Porpoising

[Michael Marcocchio]

Hello I have a question I have a 2005 Beaver Patroit Thunder 42 ft with a tag axle. After going over a dip in the road (bridge rail or frost bump) the unit porpoises a few feet after leaving the bump I red somewhere that most of that can be taken out with tag air pressure adjustment. The pressure in the tag air guage reads about 45 PSI now. Any ideas and any help would be welcomed. Thankyou Michael.

[Don Beukers]

I had the same thing happening on my 05 Marquis, I put 35 lbs in the tag airbags and changed the front shocks to KONI, No more porpoising.

[Joel Weiss]

We had Henderson's LineUp install what they call "Motion Control" units and these also significantly reduced porpoising as well as low speed "Walmart wallow."

[Jeremy Parrett]

Check your tire pressures and weight at all axles.  Adjust tag tire and air bag pressure accordingly.  If this doesnt solve porpoising then your shocks are suspect.  

[steve zannella]

I have the same problem with 2004 marquis 42. Increased the tag air bags to 60 psi from 40 that increased weight on the tag axle and shifted about 900 lbs to the front axle and lightened the dual axle with little difference to porpoising, also the higher pressure in my tags limited the lift height and increased time to lift the tag axle.
Next, I reduced tag air pressure to 40 psi installed Koni adjustable shocks on the front axle and set to minimum settings on shocks with little difference from Bilsteins. I then increased rebound / compression to 1/2 max and porpoising was reduced but small bumps and pot holes were much more noticeable. So if your goal is to control porpoising, Koni Adjustables do work but you may not like the ride.

I'm not sure if I will stay with the Konis, apparently they don't make a FSD koni shock for the magnum 10 air bag chassis. The FSD's might be the best solution if what they say is true that they  soften minor road bumps and still control porpoising.
Koni does make FSD's for 10 air bag roadmaster.

[Jeremy Parrett]

38 psi on the tag and Bilstiens all around works very well.  With a coach weighing in at nearly 49,000 lbs slight porpoising is inevitable.  Shock absorbers dont last forever either.  I have 23,000 miles on our Bilstiens and so far so good including   6000 miles   on rather questionable "roads" in Baja  California. Mexico.
 Tire pressures are 105 psi  with 95 psi in the tag.