pugslyyy
Expedition Vehicle Engineer Gal
Yeah it turns out that my new camper spring mounting system is perfectly sited to capture a leaf spring when the mount breaks. Sometimes I'm smart - other times I'm lucky. This was pure luck.
Well I broke it, in Canada
- Thread starter pugslyyy
- Start date
Yeah it turns out that my new camper spring mounting system is perfectly sited to capture a leaf spring when the mount breaks. Sometimes I'm smart - other times I'm lucky. This was pure luck.
The Artisan
Adventurer
I might be wrong but hasn't this happened before? What's the reason for the spring load mounting or pivots. You are putting a good amount of sprung mass and stress on each bolt as the box bounces Why not mount the box like all boxes are mounted with, 4 ubolts down each side?
Kevin
Kevin
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SkiFreak
Crazy Person
A bit of reading about kinematic mounting systems might answer your questions.
BTW... the mounts should take the fore/aft/lateral loads, not the bolts holding the spring/s. I know that this is how my system was designed to work.
The Artisan
Adventurer
A kinematic mount is basically a 2 plate mounting mount with 3-4 adjustment screws so each of the mounts take the loads. Not the same as guys using 2 springs taking the force.
Kevin
SkiFreak
Crazy Person
As I mentioned, the mount should take the force, not the bolt or spring.
BTW... Kinematic coupling describes fixtures designed to exactly constrain the part in question, providing precision and certainty of location.
The Artisan
Adventurer
Ski I agree with you and your mounts, but the aforementioned designs are not Kinematic mounting, thus the multiple failures.
Personally IMO, for all the types of off roading most would do the ubolt method would suffice.
Kevin
Personally IMO, for all the types of off roading most would do the ubolt method would suffice.
Kevin
SkiFreak
Crazy Person
Subframe mounting has been covered on this forum many times and it is often a very contentious subject.
The bottom line is that there is no "one size fits all" solution for mounting a subframe/camper to an expedition vehicle, as there are too many variables: brand and year of truck, chassis design and thickness, weight of the camper, terrain that will be traversed and the list goes on.
You are correct that a fixed mount could possibly do the job, but in an off road scenario the chassis will twist much more than a road going truck would experience. If that twisting is only encountered occasionally then there would be less risk of chassis damage, but it's like asking... how long is a piece of string?
On this forum there are numerous pictures and videos of Fuso/Isuzu owners doing some decent off road driving and what is evident is some pretty serious flexing when they do that.
Especially with the stepped frame of the Fuso, a fixed mounting system will create some pretty serious stress points, normally focussed just in front of the step. I have seen many trucks with cracks in the chassis in that area.
Personally, I would not like to go off road in a Fuso that had a fixed mounting system, but maybe that's just me. Each to their own...
The Artisan
Adventurer
Fair enough... What about about a fuso FE that is straight framed that has been converted to 4x4? Would you feel more comfortable for light duty off road?
Kevin
Aussie Iron
Explorer
At this stage my tray is solid mounted as in bolted to the chassis and you should see how much flex I get in the tray. My Camp Boxes are rubber mounted so as not to impart all the flex to the boxes. Spring mounts are certainly called for in a Camper that is fitted to the chassis if you don't want to impart all that flex to the Camper and end up with it cracking apart. But to each his own.
Dan.
The Artisan
Adventurer
Dan,
Thanks, what type of off roading do you generally do? Also the stress you mention did they use a 2x4 or 4x4 between camper frame and frame?
Kevin
Thanks, what type of off roading do you generally do? Also the stress you mention did they use a 2x4 or 4x4 between camper frame and frame?
Kevin
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SkiFreak
Crazy Person
Dan goes where others fear to tread... :wings:
As an example, Google "old telegraph track australia"
SkiFreak
Crazy Person
Dan makes a very valid point regarding the flexing.
No matter how you mount the camper there will be flexing when you go off road. What you have to ensure is that things do not flex too much where they shouldn't. Using something like a spring mount system you can limit the flex going from the chassis to the subframe and then into the camper body. If the camper body flexes then you will quickly destroy your internal furniture and probably develop some leaks too.
No matter how you mount the camper there will be flexing when you go off road. What you have to ensure is that things do not flex too much where they shouldn't. Using something like a spring mount system you can limit the flex going from the chassis to the subframe and then into the camper body. If the camper body flexes then you will quickly destroy your internal furniture and probably develop some leaks too.
Aussie Iron
Explorer
SkiFreak is on the mark, if there is maybe a road we will probably travel it. Canters can be up there with the best of them offroad. There are some reports that I have written up of my trips in here if you search. Also video on Youtube just look for Canter 4x4 it will come up.
My tray main frame is 3" x 2" channel steel (not cold rolled channel) and yes it flexes quite well and actually sits at the height of the top of the step and is on legs to the rear lower chassis.
Dan.
My tray main frame is 3" x 2" channel steel (not cold rolled channel) and yes it flexes quite well and actually sits at the height of the top of the step and is on legs to the rear lower chassis.
Dan.
You can't have a frame designed to flex be constrained by a rigid body. Torsion free mounts allow the frame to flex and yet protects the rigid body from that flex. Otherwise cabinet frames will crack and split, plumbing fittings will fail and window and door seals will wear and start to leak.
Cabin mounts need to isolate as well as contain the rigid body. They need to be designed such the body can't roll off the frame, restrain the body from slamming into the back of the cab or sliding off the rear.
Cabin mounts need to isolate as well as contain the rigid body. They need to be designed such the body can't roll off the frame, restrain the body from slamming into the back of the cab or sliding off the rear.
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