Just a quick note to show the final installed shock. Due to interference with the axle plate, the bottom loop of the shock has to be installed first. I used some oversized washers at the top to provide relief for the weld bead on the shock side of the upper mounting stud. It turns out that the Monroe-provided stud is NOT too long (despite my earlier post). There isn't much of the 5/8" diameter smooth shaft (see post above) for the loop to slide on, so I cut a small length of 1/2" copper pipe (fits perfectly over the threaded portion and has an outside diameter of 5/8") to provide a bearing surface for the rubber inserts.
I had some interim thoughts that I should have put the mounting bracket further inboard on the swing arm. Not so fast, Nellie! To my surprise, I found that when I went to adjust the brakes I HADN'T CONSIDERED THE LOCATION OF THE ADJUSTING HOLE IN THE BRAKE PLATE. The brake plates are not symetrical. It turns out that the stree side hole is accessible just in front of the shock bracket, but the curb side is exactly behind the tip of the bracket. I'm not sure that it can be adjusted with a screwdriver (you can get the screwdriver into the hole by angling from botht he front or the back)--due to the angle, the tip seems to slip off the star wheel. But you can adjust it easily with a brake tool (sorry, no photo, but it's one of those chisel-looking things that is bent 90 degrees at one end and has two 45 degree bends at the other). So, be careful how close you mount the bracket towards the brake plate!
I added a small retaining loop to the axle plate for the brake wire--I never liked them just hanging down out of the belly pan. You can see it here in the upper right hand corner.
Well, finally had time to actually measure the shock and axle location under the static load of the trailer. I am surprised to find that the swing arm is actually slightly "up." This does not seem right to me--makes me think the axle is really not up to its 4,000 lb rating.
My shock mount placement was designed to provide full travel on the 555003 shock, about 5.75". Under only the static load of the trailer, the axle has swung up so far as to use 4.75" of the available shock travel. Despite this, there's no sign on the mounting studs that under dynamic load (bumps in the highway) the shock was compressed to its minimum travel. Don't know...
Anyway, I need to find out if this is the normal static position for a torsion axle (I'm betting it is not). Anyway, the lines on the photo are drawn along the axle mounting bracket and along the swing arm. It appears to me that the swing arm is "up" about 2-3 degrees, which means the swing arm has rotated 25 degrees from its beginning position of 22.5 degrees "down." I guess I need to find out what the total design rotation angle is for these things.
My shock mount placement was designed to provide full travel on the 555003 shock, about 5.75". Under only the static load of the trailer, the axle has swung up so far as to use 4.75" of the available shock travel. Despite this, there's no sign on the mounting studs that under dynamic load (bumps in the highway) the shock was compressed to its minimum travel. Don't know...
Ouch.
Only one inch of travel left at static load. And if the dynamic load doesn't use that entire one inch of travel, then the axle is moving at less than an inch over irregularities of the road. Is it transmitting shock load to the trailer versus absorbing it?
Not sure how you would measure that.
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1966 Mercury Park Lane 4 DR Breezeway 410 4V, C-6, 2.80 - towing a - 1966 Overlander International Twin Bed
1996 Lincoln Mark VIII Diamond Anniversary 4.6L (275hp), 4R70W - 1990 Ford E 150 5.8L, E4OD, 3.55 ____________________________________
Phoenix ~ Yeah it's hot however it's a dry heat!
There is a work-around. The Monroe 555002 is shorter and has a minimum compressed length that is 1" shorter than the 555003, which allows more "up" travel of the swing arm. (I made an error in a previous post--the working travel on the 555003 is 5.125", not 5.75".) The 555002 working travel is 4.125". It turns out that if this axle is OK (a big if, for sure), the 555002 would be right at the middle of its working lenth, with about 2" of travel available in both directions from the axle static location. However, the 555002 shock would limit the down travel of the swing arm if you had to jack the tire off the ground.
It sure sounds odd that your swing arm is going slightly up.I think a call to the manufacture to get their specs on installed position is in order.. Youve worked very hard to get to where your at ,and very thorough job.it could be possible as you have surmised that the 4000lb rating may be wrong .I hope not, give them a shout!!
Axis has asked for the bare axle back for some analysis. It will be a couple of weeks before I get home and can comply. In the mean time, I wanted to get certified weights to make sure the local garden supply scale was accurate.
From this I conclude (the truck is an F-250 diesel, the trailer is an 18' 1971 Caravel):
Truck weight 7200# (includes generator, trailer spare tire, extra fuel)
Trailer weight 4140# (includes 28 gal of water, food, other normal stock)
Tongue weight 420#
With a trailer axle weight of 3720 lbs, the sprung weight on the torsion axle is about 3550 lbs (subtract two wheels, tires, drums, brake plates and 1/2 the swing arms and spindles). Maybe a 3700 axle would be better, which would allow for a toolbox and the occasional late sleeper.
What puzzles me is that the original axle had a spec plate for 4000 lbs. I feel like I've added weight, since I replaced all the orginal 1/8" panels with 1/2" maple plywood, added a second battery, microwave, Pergo flooring, and a new fridge that is a couple inches taller. The only thing I really removed was the carpet--I'd say that's about a one-for-one trade with the Pergo. So I'm thinking I'm a little heavier now than when the trailer was new.
Axis has asked for the bare axle back for some analysis. It will be a couple of weeks before I get home and can comply. In the mean time, I wanted to get certified weights to make sure the local garden supply scale was accurate.
Axis uses rubber rods that are stiffer than those used in Henschen axles.
Therefore, if you increase the weight rating of the Axis axle, that has the stiffer rubber rods, it will result in the trailer having a much stiffer ride. Depending on how you may or may not load the trailer, that could cause potentially a structural problem.
On the other hand, if you increase the rating to 4400 or 4500 pounds with the Henschen softer rubber rods, you would be OK.
The Axis rubber rods are made from extruded rubber, 80 Duro, that has a set test of 10.084 to 10.324 percent. They have a modulus test of 3700 pounds.
The Henschen rubber rods are made from molded rubber, 70 Duro, and have a set test of 9.026 to 9.154 percent. They have a modulus test of 2800 pounds.
The lower the set test, the better, and the lower the modulus test, the better, both of which result in a softer ride.
Andy, do you know what the Dexter modulus is? It would be interesting to compare, if indeed this number has a direct relation to ride stiffness.
If I understand correctly, the stiffer Axis rubber has about 35% steeper spring rate (for equivalent lengths of rubber), so if the Henschen and Axis axles are sitting at about the same static position under the weight of the trailer, under dynamic loading the Axis swing arm will move in a shorter arc than the Henschen, for the same dynamic load.
The softer Henschen rubber raises a question in my mind. Since both axles have an unloaded angle of 22.5 degrees down, the Henschen would have to have more rubber and a higher weight spec if you intended for the static loaded position to be about 10 degrees down. Wouldn't a higher weight spec be equivalent to increasing the spring rate and you'd wind up with similar, if not exactly, the same ride stiffness?
I think my one neuron is beginning to smoke.... ... but I'm thinking that we all want to be axle experts and just love this techical stuff.
I will admit that I'm thinking my "spring rate is directly related to the modulus" concept/assumption is wrong, since a 4000 lb axle from either Vendor ought to sit at about the same initial static loaded angle. I don't know how you do that when you have the same starting down angle and different spring rates.
Andy, do you know what the Dexter modulus is? It would be interesting to compare, if indeed this number has a direct relation to ride stiffness.
If I understand correctly, the stiffer Axis rubber has about 35% steeper spring rate (for equivalent lengths of rubber), so if the Henschen and Axis axles are sitting at about the same static position under the weight of the trailer, under dynamic loading the Axis swing arm will move in a shorter arc than the Henschen, for the same dynamic load.
The softer Henschen rubber raises a question in my mind. Since both axles have an unloaded angle of 22.5 degrees down, the Henschen would have to have more rubber and a higher weight spec if you intended for the static loaded position to be about 10 degrees down. Wouldn't a higher weight spec be equivalent to increasing the spring rate and you'd wind up with similar, if not exactly, the same ride stiffness?
We do not, unless requested to do so, use a 22 degree starting angle.
We suggest a 35 degree starting angle for two reasons. One to raise the trailer for more ground clearance and two, because of the higher profile tow vehicles today, the required drop shank hitch bar dimension can be shortened.
Henschen uses rubber rods that are 20 percent longer than the Axis rubber rods. As an example, when Henschen uses an 18 1/2 inch rod, times four on each side, Axis uses 15 inches rod on each side times four.
The Dexter information, is being compiled at this time.
I have had my Axis axle under my Minuet for a year now.
After 5,000 plus miles, some of it Upper Peninsula two-tracks, I have suffered no ill effects of having the Axis axle on the trailer. Nothing has shaken apart. The axle is still in excellent shape. The complete E-coating is far superior to the hand-painted axle and it still looks new. My "unapproved" NAPA gas shocks are holding up just fine and the trailer has not blown up from them.
I pulled the trailer this past weekend and the brakes work great. No strange sounds or movements.
As far as I can tell, this is not rocket science. I am not concerned how long the rubber cords are. I have the oldest Axis axle on one of these trailers. Mine was the first.
Someone else had a problem with their Axis axle's backing plate that came loose. It could not be determined if it was from the RV repair place that installed it or if it was from the factory. The person I am referring to received his axle last summer. It was installed by an independent repair facility in California. This gentleman called Axis and all they asked was, "What was damaged? Did you replace it already? If so, how much did it cost? Where do you want the replacement parts sent? Do you need Axis to pay for the labor of the repairs? When can we send someone by to pick up the broken stuff?". He received his replacement backing plates with new drums and hardware within the same week. At no cost and no hassling with a vendor or the manufacturer. This is the way business should be conducted. Not just with axles either; everything.
I have seen posts on here about axles damaged in shipment. Let alone after they are used on the trailer. The vendor refused to pay for the shipping damages. It was a big hassle for the customer.
I am glad that I have an Axis axle. I am not going to worry about how hard the rubber cords are or how long they are. I am going to worry if I am getting my moneys worth. I am going to worry if I have a problem and I cannot get support. I am going to have a problem if I am questioned about how sincere I am about my warranty claim.
I will not lose any sleep over 15 inch rubber cords. I will lose sleep over buying an expensive axle and not having my legitimate warranty claim handled properly. There is a track record with this already. It is well documented here on the forums.
It sounds like you had a problem with someone elses brand of axle or somthing ,you sound a little bitter and you sound like you are thinking about the rubber rod length since you mentiond it 3 times in your post ,but I am glad your shocks didnt destroy your trailer .I think we all want the best service and warranty on anything we buy.
It sounds like you had a problem with someone elses brand of axle or somthing ,you sound a little bitter and you sound like you are thinking about the rubber rod length since you mentiond it 3 times in your post ,but I am glad your shocks didnt destroy your trailer .I think we all want the best service and warranty on anything we buy.
scott
Hi and welcome to the forums. I see that you are rather new.
I hope you enjoy the wealth of information that can be found on here. You may want to start by researching some of the previous posts on this forum. I think you may be missing some of the rich message history here.
Thanks for keeping track of the word count in my post though. You never know when a skill like that may come in handy.
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... but I'm thinking that we all want to be axle experts and just love this techical stuff.
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