Recommended clearance between cab over and truck cab

I have a sheet of 3/4" ply plus 1/2" rubber between my 2017 NL 9.6 and 2017 F-350, with roughly 1.25" space above the cab. We've taken some very big bumps on the road, with no indication of roof contact. I wouldn't use foam board either - in keeping with Keithmaryq's comment.

Northern Lite specifically recommends 1' of plywood with a rubber mat directly under the TC..at least that was the response I received for our 2016 NL dry bath and 2016 F350.

More importantly I understand from other research that Northern Lite does not recommend using any of of the foam board insulation...and this may also be true for Big Foot TCs. Something to do with the fiberglass construction and that much of the weight is concentrated at the bottom of the TC walls instead of equally spread out across the entire bottom...apparently too much for using the foam board especially considering the dynamics involved in taking turns etc. which obviously increases downward pressure at along the edges of the bottom.

Keith

Another issue is the width of the tailgate. When my Northstar igloo is loaded evenly, I have about 1/4 inch clearance. Makes loading a little difficult.

Kayteg1 wrote:

deltabravo wrote:
That's just strange that a camper manufacturer is building new models that don't allow for enough cab clearance for all makes of trucks.

.

- First...Go figure out how much it costs to redesign and build a new molds for a higher Cab that a truck manufacturer decided was required.
- Then as the manufacturer of the camper go figure out how many people that buy our product will be driving that type of truck.?

When the NL plant was rebuilt after the fire, they had to build everything from scratch. This included the patterns and fiberglas molds, this was I think 2014. I’m guessing.... and this is only a guess that in 2013/14 all cab heights were close to the same.
Now 5 years later... some of the truck manufacturer changed their cab height and didn’t contact NL and ask them how high the cab should be on the new cabs on their trucks to fit your camper...
Tit for tat... it was the truck manufacturer that didn’t chnage to match NL camper, not the other way around.
oh and the 2017 GMC cabs have about 5 to 6 inches clearance, give for that a bit..
Soup.

deltabravo wrote:
That's just strange that a camper manufacturer is building new models that don't allow for enough cab clearance for all makes of trucks.

This is all the matter of compromise.
You build TC with higher cabover floor - you will be banging your head against the ceiling when getting to bed.
Or God forbid you'd upgrade to thicker mattress and you will have to crawl all the way in.
If you raise camper roof - stability will suffer and basement campers on 4WD trucks are close to allowable heights already.

That's just strange that a camper manufacturer is building new models that don't allow for enough cab clearance for all makes of trucks.

The new fully boxed frames are certainly nice and would address the porpoising problems of the older trucks. I would suggest however that while your truck frame is certainly much stronger than older trucks, the porpoising can also be caused by resonance frequencies of the truck frame, suspension and the road. Even the newer stiffer frames can be effected given the right road conditions.

The resonance issue is different than standard rough road conditions by the way which a stiffer frame will certainly alleviate. I found this resonance issue while driving on some back farm roads where I managed to hit a section of road that had some very subtle dips that were about the length of the truck and repeated for about a 1/4" of a mile. The first few bumps I didn't think much about it but as the suspension and frame started resonating with the road the bouncing progressively grew until the truck and camper were porpoising like a bull in a rodeo.

To get back to your clearance question, I would think that 2" to 3" of clearance is about right if you have clearance lights.

Grit dog wrote:
I'd be thinking plywood over rubber (stall mats) if you don't want to use foam. Rubber is 2-3x heavier than plywood and more expensive.
I'd likely try dense foam first though.
All speculative on my part, haven't need to give a TC a lift kit yet.

I have plywood in my current F350. It is harder on the bed floor and paint. My cargo capacity in my new F 350 is about 6500#. YES, you read that correctly. So despite the cost and weight, I am leaning toward the rubber.

As an aside, I probably won't need my struts with the stiffer frame on the new Sooper Duties. The were a must have on my current truck. Especially when I drove to Alaska. D*mn frost heaves.

Rick

I'd be thinking plywood over rubber (stall mats) if you don't want to use foam. Rubber is 2-3x heavier than plywood and more expensive.
I'd likely try dense foam first though.
All speculative on my part, haven't need to give a TC a lift kit yet.

3/8" probably not enough, but your current F350 has fully boxed frame members and the result is 24 times stiffer than older C channel frames. The result is less porpoising which is the culprit in cabover touching roof and clearance lights. Old guidance of 2"-3" probably not necessary with new frame design. I would suggest aiming for 1" and CAREFULLY testing the result, adding more clearance as necessary.

I'm concerned as I await my new 2019 F 350 and have to match my 2007 Lance 1181. Lance told me to consider horse stall mats to lift the camper.

Rick