softening the ride on an RTS and Gillig phantom

[mikewarmblood]

Hello is there a way to soften a ride by adding an air tank to the suspension?  On an RTS or Gillig phantom??  or any other bus?? I want my RTS to have the ride my Flxible has.  The Phantom is another story it has only 4 bags for the whole bus and it rides like a 4by4  Thanks for any answers  Still hoping for a picture of an undercarraige of a Flx Newlook.  Mike.

[robertglines1]

Mike on my 98 prevost instead or air beams between the leveling valves and bags there are tanks about 1 gal size plumbed in the line. I assume this is to give a more cushioned ride.  Bob

[HighTechRedneck]

That's interesting.  My RTS rides very nice.  Are your tire pressures set for the actual weight on them?

[Busted Knuckle]

I'm with you Mike every RTS I was ever around rode nice & smooth!
(maybe not SETRA smooth, but smooth none the less! )
  BK 

[mikewarmblood]

My RTS rides good,, but not nearly as good as my Flx.  My RTS is a 1978 IFS not a solid beam.. The Flx rides like a Cadillac on old huge Caddy

[HighTechRedneck]

Mine is an 82 with IFS as well.  Besides tire pressure the type of tire will make a difference in ride.

[RJ]

Mike -

First, as others have suggested, you need to check your tire pressures.  Run the coach across a set of truck scales to get the weight on each axle, plus total coach weight.

Divide the axle weight by the number of tires on that axle to obtain the average weight being carried by a single tire.  Now add 200 lbs to that number for "stuff." 

Once you have a number for front/rear, go to your tire manufacturer's website and find your tire and it's size, then look in the specs for the inflation tables.  Those tables will tell you what to set your pressures at for the best combination of ride and longevity based on the weight being carried.  If you cannot find the inflation tables, your local dealer should have them.

IIRC, the IFS RTS has a different "ride and feel" than the models with a solid axle.  Both models, however, use six air bellows, two up front, and four on the rear.  The IFS caused transit systems "fits", in terms of maintenance.  Thus the change to solid axles in later models.

(Side note: Fishbowls use eight bellows - four & four = even better ride.)

As for the Phantom:

Look at the rear axle.  Does it have a trailing arm with the air bellows located behind the axle?  If so, you have what's called a "Neuway" suspension, which was actually designed to be used on dual axle truck tractors.  You've got the front half of the duals under that coach, if that's what's there.

Now you know why it rides like a truck!

FYI, this suspension design caused more worker's comp claims for back injuries amongst transit drivers than any other.  It's like a teeter-totter, with the rear axle being the pivot point.  Easy for the driver to be, literally, bucked out of the seat by pavement dips.   

About all you can do for this suspension design is to keep the tires inflated properly.

Later model Phantoms went to four air bellows on the rear axle, and that tamed the totter.  But they still ride like a truck.  Gillig did not "tune" the suspension for a nice highway ride - it's tuned for pounding city streets.

How many air bellows on the Flx?  Some had six, some had eight.  Yours?

FWIW & HTH. . .

[mikewarmblood]

Yes my Fls has 8 bags 4 up front and 4 in the rear. Just like my Western Flyer.  Those two buses are almost the same in construction.  My RTS has the two big bags in front and four in the rear.  The rear rides like really nice. I am going to replace the tires on the RTS. When I get home I am going to to a restore on it get the new ac cover and replace the rubber on the floor and replace the battery tray.  The flx I have just rides so so so nice and it is so so so quiet.  I know the Phantom rides like crap!!! I am not to fond of it's ride!!! but it is built!!! The western flyer has as good a ride as the Flx.  I just wish the RTS was that smooth.  It am going to try the tank idea and see what that does.  The tires are about wore out need to replace them.   I know the RTS weighs about 27,000 LBS well I think like 26,678 or something like that rounding it off to 27.000 LBS. 

[happycamperbrat]

Gee...... I need to get out more! I dont have anything to compare it with, but I really enjoy the ride of my RTS, Im with HighTech on this one. 

[HighTechRedneck]

Another thing that makes a big difference on the front are the shocks.  If the current ones are shot, they will give a bad ride and cup the tires.

As for weight, coming back from Florida a couple years ago I weighed my 40' RTS:

Position	Axle		Tire
Front	11,560	...	5,780
Rear	20,220	...	5,055

That interprets to 85psi optimum pressure all around on the tires I have on it.

[happycamperbrat]

Redneck, what tires are you running..... brand, rating and size?

[HighTechRedneck]

All but one of mine are still the Michilin XZU2 12R22.5.  Which make it even more impressive that it gives me a good ride - those are the thick walled urban tires.

Except for the one new tire, they are all 11+ years old and will have to be replaced before any future road trips.  But that is not in my budget right now, for tires or fuel.  So no trips are likely for a while.  But when I do replace them, it will be with a highway tire and that should make the ride even better.

[TomC]

A lot of people are under the impression that a thick walled tire vs a thin wall tire will make any difference in ride.  I have Michelin XZE's which are thick walled regional tires.  Before mounting them, I pushed down on the tire and was able to put a bulge in the side wall.  That is enough to tell me that it wouldn't make a difference in ride.  The single biggest factor in tire ride is tire pressure.  Most are running to much pressure which gives a harder ride.

Also-some things that can be done to soften air suspension.  Try increasing the ride height.  This makes the bag higher with more air in the bag for a more cushioned ride.  Change the shocks to gas shocks or Koni adjustables to be able to play with the shock adjustments.  You can add what is called a ping tank.  It works if you can install a 1" hose from the leveling valve, through the ping tank, then to the air bag.  Once again the ping tank increases the air volume and softens the ride.  Good Luck, TomC

[HighTechRedneck]

I agree tire pressure is the number one culprit.  A lot of people, including a lot of shops, automatically air bus tires to 100-105 all around without checking their actual weights or the tire chart for that tire.

I used to think regional tires were transit tires, but noticed the Michelin site lists both regional tires (XZE) and urban tires (XZU2) with substantial differences in the specs.  The XZE regional tire is rated for 75mph (same as the XZA long haul tire) and the XZU2 urban tire is rated for 62mph.  And there is a difference in load range.  The XZE comes in load ranges F-H and the XZU2 comes in J-L (which is massively over rated for the weight of my bus).

The anecdotal way it was once described to me by a transit mechanic (Sammy) was that urban tires were for transit bus drivers who think the sidewall against the curb is a standard braking method.

[RJ]

Mike -

The anecdotal way it was once described to me by a transit mechanic (Sammy) was that urban tires were for transit bus drivers who think the sidewall against the curb is a standard braking method.

Sammy was right!  Transit drivers think the curb is part of the braking system.  The more you rub it, the faster you stop!  Extra points if you can use the rear duals, too!

Heck, I used to teach them how to use it! 

(NOT!!!!)

Easiest way to tell if it's a transit tire is to look for "dimples" along a raised rib on the sidewall about halfway between the tire's tread and the wheel.  Believe it or not, those are "wear indicators!"

FWIW & HTH. . .