Spring Mounts for Rail-on-Rail Subframe

[VerMonsterRV]

Hi Neil, how much of a gap do you reckon, and could you lubricate it or fill it with a sacrificial layer of polyurethane or wood or ally?
Also I'm quite keen on making some kind of sprung u-bolt assembly rather than normal mounts, to spread the stress a bit more. Thanks for your help
Cheers Richard,

Our vertical guide plates are bolted onto the chassis, essentially they just guide the subframe and keep it directly above the chassis rails. There is no gap and so far there has not been an issue as the guides are taller than the spring mounts will allow the subframe to move. There is no sacrificial layer or lube at this point though I am considering working so grease in there to slow rust. These guide plates were installed in a truck body builder shop.

Not sure about your rear hard mounts. In the Mercedes guide they say not to drill any holes in the chassis rails. We were able to use the factory holes already in place for our hard mount. I am guessing you will need to drill holes in your chassis rails and just in front of the rear spring hanger would be ok (though I am not a truck builder or engineer so take this as just internet advice).

 

[dermal fauna]

Jon

Dont forget to leave adequate clearance between the vertical guides at the front and the chassis. These to will deflect and if too close will foul with the chassis.

Neil

Hi Neil, it's this bit that's thrown me, I thought the clearance you mention is between the inner face if the guide and the outer face of the chassis rail?
Thanks again for your help, also my chassis has some holes already that may be suitable for the fixed rear mounts, I'll take a photo.
Cheers Richard

 

[Dave Anderson]

Lots of ways to solve issues, and I appreciate the dialog here.

Every system has its pro's and con's and nothing done so far is the perfect solution. If you drive it too hard over bad terrain, there is a "redneck" term for that... "full send." Which normally ends up costing a bunch of money. This is what we all want to prevent. Half the battle is knowing your risks and mitigation of what risks you're most likely to encounter. Naturally, there will be outliers and hurdles that you will come across that exceed the planned risk. At that point, the choices are to avoid it, or continue cautiously (which again, mitigates the risk). Because of the extreme environments this community is likely to find in our travels, we all know that if we make stupid decisions, we win stupid prizes.

At the risk of offending everyone with a rail on rail spring over system, I offer the following video for your honest feedback. I am constantly looking around for better ways to improve what is offered in this community. Now that I have an engineering team at my disposal that has a lot of experience in the automotive industry, together we want to continuously improve and provide the best products for the like minded enthusiasts and full-time overlanders that we come across. I consider your feedback a gift to help us improve. *Trolls need not bother. Thank you very much!

 

[VerMonsterRV]

We have a rail on subframe and no offense taken. When making our decision on which way to go with the subframe several factors helped with our decision. Things like your chassis, the intended use and cost. If we had decided on a Unimog/Kat and serious offroad we would have gone with a torsion free subframe with aggresive tires. But since we went with a 1120 AF with leaf springs and on/off road tires we went with the much simpler/less expensive rail on subframe. When we got the truck, it was a retired firetruck that used a rail on subframe. It was way lighter built than ours and it did have a couple of weld cracks. I also think of the truck suspension and subframe together. We have upgraded the springs to parabolics and higher quality shocks. Since I own an 1120 I think I can say they were never intended for serious off roading. A friend's 6x6 Kat v(which is a hard mounted habitat, no torsion free at all) is and you can see the difference in the chassis/suspension. But this serious offroad comes at a cost, and not just the build. The 6x6 gets 6MPG, we get ~12MPG. And since most of our time traveling any real distance is on pavement (which I think is true for the majority of these trucks) it makes sense for us. Plus we can afford 12MPG, 6 not sure about that. We have taken the truck from the east coast USA to Baja then north to Alaska (and are now prepping to head to South America). We have gone on roads/beaches we wouldn't take a regular RV, but nothing that would require a well setup Jeep. If you do break something in a 20,000lb truck out on a jeep track you are in for some serious difficulty and expense to recover.

Some of you also know we sailed a bit before the truck, once again we setup/chose the boat for the given trip (around the world via the tropics). Was it the right boat for high latitudes? Nope, but it worked very well for the tropics and gave us 6.5 years without many issues. I approached the truck the same way, build it for 90% highway, 5% rough roads and 5% crawling. With a bit of caution things have worked well for us and we plan to take this truck back around the world.

 

[Overlandaisy]

Can you specify the type of springs you used in this set up? Mainly the LBS/IN used. My Camper is near 7kLbs on a 20ft frame. Many Thanks