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Porpoising along the highway

Yahoo Message Number: 35080
Our coach did some rather nasty porpoising during our recent trip to Florida. We hit several stretches of interstate where I had to drop back to under 50 mph to get the coach and toad to stop bouncing up and down.
Do I need new shocks? The coach has about 48,000 miles on it. Will Bilsteins cure this problem?

David

2002 Allure #30682

Re: Porpoising along the highway

Reply #1 –
Yahoo Message Number: 35083
David, you do not mention just where this extreme porpoising took place or the length of your coach.
In the case of the porpoising, size does matter and the shorter the coach, the more tendancy to have the problem you mentioned.
It also can be related to worn shocks or a combination of both shocks and tire pressures. You may also include the weight balancing from front to rear of your coach. A balanced coach with proper weight on the front axle will have a less tendancy to porpoise than when the front end is lite.

With all that said, there are sections of highway going East and West and also North from Florida that will inhance the problem.
A number of years ago, I was operating a 40' American Eagle with IFS.
This coach is built on a Spartan chassis. The porpoising was extreme, and all the systems where in tune.
The 40' coach would pick the front tires off the ground along certain sections of highway. The porpoising was that accute. This occasionaly would accure through out the US.

Bottom line was that heavily truck traveled highways, on not so firm terrain, would cause and enhance this condition. The only way to stop it was to slow down. Slowing down to gain control was not just for our form of vehicle. It included others on the same strech of highway.
I have noticed that motor homes with a tag axle have much less cause to worry. Even where the roads enhance the situation porpoising does not seem to pose a problem.

I know this answer does not help your problem, however it adds to the information you are asking for.

JF/06MAGNA/#6558

Quote from: David Cole \[br\
]
Our coach did some rather nasty porpoising during our recent trip
to Florida. We hit several stretches of interstate where I had to drop back to under 50 mph to get the coach and toad to stop bouncing up and down.

Quote
>

Do I need new shocks? The coach has about 48,000 miles on it.
Will Bilsteins cure this problem?

Re: Porpoising along the highway

Reply #2 –
Yahoo Message Number: 35085
If you were on I10 anywhere close to New Orleans, Porpoising becomes a way of life. We're in Orlando and considering an I10 route back in to TX. Throttle back and take it easy!!!!

Judy n Joe

98 Intrigue 10578

Quote from: David Cole \[br\
]
> Our coach did some rather nasty porpoising during our recent trip to
Florida. We hit several stretches of interstate where I had to drop back to under 50 mph to get the coach and toad to stop bouncing up and down.

Quote
>

Do I need new shocks? The coach has about 48,000 miles on it.
Will Bilsteins cure this problem?

Re: Porpoising along the highway

Reply #3 –
Yahoo Message Number: 35086
David, concerning porpoising I have found shocks need to be set on firm, and ride height adjusted, solved the problem. Non tag axle coaches seemed more sensitive to this, then tag models.

Ray G

03 Magna 6267

Re: Porpoising along the highway

Reply #4 –
Yahoo Message Number: 35098
David

You probably only need to adjust your shocks to improve the dampening. CC does not set them to firm at the factory normally. Your book or the files section of this web site will tell you how.

ddtuttle

(aka Billy Byte, trusty hound)
2000 Allure #30443
 

Re: Porpoising along the highway

Reply #5 –
Yahoo Message Number: 35126
Mine was doing the same thing and while I was in Junction City at CC, Dave Rutherford suggested I put the Koni FSR shocks on. After the installation, the coach doesn't bottom out and porpoise like it did. My shocks had already been adjusted to the firmest level and they were only 2 1/2 years old.

Kevin

05 Intrigue