Inverted overlay axle

G'day Guy
I bought second hand Jayco sterling 2008 24ft. I was after a small lift to get in and out of those lumpy roadside stops. I had the axles "underslung" moved from on top to underneath the springs in WA. This had been recommended to me by a friend. After 4000kms one of the tyres began scrubbing out, so I took it back, the axle was 5mm out. The problem was rectified and I was happy. Now done 25000kms and no problems. Tows well, I estimate the clearance is only 50mm not 90, but this is all I was after.
I don't know the tech about Inverted camber and the mob that did it a a popular caravan service centre, but I'm happy so far.
Cheers
Joel.
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I have underslung our camper trailer and it works well and gives the extra clearance I needed, as well as towing perfectly and with normal tyre wear.

There are a few things to be pedantic about when converting, in my situation anyway I had to swap the base plate over and if you don't make sure everything is measured carefully and that the alignment is correct you could get tyre wear and the trailer would also crab along to some degree.

I have not inverted an underslung axle, but the story about the camber being a problem I am told by an experienced caravan repairer is no longer true, as the camber setting problem was quite a number of years ago when there were special biassed tyres that had to have a special camber setting built in.

I am about to undersling our Jayco Freedom, because I am sick of the rear dragging when we leave service stations etc. If the undersling (probably about 90mm extra height) is too high then I will buy a new straight axle (probably about 50mm extra height) which will probably halve the height of the undersling. I also thought of inverting, but thought that an inverted axle might tend to make the axle tend to turn if it was not exactly perpendicular, thereby putting extra strain on the ubolts etc.

I would talk to a specialist before inverting.

Many people also are very against underslinging the axle, but if you do your research you will find that several camper trailers, off-road caravans and utilities are underslung from new, so there can't be any real problem with the engineering of underslinging.

Brian DJ

i dont know about the "overlay" set up but for a normal axel .......get under it and have a look, you will see that the axel "hangs" on the "u" bolts, if you invert it the axel then sits in direct contact with the springs and actually takes a fair bit of load off the u bolts and makes it a far more reliable method .....
On the axel they normally weld a small square plate to line up the center bolt of the spring with the axel, it holds it all in alignment, when you move it from the top of the spring to the bottom it is best to carefully cut this plate off and weld it on the TOP of the axel, a very simple job and does not have to be any special weld as it simply is a guide to align it all whilst the u bolts are tightened, the other problem you "may" have is the bolt that clamps the spring togeather (center bolt..) sometimes has a round head (hex) on the top to be a perfect fit into the hole in the axel "alignment" plate, you "may" have to remove this and invert it also, again a simple job but clamp the spring first before undoing the bolt .... check all of this before attempting to bolt back up ...
If you have brakes dont simply turn it up-side down as some brakes have leading and trailing shoes and this will give you problems down the track ...
I have done it a few times now and it is an afternoon job but do it right and it will be better for it with only one drawback, it increases the center of gravity, may not seem much but it all adds up so may have a tendancy to "roll" or "sway" a bit more but it is worth it ....
Cheers.
Joe

I have a Jayco Sterling which when delivered as standard came with 14' wheels and top mounted overlay axles. I wanted a bit of extra clearance and as I already had an annex went for around 50mm. The axles are 45mm square and the spring stack 45mm, so mounting the axle under the spring would give me 90mm , and more than I wanted. I went for two new straight axles which gave me 45mm. All the running gear etc, just got move across. I looked at 15" rims and tyres but that was at least a $1500-2k project for 5, so this way it came in at under $200 plus my time.

Inverting an over lay axle in my and a lot of other peoples view is a very bad and risky exercise,as any pot hole etc. is going to try and flip the axle and puts stresses on the components that they were never designed to take.

Before I started this conversion I posted this topic on this forum (about a year ago) and contacted Jayco as the van was still under warranty. Jayco had no problems with the straight axles, but If I inverted the overlays they said forget any warranty, which I fully expected as I never took that option seriously in the first place.

Hope my experience helps with what you require.