Axle Measurement Data Base

[Hummer]

Here is what the old (1976)factory 3200 lb axles looked like after having weight off them for three weeks up on jack stands and the new 5200 lb axle just installed.


This is bracket I made. One set of holes locates 8 Lug Hub face and the other a 6 Lug (Airstream) Hub face.


This shows how bracket is attached to hubs to measure the hub face on one side.



And this is the other side. This way you get a dead match for the axle you are removing and you can look at how your wheels locate in the wells and you can change this dimension. On mine the left side mounted closer in than right side so I increased the hub face dimension a tad to center the wheel a little better in the well.

[Inland RV Center, In]

Originally Posted by Hummer

Here is what the old (1976)factory 3200 lb axles looked like after having weight off them for three weeks up on jack stands and the new 5200 lb axle just installed.
On mine the left side mounted closer in than right side so I increased the hub face dimension a tad to center the wheel a little better in the well.

Henschen always said, never increase the rating more than 15 percent, or there abouts.

Your's have increased over 60 percent.

Unless your Airstream is very heavily loaded, which the chassis cannot handle, watch for sheared rivets, and fatigue crack damages, to the shell and chassis.

Those are the warnings issued by Henschen many years ago.

Andy

[crispyboy]

Originally Posted by outofcontrol

Thanks Greg. I got a PM that 2 of my measurements were off, but no indication of which two. It really did scare me because if it's done wrong, it's on me. Well, the Six Robblees Distributor has a 50% restocking fee. Which I think is generous knowing that if it's done wrong, it's pretty much scrap metal.

It's also pretty difficult to make the measurements by yourself with them on the trailer. I would take one off to measure it, but I have to cut one of the bolts to get it off. The spindle arm doesn't move out of the way.

You're right, the Hub face probably won't make a difference, and 1/16th on each side of the mounting plate won't be a deal killer. I'm just surprised that I was off by that much.

I haven't made the order yet, but I will this week. I might do my measurement with a neighbor since the wife is not really excited about being my helper.



-Kevin

Kevin,
When I changed axles in the past (previous trailers) I took my own measurements and then I took the old axle to the axle distributor, let him take the measurements, compare the measurements and if the axles come in wrong it is the distributors problem.
I like the idea that you upgraded the down angle but I am curious about why you needed to upgrade the axle capacity. There seems to be plenty of weight capacity. I will have to do this job again in a few years.

[Hummer]

Andy,
I completely understand the concerns you have and I may have completely mis-understood the rationale for getting such but here is my understanding of torsion bar axle characteristics after I got a mini lecture from a torsion bar design engineer that works for one of the major manufacturers of axles mentioned in many forums.


I wound up talking to him after I queried the engineers I worked with and could find no one that took a course on torsion bar axles in school but their consensus of opinion coincided with mine and that axles loads should be 50 thru 66% of axle capacity.


As a back up I called one of the major vendors and asked to speak to a axle designer as I had some technical questions and he explained it as follows:

Torsion bar axles rotate in three segments. The first segment involves a rotation of the axle 22 ½ ˚ so in this the original case when the AS axles reach 6400 lbs they have maxed out at their design.

The second segment becomes much stiffer quickly and when the load doubles to 12,400 lbs it only takes another 11˚to be at the end of that range.

The third segment becomes really stiff and this threshold is attained with a further rotation of only 5 1/2 ˚ and then it becomes “solid”.

As I understand it the original AS axles had 22.5˚ down angle as new and as you can tell by the picture they were then neutral with no load on them even including the 16” 10 Ply rated tires and new rims.

Thusly I must conclude they had already rotated to the 6400+ pound range that would give very limited movement between there and 12,800 lbs which was confirmed by the power supply unit had completely broken it’s mounting location and it with a large piece of the plastic mounting wall bracket had completely broken away and was laying on top of the pump when I got the AS several years ago. Rivets had already popped that secured the cabinet and closet door hinges.


It wasn’t long that I came to the conclusion that back in the 70s when she was built there was not a lot of thought about what they would see in service.


Before I could launch her I had to work on her about 12 hours a day for ten days to fix hinges, pack bearings, fix burst water lines etc. I straightened out the hinges that had not broken, drilled out the failed rivets and I remounted them by drilling a hole all the way through the tubular aluminum but before drilling I cut pieces of 1/8” X 1” strap stock and clamped them on the back side. I tapped the holes (and backing plates) 8X32 and every place I could get to I put a 8X32 lock nut on the back.
I changed the closet door hinges to stainless steel hinges about 3” long from Home Depot and had to fabricate door catches from ½” angle on my milling machine. The hinges are also back face reinforced. So far I haven’t had any screws come loose on anything.


The shelf under the sink was ripped out and a half inch piece of plywood now goes all the way to the hull and will now support 225 lbs with ease. I pocket hole screwed vertical 2X4 piers to the deck that the shelf now sits on and there is no flex as it is reinforced with 1”X2” ribs glued to the shelf.


I pulled the power supply and got a lighter one and repositioned it on the bulkhead between kitchen/bedroom areas and it plugs into 115V wall plug so when not on the road it is unplugged and a trickle charger is on the battery.
As well on the last trip from SC to Ohio to Vermont and back to SC with the original axles and original pick up truck style tires I opened the door at one stop and found the overhead storage on the port side broken away and laying on the bunk.


Subsequently we made another trip to Ohio and back with the 3040 lb 16” rims and 10 ply rated tires and nothing came loose but the brakes failed about ten miles from home and the magnets and hubs were gone. Thus new axles were in order.


At the end of the conversation with the torsion bar axle designer I told him I had already replaced the tires and put heavier rims on it rated at 3040 lbs each and I put it to him like this. “If it were you what would you go back with?”


He said he would go with 5200 lb axles and 22.5˚ down angle and this would give me the full range of motion of the first segment and the vast majority of major road dips should never get me into the second load segment and make for a smoother ride. As well at 5200 lbs the brakes are the max size and rated at I believe he said 12,000 lbs???


I also found when mounting them the hole locations required spacers on top of the mounting brackets which I think were ½”. I cut them two inches longer than the axle mounting brackets to distribute the load to the frame in a wider area. I was confident they would not move but to make sure I had my buddy tack weld the spacers to the axle brackets.


I also examined the frame and the side mounting plates closely for signs of material fatigue and found nothing. I examined all welds as well. I replaced the factory mounting bolts with cad plated Grade 8s that are longer so if I have to get into reinforcing I can measure the C-C of all four bolt holes and go down the outside with 1/4” or 3/8” plate and use those bolts to mount it.


I have a utility trailer I put an 8000 lb torsion bar axle under about 12 years ago. It is a 40˚ down angle and 8 lug. It has two piece rims and 10 ply tires. I did not order it but found it at dealer who said it was ordered with up angle and they came in down angle so they gave me a really good deal on it. It just happened to be the perfect spacing for my trailer. Empty it does tend to bounce a little but with a load on it (my tractor at 4200 lbs) it rides very smooth and on bumps it makes one big movement, recovers and followed by a second minor movement and dampens immediately. I could not ask for a better tracking trailer as I mounted the axle exactly as they recommended it which at all speeds it just sits there with no side movement. Previously it had mobile home axles under it but they went south.


When I got her out of “dry dock” I pulled her about 30 miles on back country roads with lots of dips etc and I could tell she rode much smoother than the worn out factory originals. Hopefully within the next couple of weeks we will take her to Charleston for a couple of days which will include about half of it on back roads that are not nearly as smooth as I-26.


I carry a pretty good assortment of tools for roadside repairs inclusive of battery powered drill for inside repairs soldering gun, etc.


I also have about ten gallons of drinking water over the axles on the deck and the usual “things” that go with a trailer and if I am going to a match my shooting gear in back closet.


Will give a follow on report when I get back.

[Swimhard4]

Originally Posted by GT1963

Thanks Henry - you women rule right.....but we do need your help though

Actions idea of using the trailer forums is a good one - but what we need is a consistent form so that each of us could post the measurement in the same manner - and what are the measurements.

I have the order form from Axis but I don't know if that is what we need.

I know too that say my 63's axle could be very different to anothers.

Thus what about just the frame measurements of where the axle would be mounted?

There are also options that people have as their own preference that you would not want muddying the waters - so we would have to look at the basic replacement - and then state all the extras after - like people who bump up the angle degree and the weight and the type of mounting hardware such as nickle, galvinized powder coating and the list I am sure is long. As well the brakes, hubs, drums they would all come into play.

But if each year and model had the basic listing to start from then that would be perfect.

By using the trailer forum - that would mean there would be a thread started in each section - and then people would start chatting in each of the threads like we do already and it would end up being so bulky - unlike people submitting to one thread and someone charting the information on a spread sheet and then offer is as a pdf link being updated monthly or something - somewhat like the Inspectors document. I would offer to help somehow.

Hopefully the fellow will be able to measure for us in the right place - or we may have to travel on the Sat do our own measurements put the order in and hope we can get a quick turn around from Axis. In the meantime I have to do some research here to find out if someone has in their possesion a 63 Globe Trotter with the Douro Torque axle installed.

Henry there is a nice 55 hanging out in the mud in South California on e-bay right now - Whale Tale!!!!! not in bad shape for a 55 sitting in the mud for 20 years.....or was that you who snapped up that little 65 for a buy it now of $2500.00 down in Cape Cod?

Wathca doing with yourself?

To all you other fellows hang in there - soon we will figure out what route to take and then we will do a call for input....toss in any ideas on how to administer this...as you think of them

Hi, We need to replace our 1965 globetrotter axel. Do you know where is a good place to find them and the measurements? We are in The Woodlands Tx just out of Houston.

[Inland RV Center, In]

Originally Posted by Swimhard4

Hi, We need to replace our 1965 globetrotter axel. Do you know where is a good place to find them and the measurements? We are in The Woodlands Tx just out of Houston.

Call Bob Jones RV in south Houston.

Andy

[REDSLED88]

Originally Posted by Inland RV Center, In

Henschen always said, never increase the rating more than 15 percent, or there abouts.

Your's have increased over 60 percent.

Unless your Airstream is very heavily loaded, which the chassis cannot handle, watch for sheared rivets, and fatigue crack damages, to the shell and chassis.

Those are the warnings issued by Henschen many years ago.

Andy

Andy, is that because the heavier weighted axle rides stiffer, or because people load the trailer up more, and therefore add extra weight to the frame?
I woud think that a larger axle won't make a difference if your weight is not increasing.... although I'm not an axle engineer.
Just wondering.
I can imagine it being a little more stiff, and therefore riding harder, but not sure that it would make a huge difference.

Swimhard4, take a look at a 4200lb. Dexter torsion axle for your '65, that's what I was recommended.

TIMK

[Inland RV Center, In]

Originally Posted by REDSLED88

Andy, is that because the heavier weighted axle rides stiffer, or because people load the trailer up more, and therefore add extra weight to the frame?
I woud think that a larger axle won't make a difference if your weight is not increasing.... although I'm not an axle engineer.
Just wondering.
I can imagine it being a little more stiff, and therefore riding harder, but not sure that it would make a huge difference.

Swimhard4, take a look at a 4200lb. Dexter torsion axle for your '65, that's what I was recommended.

TIMK

The heavier the axle, the stiffer the ride, unless additional loading takes place, with reason.

An axle rating increase out of limits, will destroy an Airstream, in part because the trailer as a whole, simply cannot handle it.

As an example, putting a 5000 pound axle on an older Caravel, is an absolute death sentence, even if you add the additional loading. The trailer will fall apart.

And, the longer the trailer, the worse it becomes.

Keep in mind, the method of construction of an Airstream is semi-monocoque.

Opinions don't count but physics does.

Shops make big money restoring or trying to restore an Airstream that has be punished.

Bad rubber rods in torsion axles, under rated axles, over rated axles, excessive rated tow vehicles and excessive rated load equalizing hitches, along with unbalanced running gear, are all huge enemies of the Airstream and Argosy travel trailers.

Going back 50 years, more than proves that, over and over again.

For those that disagree, my only suggestion for them is to have a healthy check book.

Andy