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Author Topic: Tow Capacity  (Read 1967 times)
viking1
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« on: August 31, 2011, 11:18:28 AM »

Does anyone have any idea what the max towing capacity and max tounge weight would be for a 102C3 with an 8V92? Also are there any bolt on or weld on kits out there or do I need to custom build a tow hitch?
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RJ
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« Reply #1 on: August 31, 2011, 10:36:24 PM »

Viking -

This topic comes up over and over again, almost as much as which oil to put in your two-stroke Detroit.  Here's the Cliff's Notes version of the Reader's Digest version of the answer:

Since buses were never built/designed as tow vehicles, the information you are seeking has never been published.

That helps, doesn't it??   Grin Grin Grin

If you use the Google search box up on the right, you'll find lots and lots of discussion about this, for all the various makes/models.

Seriously, one of the factors you need to consider is what are you going to be towing?  Flat towing a Suburban or a CR-V?  How about a 16-foot aluminum fishing boat, or a 27-foot, three axle stacker trailer?

Static tongue weight isn't as serious an issue as is the dynamic tongue weights imposed by the trailer while under way.

WWTM, IMHO, regardless of trailer type (your coach chassis will thank you, too!), is this goodie: http://www.trailertoad.com/

You won't find a hitch at your local Camping World specifically for your coach, 99.9% are all custom installations.

Do your homework!

FWIW & HTH. . .

 Wink

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RJ Long
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« Reply #2 on: September 01, 2011, 05:49:53 AM »

  Just to run a bit with what RJ just posted.

  Dynamic loads come from the motion of the trailer, the bumps and chuck holes its running over, loose mobile objects within it, and the swing and sway of the trailer as its running down the road. So you should easily be able to visualise the trailer thats putting high static loads (like when your parked, not moving), vs the same trailer in motion.

  You could easily load up a trailer to place maximum rated tounge weight down on the hitch, and on a good strong hitch setup you could exceed that weight several times and not see a problem. Same with the maximum load. You could hitch up something that weighs a million pounds, and as long as its not putting great vertical loads on the hitch, it could sit there parked like that forever, no problem. The problems start when you start dragging that load. You could easily pull a heavy Suburban down the freeway, no problem, but tear the hitch off coming out of a parking lot with a sharp curb, and turning out onto a street as all that mass tries to follow the Bus.

  Buses were never built or designed to pull trailer loads. The rear engine, the Detroit engine alone weighs a ton and a half, and 90% of its being held up, carried if you will, by the back wall (back glass) of the bus. A trailer is just going to add more weight back there. And that motor isnt sloshing around its weight like a trailer, its more or less rigid.

  Some Buses are stronger back there than others, but in all cases, keep the weight down, keep the weight low, keep the weight balanced, keep the loads within it secure from movement. Doing all those things can allow you to carry much greater loads with much less risk than the opposite effects will create.

  Before installing anything, first, the rear chassis needs to be inspected for structural damage, rust etc., and repairs made. Find a welder that knows what hes doing. The hitch should be welded as an assembly and bolted to the Bus, not welded to it. It should attach not only to the rear bumper/crossmember, but run forward under the engine and attach to the rear bulkhead. Regardless of what your intending to pull, and regardless of the capability of the Bus, the hitch itself should be built to class 5 rating as a minimum.

  On a funny note...There was a guy went out to Chicago and bought a small project airplane. Wings were off, tail feathers were off, so he put it all inside an enclosed trailer and headed off to Minnesota with his new mid life crisis. I dont recall if he tied it down, or if he did if it wasnt tied well, but in 500 miles he never thought to check on it. He gets home and all his neighbor buddies walk over as he opens up the trailer with a big smile on his face. Until the door opened. The trailer had been rolling back and forth, running over the wings and tail feathers, running the tail of the fuselage into the front of the trailer each time he slowed, bumping the engine into the back door each time he accelerated. The only part of it that wasnt destroyed was the engine. Pretty funny. Tie down your loads lol

 

 
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viking1
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« Reply #3 on: September 01, 2011, 09:17:28 AM »

Thanks for the info.

I am thinking an enclosed trailer big enough to haul my camaro and my bike and have a small work bench in the front. Im guessing the whole thing might weigh 7500lbs trailer included.
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bevans6
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« Reply #4 on: September 01, 2011, 11:19:37 AM »

I would figure a bit more for the trailer.  I've owned and towed race trailers for years.  I literally build spreadsheets to help me load them out for weight balance and total load.  The (current model) Camaro alone is 3800 lbs with an empty tank, the bike is call it 675 for a typical HD non-dresser, add 1,000 lbs for the tools, stuff, spare tire, jack, etc, along with the tool bench.  Quite reasonable.  You will need a 24' trailer, the Camaro takes 16 feet plus a couple to spare at either end, the bike goes catty-corner at the front and you build your bench to double as a stabilizer spot for the front tire.  Call it 5500 lbs of payload, trailer to carry that is going to be heavy duty, dual 5200 lb axles, I would get a heavy duty floor personally, and is going to weigh 4500 empty (no, it's not the cheaper trailers you see advertised for rock bottom prices).  You are going to have a 10,000 lb trailer and with the bike and the front engine car it's going to have a big tongue weight, probably around 1300 lbs.  You don't want to load the car backwards because the beavertail section of the frame is the weakest part, and I've known them to crack and break off.

Now, I think that's a lot for your MCI, but I really don't know anything about those buses.  There are devices to take the load of the tongue on an extra set of wheels http://www.trailertoad.com/    I've spoke to people who use that thing and swear it's great, so I would consider it an option.  You are going to be long, as well.  I like a 5.5' tongue on trailers towed behind motorhomes so they can't hit on a tight corner backing up.  Add a foot for hitch stick-out, you will be over 70 feet.

FWIW, just some thoughts on your plan.
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1980 MCI MC-5C, 8V-71T from a M-110 self propelled howitzer
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prevosman
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« Reply #5 on: September 01, 2011, 01:21:59 PM »

I have no clue about how an MCI is built or its limitations but a typical Prevost is placarded for 1000 pound tongue weight and 10,000 gross weight. The tongue weight limitation is based on 8" from the bumper.

Pulling a heavy trailer on a trailer hitch that in essence is mounted to the engine support cradle is very hard on the coach. As can be imagined the engine cradle which is cantilevered off the rear axle structure is flexing up and down and evidence an owner has probably exceeded the limitations is the rear cap starts to show stress cracks across the top rivel line or below the belt line across the bottom. For commercial operators who need to tow heavier trailers Prevost offers a 20,000 pound option which beefs up the structure to handle the loads.

Ironically probably the most common overload is when the owner uses a motorcyle lift that has its center of gravity about 24" out from the bumper supporting a 700 pound motorcycle. Less weight than the specified tongue weight and certainly less than the gross weight, but by being so far out from the 8" limit it is the equivalent of a severly exceeded tongue weight limit.
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Jon Wehrenberg
Knoxville TN
1997 Prevost Liberty
RJ
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« Reply #6 on: September 01, 2011, 07:19:53 PM »

Viking -

Based on what you'd like to tow, spend the $3K > $4K on a Trailer Toad after you install your Class 5 hitch, but before you hook up your trailer.

Might sound expensive now, but it will be cheap compared to rebuilding the rear of the coach due to structural damage from the heavy tongue loads.

My neighbor is the body shop service manager at one of our local RV dealers.  You wouldn't believe how many relatively new RVs are totaled because of frame damage from trailers - and it's NOT covered by insurance!

Pay me now, or pay me later, you choose.

FWIW & HTH. . .

 Wink
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RJ Long
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« Reply #7 on: September 01, 2011, 07:59:21 PM »

I am following this thread with great interest,

The toad here would probably be a Hyundai Verna (2,500 pounds). We were considering putting it up on a one-axle trailer. The only other thing maybe on the trailer might be a pair of bicycles.

And the welder guy took a tow hitch from a one-ton Chevy van and modified it to fit under the frame rails and behind the engine mounts.

The bus came with a 8V71, and now has a 6V92TA. How much weight difference is there between the two engines? Enough to equal tongue weight of the trailer? Am I in trouble?

I will try to post pictures of this tomorrow. We want to be as safe as we can.
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Dr. Steve, San Juan del Río, Querétaro, Mexico, North America, Planet Earth, Milky Way.
1981 Dina Olímpico (Flxible Flxliner clone), 6V92TA Detroit Diesel
Rockwell model RM135A 9-speed manual tranny.
Jake brakes
100 miles North West of Mexico City, Mexico. 6,800 feet altitude.
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