Class A BOUNCES VERY BIG over dips and humps

[botiemad]

[QUOTE=HECthe2;4343820]After 2 years with a 40' 2008 DSDP, it's getting pretty old that the dips and humps in all highways cause a bounce that feels like the MH is about to launch into the sky. I kinda feel that this is somewhat normal, but want to verify that it really is. PLEASE don't make a knee-jerk reply to "buy new shocks!" UNLESS you have PERSONALLY experienced that it was THE BIG problem-solver. Our circumstances that MAY be exaggerating the problem are (1) 5000# dinghy, and (3) motorcycle carrier added to rear (with no big bike on board...yet). That was the situation with my older Beaver. Considerable porpoising on dips in roadways. It was indeed the shocks at fault. At an FMCA rally, I bought a pair of Road King shocks from a vendor, and he installed them. The drive back home was pure heaven. I bought two more (for the rear) at that point and installed them myself. About 10,000 miles later, while servicing the coach, I noticed oil on the front shock. Yup! The seals were shot. After 6 weeks of delay and being promised they would rebuild them, the owner of Road King called me and said I would have to pay for new pistons and they decided not to warranty them. I told him to ***** them, and bought 4 new Koni shocks for less than what the rebuild cost would be. Nothing went wrong with those shocks in the next 40K miles.

[CountryB]

Originally Posted by SmokyPond

FSD's for the rear and EVO's for the front based on Koni's recommendations...

the shop had installed the Koni EVO front shocks in the rear and the FSD rear shocks up front! I had the shop swap them around the next day... and what a beautiful ride! The best it's ever been!

Matt, what is the different between the FSD and EVO. Why does Koni recommend the EVO on the front?

I thought we were supposed to use the same shocks front and rear.

[pobstlmo]

I would start at the beginning to find the problem.

Empty coach and drive it on a section of BAD ROAD, then put your stuff back in, distributing the (your stuff) load in the coach has an effect, you may have forgotten about those gold bars you drag around for emergency, and all that extra crap you never use, just like a house.

Add the motorcycle carrier, this is a fulcrum lever so it will have an effect on the coach.

Add the toad only and see what effect it has.

You may find that without the toad and motorcycle carrier it rides fine which means the suspension can handle that load, but as you add more, you overload the existing suspension.

Best of luck.

[TUCSONRAIL]

The shocks just don't have enough compression and rebound dampening. Some brand new DPs on a Spartan are this way. Try Koni adjustables on the front. This worked for me.

[ItalGerBrit]

I am going to chime in late in this discussion that has boiled down to shocks, weight distribution, etc. and all points are good ones but the bouncing and wallowing like a fat whale is the nature of the Class A beast I think. Some are just worse than others.

I drove a 40 foot Beaver for a few months and then a 42 ft Amer Tradition for 10 years and they both bounced and wallowed on undulating roads but always towed a heavy trailer. Either a stacker race car trailer or utility trailer with a heavy H1 Hummer on it. Eventually realized that I was grossly abusing the MH suspension with all the weight. The Amer Trad was rated for towing 15 K but that is BS. The dif on the Amer Trad was shot at 100K miles. A lot more miles than most RVrs put on they MHs. The Amer Trad(400 HP) struggled in the Mtns as well so the light bulb went off and I traded it for a true truck(semi-tractor) RV. A 43 ft Freightliner with 650 HP diesel and a 45K hitch that pulls the trailer like it is not there and no bounce at all. Handles like a race car compared to the wallowing RV.

My point is, RVs are designed to glide smoothly down the road pulling a rela light toad behind it or relatively light trailer and they are not unlike Land/Range Rovers with the soft airbag suspensions which also wallow down the road. Stiffer springs and bigger shocks tuned stiff for less bounce might be the only way to eliminate the RV whale wallow but then you will rattle and beat up everything in the MH and you may dislike the stiff ride more than the whale wallow.

Sorta high jacked the thread and 99% of RVers do not want a Truck Conversion but thought I would share my observations about the RV bounce after driving another type RV with no bounce at all. I miss the Amer Trad in many ways but not the mushy ride.

[Tobys96]

This thread drives me crazy. Yesterday I posted the fix and the part numbers. Koni does not make a direct replacement for the Bilsteins used on the Spartan frame for the Newmar DSDP, or if they do it has just happened. At Henderson's RV Repair (SAFETY STEER)in Grants Pass, OR they know suspensions. They looked at the front axle weight on my DSDP and determined that the shocks used by Spartan were not able to handle the weight. After looking and test fitting several bus type Koni shocks, they came up with the perfect replacement. I had them install new rear and tag axle shocks also, part numbers on my previous post. I put 13000 miles on that coach before selling it and never had one bit of bouncing at a bridge transition or dip in the road. Shocks control the bounce and springs or air bags control the ride. These shocks are now a standard replacement for several coaches on Spartan frames. Not cheap but well worth the difference control and safety.

[Tobys96]

Koni 99B-3209

This is the New Front Heavy Duty replacement shock for the 8805-1021 used previously on the front axle of the Alpine Peak, Roadmaster RR4R, Workhorse UFO & Spartan MountainMaster I-Beam chassis. It became evident after a few years that the 8805-1021 just wasn't holding up to the weight and demands of these chassis. The Koni engineers went to work and did real world testing to come up with a shock that would increase the ride comfort yet be built to withstand the most punishing demands thrown its way.

The main difference between the 8805 and the 99 series piston is that it is almost 40% larger than the 8805 series (50 mm vs 36). Which means it can take a lot more force, or the same force with less pressure. This improves durability and performance. The 99 series is also Koni's latest shock design. It was developed for high end motorcoaches in Europe, and Koni is just starting to introduce it in America in the RV market. Both shocks control up and down movement, but Koni has found a better balance between the two with the 99 series setting.

Ride Quality:

Experience a smooth controlled ride on your Class A motor home with Koni EVO 99 shock absorbers. Koni's patented open intake valves ensure that you get a smooth ride along with enough force to keep your RV from bouncing down the road. EVO 99 is especially good on independent front suspensions that have a limited amount of shock travel. Large piston holes and custom tuned valve stack ensure that you have extra body control when you need it without undue harshness.You don't want poor road conditions to spoil your cross-country trip. Our 50mm bore piston reduces internal pressure for smooth operation over rough roads, and our digressive valve stack and modular piston design control bouncing over bridges and large bumps.

Durability:

Performance parts should last, and Koni EVO 99 shocks can go the distance with our industry leading 9 T tensile strength. We back our products up with a lifetime warranty for the original purchaser.

Worldwide Reputation:

Koni is known as the shock absorber specialist worldwide. We have committed ourselves to delivering the finest quality product with the best performance. This philosophy results in unrivaled durability, superb road performance and maximum customer satisfaction.

Applications:

Alpine Peak Front
Roadmaster RR4R (4 Air Bag) Front
Workhorse UFO (Rear Gas Engine) Front
Spartan MountainMaster I-Beam Front
Spartan MC2000 w/ 510AR Front
Tiffin Phaeton w/ PowerGlide I-Beam Front
Roadmaster RM4C Front
Safari Sahara (8 Air Bag, 4 Shocks) Front
Monaco Vesta 2011-2012

Collapsed Length Extended Length Upper Mount Lower Mount
14.92"
23.59" Eye 19.15mm Eye 19.15mm

[Ray,IN]

Originally Posted by plahaye

I am going to chime in late in this discussion that has boiled down to shocks, weight distribution, etc. and all points are good ones but the bouncing and wallowing like a fat whale is the nature of the Class A beast I think. Some are just worse than others.

I drove a 40 foot Beaver for a few months and then a 42 ft Amer Tradition for 10 years and they both bounced and wallowed on undulating roads but always towed a heavy trailer. Either a stacker race car trailer or utility trailer with a heavy H1 Hummer on it. Eventually realized that I was grossly abusing the MH suspension with all the weight. The Amer Trad was rated for towing 15 K but that is BS. The dif on the Amer Trad was shot at 100K miles. A lot more miles than most RVrs put on they MHs. The Amer Trad(400 HP) struggled in the Mtns as well so the light bulb went off and I traded it for a true truck(semi-tractor) RV. A 43 ft Freightliner with 650 HP diesel and a 45K hitch that pulls the trailer like it is not there and no bounce at all. Handles like a race car compared to the wallowing RV.

My point is, RVs are designed to glide smoothly down the road pulling a rela light toad behind it or relatively light trailer and they are not unlike Land/Range Rovers with the soft airbag suspensions which also wallow down the road. Stiffer springs and bigger shocks tuned stiff for less bounce might be the only way to eliminate the RV whale wallow but then you will rattle and beat up everything in the MH and you may dislike the stiff ride more than the whale wallow.

Sorta high jacked the thread and 99% of RVers do not want a Truck Conversion but thought I would share my observations about the RV bounce after driving another type RV with no bounce at all. I miss the Amer Trad in many ways but not the mushy ride.

Someone who understands the dynamics.

[harley4life]

I know its off subject a bit, but I hit that "bump" they called it in Jackson ms. We left the ground and I for the life of me don't know how that trailer stayed hooked up. That was the worst I have ever exp. My wife and I literally left our seats.

[SmokyPond]

Originally Posted by CountryB

Matt, what is the different between the FSD and EVO. Why does Koni recommend the EVO on the front?

I thought we were supposed to use the same shocks front and rear.

Apparently not, and it makes sense to me.

The rear sprung weight of my coach is much heavier than the front. In addition, the unsprung weight of the rear has to be at least 3X that of the front. The shocks have to be designed to accommodate both weight parameters and then some.

Koni's recommended shock for the front of my coach is the 99B 3209 RV EVO Shock (Black). This is the same shock that Tobys96 post provided the specs for. For the rear they recommend the 8805 1022 FSD Gold RV Shock (Gold).

Using the right shock makes a huge difference in ride quality as evidenced by what I experienced due to the mixup between the front and rear shocks.

[Dockerbee]

Do you have air ride? I have a 2005 45’ country coach, have a hydra lift with full dress Harley, tow a 7000 lb Chevy 4x4 and really have no problems unless really bad road

[Terry L T]

Google "Comfort Control Valves"

[Dutch Star Don]

"CountryB".....Coaches with Independent Front Suspension (IFS) have VERY short shocks, with a short throw. The Koni FSD's were not designed to work with such a short throw and consequently were not available for IFS coaches. Since IFS coaches are now he new front end of choice, Koni developed the EVO shock primarily for the IFS front ends.

[FatChance]

I just ordered the new Koni EVO shocks for the IFS front end on our 2004 MADP (Freightliner) to replace the worn out Bilsteins. I can't wait to try them out.