Why is my bus leaning?

[Brad_SwiftFur]

Time to crawl under the bus and give the suspension a good inspection. I would suspect a broken leaf spring, or if it's an air ride, a deflated air bag.

 

[flattracker]

Crowns lean to one side by design. They actually have more leafs in the springs on one side. My "new Crown" has air ride in the rear so that can mostly be adjusted out.

How about your shocks? Are they good? Are all your rear tires the same size? Dumb questions I know, but if you can eliminate those issues, Then to the next steps.


If you have air ride suspension that can be adjusted at the leveling valve.


One last dumb question: Are both rear springs identical? Same number of leafs?


Is the distance from frame to ground at front of rear springs the same?
Same at the rear of the spring mounts?


When you replaced the springs, were the replacements new or used?

 

[Theory-SKO]

Ok so y is no one talking about 1300lbs of engine and transmission offset 6” to the passenger side of the e series vans.?!?!?!

 

[rossvtaylor]

Ok so y is no one talking about 1300lbs of engine and transmission offset 6” to the passenger side of the e series vans.?!?!?!

If I did my math correctly, that offset would only result in about a 110 pound downward force on the suspension on the right side of the vehicle. There are definitely some estimates involved here, as I don't know the exact vehicle width and some other variables (like engine weight distribution from side to side, due to design and accessories). But I think the end result is that the offset wouldn't equal one average sized human sitting in a passenger seat.

 

[BarnYardCamp]

Someone mentioned shock absorbers....shocks are not load bearing so you can rule that out. (Unless one is damaged and not letting the suspension move as designed.)

 

[Theory-SKO]

Any way u can show me how u got to the average size person #? The van is 70”wide center of wheels front and 144” center of front axle to center of axle. Now putting the 1300lbs in the four corners is the tricky part. So it’s 6” off center and the 970lbs starts right at the front axle and ends at the rear shackle it’s leaf spring, the rest of the weight follows it up transmission tcase

 

[DeMac]

Welcome!

Any way u can show me how u got to the average size person #?

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[rossvtaylor]

Any way u can show me how u got to the average size person #? The van is 70”wide center of wheels front and 144” center of front axle to center of axle. Now putting the 1300lbs in the four corners is the tricky part. So it’s 6” off center and the 970lbs starts right at the front axle and ends at the rear shackle it’s leaf spring, the rest of the weight follows it up transmission tcase

Hi Theory. My calculations were pretty quick and, like I said, made some assumptions. But I didn't split the front-to-back and I'm not sure where the 970 fits into this. And I didn't worry about front to back, since we're talking about side-to-side lean.

But, since we're talking about leaning and off-center mass...here's the quick thought experiment I did. Assuming the 1300 pounds is centered, there's 650 pounds on the passenger side of the center line. Guessing that the engine is 2 feet wide, that means there's about 650 pounds in the middle of the 1 foot of mass on the passenger side...so I called that about 6 inches from the centerline. If we extend that leverage disadvantage outward (650 at the 6 inch mark, half that at double the distance) and continue out a few feet...3 or so...to the side in line with the tires...then what is the downward force which would lead towards a leaning tendency? Zero. Because there's an equal balancing force on the driver's side. Shifting that entire balanced mass 6 inches to the passenger side of the center line changes the distribution, so now I estimated that 975 pounds of that driveline were about a foot to the right of the center with the remaining 325 pounds on the driver's side. Do some balancing math, factor in the leverage over distance to the side, and I think I'm pretty close. But like I said, I assumed the engine mass was pretty evenly distributed (it's probably not) and I made some estimations.

Hopefully someone here can do exact calculations and clean up my mind! Do we have a mathemagician here in the group?

 

[La Camioneta]

step one measure ground to body at four points... pick a point like.... um right above the tire. write down the numbers to the nearest 1/4 inch.

measure frame to ground at four points.... I would pick where the bumper bolts to the frame......... measure the frame! not bumper brackets, not bumper bolts the frame. write it down...

now sit back an look at the numbers... do the numbers indicate what your eyes and brain tell you?


If yes, then when a body corner is low the frame on that corner should also be low.

If no, figure out why.

The next step is to find the amount of weight on each wheel corner left front, right front left rear right rear.


is the saggy side the heavy side? if weights are near equal, and frame body measurements are askew in a manner that agrees with body lean, then something is bent, mismatched parts, or bad springs. To a point, shock absorbers should not be a part of this problem... even high pressure gas charged shock absorbers should not amount to much.

It is possible the whole body is askew and not sitting on the frame evenly. It is possible the body is not "square" It is possible the two corners of the bus are carrying more of the load and causing a twist that is seen more from the rear than the front.

numbers first... evaluate 2nd decide 3rd

william

While you're there parked on level ground, check the floor with a carpenter's level parallel to the rear axle.

A 'helper' air spring kit with more pressure on the low side airbag is probably the cheapest fix for that lean. You'd not want the bags to fill as a pair with a crossover line, you'd want to fill each airbag individually until it takes the lean out.

 

[Walter62]

I have a 2003 3800 30ft school bus with the wheel chair lift and airbags on the rear. I was missing a spacer shoe located on the forward end of the leaf spring. I replaced it but I still had the lean on the passenger side. I drove it around maybe 100 miles or so an one day I looked under the bus and the spacer shoe was hanging there ready to fall off. If anyone has an idea about this one please Holla. I am going try and air up that passenger side airbag more than the other. I will have to seperate one side from the other. I will see about putting a valve in .

 

[rossvtaylor]

I have a 2003 3800 30ft school bus with the wheel chair lift and airbags on the rear. I was missing a spacer shoe located on the forward end of the leaf spring. I replaced it but I still had the lean on the passenger side. I drove it around maybe 100 miles or so an one day I looked under the bus and the spacer shoe was hanging there ready to fall off. If anyone has an idea about this one please Holla. I am going try and air up that passenger side airbag more than the other. I will have to seperate one side from the other. I will see about putting a valve in .

Hi Walter,

Unless your bus had springs to which someone added helper airbags, you won't have leaf springs in the rear. If your bus originally came with airbags (air springs), the forward end of the syspension's control arm is attached to a bracket and the rear end connects to a shock absorber. Ahead of that shock, above the axle, there's an air spring. On the 3800s there's also a lower control arm to keep the axle aligned. Below, I'm sharing some photos from a 3800 suspension and, perhaps, you could circle the missing part on your suspension? Or post a photo of it?

As far as modifying the air spring air pressures, there are two options. The proper way would be to install another air leveling valve and separate the air lines, so that each side of the bus's level is measured (and adjusted) by its own leveling valve. The other way would be to just cap off the pressure line and put a Schrader valve on each airbag, then air them up as you need. The big disadvantage of the second method is that it won't self-adjust for loads.

One quirk of the 3800s is that the rear suspension leveling valve and control rod is installed off-center, so it's going to respond more accurately to the height of the passenger side (as shown in the photo below). Because both sides are tied together with a tee, the air pressure in each bag should be the same. But the single leveling valve cannot correct for imbalanced loads from side to side.


[/ATTACH][/ATTACH]

 

[joeblack5]

If you have a swaybar it can be bend or the links can be have an unequal length.

Good luck
Johan

 

[Walter62]

The middle picture I see on top of the one leaf is a silver spacer with a bolt in it that is the part that comes loose on mine. Only thing that spacer looks like it’s on the rear side of the wheels mine is on the front side of the wheels on top of the leaf?

 

[rossvtaylor]

The middle picture I see on top of the one leaf is a silver spacer with a bolt in it that is the part that comes loose on mine. Only thing that spacer looks like it’s on the rear side of the wheels mine is on the front side of the wheels on top of the leaf?

That bracket assembly is in front of the wheels. I'm afraid, though, I'm not clear what you're referring to. Pics would help or, maybe, download my photo and mark it up for us?

 

[Walter62]

I’ve been busy, but I’m going to take a picture of my bus underneath and pin point the Silver spacer and a few more views..
Thank you for the replies.

 

[PiaB]

My 2001 E450 7.3 diesel shuttle bus just started leaning on the front passenger side. The springs and shocks check out ok. The only thing new is the victron solar system installed behind the rear duel tires on the passenger side. The weight: 2 batteries 100Lbs each. Victron equipment under 100lbs. 4 Solar panels on roof each 50 lbs and the are distribuited: 2 before the escape hatch and 2 after the escape hatch. Nothing over the front of the bus. How can this (in the back of the bus) make the front of the bus lean down on front passenger side (idea of mechanic)? Tires are new. Any suggestions?

 

[FawnaFox]

I don't think it's likely, but could the standoffs that hold the bus body to the frame be askew? I have only seen it once and it was on a bus that had sat in a field for years. I could also suggest that because the bus was meant for a load of heavy seats and rubber floors in the back, and the suspension was spec'd to carry that specific load, changing the load could result in uneven suspension sitting? When I took the interior out of my bus, it started to sit raked forward, because the suspension was made to hold the weight in the back, that no longer exists. Even if the seats and floor seem like a small amount of weight, my floor, rotten subfloor and seats made up almost 1700 pounds.. that isn't nothing. Just something to think about.

 

[PiaB]

Here is more of my research: Diesel front end is 1000Lbs. The Firestone airide capacity is 1000Lbs. Not an option. Looking into Timbren suspension enhancement system for $316.90 capacity is 3000lbs. Has anyone used this?

 

[Iceni John]

My Crown is now about 1-7/8" lower on the right side, for two reasons:

1) Crown used 19 leaves in the left rear spring and 17 in the right, because of the weight of the two original 8D batteries and the radiator on the left. This means that the right spring is 3/4" lower overall height than the left's; to compensate for this I will install a 1" spacer under the right spring. However, this will require longer U-bolts there, but I am dealing with L&H Bolt to get some longer U-bolts made (they will be EXPENSIVE!).

2) I now have about 1400 lbs extra weight (kitchen, shower, ten batteries, generator, inverters, etc.) on the right side that is also contributing to the starboard list. To compensate for this I have made two brackets that each hold three Firestone 110/70 rolling-lobe airbags (the widest that will fit between the frame rails and wheels/tires) to push down onto the top of each spring; the left airbag assembly is already in place, even though I don't need any extra downforce there for now. After I install the spacer and new U-bolts on the right side I can then install the airbag assembly there. Each group of three airbags has its own regulator and individual shut-off valves for each bag, so I can fine-tune exactly how much downforce I'm putting onto each spring. The three airbags can push down onto the spring with a total of 3600 lbs maximum downforce at 120 PSI, so I'll not need to run them at full pressure which should prolong their life. (If an airbag ever needs to be replaced, this can be easily done without even removing the wheels.)

By doing it this way I have separately addressed the two completely different but interrelated factors here. The right spring's lower height is addressed by the spacer, and the extra weight on the right side is addressed by the airbags. There is no single solution that will effectively address both factors.

Yes, this is a lot of work to do, but it's the only way, short of completely replacing the rear suspension which would now be impossible. If Crown's engineers were still alive now I would like to think that they would approve of my design and think it worthy of their original work!

John

 

[nikitis]

I would want my build to lean left a bit as all roads are mostly at an incline heading downwards towards the right.

My bus is perfectly leveled right now but it won't be when I'm finished with it and I plan to be more weight heavy on the driver side just a tad as I'd rather the bus tilt left so i'm level while on the road.