F550 Surf Camper Build - Adrift in the Green Room

An undamped spring is typically a mess. You would not run your car or motorcycle down the road without shocks, so why do people attempt to rely on basic coil springs or truck frames to be part of a suspension system?

IMO, a truck frame should not twist much and certainly should not be "noodly". That truck frame twisting back and forth is basically an undamped springs. You have no way to control where, when or to what degree it flexes. Making a rigid frame, whether frame rails, sub frame or carbon fiber monocoque on an F1 car, allows the other components of the system to do their job properly and effectively. Further, if you have the ability, a rigid frame allows adjustment and tuning of those systems.

Can you imagine your Baja 1000 buddy trying to tune his suspension for a race with a chassis that bent and flexed everywhere? How do you know what the coil-overs are doing? Is the suspension moving or is your chassis flexing? It would be a nightmare.

I realise that truck frames flex some and someone will chime in a with a picture of a Unimog all twisted up. I get it, Daimler designed the frame to flex and many builders insist on a three point mount, though that is slowly being replaced by something along the lines of what is pictured above. In the Unimog example, flex is designed into the system, but it is still not damped or controlled in any way. You have no way to adjust or minimise the movement of the camper box, as it flops back and forth from side to side.

Ideally, the F-550 frame should be reinforced, either with double C-channel or with inner wall plates, everywhere there is C-channel and not a fully boxed frame. The advantage of a fully boxed frame is that you can actually use a thinner gauge metal because you have the strength of a box section. This improves rigidity and actually decreases weight.

In mild steel, per foot of frame rail, you could easily see a savings of two pounds. Multiply that by 50-60 feet (both frame rails and all cross members, and you have a weight savings of over 100 pounds, plus you have a more rigid chassis or frame to boot. Unfortunately adding reinforcement to reduce "noodly" is going to add some weight, but I would be willing to take the hit to have a proper suspension, were I to be in your shoes.

The same goes for the RV box, consider some mountain bike shocks or something similar that can be adjusted to control the damping as the box moves around. (Notice Damping, not Dampening) Unless you are continually soaking your suspension with water, the latter simply does not apply)

Pick your Baja buddies brain, I bet he has some ideas or can get you to the right people.

Cheers
There is a reason heavy trucks are meant to twist. The springs holding the camper box to the frame should only move when the truck is really twisting and you are only going a few mph and not much damping is needed,the friction of the shear plates is probably enough.Although it wouldn't hurt to have some heavy, low speed damping, it's probably not needed.
 

heimbig

OnTheRoadAtLast
twisty frame

besides UHAULER and pappawheely coments, I'ld add: ya sure you want a stiff frame if you are building a racing buggy, but it isn't necessary good and increases the likelihood of frame breakage to be high risk - unless you have the stiffening extremely well engineered. Also spring mounted sub-frame is standard procedure on trucks and one of the recommendations of manufacturers. The other is that the weight should be spread out along the ENTIRE truck frame. I did something a little bit different but still follow Fords recommendations. For my 550 I have a 2 point hinge mount on the end of the frame. the entire load can 'lift' - really the twisty frame actually moves away from the load sub-frame, the sub-frame does not flex thus you do not put torsional forces on the camper. you can see the result: http://forum.expeditionportal.com/t...ehicle-Economical-build?p=1515395#post1515395
and scroll to the second photo: http://livingstonejournal.com/learning-curve/
and about half way down: http://www.truckcampermagazine.com/off-road/extreme-rigs/how-to-build-a-world-ready-rig-part-1/
 
Ask Doug Hackney and Robinson Fuso how their flexible stock frames (both of them) worked out...

I realise that a completely rigid frame is not possible, but I also understand how torsional and axial forces impact a frame and further an RV box mounted to that frame.

Good luck with whatever decision you make.
 
Thanks everyone for the advice. Its been a disappointing process. We built everything ourselves, but outsourced the construction and design on the flatbed and mounting system to Overland Explorer, as I felt those were items that might better be built by professionals than homebrewed. Despite them being very expensive, those were the parts that failed.

Overland Explorer wanted to know what failed, but has remained totally disinterested in fixing or warrantying any of it. We've essentially ended up with 70k (~3X the agreed upon price, a story unto itself) in yard art, and an extraordinary quantity of lost time and money removing, redesigning and subsequently rebuilding.

While I can see the potential benefits of the stiffer frame (boxing in the C Channel), I don't think anything other than a seriously engineered solution on that front would be wise. I added retaining plates on our subframe, and am going to experiment with stiffer springs and rounds of articulating the suspension until I find a combination that works better. The current new subframe design and rebuild on the inplace locker is already significantly stiffer and seems to have addressed the issues that led to the mounting failure. Truck is going back in for a final paint, so we'll know more when we get it back and can do some real world testing.
 
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Scott, you will end up with a very mobile, useable camper. I am sure with the level of thought you have put into it so far it will work out better than ever!

Ward
 
Building a custom vehicle is not for the weak. I built three different rear suspension designs before I got what I wanted; so I know how it feels. It's better you found the weaknesses while you could revise them easily. Having a failure in the boonies really sucks.
 
Hi. I am extremely interested in your experience with four LA36 units from Linak. I am looking at building a custom pop-up camping trailer and would like your views please, especially on how reliable they have been and the appropriate model. the LA36 may well be huge overkill for my requirements
 
Hi. I am extremely interested in your experience with four LA36 units from Linak. I am looking at building a custom pop-up camping trailer and would like your views please, especially on how reliable they have been and the appropriate model. the LA36 may well be huge overkill for my requirements
The LA36 has worked well and been reliable. Depending on the weight of your roof, and how much syncing you need when it is going up, they may be overkill, but its nice to have the options. Because my roof is a cabover and I am using motion control slides, I really needed it to go up square.

I have an extra set for sale in the for sale and wanted section at half of what a new set would run. Linak came out with a new control system that I wanted and I ordered the first set with the wrong clevis end for the mounts I'd made, so I decided to buy a new set.
 
Old replies but I figured I'd chime in as I've just gone through a month long balancing process with my tires and they have improved alot!

I ran Dynabeads in my Hutchinsons and it was a nightmare. The rubber Beadlock inside the wheel has two finger sized holes to allow air to pass through them. After not being able to get my wheels to balance, I took them apart and discovered beads had easily fallen into these air holes and were on both sides of the Beadlock, if that makes sense. No way to prevent it and get a decent balance with this design. Not to metion, Dynabeads customer service was absolutely terrible. Just my experience though.

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You can solve that by installing 2 air filters into the holes in the beadlocks. Stazworks came up with that solution.

I believe that you can add the beads through the valve stem and not have to split the rim. I'm sure that is not the case for all beads (airsoft bb's will not go through a valve stem) but the ones that are sold for dynamic balancing specially should.

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If you are running bead locks you absolutely can't add them this way, they'll get stuck.

What I've been 'told' is that the hutchinson beadlock won't reliably let the beads through the rubber ring and into the outer portion of the rim. But thats not coming from any personal experience, so could very well be wrong.
When I opened up my Stazworks wheels, which are split with the plastic beadlock inside, I had absolutely no beads that got past the beadlock. Most of them were stuck to the tire where they should be actually. I ended up vacuuming them all out!



I guess my concern if how well they work for dynamic imbalance, a bead lock that is constantly changing position. I tried centramatics and am not sure they helped much. If the beadlock is moving, it is also likely not reliably pinching the bead in position during air down maneuvers, so I am hoping to figure out a way to get them tight and stable first off.
I took it down to Nate Jones who did a combo of tire shaving, old school traditional balancing, and then a final balance with the tire on the truck, which balanced the entire wheel and rotor assembly. Its now amazingly smooth. He's really a master.
I was also having alot of irritation with the shimmy at speeds. When driving 10 hours a day it gets on your nerves!

My end solution to help the balancing was to vacuum out all of the beads and take them to a Goodyear truck service center who had a large enough balancer for my tires. I also was concerned about the inner beadlock donut, and was considering splitting the rim and removing it for balancing and then reinstalling marking where the tire and rim was, but I figure that in itself will cause more problems moving things around so I would just balance with them in place and hope they are negligible in how they affect the balancing.

After balancing I also added the centramatics and they seem to do well at nipping the final balancing of the tire. Perhaps they compensate for any movement of the donut?

In the end it still has a little bit of a shimmy at 65mph, but nothing like it used to! I do yearn for the days of 35" completely smooth ride tires at times, but the trade off is worth it now. Perhaps I need to drive to visit Nate Jones, lol. I never even heard of him or that he could take on balancing problems like this!
 
Die Spring Rate Advice

Part of the failures on the OEM build were too soft a rate on the die springs. I replaced them later, and these also seemed too soft. Anyone have advice on what rate to run on the springs that attach the new subframe to the truck frame?

I have a shear mount on the rear, a new UHMW lined retaining plate upfront, and then 4 springs on each side. Its a little hard to say how much swing weight I really have given that the rear is a shear mount, so the front is only controlling a portion of the motion. My total weight on the rig fully loaded is around 15k and the truck weighs close to 9.
 
Good morning everyone. From what I can tell by the California Fire Map, the fire is very close to Scott's home. By my calculation less than a mile. Sending positive vibes to S2DM in the hopes that the fire stays away!!

Ward and Annie
 

java

Expedition Leader
Good morning everyone. From what I can tell by the California Fire Map, the fire is very close to Scott's home. By my calculation less than a mile. Sending positive vibes to S2DM in the hopes that the fire stays away!!

Ward and Annie
Damn, good thoughts headed your way Scott! Hopefully the truck is packed and they are long gone.