front suspension valve question

[bevans6]

my bus (MCI MC5C) sometimes rocks from side to side more than I think it should, aside from new shocks, which I have and will be installing soon, I wonder about the front ride height valve.  I think there is supposed to be some hysterisis built into that valve, with a viscous fluid of some sort.  How does that work, and how could I test it?  Or is it worthwhile just replacing it on spec, as part of a general ongoing maintenance program?

Brian

[RTS/Daytona]

The delay should be between 2 and 9 seconds

The Height control valve section section from my RTS manintenance manual is on it's way to your addy - the 9 page .PDF was too big to post here - hope it helps

Pete RTS/Daytona

[bevans6]

Thanks!

[TomC]

The single front leveling valve will not do a thing for rocking back and forth.  Neither will the rear valves-since the valves are slow response (even if you had fast response valves, it won't stop rocking).  You should check your tire pressure (not the max tire pressure on the side of the tire-the proper tire pressure from you weighing the bus by axle and looking up the tire pressure on line for the tire manufacturer), loose shocks at the mounts or worn rubber isolators, loose air suspension linkage.  I know of one owner of a 4104 (not too different then yours) that double shocked the whole bus and was very pleased with the results.  Personally, I just live with it.  Since if you do double shock it, the reaction time of the suspension system will be more severe and will cause a whipping action when reacting to a bump.  Rocking is just something you have to live with with our older buses.  The newer buses have the air bags mounted outboard near the edge of the bus that have just about eliminated the rocking motion.  Good Luck, TomC

[bevans6]

Thanks TomC.  I think that you are right, I'm trying to explore options, learn, etc.  I agree that shocks may help, hence I already have new front shocks to install.

But on your tire pressure thought...  I have the typical 12R 22.5 bus tires, Firestone FS560, and when I compare my tire loads to the pressure chart, my rears in particular are loaded less than the lowest load, and the Firestone load chart is calling for 70 PSI as the lowest pressure on the chart.  The fronts are a little closer, and they would be between the 70 psi and 75 psi pressure range.  That just seems too low to me.  I'm currently running all tires at 85 psi.  the previous owner said 105 PSI.  When I dropped down to 85, the ride got better and the wander got less.  I wonder if I should drop down as far as the load/pressure table says to, or if there is a reason to run the higher pressures?

Brian

[TomC]

Whatever the lowest tire pressure on the tire chart for your tire is, you can run that pressure.  The lower the pressure, the better the ride.  My tire pressure chart says 85 in the rear and 90 in front.  I just run 90 all around for ease.  If you're within 5psi of the tire chart you should be fine.  Good Luck, TomC

[Ncbob]

Hi Brian,

Any MCI owner (who's knowledgeable...so we can expel the GM and transit owners from this discussion....well meaning though they be...) knows that the front leveling valve on a 5 does only one thing....maintain highway height. Any pitch-out of the body on curves is handled by the rear leveling valves.

On my '5' it usually takes 2-4 seconds because it's an 'action/re-action' situation. Your '5C' manual will give you a better picture of this.

Best....

NCbob

[gus]

12R 22.5  tires are probably too big for your bus which is pretty much the same size and weight as my 4104.

Lower pressures will increase the rocking since the sidewalls will flex more.

Smaller tires will have lower weight limits and call for higher pressures.

My 4104 is a rocker too but since it is old technology it probably cannot be helped very much. Increasing tire pressure helps tone down mine some but then the ride becomes harsh, it is a tradeoff.

[pvcces]

Shortly after we bought our coach, it used to rock right and left when going down the road. I found that the swaybar rubber mounts were worn out, so I replaced them. There was an immediate improvement; then I installed new shocks and got more improvement.

For what it's worth.

Tom Caffrey