Correct Ride Height ?

[Jeff Bayley]

Dear Abby-

It has seemed to me recently that my bus ride height is too low. It hasn't changed, I just started noticing other buses and a lot of them seem to ride higher. I'm CERTAIN that XL II's ride higher (mines a 95 chasis XL). Prevost confirmed that the XL II is indeed higher. I had Prevost check my ride height and they said it was good but I need to get a 2nd opinion. Can you measure from the bottom of a bay door to the ground and what is that supposed to be ?

Also, I finally got the bright idea to raise the coach an inch or two with the level low and just leave it there when I drive and I'm trying to experiment and get a sense if the ride is better or worse and it seems to me to ride a little bit better when I leave it up an little bit. Not too much, just a touch. I'm not hurting anything in my level low by doing this am I ?

[Jon Wehrenberg]

Jeff, I will try to remember to look up the proper height and post it. I seem to recall that the measurement is the airbag height when the coach is in the road position. I have a perfectly flat garage floor so rather than trying to get that dimension I measure from the floor up to the bottom of the bay doors all around. There are other points you could use if you are on perfectly flat ground, such as a body seam.

But let's discuss riding with the level low on. DON"T.

There are so many potential problems with doing that I would urge you to reconsider. There is a reason why your dash has a big red light on when you are in the level low position while you are driving.

You may think you can detect a change in how your coach sits relative to the road when you drive, but you cannot. In the level low position you eliminate the part of the system that maintains your air bag inflation level, and when the air bags are not where specified it has the potential to change your steering geometry (among other things) causing steering control issues.

As long as the air bags remain inflated to the specified height life is good and everything works as intended, but if the coach is too high, too low or leaning it may create problems.

[MangoMike]

Jeff,

You might want to check out this post from stuff.com about ride height.

http://www.prevost-stuff.com/cgi-bin...=000096#000008

Also, although I'm not positive, I think when you're in level low, the 3 ride height valves that help distribute the load are now disconnected. Unless you're trying to traverse something say like Jon's driveway I would stay in ROAD mode.

Keep us posted.
Mike

[dalej]

Jeff this is the bit of info that I have....let your coach down on the ground, or let the air out of the bags. Then start your aux. air and let it run. Turn your key on, but don't start the Detroit. Your bus will air up to to ride height. Measure the distance between the steel plates where the air bags are. This distance is 11 and 1/2 inches. You can preform this with the engine running, it is just loud and you can't hear the valves working. If you need adjustments made, you do so. Note: it is really nice to use aux air. If you don't have it, hook a air compressor to the aux. tank in the steer bay.

[rfoster]

Dale, Your sure have been busy posting the map lately,(keep up the good work) But I need to interrupt and ask --how much pressure does your aux compressor generate in order to lift your coach? Do you know the magic PSI number that works? My Aux Air will not lift it, and I have 110 psi shop air and it will not lift it. I tryed what Truk4u suggested by raising the tag and I may have gotten an inch raise out of the front bags.
The only way for me to lift is with the engine compressor running and when the air gauges on the dash reach about 110 it raises the front.

Does this sound unusual or normal ?

[dalej]

I bought one with 135 pounds, it works great! I had posted photos earilier in some thread.

[dalej]

Jeff, I forgot, use safty blocks when you are going under the bus. Don't block the bus up just keep it from dropping if somthing goes wrong. If you can run the bus on planks at least 4 inches when you work under the coach, it help out. Or better yet just head over to Jons. Having a pit must be the best!

[Jon Wehrenberg]

Dale and mango are definitely on their games. The space as Dale describes is the top of the heavy plate the air spring (air bag) base rests on to the underside of the top plate that the top of the air bag bolts to.

As Mango posted the ride height valves have a small time delay before they react so use extreme caution.

[Jeff Bayley]

Thank you for the feedback.

1) I don't THINK I have an aux compressor but I'm not sure. I've read prior post regarding this and glossed over it thinking I probabley had it but didn't know for sure but I just now realized that what I see that make me think I might have that is an "Aux Air Guauge" which shows the presure in the aux tank which does control the air bags but this very well may be fed from the main air system (not sure how to reference the main air system)

2) If I don't have an aux. air, then can't I just level the coach and turn the key off ? Why the process of dropping it and then leveling it yet again ?

3) Do you take the measurement of the air bag from the wheeel well or do you have to crawl under the coach ? From your description of getting under the coach it sounds like you at least need to get underneath to make any adjustment. I don't know how to adjust the air bags for the correct ride height but if it's involved I suppose I should check the height first. Measuring from the bottom of a bay door sounds a lot easier than rooting inside for the air bag measurement. Is there any reason why this would not be a good measurement if I'm on a level laid pad in an RV park ?

Thanks guys.

[dalej]

Jeff you need to drop the air and let it get back to ride height on its own. Measure the bag plates, write them down and then repeat. You will see what is happening when you do this. Your bus should come back within a quarter of an inch each time but the average should be 11 and 1/2.

Jon, I measure mine on the inside of the plates. bottom of the top and top of the bottom.