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Old 09-05-2020, 04:05 PM   #1
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Does your Spartan chassis bounce?

Does your K3 Spartan Motorcoach bounce severely or porpoise when hitting a dip in the road?My new London Aire does. It is severe and dangerous.
It bounces three times.
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Old 09-05-2020, 06:37 PM   #2
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Yep,

My 2020 Newmar DS4369 on a Spartan chassis bounced/porpoised at least 3 or 4 full times on every bridge transition and even when driving 3 mph over speed bumps in the parking lot. Without our seats belts on, we would have hit the ceiling a many times while on the highway. I hated it.

Spartan said the front shocks were the latest and greatest version approved by Newmar, and to check my tire pressures and ride height. I did, and they were all at spec. So, I followed the advice of others online and paid to have the Koni EVO shocks put on the front of our coach. HUGE difference! Still not as firm a ride as my Tiffin Allegro Bus, but way better. It has been well worth the price for my wife and I, and I would do it again in a heartbeat.
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Old 09-06-2020, 09:44 AM   #3
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Bouncing Motorcoach

Thank you very much for the tip on new Shocks
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Old 09-06-2020, 09:50 AM   #4
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Quote:
Originally Posted by jcarmic777 View Post
Does your K3 Spartan Motorcoach bounce severely or porpoise when hitting a dip in the road?My new London Aire does. It is severe and dangerous.
It bounces three times.
By far, the best money you will ever spend on you London Aire is to install Koni shock's all around it. I just installed them on my new to me Essex, night and day difference in ride........Smooth. I had installed them on my Mountain Aire and knew then when I made the move to upgrade, it was the first thing getting done. Could not be happier with the ride and handling!
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Old 09-06-2020, 04:20 PM   #5
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Thank you for the tip on shocks and your better ride.
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Old 09-19-2020, 04:20 PM   #6
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Spartan Shock Bouncing

I'm currently driving 2x 2017 London Aires + a 2019 King Aire all at the same time. One of the Londons is Freightliner SL600 frame w/SACHS shocks +Valid Leveling creamy, fully dampened ride characteristics no bounce ever. Both Spartans I have (equipped with Hadleys auto air ride) ride like I'm sitting "above the chassis", Freightliner feels like I'm "inside the chassis". I've set tire PSI, set Governor PSI, adjusted the ride height a tiny bit(helped) and swapped front IFS for KONIs. Still scratching my head. I found that completely dumping chassis air, then engaging STD ride again every time I cruise the highway seems to help. One recent journey, I hit the STD ride button while at highway speed and I kid you not, it suddenly made the coach ride like a coach but it didn't last very long. That all said, I'm having one of my London Aires checked this week for a "Hadley/Norgren" valve issue. It just seems like "too much" air is being pumped into the bags. Feels like I'm on air only and no shocks are installed. I haven't given up, Spartan knows I'm committed to helping them figure out a solution! Its definitely not a body issue, its something goofy about that Hadley System, its just putting too much air in the bags.
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Old 09-20-2020, 08:13 AM   #7
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Funny. I never had porpoising ... then I put Konis on, and started getting it occasionally on bridges with just the right spacing between road joints. Then when I put new tires on, it started happening less often and not so badly. I guess it just depends on your specific combination of suspension parts on your rig...
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Old 09-20-2020, 08:39 AM   #8
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Porpoising means the shocks are inadequate for the suspension, either because they are worn or the wrong specs for the vehicle. The damping rate of the shock has to be chosen for the rebound rate of the suspension. Engineers can make mistakes, either at Newmar or Spartan, when they guestimate how the loaded suspension is going to respond to various road conditions.


The fact that yours is porpoising is prima facie evidence that the factory spec isn't the right one for our coach configuration. Maybe yours is heavier at the front, or maybe even overloaded up front. There may be a different model of shock than the factory/Newmar recommended one, one that provides greater damping. Koni shocks tend to be designed for stronger damping than some other brands (more performance oriented than ride comfort) so the Koni that fits your chassis might be an improvement.


Have you been able to get Newmar to review the problem? It's a fairly serious issue, since rebounding means the steer tires are losing contact with the road. They ought to be concerned (you could even report it to the NHTSA for review).
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Old 09-20-2020, 05:58 PM   #9
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What Gary said X2! Shocks are for keeping the tires on the road, ideally there should be only one rebound. Shocks age-out, it's not only mileage and road conditions that wear out shocks.
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