Rear Axle Overloading in RR Coaches

[Robin_M]

Quote:

Originally Posted by moisheh Still some confusion. I have never heard of the axle itself failing. Are you saying that on the 40 ft. models( non tag) there have been rear axle failures? If so what is failing? Is the housing bending under stress? Is it cracking? Is the differential unit failing? The axle itself is not unique to Monaco. Probably used in many other units. If there was a problem we would have heard about this long ago. The overloading of rear axles on 40 ft. units is rampant in the industry. In the last 10 years the mfrs. have added: Washer dryers, tile floors, Corian counters, real wood cabinets, multiple batteries and more. The legal limit for a single rear axle is 20,000 lbs. Therein lies the problem.

Exactly! Thank you, Moisheh, for bringing some clarity to this new discussion. And, as you point out, this is not just a Monaco problem, it is an industry wide problem. We are no longer talking about the trailing arm issue on RR4R coaches, but a whole different topic, and one that is real and much more widely spread, though perhaps not as troublesome. I think this rear axle overloading problem needs some discussion in it's own right, so I'm going to take a chance and start a new thread here with Moisheh's astute observation.

Case in point... My Dip is a 41' coach with no tag. With full cargo, fuel, and fresh water, and nothing in the waste tanks, there is about 20,800 pounds on my rear wheels, with an axle rating of 19,000 or 20,000 pounds. My coach not only has Corian counters everywhere, but it has real stone tile floors covering at least 60% of the coach. It is beautiful to look at, but I didn't ask for that with my 2-axle Dip. It was just there. I can't even imagine how much weight that tile floor must add. Not to mention that the coach actually needs a heavy 400 hp ISL engine to comfortably push all that weight around.

I realize that 800 pounds only overloads the axle by about 4%, but it does beg the answers to a few questions:

1. Is this rear "overload" situation actually causing problems with the axle that have been experienced? Like Moisheh says, you don't hear about any.
2. If not, is there a potential for problems, assuming adequate tire pressure is maintained? Or is the leeway in the quoted rating great enough to safely absorb another 5-10% of weight in the rear.
3. Should the axles be improved or altered in such a way as to qualify for a higher weight rating without adding a tag. And how practical would that be?
4. And lastly a more philosophical question... Do we actually need all that weight to sell motor homes, or should the manufactures do away with things like "tile floors".

[Sixpack98]

Quote:

Originally Posted by Robin_M Exactly! Thank you, Moisheh, for bringing some clarity to this new discussion. And, as you point out, this is not just a Monaco problem, it is an industry wide problem. We are no longer talking about the trailing arm issue on RR4R coaches, but a whole different topic, and one that is real and much more widely spread, though perhaps not as troublesome. I think this rear axle overloading problem needs some discussion in it's own right, so I'm going to take a chance and start a new thread here with Moisheh's astute observation. Case in point... My Dip is a 41' coach with no tag. With full cargo, fuel, and fresh water, and nothing in the waste tanks, there is about 20,800 pounds on my rear wheels, with an axle rating of 19,000 or 20,000 pounds. My coach not only has Corian counters everywhere, but it has real stone tile floors covering at least 60% of the coach. It is beautiful to look at, but I didn't ask for that with my 2-axle Dip. It was just there. I can't even imagine how much weight that tile floor must add. Not to mention that the coach actually needs a heavy 400 hp ISL engine to comfortably push all that weight around. I realize that 800 pounds only overloads the axle by about 4%, but it does beg the answers to a few questions: Is this rear "overload" situation actually causing problems with the axle that have been experienced? Like Moisheh says, you don't hear about any. I think Moisheh is correct, you don't hear of any axle failures, or at least I have not heard of any. It sounds like there is a great deal of "fudge" on the weight capacity of any given axle or maybe there are other factors that impact the rated capacity. I read somewhere that MH's are relatively easy of drive train and other suspension components. They are driven mostly on-road and not subjected to the shock most utility vehicles experience, whether it be the road environment or the shock of extra weight suddenly loaded a dump truck or a trailer being hooked up. If not, is there a potential for problems, assuming adequate tire pressure is maintained? Or is the leeway in the quoted rating great enough to safely absorb another 5-10% of weight in the rear. There must be other factors that impact the rated weight capacity of any given axle, such as shock as mentioned above. Should the axles be improved or altered in such a way as to qualify for a higher weight rating without adding a tag. And how practical would that be? Monaco did change the rear axle '08 or '09, increasing it to 21k lbs. They also added a tag axle to the Dip and End line. At this point I don't think it cost effective to swap out my Dana 19k lbs axle. It would probably be cheaper to trade coaches and take the depreciation. LOL And lastly a more philosophical question... Do we actually need all that weight to sell motor homes, or should the manufactures do away with things like "tile floors". Probably not but it sure is nice. I don't think the Marketing group would let them get rid of all the bells and whistles, it helps sell coaches. Or, at least, it did until the down turn. I think slides have also bulked up coaches, probably as much or more than washing machines and tile floors. I think Monaco realized all the goodies being added was pushing the envelop of the 19k axle and went with the 21k axle and are now offering the tag axle. I suspect the 40' MH with a single axle will fade into the sunset.

Just my opinion.

mark

[Jim Stewart]

There is also that pesky little regulation that eliminates the exemption on October 1, 2009 for over-the-road busses (what is what a Diesel Pusher MH is) with axle loads over 20,000 Lbs. Legally, many will be overweight by law on October 1st.

[Sixpack98]

Quote:

Originally Posted by Jim Stewart There is also that pesky little regulation that eliminates the exemption on October 1, 2009 for over-the-road busses (what is what a Diesel Pusher MH is) with axle loads over 20,000 Lbs. Legally, many will be overweight by law on October 1st.

Jim,
Will this eliminate the grandfathered GAWR? The current USDOT regulation says 20,000 for single axle unless grandfathered by individual states? Or is it some other equally obscure regulation?

[Jim Stewart]

The "grandfathered" exemption expires on October 1, 2009. This timed expiration was in the regulation that granted the original exemption.

[Ed S]

ok, so with that said, are you suggesting we will have to stop at the scales after Oct 1???

[Jim Stewart]

Nope, you do not have to stop now, I doubt you will have to stop then.

Just an interesting note. It's seems that MHs had an exemption with the "over-the-road" bus definition that will no longer exist. I do not think they will actually start making MHs stop. It will cause the manufacturers to pause when shipping units that will be over the 20,000 axle limit out the door.

There is an implied intended use warranty that is enforceable in most State courts. If you have "X" amount of cubic feet of storage and "Z" amount of capacity in holding tanks, that you would expect to be able to use your loaded coach without breaking any laws!

[Robin_M]

Jim,

In my opinion, BOTH of the statements in your last post make a lot of sense. I don't think existing 2-axle motorhomes pose a lot of threat to their owners either from a hazardous or a regulatory perspective, when the rear axle weight is just a few percentage points over the rating. However I agree that the expiration of the MH and bus exemption may give the manufacturers pause.

How do you think the manufacturers will react to the "problem"?

[Jim Stewart]

In the future, 2 axle MHs will be less than 40 ft., currently, several manufacturers have models up to 43 ft on 2 axles. They will limit the number of slides in the shorter coaches, one manufacturer currently has 6 in a 39 ft coach. They will use lighter materials and fewer options. I also think you will see a return to tags on 38-40 ft luxury coaches.

[Sixpack98]

Quote:

Originally Posted by Jim Stewart There is an implied intended use warranty that is enforceable in most State courts. If you have "X" amount of cubic feet of storage and "Z" amount of capacity in holding tanks, that you would expect to be able to use your loaded coach without breaking any laws!

The gotcha here is "enforceable in most State courts". I understand that the chances of getting stopped and weighed are slim. However, if it does happen and you are over the 20k lbs limit wont the weight enforcement group fine you and not allow the coach to be moved until you shed some weight? This could happen until the courts hear the case(s) and issue a waiver for MH's or grant overweight permits for those that apply.

I agree with your statement about tag axles on most, if not all, 38 to 40 ft coaches. The next gotcha could be the USDOT bridge weight formula and the distance between the wheels in tag axles. In some cases tags with less than a certain distance are considered a single axle in terms of weight. Don't know how that impacts MH's since I don't know the tag spacing on a typical coach. Hopefully, the MH manufacturers will consider this but unlikely they will.

[Flagelpater]

Just playing "Devils Advocate" here.

A Dump Truck comes unloaded, Empty Compartment, the loading within limits is the responsibility of the operator.

The Operators Manual, My Manual, says to Not drive without first emptying the Black Tank. It also says to flush the hose with the Gray Tank after dumping the black.

Also, with respect to the distance between the Tag and Rear Axle, wouldn't this be with respect to the damage that could be done to the road surface? I think the distance between the Tag and Rear Axle is relevant to the amount of weight that is going to be transfered to the Front Axle. The distance between the Front and Tag relative to the Main determines the mechanical advantage of the fulcrum.