Jon Wehrenberg
08-30-2006, 07:42 PM
This comes under the "for what it is worth" department.
This week on a trip we heard a new noise in the rear while driving. It seemed like it was the shower door banging or something loose. After a while my wife found it coming from beneath the coach so I looked when I got it stopped.
Our coaches use a hard but flexible plastic bushing in the shocks and hydraulic cylinders (an option on 45 foot coaches with automatic tag axle unloading in the turns). As I found out on a car I have been maintaining the material is great right up until it starts to fail, and then in a very short period of time it fails catastrophically. Unlike the rubber bushings which tend to dry out and elongate the holes, but still remain, the plastic, which I think is polyurethane comes apart rapidly in chunks, and you have a shock (or radius rod bushing) banging metal to metal under the coach in your suspension.
I removed the shock with the failed bushing so the constant metal to metal banging would not destroy the mounting stud or the ring on our return home. I think the damage that could have occurred would be substantial because once the bushing failed and came apart in chunks, every slight variation in the road resulted in a loud banging noise.
The good news is that Prevost stocks these bushings in large quantities and they are only a few dollars, so if caught early their replacement is easy and cheap. If allowed to bang around a while the cost to repair the damage could even involve welding a new stud in place or replacing an entire shock absorber or hydraulic cylinder.
This week on a trip we heard a new noise in the rear while driving. It seemed like it was the shower door banging or something loose. After a while my wife found it coming from beneath the coach so I looked when I got it stopped.
Our coaches use a hard but flexible plastic bushing in the shocks and hydraulic cylinders (an option on 45 foot coaches with automatic tag axle unloading in the turns). As I found out on a car I have been maintaining the material is great right up until it starts to fail, and then in a very short period of time it fails catastrophically. Unlike the rubber bushings which tend to dry out and elongate the holes, but still remain, the plastic, which I think is polyurethane comes apart rapidly in chunks, and you have a shock (or radius rod bushing) banging metal to metal under the coach in your suspension.
I removed the shock with the failed bushing so the constant metal to metal banging would not destroy the mounting stud or the ring on our return home. I think the damage that could have occurred would be substantial because once the bushing failed and came apart in chunks, every slight variation in the road resulted in a loud banging noise.
The good news is that Prevost stocks these bushings in large quantities and they are only a few dollars, so if caught early their replacement is easy and cheap. If allowed to bang around a while the cost to repair the damage could even involve welding a new stud in place or replacing an entire shock absorber or hydraulic cylinder.