wheeling (710m and a 712a with box removed) we were in typical Ontario woods with rock outcrops. Stock Jeep, up and over off-camber lines with zero issues. Both Pinz had serious issues and in one case the 710 flopped. It seems they shine in mud and on rough forest roads

My Haflinger has the same stability issues in areas of steep slopes and deep holes (wombat holes) and for offroad work I am also considering wheel spacers to assist with stability - yes the pinz and and the haflinger have great ground clearance because of their portals but that comes at the expense of stability in some circumstances - not helped by the swing axle design - so with advantages come disadvantages.

I also have a Landrover FC 101 - basic suspension and no portals but I do have diff locks. I have been 4wding in it with a couple of Pinz on a few occasions. The vehicles overall are very similar in offroad capabilities - the Pinz has better clearance under the diffs (though not as bad an issue as you think) but the 101 is far more stable because of its lower centre of gravity and solid axles so sideways it is better than the Pinz.

However where there are holes that you can drop a front wheel into - both have the same issues - lifting back wheels high in the air and if going down hill easy to tip - I have nearly gone over a couple of times.

So in my mind with all three vehicles the solution is to widen the track as far as you can within reason - load issues may come in. On my 101 I have increased rim width from 6" to 8" an increased the offset of the wheel so that the track has increased by about 1 1/2".

With my Haflinger I have 14" rims that are 6" wide so increasing the track but this is offset by the larger diameter tyres so remains unstable offroad. In this pic you could imagine what would happen if my front wheel went into a hole on a slope. For offroad I am also looking at spacers and ATV rims and tyres.


So for the Pinz, I think the preferred option would be wider rims with different offset to increase the track but spacers would also work as long as they do not over load the hubs.

However driving these cab over designs with this tip tendency in mind goes a long way to reducing the chances.

Garry

I think the Land Rover FC101 track is about 8 or 9 inches wider than the Pinz also.

I wonder how much of the Pinz's instability is due to the swing arm suspension and limited articulation?

Unimogs have portals but straight axles and great articulation and seem to have less issues with rollovers - but I think their track is about 15 inches wider than a Pinz.

I also think many 4x4 710 Pinzgauers would benefit from trimming the coil spring length on the rear - it reduces the camber when unloaded which is how many pinzgauers typically operate. I did mine many years ago - I think it was just one of the "dead" (non active) coils on one end or perhaps a half coil on each end. Easy to do and worth considering - although if you are going to add spacers it would be better to wait and see what the additional leverage the extended track has on the camber.

Was waiting for my kid to get off work so I looked it up -


Model --------------- Track* -------------------- Width

Pinz 710 ------------ 1440 ( 56.7" ) ------------ 1760 ( 69.3" )
Volvo C303 -------- 1540 ( 60.6" ) +3.9" ----- 1900 ( 74.8" ) +5.5"
LR FC101 ---------- 1550 ( 61.0" ) +4.3" ----- 1830 ( 72.0" ) +2.7"
Unimog 404 ------- 1630 ( 64.2" ) +7.5" ----- 2140 ( 84.3" ) +15.0"

*Note - Track is to the center of the tire so wider wheels would not influence this value.

Haf-e wrote:I wonder how much of the Pinz's instability is due to the swing arm suspension and limited articulation?

Unimogs have portals but straight axles and great articulation and seem to have less issues with rollovers - but I think their track is about 15 inches wider than a Pinz.

I think you will find it is a combination of the raised CofG caused by the portals, the swing arm suspension allowing the wheels to curl under a little and the cab over/forward control layout. To a more or less extent these are typical of most 4wd cab overs. In most other scenarios these characteristics are a positive and gives the Pinz its superb offroad ability.

The Australian Military has had some rollovers with the Unimogs and has unfortunately resulted in deaths.

The name of the game is to know the strengths and weaknesses of our vehicles and drive accordingly - easier and said than done.

Garry

According to basic trig and a few references http://www.nhtsa.gov/cars/rules/rulings ... apt05.html
given a 710M roll-over angle of 43 degrees, track width = 57", Center-of-gravity = 2.55'. That seems about right
(formula SSF = T/(2*H) = Tan(roll-over angle) ).

With the modified 8" rims, my Track is 60" (+3" over stock as assumed). That increases my SSF +5% or from stock
value of 0.93 to 0.97. Adding at least another 3" of spacer gets to 1.01. If I had these spacers I would put them at
least on my rear hubs for added protection (maybe fronts too). If anyone gets more info on these, please post the
results I'd be interested.

For comparison, a Jeep Wrangler SSF=1.2

We are indeed more susceptible to roll-over than many 4x4's, as the TechMOGogy avatar suggests
What's up with that Dan

rmel wrote:
SNIP

We are indeed more susceptible to roll-over than many 4x4's, as the TechMOGogy avatar suggests
What's up with that Dan

Experience

Just got some spacers fabricated by HEM Industries in Dewey Oklahoma for the Hutchinson wheels. Fit great and gave me 2 inch wider print. Pics coming soon.