33" is the listed as the proper ride height from factory, but no reference to what. Front end is ridiing low after 1500 mile trip on the east bound I-40 road from hell. So the front ride height. rods are bent or have slipped. Hit a dip in the Mojave, that I'm pretty sure suspension hit the stops big kaboom.
OPP. if you are reffering to what to measure to check the height it has been mentioned numerous times by at least Brett W of were to measure.
JohnH
Measure from the top of the frame to level ground, with the air bags inflated. need to add this is with 9R tires inflated to around 100psi.
bags have eight inches of travel.
Dump air. Measure something to ground. Refill. Should be four inches higher.
Repeat three times. If not same height a height control valve is bad
"Trip from hell?"
I thought OREDs had leaf springs.
Not a 300 cat.
The majority of Oshkosh Chassis were equipped with air bag suspension. There were a few under 40 ' that came with springs or rubber band suspension they just didn't work out.
Not aware of any torsilastic suspensions on Oshkosh chassis. Only on U225 and U240's.
Anyone ever see one on an Oshkosh chassis???
Would suspect that there some published specs for ride height for the ORED air suspension chassis giving more specific dimensions than "bag inflated to 1/2 full height".
May need to check with James Tirana.
While I am sure their are specific dimensions the 4 inches up from deflated should get him close.
The multiple repeats of the deflate/reinflating cycle catches the worn ride height valves i replaced on these many times.
If the front does not return exactly to the same height the steering wheel is off center and the coaches steering is off.
Unihomes and unicoaches are insensitive to ride height altering the straight ahead mode.
Not so the ORED's
Yup with a trailing arm front suspension design, ride height affects alignment-- primarily CASTER.
I lowered my ORED to match the sweet spot of the new shox. While castor reduces with right height a little bit, the slightly lower Cg helps it drive nicer. Lower drives better as a rule as long as the suspension has enough to not hit stops up or down.
I will measure my ride height value and give a reference to the frame , trailing arm so that tire size is not part of the dimension.
I will be back to the bus late next week.
Thanks, Mike.
That is what he needs: a chassis rail to some point on the axle/trailing arm.
Again, would be interested in factory spec if anyone has that.
Phred with engine running and full tanks of air front and rear set the ride height to 33" from top of frame rail to ground( reach around front tire from the rear to measure, better yet get on a rack or pit), set front, then set rear and re-measure front to make sure it hasn't changed, those are words of wisdom from the FT Factory 5 years ago.
Thanks, NancyS,
That is the info he needs.
But, I have a question-- are there two ride height valves in front (unusual, but possible) or are the two in back.
You always set the axle with the two first, as that will affect left/right height, even on the other axle. So, after getting the axle with two valve set properly, you "average" the ride height of the other axle. The axle with the single valve is very rarely exactly the same side to side-- perhaps one side 1/4" high, the other 1/4" low. No problem.
But, if you start on the axle with one ride height valve, you will change ride height if you do adjust the other axle's valves.
2 valves in the rear and one in the front each with it's own dump valve, when setting up I place the jacks into vertical position, then dump the air bags and bring the coach level with the HWH Jacks, leaving it as low as possible.
Thanks, passenger rear is about an 1" lower than driver's side rear. Can't get the leveling jack down due to that, and the crown in my driveway. I am down to single water pump belt and it's squelling like a pig to move to a level site. I will start with passenger rear first, to see if I can cycle the valve.
Phred, with Ign. switch on, turn on HWH master switch, now select auto retract for all jacks, sounds to me like the rt. rear cylinder is not fully retracted, they will get confused once and a while. Now try the vertical switch and see what happens.
Brett,
Have a NTM '87 40' GV ORED. Contacted FOT about ride height. He stated the correct way to measure is from bottom of floor to ground. Under my front dash is a sticker with Ride Height of 33 & 1/3" . Also has front end alignment specs.
This unit was poorly maintained and I'm going thru it. Got Oil and Coolant analysis and everything looks good. Changed fuel, oil & filters. Changing out Belts, Shocks and Height Valves. New Conti tires all around. Saved big bucks using new FMCA discount.
Sooooo, how does "top of frame rail" to ground compare to "bottom of floor" to ground?
Thanks.
Brett
Foretravel rubber mounted the body to frame. You can see the pads if you look underneath.
Hence the height difference
As of yesterday I was told by a guy in parts at FT they are no longer interested in providing info for Oshkosh chassis. Seems that Freightliner bought Oshkosh just for the military side of the business and we are screwed for parts. This all started several days ago with those Bilstein shocks on E-bay, seems like a good deal, and from what I have found out they will work on a 4 corners.
Now about ride height, I went to my Oshkosh Service Manual which was a mistake, there are 4 pages in adjusting ride height according to Oshkosh. I can scan them, but how do I download to the Forum?
After adjusting ride height at rear so that distance between the axle bump stops was equal. Got Jack's down. I will test Freightliner parts tomorrow when I order filters and other odds and ends.
How do you dump the air bags, tried dumping all air from tank valves, but bags must have good check valves as it set that way for a day and no movement.
HWH has a auto dump for the bags ,but you can wire a manual dump. Find the front solenoid valve and the wire colors, same for the 2 back ones. Now find those colors on the back side of the HWH control panel. Wire them to a push button switch, now you can manually dump the bags. Notice that the solenoid valves have a manual shut off valve, with this you can dump the front only or the rear only or both, once you get it figured out it's pretty slick. Foe example right now the rear is aired up so I have access to the danmn HWH Jacks the I am working on, and the front is blown off so the shower will drain.
Second step of the auto hwh cycle is to dump the air after the jacks swing down with the first push.
After that shut off the panel power.
Yes the jacks are down. I do not remember if there was a manual dump without the jacks on the auto panel
Will check for mud daubers nests on vents or other obstructions.
Phred,
I ordered all my belts, filters, thermostat from Rockauto. Cheap fast shipping. They were listed as Gates Standard but received Premium XL Green stripe for about $9 ea. Wix filters for fuel, oil, tranny, hydraulics $6-$9. Use 5% discount code 6556913558762115 if you don't have one.
Also they have a Gates tension gauge for $12. Very valuable. Should test to 160 new, 120 used, acceptable range of 105-145.
Sorry to take so long Phred.
My front altitude; measured by hanging the tape measure over the top air bag plate and reading at the bottom edge of the bottom plate . Yes the tape has a sag as it passes the bag a little tiny bit. 8in.
My shock centers are 15and 7/8 in. I lowered the ride height a little to ride well with those cheap E bay Shox. They range from 12 to 17 in. 15.5 or 15.87 should be a good place in bump with some extension.
Moving the ride height a little should also run the bags in a new spot , maybe last longer.
AS far as mounting the shox; You need a special bent offset dropped wrench to hold the inner nut , right inside of the fuel tank . Maybe the drop is the width of the frame edge , about 2in. You can RTV the washer in place so that it stays long enough to fit the bolt back through .
Once this nut is loosened the job is easy , all of my pieces came out easy . For installing those 300psi Shox, I used a 1in rachet strap around the entire thing. Turning the wheels to one side and then the other opens up access pretty well.
If you need to borrow my special wrench , send me an email and I'l send it to you.
To finish, you may need a half turn of the drag link to center the wheel.