Those bridge joints are awful. We have a 2012 3170. We have added Bilstein shocks, the heavy duty models designated for the E450. They helped, but the bridge joints continue to pound when they are hit. I have looked all over the Internet for a solution to the rough ride. Kelderman makes an air suspension which does away with the rear shackles on the leaf spring packs and substitutes arms supported by air bags for the shackles. But it appears to me that the package won't fit because of the lockers. Also, the shackle hangers are permanently removed. There are also a couple of rubber suspensions which remove the spring packs and their shackle hangers all together. In all these instances I don't want to remove the hangers for fear I may want to go back to the original spring configuration. What we ended up doing was mounting Sulastic rubber shackles in place of the stock shackles. www.sulastic.com
. The original Ford shackles are one piece of metal with no give. A shock to the springs is transmitted directly to the frame. The Sulastic shackle is made up of two metal pieces joined in a V with rubber holding the angle of the V against the pull or push of the spring. The rubber provides a softer "hit" when a bump pushes the axle against the spring which pushes the spring against the frame. The website shows how it works. These shackles have softened the ordinary small irregularities of the road. But those big bangers that throw you up off the back bed are still there. And I don't think any suspension modification short of a complete replacement of the rear suspension with a total air suspension will stop those big bangers. Even then, I think the smaller tire size of a C will make a big bump worse than if the tires had a larger diameter. Stopping all of the rattles that you can helps. All that being said, we still would not trade our 3170. The layout is perfect for us and the cost and ease of maintenance and parts replacement is a big plus. The simplicity of operation of everything from heating to toilet appeals to me. I have friends with diesel pushers and they have had problems with everything from lighted door handrails shocking them to water and interior heating systems needing repair to air suspensions letting the coach down on one side. The limited life of the rubber supported shackles bother me, but I am keeping the original shackles on board. And no, although I enjoy working on the coach, I did not install the Sulastic shackles or the Bilsteins myself. And I won't get under the back half of the coach without solid frame supports just in case the rubber fails.
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