Last weekend I drove the RV 12 miles out and 12 miles back with 80psi in the front tires, and 75psi in the 4 rear tires. The result was not good. Not just a rougher ride, but also a little "tug" on the steering wheel over irregular road surfaces. It reminded me a bit of what I experienced before the suspension upgrades were done.
It was an experiment that demonstrated you could go too far with extra psi. I want to increase tire pressure for improved fuel economy. I hope to find a compromise......5 psi at a time.
Bought new in June 2007, Phoenix Cruiser-2350
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Dingy towing a red Toyota MR2 Spyder
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If you do decide to replace your shocks with Koni or Bilstein shocks, please do post your results along with which shocks you chose.
I am veryinterested as I have the identical issue - a rough ride with a rig that is about 2,000 - 2,500 pounds under the GVWR.
It's a pretty rough ride in the rear. The cab is not too bad (the ride is okay up front, though it is noisier than I'd like), but I had my wife drive a little and went back into the rear and got bounced around a great deal.
Folks it is like a PU that you put a couple bags of sand in for a better ride because it was engineered expecting to be loaded nearer to capacity. Just filling the fresh water tank helps our ride.
Gale Hawkins wrote: Folks it is like a PU that you put a couple bags of sand in for a better ride because it was engineered expecting to be loaded nearer to capacity. Just filling the fresh water tank helps our ride.
Sure, but when you ride around (even with full water and fuel) 2,000-2,500 lbs under max weight, it tends to be a rough ride.
I wonder if new shocks will cure that? Ideally, they'd be shocks that can be tuned for weight.
I have 24 foot Class C on the E450 chassis and have a somewhat rough ride in the rear too - front ride is OK. Like yours, my door sticker says 80 psi rear, 65 psi front. However my sticker also says 14,050 lbs. GVWR.
I think two things might help with the sharp jolts in the rear that don't cost a lot to try:
1) Since your small rig does not reach anywhere near 14,050 lbs. GVWR, you can use LESS inflation pressure than the door sticker says. I use 5 psi less everywhere, this definitely helps with the sharp jolts in the rear. Check your tire manufacturer's load carrying specs per tire. Perhaps you can even go 10 psi less in each rear tire - this should help quite a bit. I'd stay at no more than 5 psi less in each front tire.
2) I'm sure that Ford's stock shocks are A) not the best and, B) are sized to handle up to 14,050 lbs. GVWR. Actually, softer and better shocks in the rear should definitely help. I haven't been able to locate softer and better shocks that I'm sure of yet. (Perhaps someone can help identify one.) Most of the BETTER shocks emphasize better heavy load handling and/or reduced side sway. These are NOT our problems ... we don't need heavier load handling obviously and the heavy duty E450 sway bars in the rear already address side sway very well on our small rigs. I WISH Rancho 9000's were available for the E450 so I could play with the five stiffness settings to determine a good one for our rigs (like I do with the 9000's on my PU), but so far I don't believe they have ones for the E450.
The ULTIMATE fix is expensive - a full blown air suspension system like the E450 shuttle buses have on them - probably around $3000 on up ... ouch!!
* This post was
edited 06/19/08 05:52pm by pnichols *
If you think a softer but still premium grade shock absorber would give you a better ride, you might consider the Monroe Gas Magnum type. I have no personal experience with them, but three years ago when I began inquiring about shocks here, several people reported good experience with them. I went with Bilsteins and have been happy with them. Konis hadn't really appeared on the RV radar then. Konis are adjustable, so perhaps they can be "tailored" to your needs.
cptnhook wrote: ANY ideas or expertise...would be sincerely appreciated.
My "Pre-Owned" 1999 22' Four Winds Class C (Chevy 1 ton chassis) acted EXACTLY the same way. The BAM-BAM-BAM going over the expansion joints on the Interstate would cause the silverware drawer to open and the knives, forks, & spoons to end up on the floor. Pot holes would TOATALLY lift the back end off the ground. We actually broke glasses in the overhead cabinets.
I tried changing the tires from "LT" (Light Truck) to a more flexible wall "P" (Passenger) tires and adjusted the tire pressure all over the place.
Being a "car guy", I crawled under and looked at the rear springs. The top leaf had a loop in each end that attached to the frame bracket. The spring stack consisted of 13 layers of 1/2" spring steel. Each leaf of the stack was 1" shorter on each end than the leaf above it.
The problem was that the top leaf was pertectly flat, with NO flex arch, and each leaf below was FLAT against the leaf above. The bottom leaf was bolted to the axle tube bracket. The spring stack was a NO-ARCH, metal-to-metal, stack of 1/2" steel plates.
There was absolutely NO ability for the spring to abosrb the vertical movement as the axle housing was driven UP over bumps (etc.) There was also absolutely NO shock absorber movement as the vehicle chassis was actually sitting on the axle housing (with a stack of 13 metal plates between them).
Rather than spend $1,000 to have the rear springs removed and re-arched, which might not have solved the problem, I elected to buy a pair of Air-Lift air bags from Camping World for $236. At 100 psi, the bags add 5,000 lbs of help to the springs.
I installed them myself in an hour with only a socket wrench. I didn't even need a jack. I ran fill tubes into the storage compartment under the couch.
Now as I fill the bag with 50 psi, the chassis lifts up 1 1/2".
I now have 1 1/2" of spring/shock absorber travel and my Class C is an ENTIRELY different vehicle. It rides almost as well as my 4WD Suburban.
Of course, I don't know what your ride problem is, but I'd check your rear spring travel and for $250, I'd look at Air-Lift air bags before I did ANYTHING else.
Good Luck
Tim
* This post was
edited 06/19/08 06:29pm by Healeyman *
I second the use of the Monroe Gas Magnum RV shocks. We replaced our OEM shocks at only 4,000 miles and the change was like night and day! The coach was a 31' 05 Minnie and it rode like a limo afterwards. We were very pleased with the Monroe's and they are a bit easier on the wallet.
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