Community Forums

CountryB · 11-17-2021, 09:53 AM

I add some air pressure gauges to monitor the pressure in the air bags (front and rear). Mainly just to know if they are leaking and how fast. Then I can build up air pressure as needed (when parked). They do leak down a little over a couple of weeks.

But now that I have the ability to monitor, and I can see that the pressures are slightly different in the rear, between the left and right sides, I'm wondering if I should adjust the Ride Height Valve to make these equal.

The Coach appears to be level but its hard to tell exactly. I did measure the air bag height and adjusted them to 10" each, but later had to go back and adjust one RHV to get the side-to-side more even. They still measure 10" which tells me there is some variation within that 10" measurement.

So should I adjust the RHV to equalize the air pressure between the left and right side in the Rear. The front air bags are equal in pressure (which is expected since they share a RHV).

This is in Travel Mode. Left photo is front air bags, right photo is the rear.

What do you think?

96 Wideglide · 11-17-2021, 10:02 AM

Your probably heavier on one side.

twinboat · 11-17-2021, 10:06 AM

If one side of the rig is heavier, it will need more pressure to keep level.

The ride height valves level the chassis to the axle, not to the ground. If the ground is not level, the rig won't be.

When using air leveling while camping, then the system is leveling the chassis using the ground.

CountryB · 11-17-2021, 11:00 AM

Good points.
According to my weights, I am heavier on the Left side.

However, I think there may be an error in recorded weight as I find it hard to believe the Tag axle weights could be that far off (different from left to right). I plan to get the coach reweighed in the near future just to be sure.

So heavier on the left should require more air bag pressure on the left... ?

96 Wideglide · 11-17-2021, 11:05 AM

Yep.

It just keeps adding air to those two bags till it reaches your pre-set ride height.

wolfe10 · 11-17-2021, 11:14 AM

As suggested, takes more air to carry a heavier load.

Just keep ride height to spec!

Timaz · 11-17-2021, 12:50 PM

I would guess your tag is out of adjustment left to right. (valve/s leaking) As I have stated before my 6 pack valves were leaking and made my corner weights way out. Once I resealed them everything was good.

Tim

CountryB · 11-17-2021, 02:01 PM

Quote:

Originally Posted by Timaz

I would guess your tag is out of adjustment left to right. (valve/s leaking) As I have stated before my 6 pack valves were leaking and made my corner weights way out. Once I resealed them everything was good.

Tim

I'm not sure what you mean Tim. There is only a single adjustment for the Tag axle. You set the air pressure at the regulator at the back of coach and the air pressure is the same going to both tag axle bags (in Travel Mode).

I resealed the HWH 6-pack valves a couple of years ago. No leaks back there that I'm aware of.

wolfe10 · 11-17-2021, 02:11 PM

Mike,

Agree your tag axle side to side weights look wonky.

But, looking at each axle weight divided by GAWR you are as good as you can get it.

Front axle 96.7%
Drive axle 88.6%
Tag axle 78%

You can't up the weight on the tag without adding weight to the front axle.

So, NO CHANGE (assuming your axle weights are accurate of course).

CountryB · 11-17-2021, 02:30 PM

I think the guy at SmartWeigh wrote the tax axle weights wrong. I didn't notice that until after I had left. I plan to go back one day (it's about a 2-1/2 hour drive) and get it reweighed.

I also used the CAT scales on a previous trip but that doesn't give individual wheel end weights - and I think it is inaccurate regarding the Drive and Tag axle weights, because it's hard to position the Coach on the Cat Scale accurately as the Tag has to be positioned at edge of the scale for the trailer (rather than centered on the scale) with the Drive axle positioned on at the edge of the front scale. I think it is showing some Tag axle weight on the Drive axle.

SmartWeigh is the best method (individual scales under each tire set). Just need to pay attention to what the guy writes down and ask questions if it seems off.

Timaz · 11-17-2021, 02:53 PM

Quote:

Originally Posted by CountryB

I'm not sure what you mean Tim. There is only a single adjustment for the Tag axle. You set the air pressure at the regulator at the back of coach and the air pressure is the same going to both tag axle bags (in Travel Mode).

I resealed the HWH 6-pack valves a couple of years ago. No leaks back there that I'm aware of.

That's my only thought with more weight/pressure being put on the ground.

Tim

96 Wideglide · 11-17-2021, 03:05 PM

7800# sounds more believable on your tag axle.

Last time I weighed, I was a bit over 7300, with the same 40# loading pressure as yourself.

rpasetto · 11-18-2021, 09:31 AM

Mike, I have to ask a dumb question. Have you tried swapping the air lines to the rear gauges to check for variations in the gauges?

I agree with the others that the tag weights are way off. However if there is something (cannot imagine what) which keeps the PS tag from bearing weight, increasing load on the PS side of the drive, would that result in a pressure increase in the PS drive airbags?

CountryB · 11-18-2021, 11:34 AM

Quote:

Originally Posted by rpasetto

Mike, I have to ask a dumb question. Have you tried swapping the air lines to the rear gauges to check for variations in the gauges?

I agree with the others that the tag weights are way off. However if there is something (cannot imagine what) which keeps the PS tag from bearing weight, increasing load on the PS side of the drive, would that result in a pressure increase in the PS drive airbags?

I have not tried swapping lines. I just got this installed over the last weekend.

It looks like about a 10 psi difference between the right rear and left rear. Maybe that is due to loading (storage compartments) but it seems like a lot, and I don't have that much heavy stuff in the compartments (at least not all on one side of the coach. Maybe the interior layout (kitchen, refrigerator, sofa, etc.) makes it heavier on one side.

If the drive axle air bags were out of adjustment (due to mis-adjustment of Ride Hight Valves) and therefore putting more pressure on one side, perhaps that could explain the difference in air pressures. I'm not sure how much change i air pressure it would take before a noticeable lean would occur.

I may just climb under the Coach and adjust the RHV until both gauges read the same (and then see if that affects the lean of the Coach any). Possibly adding 5 psi to one and removing 5 psi from the other will make no noticeable difference in how the Coach sits, but perhaps could improve handling if they are even.

My OCD is in high gear now.

I have a tendency to look for problems were none exit. And sometimes create new problems were none existed...