Ground Clearance for Eggs - Fiberglass RV

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Old 10-30-2002, 11:29 AM   #1
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Ground Clearance for Eggs

I just made a post to the Casita Forum regarding ground clearance and know it will be of interest to some of us.

Here 'tis:

I am in the middle of having a second axle replacement done.

For the faint of heart, the failure of the first axle was MY fault for not checking the bearings before I set out for a long trip when it had been sitting in one place for a year. Living in it does not mean water can't penetrate the seals and contaminate the grease. The current axle was ordered incorrectly (missing brake flanges, didn't have EZLube and was Low Profile rather than High Profile).

There are several ways to raise the body of the trailer. The first is to order Dexter's High Profile axle rather than the Low Profile, which refers to the bracket, an integral part of the axle assembly. On my '91 Scamp 13, the high profile bracket was the norm; I dunno about other models or brands -- the difference between the two is only 0.88", but that's almost an extra inch of clearance between the tire and top of wheel well.

The next way to get some height is to have a spacer welded between the trailer frame and the axle bracket; I believe Casita uses a 2" spacer and Scamp doesn't offer a spacer at all (not at all certain about some of this as things are subject to change).

Obviously, both of the above are things best done when the trailer is ordered, altho an axle shop could cut off your axle, insert a spacer, and weld axle to spacer and spacer to frame. In total, these two options will raise the body 2.88" above the axle, BUT the ground clearance of the axle and running gear will NOT change, as all you have done is raise the frame and body. Also, you will have to adjust your hitch ball height to keep the trailer level. NOTE: Off level or side-to-side imbalance affects axle loading, wheel toe-in and road handling in general.

A third way to raise the frame/body is to specify a larger upper load range on the axle when it is originally ordered. Dexter will build the axle with more rubber cords, making it stiffer. However, more is not always better; a stiffer ride will result in more vibration, closet doors opening, rivets popping, frame flexing, stress on frame welds, stress on doorway opening, etc. (If you have ever pulled a boat trailer for a heavy boat without the boat on top, you will know exactly what I mean. If you get too much stiffness, the only way I can think of to ease the ride and resultant damage would be to run with your tire pressures on the low end or use tires with lower sidewall ratings.

If you are really serious about getting ground clearance, the next step, having raised the frame/body with respect to the axle stuf, which gives you clearance between the tire top and wheel well, you now replace your existing rims and tires with the next size up. The effect of this is to actually raise everything by the radius difference of the orig rim/tire and the new rim/tire.

Why do all this? The two big advantages to raising the trailer are to get a lot of ground clearance and to bring the trailer bottom level with the truck bottom (or at least more level). Ground clearance is obvious; less dragging of tail on steep driveways and rough (or no) road conditions. Having a level with the truck means that the trailer isn't creating an "air dam" between the truck and trailer, altho this is partially offset by the increase frontal area above the truck. I raised a 16' Jayco and a friend raised his 26' Avion; we both got towing improvement with regard to wind resistance.

What are the drawbacks? For the rapid drivers, the better air profile is a good thing, but the resultant higher center of gravity is a bad thing. Because the COG is higner, the trailer is more likely to rock side-to-side from air currents, road roughness and steering input. When it rocks, weight transfers between wheels, changing suspension and tire geometry and causing "dog-tracking", all of which will negatively affect handling and mileage.

Effectively, when you raise the COG, you are going from an automobile configuration to an SUV configuration. Just like the SUV, a trailer with a high COG is more likely to actually roll over than one with a low COG. Options high up, like power fans and roof air conditioners make things worse, of course. If you should decide to have a raised trailer, you must be very careful about packing your heavy stuf, like canned goods and even clothing, low. (It's surprising how much stuf like clothing and bedding can weigh in total).

Pete and the RatLadies who adjust their ground clearance and COG on the fly to suit conditions


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Old 10-30-2002, 04:49 PM   #2
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raising your trailer

So where are you and the rats staying while they have the trailer down? or is it just a day job and you don't even have to unpack?


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Old 10-30-2002, 09:30 PM   #3
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Last time the work was done, I moved all my junk and rats into my friend's garage (truly impressive pile for a 13' Egg; got rid of still more stuf) and myself into a spare bedroom while I very cautiously towed the much lighter (still kicking myself for not weighing it empty) Egg down to the welding place for measurements. Left it there for a couple of weeks until the axle came in and was welded on (it's presence annoyed the shop management because at least a half dozen people stopped by to ask the price!) and they called me.

This time is different however because I want to see the axle BEFORE it is welded on to ensure that it is right, so once the axle is in (shop estimates anywhere up to four weeks, but I know Dexter actually only takes five working days from order to out-the-door; but of course the order and delivery go from shop to distributor to Dexter to dist to shop), I will bring the Egg down, check the axle and take it away again. First time, labor was charged as three hours.

In previous repair work done to the truck, I stayed in the trailer either at generous repair place or nearby CG. I also have a plywood bed in the back of the pickup, plus backpacking stuf and a credit card, so I have lots of housing options.

Pete and Rats who sleep in cage regardless of where it is :zz :zz :zz

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Old 10-30-2002, 10:36 PM   #4
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nother question

Is Dexter the only axle to use? I thought EZLube was for constant moveing trailers not sitters so would work. But as my head is spining on all the hub and wiring post, maybe I'm confused. is a new axle really something I need to check into? is it dangerous to have a saggy axle. I had not planned to consider this. I thought if it rolled it was OK. What have I got myself into????:sad (add hand pulling out hair)

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Old 10-30-2002, 11:16 PM   #5
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The Dexter axles now have three factory options for lube systems:

1. Standard grease packed bearings; must remove to relube.

2. EZLube where one pumps in grease while rotating wheel until fully greased. Basically same lube properties as standard without the labor to regrease. Especially good for boat trailers

3. NevRLube, which is an oil bearing cartridge where one just adds oil, but bearings are subject to drying and rust if sitting too long without periodic rotation.

There are other manfs of rubber-cord torsion axles out there, like Flex-Ride and Henschen, but Dexter seems to have the Egg trailer market.

A Yahoo-Scampers poster pointed out that I forgot one more way to get a little height and that is to order a greater down angle on the idler arm. Depends on what is standard for your trailer, but if I were to substitute a 45down/HiProfile axle for my standard 22.5down/HiProfile axle, my loaded gain would be 2.29" if I read the Dexter chart correctly.

Pete and Rats

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