How Much Bounce From Your Cabover?

[Sheriffdoug]

Hello,

How much bounce, movement up & down from your Cabover, 1 inch- 2inch?, as you drive along?

Does balance, centre of gravity have an effect?

Weight in Cabover effect on movement?

How tight do you secure your Fast Gun Tie Downs?

Does a rubber bed mat affect Truck Camper movement?

Maybe it's because Eagle Cap 1160 cabover is so much bigger that I notice it.

Super Springs keeps chassis very igid, no bounce, and I have Dually rear wheels at 80lbs, as with the front.

Just wondering.

Please offer your suggestions.

[tommykelly]

Someone on this site suggested a rubber mat for horses in a stall.
not being a horse person myself I went to Tractor supply

I bought 3 pieces I think... cut to size and ..for me it is great..

plywood first horse mat on top then camper...I do have the struts but the camper sits more firmly and no cabover bouncing..

the mats are heavy

[bcbigfoot]

I found that much of my camper bounce was from a beer canning effect of the bottom of the truck box, once I placed a sheet of 3/4" plywood between the truck box and camper bottom bouncing was reduced.

I also placed/slid wood slates between the plywood and the convolution's of the truck box floor, so that the entire surface of the truck box is supporting the weight of the camper, not just the high sections of the truck box ridges that are raised above the truck box's cross members.

My Bigfoot camper floor bottom was also not level, it had a 1/8" plastic inspection plate cover that caused the camper to sort of rock on the newly stiffened truck box bed. I could actually feel the camper move or shift when cornering. So I leveled the bottom of the camper by adhering 1/8" rubber sheeting to bottom of the camper wherever the inspection cover isn't.

The camper now feels like it is much more a part of the truck and not a separate item.

I think if you take a close look at how lightly the truck box is built between the truck frame and the bed surface it could become obvious to you, where the bounce is perhaps originating from and how the heavier the camper, more the issue.

[Sheriffdoug]

Thank You, All, interesting comments & suggestions. Body & Bed torsional twist/flex certainly is an unknown. And becomes more prevalent with heavier campers. Doug

[silversand]

The short bed Dodge has little frame twist or deflection making the movement of the strut piston very small.

Jefe has it dead on. Frame flex (specifically: deflection and torsional twisting) is/are probably the main cause/causes of a camper cab-over dynamically approaching the truck cab. The longer the truck bed and the longer the cab-over = the greater potential for this to happen.

To a lesser extent (assuming your rear tie-downs are adjusted correctly): the material between your steel truck bed deck and the underside of the camper will contribute (unless you sit your camper on a queen-size foam mattress, or your cab-over is waggin' like a dog's tail :B )

Contemplating more: each truck manufacturer's *frame* would offer differing deflection and torsional flexing characteristics, and this would vary widely with payload COG...

Lots of unknowns; lots of experimenting needs to be done...hmmmm?

S-

[Sheriffdoug]

This morning, I went online and checked out Torklift Fast Gun Install Video.

After viewing, then going outside and checking each one, I believe I had them too soft, not hard enough.

Looked at the viewing eye for half across for bar and that each Fastguns when closed the rubber O-Ring at top of threaded shaft is 1/4 inch down in locked position.

And listening to video, they says each Fastgun has 300lbs force when secured, was clearly not the case,

Camper now sits firm on Truck bed, lot less movement.

I don't know why but, I had decided that they were too tight, so I loosened them., worried that they may damage TC mounts if too tight.

But if too loose, damage will occur, through TC, flopping around.

Being a much bigger TC, more weight, it is critical, load is secured properly.

They have to be firm.

So clearly I had them too soft.

[jefe_4x4]

I see less than one inch travel of my Lance struts, which are on a diagonal to the movement of the camper v. truck. I learned the hard way to disconnect them on bad roads. The short bed Dodge has little frame twist or deflection making the movement of the strut piston very small.
jefe

[JumboJet]

The Lance Struts allow almost 8" of play (4" up and 4" down). My wife's cousin mounted his struts incorrectly and tore the mount loose from the camper while on a very undulating road.

I never saw more than 2" of actual movement with my struts and the 2008 Ram 3500.

[rooney77]

Think of something like this. Long piece is bolted to the camper. The bottom piece may not be needed. The green pieces would be some sort of shock absorbing material, like a pool noodle. The spring points would sit roughly behind the clearance lights and as close to the drip rails as possible. Sorry for the bad pics but maybe it'll get the point across and I can get feedback. If it works it would help the sheriff and myself.

[rooney77]

mkirsch wrote:

rooney77 wrote:
I'm trying to design something that would absorb some movement and sit between the cabover and the cab yet still allow my sunroof to open..

Don't waste your time.

Your cab doesn't have the structural rigidity to do much supporting. The sheet metal up there isn't much thicker than a beer can.

If you put something between the cabover and the cab roof, all you will end up with is severe body damage on the truck.

That's not completely accurate. The corners are strong as are the edges. It's the expanse across the middle that's weak. That's what the ridges are for. What I had thought about doing was having some c-channel that spanned all the way across the roof just behind the clearance lights and some sort of spongey material between that and a similar piece of c channel running across the underside of the cabover.

I'm drawing it up in Creo right now. Depending on the material it's a sound idea. But I've also had a member PM about a set of used struts that I'm waiting to get approval from the wife on. 😄

[mkirsch]

rooney77 wrote:
I'm trying to design something that would absorb some movement and sit between the cabover and the cab yet still allow my sunroof to open..

Don't waste your time.

Your cab doesn't have the structural rigidity to do much supporting. The sheet metal up there isn't much thicker than a beer can.

If you put something between the cabover and the cab roof, all you will end up with is severe body damage on the truck.

[JumboJet]

I just returned from a hunting trip and was very pleased with the Lance 1050S while traveling down a very rough forest service road.

My setup - 2013 RAM 3500 DRW with tow package - 1/2 set Stableloads installed on the forward end of the overload springs - Fastguns - front two tighter than rear two. That is all I have done.

Lance 1050S weighed 4,400 lbs. with guns, hunting gear, etc.

I had cabover struts on my 2008 but with the current setup, I see no need for them.

[narcodog]

I also don't experience much bounce except on dirt roads but that is expected. IMO I would lower the pressure in your front tires. Say to about 65 or 70. I don't have dually but I also think your tire pressure in the rear is a little high, Someone else might address that issue.

[Sheriffdoug]

I usually put piece of 2 x 4 inch, at front of truck bed, between TC.

Will put it back over the weekend, to see if makes a difference and watch Torklift Fast Gun Video, to see if I am doing it right.

[NRALIFR]

My answers in RED

Sheriffdoug wrote:
Hello,

How much bounce, movement up & down from your Cabover, 1 inch- 2inch?, as you drive along?

An inch or so I believe.

Does balance, centre of gravity have an effect?

Probably, but we're usually loaded the same way on each trip. Take aobut the same amount of stuff, load it the same way, usually have the fresh water tank full.

Weight in Cabover effect on movement?

Again, probaby but we usually have the same stuff in the cabinets there.

How tight do you secure your Fast Gun Tie Downs?

Adjust the threaded rod so that about half the pin hole is covered just before compressing the spring.

Does a rubber bed mat affect Truck Camper movement?

Bounce? No, I wouldn't think so. It does help keep the camper from sliding around on the slick bed surface though.

Maybe it's because Eagle Cap 1160 cabover is so much bigger that I notice it.

Super Springs keeps chassis very igid, no bounce, and I have Dually rear wheels at 80lbs, as with the front.

Just wondering.

Please offer your suggestions.

Personally, I think the pickup beds used on all the light duty trucks are pretty flexible, and account for the majority of the movement you're seeing.

:):)