When to replace shocks? 2013 Sunova 35G

[Sunova121]

Hi. We bought a 2013 Sunova 35G a year ago that had only 8K miles on it. We are now driving 6k miles per year and before we hit the road, I installed sumo springs, Save T Plus stabilizer and a rear track bar. Before those improvements, it was a little scary when a truck passed us on the highway.
My shocks are not leaking but when do you know when its time to replace shocks? Are they replaced when old or is it a factor of miles?
Ive read a lot about Koni shocks and now they have two different models for the F-53, 22,000 chassis, the Koni FSD or the Koni FSD EVO. There is about $50 a piece difference in price between the two models. Which ones to get?
We will be driving across county again this summer so want to get all PM completed before our journey.
Thanks!

 

[creativepart]

In general, when shocks are bad you will notice more "porpoising" (bouncing) on bumps. You can use your brakes to bring the RV to a sudden stop and see if the front end makes one or more than one bounces as you stop.

I installed Koni FSD shocks at around 24,000 mi replacing the OEM Bilsteins. People had made out like they would solve every problem known to man. But I felt they helped tame small movements and not much more. I asked my wife to rate the "improvement" and she said "Less than 5%?"

My Adventurer has the 26k chassis and I do think the shocks have more effect on lighter RVs.

Also, the FSD shocks were "the" motorhome shock a few years back but I think there is a newer model Koni that is suppose to be the latest and greatest now.

 

[RayIN]

Most shocks are gas shocks, when the gas leaks out it's unseen. As creativepart said, make a low speed sudden stop and observe how the front end dips. You can also make low speed swerves and observe coach "roll".
This is the heavy duty version of bouncing on a car bumper to observe how the shocks control bounce.

 

[Americanrascal-WO]

I'm at about 86000 miles on our 2016 Adventurer (26000 kb chassis). I've read that they generally should be changed between 50,000 and 100,000 without a firm set mileage. I felt it was time for mine to be changed. The rig came from the factory with Bilstiens and I decided to go back with the same when changing them out. I've finished doing the fronts and did new sway bar bushings and sway bar links as part of the project. I still have to do the rears and all seems to ride well. I've done the work myself but am using an electric impact wrench to get the shocks on and off.

 

[Sunova121]

I'm at about 86000 miles on our 2016 Adventurer (26000 kb chassis). I've read that they generally should be changed between 50,000 and 100,000 without a firm set mileage. I felt it was time for mine to be changed. The rig came from the factory with Bilstiens and I decided to go back with the same when changing them out. I've finished doing the fronts and did new sway bar bushings and sway bar links as part of the project. I still have to do the rears and all seems to ride well. I've done the work myself but am using an electric impact wrench to get the shocks on and off.

Yes. I have Bilstiens as well. One of the biggest concerns if I move forward is if I can break the nuts with a cordless impact gun or my breaker bar. Sounds like you are getting the job done!

 

[Americanrascal-WO]

One of the biggest concerns if I move forward is if I can break the nuts with a cordless impact gun or my breaker bar.

My cordless did ok on the fronts shocks (550 ft lbs torque). My air impact has far less power and would not even budge them. However , I started work on the rears and I'm going to have to soak them in kroil and probably heat them as they would not budge. They are also a bit harder to access than the fronts on my chassis. May have to use a breaker bar??? But I think the cordless impact wrench has more power than me on a breaker bar

 

[Mongobird]

When you work on those hard bolts, try reversing the impact periodically. This helps load the metal oxide pieces differently, and may create new stress points to fracture under impact.

Sometimes brute torque doesn't work as well as changing loads, which reversing the impact will help you accomplish.

 

[Jim_HiTek]

As mentioned 'porpoising' is a strong indicator of bad shocks. Konis are raved about by RV'ers but I've not read anything comparing their two models as yet. I installed Bilsteins replacing the OEM Bilsteins and they immediately made an improvement, though slight. Immediately stopped the porpoising problem I was having.

As far as being tossed around by passing semis or buses or other RVs going either direction, with any kind of quartering winds, look into the low cost solution of adding Airtabs, or Vspoilers, or Ecotabs. Available at eBay. They completely stopped those problems with my 26K Freightliner chassis Class A Diesel pusher. For under $200. Saved thousands against all the recommendations for chassis work I'd read on the various forums. I did a product eval of them on my ad free blog: V-spoilers.