pivoting frames and mounting campers

[IdaSHO]

I understand where you are going now.

But the assumption is false as the OEM bed is no-where near as stiff as the cab.
The OEM bed is hard mounted, and flexes along with the chassis.

The cab, while being considerably more rigid, is soft mounted, and has a good deal of give.
The cab mount rubbers provide quite a bit of isolation, for noise, vibration, and chassis flex.

 

[Coachgeo]

I understand where you are going now.

But the assumption is false as the OEM bed is no-where near as stiff as the cab.
The OEM bed is hard mounted, and flexes along with the chassis.

The cab, while being considerably more rigid, is soft mounted, and has a good deal of give.
The cab mount rubbers provide quite a bit of isolation, for noise, vibration, and chassis flex.

and a typical chassis is designed to have less flex in cab portion of the vehicle. In larger rigs though.... the cab is actually a captured spring mount system. sold mount in front.... with springs (air ride cab shocks or shock absorbers) at back of cab.

 

[Chorky]

and a typical chassis is designed to have less flex in cab portion of the vehicle. In larger rigs though.... the cab is actually a captured spring mount system. sold mount in front.... with springs (air ride cab shocks or shock absorbers) at back of cab.

Really? how so? Looking at my truck's frame there is only 2 structural differences I can see. The pan-hard bracket (which is mostly for supporting the extra engine weight I would assume, and a very small section (maybe 2' worth) of boxed frame up front. Everything from the firewall back to the rear bumper is the exact same. I guess I'm not seeing how the same design could be meant for being flexible under the bed in the rear, but for being stiff under the cab.. Mentioning air ride systems I would assume your talking about a big truck, not a pickup, so maybe were talking about different trucks/designs?

The body mounts Idasho mounted sound more on par with a pickup - but I wouldn't have thought they would have that much give - considering how much noise my cab makes on uneven terrain.

 

[IdaSHO]

Your OBS PSD doesnt have a boxed frame under the cab.

Not sure when the change happened, but my 2011 does.
It creates a much more rigid platform for the cab to ride on.

From cab-forward it is a combination of boxed and open C
Cab-back, is all open C

Like so...

And 2017 and newer receive the new, fully boxed frame.

Whereas, the older nearly 100% open c-channel looks like so....

 

[Coachgeo]

Really? how so? Looking at my truck's frame there is only 2 structural differences I can see. The pan-hard bracket (which is mostly for supporting the extra engine weight I would assume, and a very small section (maybe 2' worth) of boxed frame up front. Everything from the firewall back to the rear bumper is the exact same. I guess I'm not seeing how the same design could be meant for being flexible under the bed in the rear, but for being stiff under the cab.. Mentioning air ride systems I would assume your talking about a big truck, not a pickup, so maybe were talking about different trucks/designs? .....

the engine will act somewhat as a structural member in the front of any vehicle and am sure the engineers take that into account.

the mention of air ride mostly as a side note...... their are pickups with cush air ride cabs though.

 

[Chorky]

Your OBS PSD doesnt have a boxed frame under the cab.

Not sure when the change happened, but my 2011 does.
It creates a much more rigid platform for the cab to ride on.

From cab-forward it is a combination of boxed and open C
Cab-back, is all open C

Like so...

Ok thank you for the info! this clears up things a ton. I didn't realize your year had so much of a boxed frame. It's interesting its' only half boxed, and half open C.

Looking forward to seeing your progress!

 

[Mlemaster]

Project Ole' Blue, 1972 Ford F250 Crew Cab
Started a build thread recently here. Looking for suggestions on the 3-point mounting system. Specifically, should my 3rd point be at the cab or at the rear? Rigid box will be 84"s on 75"s of frame. Thank you!

 

[Mlemaster]

Project Ole' Blue, 1972 Ford F250 Crew Cab
Started a build thread recently here. Looking for suggestions on the 3-point mounting system. Specifically, should my 3rd point be at the cab or at the rear? Rigid box will be 84"s on 75"s of frame. Thank you!

Edit... Likely will do similar set-up to Sitec's sketch on Post #465. Just deleting one center pivot since my bed will be quite short. If I am missing anything let me know.
Thank you all!

 

[Sitec]

With your shorter box one rear pivot will be enough. I've finally started stripping my living body out ready for the mods and have been thinking about the mounting quite a bit of late. At the rear where the single central pivot is going to be on my build (#465), I now also plan to add some sort of additional support either side of the chassis either in the form of 2 stumpy shock absorbers with springs (like the 300mm long units found on the back of euro truck cabs) to dampen body roll either side of the central pivots, or two short 300mm rams that are piped/linked together with only a tap between them.... When on the road, the tap can be closed, locking ram travel and giving two fixed outer rear supports (held in place by the center pivot) to stop body roll, but when off road, the tap can be opened, allowing the rams to expand and contract between the body and chassis allowing the body to sit and the chassis to twist underneath it. The reason for this is because I have 2 of my 4 points at the front near the cab to minimise movement between cab and body at the crawl/walk thru point, and I want to minimise body roll on the 3rd and 4th central points.

 

[Ex Animo]

Question about the the pivot point on a three point mount. Do folks use a bushing for the "Jesus bolt" that holds up the entire camper or just run a bolt through the mounting points (metal to metal)?

 

[IdaSHO]

Some use bearings, and Im sure some probably go metal on metal.

I prefer to use bushings, as it provides movement with much less chance of binding.

I run these greasable 4-piece bushings
3" wide, 2" OD, designed for use with 5/8 bolts.

Barrels mocked up... note zerk location on the bottom

 

[IdaSHO]

BTW, they are typically referred to as 4-link bushings, normally being used for 4-link suspension builds.

Can be sourced here.... (one of many options)
https://thorbros.com/category/catalog/4-link-parts/4-link-bushings

 

[Amertek Rob]

NO metal on metal in my opinion , why would you ever go metal on metal ? It gives no room for error or any twist uncounted for ? There are many affordable options depending on the weight of your box, A light box could use urethane leaf spring bushings and a heavy box build could use the urethane equalizer bushings I use out of a Semi Trailer, Cheap and effective !

 

[Ex Animo]

Some use bearings, and Im sure some probably go metal on metal.

I prefer to use bushings, as it provides movement with much less chance of binding.

I run these greasable 4-piece bushings
3" wide, 2" OD, designed for use with 5/8 bolts.

Barrels mocked up... note zerk location on the bottom

Thanks for the input and the photos, that really clears it up for me. I figured most set-ups used bushings like that but it helps to see how they are installed!

NO metal on metal in my opinion , why would you ever go metal on metal ? It gives no room for error or any twist uncounted for ? There are many affordable options depending on the weight of your box, A light box could use urethane leaf spring bushings and a heavy box build could use the urethane equalizer bushings I use out of a Semi Trailer, Cheap and effective !

My eventual build will be small and light so I figure leaf spring bushings would be the way to go, thanks!

 

[Ex Animo]

Anyone used bushings from Ruff Stuff? They seem legit. https://www.ruffstuffspecialties.com/catalog/BUSHDOM.html