MCI 102-C3 tag axle air plumbing

[lhwood]

Hi, I'm looking for some help on the plumbing for the tag air suspension.  My, new to me, 102-C3 currently has the tag air source plumbed from the drive axle suspension.  The air system diagrams show it supplied from the aux air tank.  To clarify, mine currently gets air from the drive axle air bags and then through a pressure regulator and on to the tag air bags.  Is this common or is the manual diagram correct? 

As it is now, it crosses sides so the driver side drive sends air the the pass. side tag.  The only logic I can think of for this might be to counter "cornering body roll"??

Thanks in advance,

Durwin
1992 102-C3 conversion

[buswarrior]

Schematics have to translate to practical install. You found the tag plumbing attached to a hose that also happens to serve the drive axle bags, which also are supplied at the other end of that hose, from the aux tank.

So the tag is supplied by the aux, by the same line, which happens to ser ve the drives on the way by.

Economical.

Happy coaching!
Buswarrior

[lhwood]

To be more clear, the tag air supply isn't from the aux air.  It is connected to the line between the height control valves and the drive axle air bags. 

There is a tee plumbed into the inlet of the drive air bags, one port connected to the HCV and the other to the tag suspension air supply.


Durwin

[dtcerrato]

That would still be auxiliary air unless I'm missing something here...

[lhwood]

The concern is that the air supply for the tag passes through the height control valve before supplying the tag.   
It may be normal and not a problem, but it is different than the book and I'm having an issues adjusting the ride height.  I think the problem is that the tag air supplies are crossing to the opposite sides of the coach.  When I adjust the valve to raise the passenger side of the coach to the correct ride height it sends more air to the driver's side tag and causes the ride height valve on the driver's side to exhaust air to compensate and vice versa.  It's proving difficult to get the correct heights on both sides.

My understanding of the tag air system is that it is supplied with aux air at full pressure and then is pressure regulated to a constant pressure (35psi if I remember correctly) in the tag bags.  That would give a constant load to the tag axle and wouldn't cause the side to side issue that I'm having with the ride height.  Am I correct in my understanding of how the system is supposed to work?


Durwin

1992 102-C3

[buswarrior]

Crossing the connections side to side is unconventional. That needs correcting.

Plumbing the tag into its respective side height control valve has been known to be done by many, with no ill effects reported.

Your call.

 Beware that insufficient down force on the tag flat spots tires under heavy braking.

Happpy coaching!
Buswarrior

[lhwood]

Thanks for the information.  I've corrected the crossed tag plumbing but have retained the air supply from the drive axle air bags.

Durwin
1992 102-C3