Porpoising with camper

[rskeans]

Originally Posted by rskeans

<snip>
The problem is the Firestone upper bracket hitting the Firestone lower bracket with a heavy load and a bump in the road, driveways, speed bumps, etc. <snip>It appears to be a Firestone design problem. The next time I load the camper on the truck I'll take it to the shop (located down the mountain) and let them comment on my observation. In fact, maybe I'll just do it today. <snip>

I loaded the camper on the truck, put 64 gal of fresh water in the tank and drove it to the shop. With 90 lbs of air in the Firestone air bags there was only 1" clearance between the Firestone brackets! That's all I had for bumps.

The shop is going to remove the Firestone air bags and install overload springs on Tuesday 9/16. This will give me the factory up/down wheel motion. The Firestone system removes 2" of wheel travel in this installation. The shop will credit me the costs of the air bag system and figure out the cost of the springs as if we just did that in the first place. Of course I still don't know if the Porpoising will be solved. The shop believes that will be significantly improved.

The next lesson is that I should have just purchased an F450 in the first place. I just didn't think I needed such a heavy truck. -wrong-

[walleye1]

My 08 F350srw 4x4 has the air lift bags on the rear, the first time i put the camper on the new truck the bags were close to bottoming out!! i was not happy!! looked at the instructions on the web and found the dealer put a 1" spacer bracket in that was not for my aplication but comes with it, i removed the spacer and now have much more movement room! i dont run over 40lbs in either bag to level it with a lance 861...maybe check into the air lift bags, kit for the 08 350 was airlift 57212

[rskeans]

Many thanks Walleye for your experience. However, my camper is significantly heavier than most campers with a double slide, 4' rear overhang, 64 gal fresh water, 3.9KW generator, 14 gal propane, 62 gal fuel tank, etc. I plan to take it to Alaska next year and I believe that I will need all of the road axle clearance available. I just didn't realize that the airbag system would take away any clearance. I can't live with that. So heavier springs will be the solution. After the new springs and some new miles on the ride, I'll report back. Hopefully I'll be all smiles.

Regards,

[dmd]

Originally Posted by rskeans

Many thanks Walleye for your experience. However, my camper is significantly heavier than most campers with a double slide, 4' rear overhang, 64 gal fresh water, 3.9KW generator, 14 gal propane, 62 gal fuel tank, etc. I plan to take it to Alaska next year and I believe that I will need all of the road axle clearance available. I just didn't realize that the airbag system would take away any clearance. I can't live with that. So heavier springs will be the solution. After the new springs and some new miles on the ride, I'll report back. Hopefully I'll be all smiles.

Regards,

When I drove the AK highway to Fairbanks (I drove all the way, didnt take
the ferry) 12 years ago, I could have been driving a Corvette and had
plenty of clearance. Just watch out for the marked frost heaves and maybe some construction. Could be different now though, but I would guess that
a mini-van could do the trip without a problem.

[rskeans]

Originally Posted by dmd

When I drove the AK highway to Fairbanks (I drove all the way, didnt take
the ferry) 12 years ago, I could have been driving a Corvette and had
plenty of clearance. Just watch out for the marked frost heaves and maybe some construction. Could be different now though, but I would guess that
a mini-van could do the trip without a problem.

Well that's good to hear. I hear others talking about doom and gloom and swear they will never take an RV there again. My position is that is what I bought it for. It'll be nice to return without any battle scars.

[Clattertruck]

rskeans,
We went to AK from Denver in May, June, and part of July this year. The trip was 8500 miles. The roads in BC are fine. The Alaska Highway is for the most part very good (better than a lot of Colorado roads). The worst part this year was from Destruction Bay to the AK boarder. The frost heaves were terrible. We would pray for construction areas because they are much smoother even if a bit muddy. I hit a couple of frost heaves that were not marked and that I did not see in time. I thought we had lost the camper, but the Tork Lifts survived and every thing was fine.

A Ford Explorer was going too fast, and it rolled. It must have gotten air born and gotten a little sideways. The driver was not badly hurt.

Yukon Territory is on a 15 year construction project, but they are not doing much good patching.

I had airbags on two trucks with mixed results. I would go with additional springs in the stack by a truck spring shop.

Another thought on the bucking, the center of gravity of the camper may be too far back. It should be at least two or three inches in front of the drive axle. The steer axle should pick up 300 to500 lbs over the empty weight. Mine is 500 lbs heavier up front than the unloaded weight.

[rskeans]

Originally Posted by Clattertruck

rskeans,
I had airbags on two trucks with mixed results. I would go with additional springs in the stack by a truck spring shop.

Another thought on the bucking, the center of gravity of the camper may be too far back. It should be at least two or three inches in front of the drive axle. The steer axle should pick up 300 to500 lbs over the empty weight. Mine is 500 lbs heavier up front than the unloaded weight.

Thanks for the AK road info.

Additional springs is exactly what I did yesterday by a truck spring shop. On each side they added 1 spring on the lower set and 3 springs on the upper set. The upper set is the overload spring set. Limiting the lower set to just one spring won't have a negative effect on the unloaded ride. Plus, they put in an additional 1" spacer to boost the upper set higher so that they enage sooner. Then they removed the air bags from the outside of the frame where the air bag bracket was interferring and replaced them with air bags mouted on the inner frame. I drove the truck on the I-210 and up on the I-215 and it appeared to be solid. Handling was excellent. I then drove it up the mountain where I live (CA Hwy 330) and it handled great around the curves with the camper and 64 gal of fresh water in the tank. BTW, the fresh water tank is up front and should increase the weight on the front wheels. My first impression is that the problem is fixed. The air bags were a bad choice from the beginning. Should have went the 'spring' route. I doubt that I'll need to inflate the air bags now. Maybe just use them for leveling at night. The truck is now totally level on the road with no air in the bags.

There's nothing I can do about moving the center of gravity. One of these days I'll take it down to the truck scales by the I-10 to get some real numbers.