Still working on getting MC9 to sit level...questions
 

Still working on getting MC9 to sit level...questions

Started by Seann, November 19, 2025, 01:44:49 PM

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Seann

Good afternoon all,
Just took the left drive wheels off to visually inspect the leveling valve, I was hoping it would be "stuck" considering my issue, but it wasn't. If you see the photos, when aired up there is 5" of clearance (tire  to fender) on the left rear, 3" r/r, 1 1/2" l/f, zero r/f. Can the high l/r be jacking the r/f down? How do I determine that the l/r valve is faulty? I sure wish I had a pit...
Seann
1984 MC9

Coach_and_Crown_Guy

The physical link, between the axle and the leveling valve is intended to be bent/formed to either raise or lower the resting position of the body. Nothing rocket science about it and if yours are distorted or corroded, to the point they can't be adjusted to the desired ride height, simply go buy another pair of links from a truck supply source for air-suspension parts, these are very common and cheap, and install new ones. The MCI Manual describes how to set the height and that's how they describe it. Bend the link to shorten it and lower the body or straighten it and raise the body. The leveling valve really doesn't determine the actual ride height. All they do is dampen out the massive random axle movements to create an average and stable air pressure to the air bags. You can set/adjust the lever on the leveling valves' shaft for a gross adjustment then fine tune it with the bending of the axle attachment links. The procedure is in the manual and another reason to have a manual in hand for all those little questions and answers you'll need to keep your '9 in good shape. By the way the leveling valves themselves are rather standard today used in any air-ride suspension truck or bus, and only around $100 new, barring any outrageous inflation caused price increases, still reasonable priced. Nothing MCI proprietary about them any off the self leveling valve should work

luvrbus

Take a broom handle and move the leveling from the out side that will tell you how much to adjust the valve ,i do it without getting under the bus, sometimes the valves get where you cannot adjust it, make sure the air bags are not different on each side I ran into that on MCI 9 one time the bag would not extend high enough to adjust the correct level, the tag axle adjustment can throw level off too on 1 side ,been there before with a tag axle seized on the passengers side for lack of grease , a teenager showed me how his dad checked his cement truck tag with all things using silly putty under the tires it was stupid but it showed me tag was the same on both sides .You can buy leveling valves on Amazon for $30 up I never had any problems with the ones for Peterbuilt sold there some cases I would spend another 20 bucks for new arm kits and linkage
Life is short drink the good wine first

Seann

OK, thanks for your input...I'll try adjusting the back side to side with the links, but what should I be looking for at the front? If the leveling valve only does front to back, what can cause the difference left to right...seized shock(s) maybe not letting the pass side come up?   
1984 MC9

Seann

Any reference on ratio between link length and height change? If I shorten the l/r link by "X", should it drop that corner by "X" ?
1984 MC9