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Old 06-23-2021, 07:02 PM   #1
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Equipment Relocation for Installation of Hydraulic Levelling Jacks

As you can see to the left, I have a Cummins Bluebird 40' pusher.

I want to install Grizzly levelling jacks. https://www.shop.thebigfootleveler.c...On-AQ-DPA1.htm

Here's the situation, lots of room to work with on the frame rails on the front end, I have free real estate between the front axle and the belly cargo boxes.

However, the back end is all kind of messed up. Jacks are supposed to be mounted close behind the frame hangars between the axle and the engine. On the driver's side, there is an air tank, which shouldn't be all that hard to relocate. But on the passenger side, there is both the battery box and the muffler.

No muffler is not an option. I hate obnoxious loud diesels. And nothing sounds worse loud than a V six cylinder automatic. Fortunately mine is a straight six, but still, want a decent muffler.

So I'm asking for thoughts and relevant experience on the subject. Has anyone mounted hydraulic jacks like this? I've seen it done on the "Life is a Joy" bus but I can't tell exactly how he did it on the rear end.

My thoughts are the following: The muffler can simply be moved a foot or so outboard and the pipe extended to match. The exit pipe I was already planning to do a right angle out the side rather than through the bumper in the back, so as to soot my trailer up a little less. My muffler is brand new, so I would rather not scrap it.

The battery box is a little more of a conundrum. I don't exactly need a slide out shelf battery box that could hold probably twice as many batteries as I'm using. Perhaps I could reconstruct the shelf to hold two batteries end to end and thus have more space inboard. I just thought of that, I'll have to measure. I'm one of those people who doesn't know what I'm thinking until I say it out loud (or type it).

I don't know where to put the air tank. There is some space inside the frame next to the drive shaft so maybe that's an option.

At any rate, I want to do this as the first major construction project because I want to elevate the bus for the rest of the conversion and make it easier to work on.

Anybody use the Bigfoot jacks?

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Old 06-24-2021, 07:11 AM   #2
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Location: Rapid City, SD
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Year: 2001
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Chassis: CS RE
Engine: ISC 8.3 L 260 hp
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I had the same dilemma. I got a great deal on some hydraulic landing gear that was way to big to fit behind the rear axle. I ended up putting it jut in front of the rear axle. Not ideal but the only place I could make them fit. I have air ride front and rear so I plan on seting up valving to bypass the leveling valves on the air ride so the air bags will take some of the vehicle weight.

Ted
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Old 06-24-2021, 09:22 AM   #3
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I ended up putting it just in front of the rear axle.
Yeah, I hear you. I thought of that. There is just a little space between the rear axle and the belly cargo bays.

However, that's a lot of weight back there to be hanging off a single point on the frame. I don't know how it is on your bus, but two thirds of the weight is on the rear axle for mine. Empty it's 15,500lbs on the rear axle. And after conversion, that means the water tank will be back there also, which may be 1500-2000 lbs more.

It's not the weight on the jacks I'm concerned about, they're rated for 17k each, it's the bending moment on a single point on the frame. I can't do the structural analysis off the top of my head, but assuming a 32,000lb final build weight, probably 22,000+ would be resting on that single point in the frame and I'm not sure what number I'd be comfortable with, but I'd like to get it below the axle number, so it needs to go behind the axle.

I'm thinking the best design weight wise is the rear jacks as far back as possible, between the rear spring hangar and the spot where the frame transitions to the engine section. The front jacks should go as far back from the front axle as possible. That will drop the proportion of weight held by the rear jacks, hopefully to something more like 60/40 or 50/50 if I'm real lucky.
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Old 06-24-2021, 10:45 AM   #4
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I have a front engine 40' Blue Bird with leveling jacks. The front 2 are just aft of the wheels and the rear are staggered Ike your drawing. I'll get more details this weekend.
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Old 06-24-2021, 11:25 AM   #5
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I just rewatched the "Life is a Joy" video, https://youtu.be/mQCs7ksETzA

He has air ride suspension so he has a lot easier time having space to put the jacks in right behind the axle. Where he puts his jacks, I have the rear spring hangars. In part of the video, you can see the front of the muffler, which appears to be in the same place mine is. That's where my jack has to go.

The other option is replacing my springs with air ride, but that's a whole other mess.
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Old 06-24-2021, 09:55 PM   #6
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Location: Rapid City, SD
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Year: 2001
Coachwork: Blue Bird
Chassis: CS RE
Engine: ISC 8.3 L 260 hp
Rated Cap: 36
Quote:
Originally Posted by WiredForStereo View Post
Yeah, I hear you. I thought of that. There is just a little space between the rear axle and the belly cargo bays.

However, that's a lot of weight back there to be hanging off a single point on the frame. I don't know how it is on your bus, but two thirds of the weight is on the rear axle for mine. Empty it's 15,500lbs on the rear axle. And after conversion, that means the water tank will be back there also, which may be 1500-2000 lbs more.

It's not the weight on the jacks I'm concerned about, they're rated for 17k each, it's the bending moment on a single point on the frame. I can't do the structural analysis off the top of my head, but assuming a 32,000lb final build weight, probably 22,000+ would be resting on that single point in the frame and I'm not sure what number I'd be comfortable with, but I'd like to get it below the axle number, so it needs to go behind the axle.

I'm thinking the best design weight wise is the rear jacks as far back as possible, between the rear spring hangar and the spot where the frame transitions to the engine section. The front jacks should go as far back from the front axle as possible. That will drop the proportion of weight held by the rear jacks, hopefully to something more like 60/40 or 50/50 if I'm real lucky.
Yes ideally the jacks should go behind the rear axle. I built a cross member that is 10 inches wide to help spread the load across the frame and prevent twisting. I am a little nervous about that much weight in one location but it is also a double frame in that area.

If you also have a double frame over your rear axle I think locating you jacks as far back as possible while staying on the double frame section would be a good idea.

Ted
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Old 06-24-2021, 10:46 PM   #7
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If you also have a double frame over your rear axle I think locating you jacks as far back as possible while staying on the double frame section would be a good idea.
I don't think I do. I don't recall double frame there. I could be wrong.

The only double frame section I think I have is where the main inward facing frame meets the outward facing frame that the engine and transmission sit in.
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