Hi
any body know how much a box of this type should move on rubber mounts Any helpful comment would be
welcome just click on the mac web gallery link thanks Mark


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Put weight onto the chassis which is the equivalent of the loaded body.

Measure the height of the body mount points from the ground (A).

Jack up one rear wheel until the opposite wheel starts lifting.

Measure the height of the body mount points (B).

Repeat for each wheel, so that you get four measurements for each mounting point.

Use the formula A - B = C.

Use the largest value for C as this will be the largest chassis deflection that the vehicle will take.

C is the amount of movement that either the body has to cope with, or the body to chassis mounts have to compensate for. Add 25% to C for offroad chassis deflections caused by diagonally opposite wheels being off the ground.

Go and have a look at a few military 4x4 trucks and see how they mount box type bodies - it varies. Some have a single point mount with springs and shock absorbers.

If you know that you'll just be driving on dirt roads and not driving through ditches just stick to a standard commercial vehicle mount using wood and rubber blocks.

Hi all
Keep that info and comments coming all useful
thanks Mark

My box uses the original Iveco mounts.
The box is built on 2 rails which are then bolted directly onto the Iveco mounts. I think I have 3 mounts down each side (I must confirm this) because it’s a LWB. The truck’s done 220 kkm around Africa, OZ and Europe with its 3 owners. It’s an all wood box and is still holding up fine.
When it was first commissioned the original owner took it round the LRE track at Solihull and all were pleasantly surprised; it wasn’t penalised by the box.
All that to say that you’ll get by with a simple subframe, and that the Iveco mounts are very good.
The next upgrade would be a tubular steel subframe (100 x 100 box section for example) still using the original mounts. That would seriously minimise the flex in the box. On the rare occasion that the chassis flex exceeds the mount travel, the subframe would end up working against the chassis flex (effectively stiffening the chassis) It’s not perfect, but it’s a step in the right direction without modifying the chassis mounts.
(for info, the Bremach has a welded tubular steel chassis. On the few campers that I’ve seen on Bremach, the box is bolted directly to the chassis. No mounts, just sikaflex mastic!)
If you’re a greenlining LR axle twister you need to be sure of the travel. To do this, if you have the time, you could knock up a frame which is bolted to two of the mounts and just sits on the other two (the box itself would probably do); load up to your MGVW with whatever crap you have around and drive one wheel up a ramp until another lifts. Now you can see the total travel necessary without having to do any sums ( ;-) ) I’m just lazy Roger, please don’t take offence.
If it’s less than the travel available with the standard mounts, you have the solution.
If it’s more, you can:
Either Install a chassis cross member on which you mount the original mounts closer together; the closer they are the less they will travel, for the same load capacity.
Or Fabricate a pair of long travel mounts, based on the same principle as the existing, replacing the rubber with springs and using a longer bolt (it’s possible that a commercial truck body builder has such a beast, or even that their standard model has enough travel for your application
Or go the 3 point Unimog route, raising the box up way too much.
Or the 4 point route: 2 mounts/pivots fore and aft on the centreline of the chassis, and 2 mounts left/right near the front spring hangers. On the Unicat and similar, the centreline mounts are in fact pivots, but IMHO that’s overkill, and a pair of normal mounts in the centre will happily take the twist we’re looking at.

It looks like you won’t need to twin up the rear, but if you can find some wheels with less offset the truck will look better (WM wheels?). And while you’re at it, make sure the box can clear a set of 9 x 16 (or metric equivalent). The gearing is short and they’d help. Even if you have no intention of putting them on yourself, one day you’ll probably sell the van and a future buyer might want to (apparently the front wings need mods to fit 9x16).
Oh yes, try and mount that silly little tank behind the axle. If you bolt custom tanks directly onto the box floor, you’ve gained the height of the subframe in capacity. Mine has a 130L tank on each side and the original 90L mounted behind the axle – means you can really be picky about where you fill up; and save! SWB might be less, but worth it.

Hope this helps.
Back to my other work avoidance tasks…

hey mark, very interested to se how your conversion goes, did you cut off the van yourself? i presume that was a swb panel van? are u going to keep that site updated with piccies as you convert? what did u pay for the box?

Hi

intend to keep updated. Box was a bit dearer than wanted 250 quid you can get the newer crisp white bt box for 100 quid on ebay but the wheel arches are higher and for me in the wrong place. The older ones dont invade the inetrior.

i did cut back of myself bit by bit as floor bolts were rusted areas difficult to get floor grinder into especially around folded box sections sometimes grinder wasn't bigger enough or to big. Just too are time (i day)

The problem with this type of box is that it has a skirt all the way around the bottom which start to clash with bits like wheels and tank so we had to lift it higher then i would have liked for clearance

The other issue is that its only about 6" 2 ft inside so you will need to be short or use extreme insulation in regarding keeping tHe height down Im going to ad a pop roof however always getting higher!

However the space created below provideds plenty of space for tanks and cubby lockers. If i did it again I think would go for a second hand straight insulated box from a company peteit forester!

but the advantage of the bt is its cheap one piece construction it also has a double wall construction inside that I ,am going to attempt to fill with two back closed cell foam.

Very possible but apparently have to make sure that you place plenty of 10 mm holes inside to insure foam has spread and not left spaces that can act as a cold bridge.

I wonder if i will ever get there but hey its worth it just to spend some time with the scruffy old bloke in pics (dad)

learning curve is massive but fun

keep the advice coming

Mark