Building the 102DL3 (continuation of "Bumper" thread)

[solardude]

Jim - you should start a Project thread, that way you can link to your individual threads all under one topic, then whatever contributions are made as you progress through your project, progress can also easily be searched for and used in the future more easily.

Just a suggestion.


SD

[Jim Blackwood]

Note to self: Water heater goes under sink/shower taps to minimize water waste.

SD, I'll try to look into that Project thread idea. I don't know how to set that up.

Currently browsing back issues for ideas. Apparently the 250 gal of fresh water isn't so far out of line, nor is 100 gal of black. Who knew? Guess you can't have too much water, or a deep enough outhouse.

Jim

[richard5933]

250 gallons for the fresh water tank would be at the higher end of things though. Not unheard of, but definitely towards the upper end.

I'm sure you already thought of it, but that's going to be over 2,000 pounds between the weight of the tank and the water. May take some doing to keep the weight balanced and under the max, depending on what else you're installing and where it's going.

[solardude]

Jim - I'm sure others have chimed in on the 250 gal tank weight, I have 170 gal but 70 of it is under the bed, the other 100 is in the last bay. I split it up because I have seen too many conversions that sag in the plumbing bay. You will hear stories of Old School mechanics transporting engines in the bays. That may be true, but that is a temporary situation. If you load up any one area to the point it displaces, you have almost certainly caused structural members to yield. There is an old thread on here that you could search for that outlines weight distribution using estimates of load per sqft in the living space and provides estimated guesses on max weight for each bay. I don't remember what model MCI it was for, 102C maybe.... either way, it would be a good reference.
Planning for a 1 off conversion was the most difficult part for me, take your time, I can tell you almost everything I did not plan 3 steps ahead for I ended up redoing and paying double.

Cheers!
SD

[Jim Blackwood]

Good call on the weight. Shouldn't be an issue in terms of weight distribution as I think it will end up being in the 2nd bay and the gen and propane tank will probably go in the first bay. Between water, tanks, water heater and batteries that bay could hit 3000lbs easy.

How do I find out the load limits of the bays?

156 gallon fuel tank, is that in the same bay with the HVAC equipment?

Jim

[buswarrior]

Not likely to find legitimate "rating" for the bays...

The whole bus weight thing is an ever growing problem between manufacturers and the authorities.

The latest J models have 365 wide tires on the steer...!!! And I thought 315 was wide...

If their true baggage bay capabilities were published... there's problems with the rest of the "calculations" for the axle and tire loading... best to stay silent...

Are we talking about an old 102DL?

(please go into your profile and add some particulars under your signature or whatever it's called, you see the bits under the avatar and across the bottom of other's posts, I can't remember what everyone's ride is and neither does anyone else...)

Back to the DL... body structure issues... they delaminated both the floors and the siding due to flexing...

You could feel the flex in a 7 speed stick shift going over bridge joints...

First, has your coach had the proper upgrade/work around performed, second, how much gambling do you want to do, by loading it up heavy?

Placing these heavy conversion items is a wicked science, to get enough weight on the steer axle, but not overload it... neither too light or overloaded is a desirable, or safe outcome.

The 45 foot coaches are way worse than the 40 and 35 for a busnut being able to affect the front axle as dramatically. The hobby is into new uncharted territory in this regard.

Unfortunately, not much legitimate reporting on the 45'r has shown up yet, as not many of them in busnut hands yet, and then the busnut has to have an appreciation of scientific methodology and bothers to properly record their experiments.

Sadly, it seems the engineers are all gone away from the bus boards who had the ability to model the outcome...

Sliding out of control on a wet road, or blowing steer tires and suspension will be the cost of getting it wrong.

Be careful, and weigh everything as you proceed. Sometimes an inch can be worth 100 lbs on the steer...

Happy coaching!
Buswarrior

[richard5933]

It might be a good idea to spend a few hours with that graph paper and a list of everything you want to put in the bays before you make any hard decisions.

Along with the graph paper, perhaps a few sheets of ledger paper where you can start doing the math on the weights of everything. It's surprising how quickly the weight can build without being noticed.

In the time I've been involved with bus conversions (which is not long compared to others here) I've found that everything done on a bus is a compromise. You've got a long list of things you're hoping to include in this build, and my suspicion is that you'll be overweight before even putting the first dish in the cupboard. With some really careful planning you might be able to do nearly everything you want, but the math is going to be important as you move forward and start making decisions.

[Jim Blackwood]

Thanks BusWarrior, got that added, and I have questions for which I hope you have answers. The bus will be here next week and that will make things a bit easier. I can measure and do some rough weight calculations, though I'm not real sure how to deal with the tag axle. Maybe the balance point between the axles would be 1/3 the distance between the axles behind the drive axle, that would be my best guess. Then it's a pretty easy calculation between that point and the front axle.

Maybe you have access to this information:
Empty weight on the front axle,
Max weight on the front axle,
Empty weight on the drive axle,
Max weight on the drive axle,
Empty weight on the tag axle,
Max weight on the drive axle,

and the preferred load on the steering axle.

With that I can get in the ballpark I think. I can subtract the weight of the seats but since the lavatory is already gone I have no way to know what that weighed. I can however take it to the local scales once I have tags on it. But by then the tanks will most likely be installed so I need to get close first. I also have a grain scale so I can weigh the components before they go in.

Fortunately the tank will transfer the load primarily to the sides of the bay, and the sides have what appear to be some fairly substantial struts up to the floor. I'll know more when I do a physical inspection. Steel is very strong under tensile stress so it seems it would take a fairly massive load concentrated in the center of the bay to deform the floor of the bay, and that's not what we have here so structurally I expect the bus will be OK.

For a quick reality check, I just calculated that 55 passengers at an average weight of 175lbs each comes to 9625 lbs. So I have that much to work with plus baggage I would think. Eventually I hope to find out what that is, even if I get there by weighing the bus and reading the tire ratings.

The water is a big weight, and so is the propane, but there will be less of it. Then the generator, batteries, and with each item the weight decreases. But the total is apparently going to come closer to the max weight than I would have suspected. There will be some weight upstairs also of course. It all adds up but I think it shouldn't be all that hard to stay within limits.

Jim

[buswarrior]

It is the busnut ability to concentrate weight in ways the coach in seated service is not able to.

Those passengers can only concentrate as tightly as the seating allows.

As example, your proposed water tank can put 1/4 of your passenger calculation, usually spread over maybe 10-12 feet of the chassis, into 3 feet of the chassis, and "hanging" below, not sitting above. That's a lot more "tippy" a load from a front/rear standpoint, if you get my meaning. Move it an inch or two, will be quite measurable in axle weight change.

The manufacturer plates in the coach will have the max axle ratings on them.

For the current loads, take the coach directly to the scales and do each axle. It will be gratifying later on to have the current results to compare to.

Strip the interior and go weigh it again for an accurate measure of where you started.

For busnut purposes, your 156 gallons of fuel can be counted the same as water, 8 lbs per US gallon... also remember, that weight goes away as you burn fuel... fresh water migrates to the waste tank... generators and batteries are best to stay put...

From an evolutionary point, notice the differences in where the heavy components are located between a DL and an E or a J. Fuel and HVAC... a very dirty, unspoken secret, that became known to the authorities...

Everything went hard to the rear... weights weren't good in passenger service on the steer...

There is both a "teeter-totter" effect with the drives as an off centre fulcrum, as well as a simpler front to back effect to loading. The air suspension is a wrinkle, the pressure changes to keep the coach "level"... nothing is proportional, a little more weight in the bays towards the back goes to both the drive and tag, yet also puts some weight to the steer...

The DL empty were felt to be "light" in the steer axle, as we were all coming from 40 footers, they felt more prone to side wind effects, and not as grippy in slippery conditions. Right or wrong, we always loaded the front bay full of passenger luggage in a poor attempt to get it more "solid" on the road, especially in winter.

The J are worse for being light in the front unloaded.

However, the rear has to have sufficient ratio of weight on it, or you spin the drives on a rainy day pulling away from a light, and snap the driveshaft u-joint as the wheels come spinning off the crosswalk paint and grab the pavement...

Contradictions, I know...

What to do?

I'd be working on percentages added to empty scale numbers, with a bias towards the steer being a little heavier when you are done.

I would cautiously not be concerned about closing on the front axle rating, provided some suitable proportion was also onto the rear.

That's why the current weights, the empty weights, and what the weights are with various conversion bits put temporarily in place for a trip to the scales is really important to have, and to share, for those who follow.

Happy coaching!
Buswarrior

[Jim Blackwood]

All of which makes perfect sense to me.
Now, Dave's Dimensions lists the 102C3 as having a max weight of 36,000lbs. This makes sense if you take a typical max weight for an eighteen wheeler of 80K gross, divide by 18 and multiply by 8. You get 35,555. Different tires, different values but the DOT sets the maximums based on tire loading to prevent roadway damage.

OK, so if you subtract 10K from that it means that the empty weight of the coach could be somewhere not too far from 26,000 lbs. That seems surprisingly reasonable, but maybe it's closer to 20K. I just don't know. Probably somewhere in that range.

So as you suggested, running to the scale house with empty tanks makes a great starting point, especially if the tanks have been weighed before going in. Then weighed full. Then the other items can be added and juggled somewhat to balance the load. That seems like a good plan. I will try to carefully document all weights added and removed before the first weighing.

So, if it turns out that the wet tanks go in the middle bay, and the propane tank goes in the front bay, then placement of the batteries, genset and remaining items might work out well.  Yes, the weight would be centered and low but doesn't lowering the CG add stability? It will also effectively decrease the polar moment of inertia relative to total weight, which in this case would do little for directional stability. Having not driven the bus I defer to those who have, I'm just asking.

BTW, the weight of propane is 4.2 lbs/gallon so a 100 gallon tank holds 420 lbs of propane. Bit of a bonus there. The genset may also weigh around 400 lbs but I haven't weighed it yet and then there is also the tank weight. Presumably a furnace of some sort would go in the remaining space but those are relatively light. So figure 1000 lbs in the front bay, 3000+ lbs in the center bay and an unknown in the rear bay, yes I can see where shifting up to 1600 lbs (~100 gal. x 2 waste tanks) from the center bay to the rear bay might make good sense, leaving about 2000 lbs in the center bay (250 gal water) which can be shifted 17" fore/aft. It all depends on the placement of the toilet. The current layout has the toilet about 17 ft from the back of the bus which I suspect puts it directly over the rear bay, possibly even to the rear of that bay and shifting the floorplan to move it to one side or the other may be feasible.

Except that it isn't a total of 3600 wet lbs is it? It's 2000, because you don't start out with full waste tanks. The waste tanks get filled as the water tank empties, shifting the weight rearward. I was sort of hoping to minimize that effect by putting the tanks side by side and I think it still makes a lot of sense to do that. In fact I haven't really seen a reason not to at this point. It may in fact be possible that the weight in the front bay will allow the wet tanks to be in the rear bay, leaving the center bay empty. Or, the front end could be a little light. But some math will get that sorted once I have actual numbers to work with.

As far as gross weight goes, by this point I've added about 3000 lbs total weight and have everything except batteries, A/C, power distribution, and various odds and ends, plumbing, wiring and the interior. Plus I've removed several hundred pounds of seats. Even if I add another 1000 lbs to the basement that still leaves at a minimum 6000 lbs for the upstairs. That's a heck of a lot of weight for furnishings, if I can't stay under that I give up.

But of course, who knows what the wife will want to bring aboard.

Jim

[richard5933]

Two thoughts:

Side to side weight will also be important to consider, and where you place the kitchen and cabinets will affect that. Same with that marble countertop and/or tiled shower install if you go that route.

That 6,000 pounds can disappear quickly when the things you're not yet including get added to the list. Just a few things that most of us carry can add 500+ pounds instantly (tools/tool box, emergency equipment, jack & jack stands). Heck, I probably carry 50 pounds in just manuals and reference material alone. Then there's the weight of all the flooring, the furniture, the kitchen appliances and countertop, etc. etc. What seems like a huge amount of capacity to play with will go away in a heartbeat.

[luvrbus]

You want the heaviest load in the back bay of a DL#,the HVAC system,electrical, and fuel tank is forward of the back bay,keep the front bay lite if possible the DL is easy to over load the front axle,I don't have the the factory Ac so my total house system electrical  is in that space 6-8D batteries and stacked inverters,the 2 front bays are open on my DL 3.You need to keep the middle bay on the drivers side open there is a lot of electrical in the top of that bay you need to be able to get too from time to time   

[sledhead]

best place to put all the water tanks is in the rear bay and if you can have the tanks run side to side and a tank higher then wider will work better . then the next heaviest stuff work from the back to the front . yes try to leave the front 2 bays open for light stuff .

my tanks are very tall and skinny side to side 150 gal. fresh 110 grey and 55 black . my fuel tank is between the back bay and the 3rd bay and is 190 gal. the front 3 bays are loaded light . on the Featherlite

dave   

[bobofthenorth]

While you're on the subject of water tankage I'll throw in my standard recommendation to at least consider 2 freshwater tanks - one exclusively devoted to drinking water and another for "everything else".  That will let you pick and choose where you source your drinking water and if you end up traveling where drinking water is suspect it will let you refill from known good sources.  A relatively small tank will serve a long time if it is used exclusively for drinking. 

[windtrader]

My coach was fully converted when I bought it. This topic came up previously so I went out and sketched out the placement of the heavier components. The owner/designer was very thoughtful and thorough and built during the heyday of conversions so lots of valuable opinions weighed in I suspect.


The layout and weight distribution seems logical and makes sense. The bus came with full documentation and there wasn't a single sketch, calculation, note, or spec relating to this aspect of the design.


Personally, I think doing something to this level of due diligence is about the most you can do from a practical standpoint. It seems highly unlikely you will obtains sufficient measurements and formulas and expertise to develop any even remotely engineered structural, static and dynamic load calculations. Even if you did, then it only applies if you disregard practical and usability requirements such as access to batteries, genset, etc.


Additionally, your approach of buying used stuff on the cheap adds to the difficulty of finding components that match any engineered specs.


The bus hasn't arrived and it's cold outside, so no lost cycles mulling over this sort of topic but personally, I'd be spending my time in the MCI conversion groups picking their brain about what works and what doesn't. These conversions have been on the road for many years already and I suspect you will gain far more insight from that pool of knowledge rather than on an esoteric mehcnical engineering and physics topic over which practicalities are going to win out in the end.