[ccjohnson]

Is the "raise tag" in the correct position?

[77newell]

My coach is tag-less.

Re; Forest's suggestion which is a good one. As noted in a previous postings in this thread I've already replaced the tubing from the 6-pack to the ping tank and the air lines from the ping tank to the airbags. The airbags are not leaking. I also have switched the air lines at the 6-pack and the problem stayed with the left side; they were then returned to their original positions. The air bags on the left are inflated to a pressure above those on the right even though the left side does not rise as the right side does.

I'm sure when the solution finally is clear we'll all be smacking our heads and saying: "well, duh". In the meantime I really appreciate your continued contributions to the search for the solution. This is just weird and very frustrating to me as someone who made a career out of troubleshooting.

[Fulltiming]

It is worth verifying that in level mode the front left is inflating properly. In travel mode, the two front airbags are controlled together by the center front ride height valve. In level mode, as Richard mentioned each airbag is feed independently based on signals from the computer. I would also verify that the level sensor in the top of the bay hasn't gotten knocked out of whack send extremely erroneous information to the HWH computer.

[Richard]

wow, what a tease!

I read your answer about jacking it up several times. Forgive me for clarifying. When you jacked it up, did the clearance in the fender well increase? I am trying to get my head in tune with a mechanical blockage in the suspension. If the tires stayed on the ground, and the coach rose then it kind of rules out a kink in the suspension bushings.

Another very subtle point for me to understand. The coach will rise to a certain point, measured relative tire to fender well arch. If in travel mode, does it rise to the same point, OR does it rise higher? What is the air bag pressure in travel mode?

[ccjohnson]

Perhaps the air bag has an internal problem.

[77newell]

For the past three days I've been able to raise, lower and re-raise the rear with the left side only slightly following the right side -woo-hoo!

My "solution" (yet to be confirmed with more time) was to jack up the rear, inject into the end bushing areas of the torque arms Blaster brand penetrant alternating with injections of spray white grease and PTFE lubricant. I did this several times over the coarse of 3 days, each session involved using the jack to raise and lower the coach, leaving it in the raised position until the next session. Given the "success" so far I'm going to give the torque arm ends a few more treatments.

Why may this have made the difference; the air bags on my single rear axle coach are loaded to near capacity. It would not take a lot of additional resistance to raising the coach for air bags to struggle to do their job. When lowering the coach, the weight of the coach is more than enough to overcome a relatively small suspension system resistance as soon as the air bag pressure reduced.

[Yachts]

Once again Richard's original hypotheses Of suspension resistance seems to be confirmed.. I suggest a new title for Richard. king guru. Thanks Richard your insight is always appreciated.

[89classic]

Where is the Mercury switch in an 84' that would control the ride height from one side of the coach to another? 

You had mentioned its in the storage bay, any idea specifically? Thanks...

[Richard]

Jon,

I think you may have the true root cause, in that the airbags are near capacity. On both tag axle coaches I have experience with it takes about 80 to 90 psi to " float" the coach. When you said you were seeing air bag pressures at 110 and 120 then that was a big clue. If you ever replace the bags some research may be in order to see if a slightly larger diameter bag would fit.

Not that any of you need this explanation but here is the math behind the air bag. The air bag lifting force is directly related to it's diameter and the air bag pressure. So if the air bag diameter is 6 inches, that results in a pi®squared. Or (6/2)squared X pi = 28.27 square inches. Now multiply 28.27 sq inches times 100 pounds per square inch to give a lifting force in this example of 2800 pounds . Of course this is just an example. But to illustrate just how sensitive the force is to diameter, let's make the bag 1/2 inch larger in diameter. 6.5/2 squared X pi = 33.18 sq inches. At the same air pressure of 100 pounds the lifting force is increased to 3300 pounds just by increasing the diameter of the bag by 1/2 inch.

Sorry for the lecture, the point is that when replacing air bags it is important that they are the same size or you can create suspension imbalance issues.

I don't know why the radius arm bushings do not have zerk fittings on them, but it's something to think about. I might try that before I would pull the bushings out.

[77newell]

Richard, you and I are on the same page regarding the "driving forces". Math does matter. There is a drawing in the notebooks for the coach showing Ridewell specifying a 6in plus diameter airbag for the rear. There is no way that could do the job. There is another drawing showing a 9.12in diameter top plate and a 8in bottom plate. This is the bags my coach has and it's rated for 5800lbsf at 90psi, which is less than the load imposed. It works, but it is at its limit.

Your suggestion of adding a grease fitting seems sensible to me though it would require pulling the bolts and drilling passages for the grease. At that point I'm stuck with the need for 1100ft-lbs of torque which is more than I'm willing to mess with.

Given that no Ridewell suspension uses any lubrication I'm guessing that what I'm experiencing is really rare, go figure. I'm also guessing that being this highly loaded is rare so it may never come up in normal applications. Therefore, your suggestion for installing larger bags makes sense. I will consider that if and when I need to replace the bags due to their condition.