Rear shock failure

[islandvagabonds]

Have a 2003 freightliner DP chassis. Both rear shocks were 7 years (70000 miles) when I noticed that both shocks had the piston rod become disconnected inside the shock rendering them useless. Anyone else have this happen? What causes this? They were Koni FSDs I had installed from new.

[CA_Traveler]

islandvagabonds wrote:

Piss poor design since sometimes the rear wheels are off the ground in order to level the coach.

NEVER NEVER EVER lift the rear wheels off the ground to level since they are also the emergency brake.

[John_Wayne]

I think you answered it. When you said you take the rear wheels off the ground at times to level it. You can get away with this if you have a spring mounted axle but with air bags something is going to give in your case the shocks. You could do like the off road racers and put in limiting straps that attach to the frame and axle to take the weight of the axle when the wheels are taken off the ground.

[j-d]

Wondered if dumping air once on site. Could be damaging the shocks, but that's not as forceful as topping.
A friend tells me he throws all his "warranties" out, since they turn out worthless.
You could call John at Henderson's Line Up and ask if they've had it happen maybe a way to snub the topping movement

[CA_Traveler]

islandvagabonds wrote:
The Konis really improve the ride of the coach so I guess in future I need to be more cautious of the road conditions to avoid topping out.

Doubtful that you will every be successful with this approach.

Contact FL and find out what the original shock should be and verify that it is adequate and that all suspension stops and limits are in place. Then find out what shock Koni or others is the correct one. Perhaps if you were sold the wrong ones you can get some compensation.

[islandvagabonds]

Thanks j-d. The shocks are the model that Koni specs for my chassis. Looking at the suspension in the rear after your comments, only the air bags and shocks limit the extention travel and it looks like the shocks would top out first resulting in the piston rods being pulled out of the shock body.
Piss poor design since sometimes the rear wheels are off the ground in order to level the coach. Re: the warranty, I am told these are broken so likely not covered. The cost of shipping to Koni and the hassle is just not worth it.
The Konis really improve the ride of the coach so I guess in future I need to be more cautious of the road conditions to avoid topping out.

[j-d]

I found this Koni Warranty:

"PASSENGER CAR, LIGHT TRUCK & MOTORHOME: KONI North America LLC warrants all new KONI shock absorbers (purchased after 5/1/1980) and suspension kits (purchased after 1/1/1995) to the original retail purchaser for use in the United States and Canada against defects in materials and workmanship, excluding mounting hardware and bushings, when used under normal operating conditions for as long as the original purchaser owns the vehicle registered for street use on which the KONI shock absorbers were originally installed. This warranty does not apply to, and KONI makes no warranty for, shock absorbers and suspension kits that have been:
Not purchased new by the current owner.
Modified or installed improperly.
Bent or broken indicating abuse.
Supplied as Original Equipment on any vehicle except 1984-1986 Ford Mustang SVO.
Used on any vehicle that has been modified for a use other than or in addition to its originally intended use.
Used for an application that is not specified in the KONI literature.
Used on any vehicle for racing, off-road, or other driving competition.
Exported for use outside the United States and Canada."

My conjecture is this: Shock Absorbers should control suspension motion but should NOT be expected to limit that motion. In other words the suspension should bottom out onto something in its design (like a snubber or bumper) leaving some free travel in the shocks. Likewise, something other than the shock should be the topping out limit, other than the shocks. Sp my premise is that based on how your coach's suspension is, the Shocks are either: 1. Too Short Topped or 2. Too Long Bottomed. If the rest of the suspension is right, I'd venture it has the wrong Shocks on it.

I don't understand "from new" but it seems if they were furnished with the Chassis, not under warranty. If you installed them after purchasing the coach, should be covered.