Community Forums

Crasher · 12-15-2013, 01:09 PM

I'm no expert on chassis or suspension design, but I have proven to myself, at least, that ride height has a great deal to do with what each corner is carrying. When I took delivery of our 43' MH w/tag axle, I began to suspect a difference of weight between the steer tires. The TPMS would consistently show a faster pressure increase for the right tire. Upon getting a six position weigh, I found that the front right was carrying 8200# and the left near 7000#s. the left rear dual was also 1400#s higher than the right dual. It was all caused by the left rear ride height being almost 3/4" higher than required. Our coach has four ride height valves. Another six position weigh after the height adjustment has the front tires within 150# of each other and the rear left is only 700#s more than the right. A 500# difference is considered acceptable for the front and 1000# difference is the rear limit. On a coach of this size, the distribution of weight in the basement is insignificant to the overall balance of the coach.

FWIW, I have also replaced the auto proportioning valves with manual regulators to be able to lighten the load on the steer axle and get the drive axle up where it should be. The end result of everything I have done is a very well balanced and safe coach with a supurb ride.

TQ60 · 12-15-2013, 02:15 PM

If a single air bag is running higher ride height then it is trying to lift more of the coach.

To prove this take a chunk of 2 x 6 about a foot long and put equal count of coins under each corner to support it on a table.

Say 6 pennies on each corner.

So the weight should be about the same on each.

Now add just one to any corner.

The weight is now on two corners.

The air springs will keep the tires on tye ground but one of the heavy corners MAY have ride height valve out of adjustment.

If air leveling then each corner has valve.

ahicks · 12-15-2013, 06:33 PM

Quote:

Originally Posted by targaboat

My last diesel MH had springs along with supplemental air springs. That would easily justify the readings the OP made. I like the post that suggests that one needs to understand the whole system.

Now, time for my nap, have fun.

The OP's coach is on air bags. Regarding corner weights, it absolutely does make a difference if one is running a lower or higher pressure than it should be, for whatever reason.

First you make light of the OP's concern, then, after accusing somebody of "over management" and basically no comprehension of the subject at hand, it would appear the person without comprehension is you?

Now, rather than explaining yourself, you issue a statement about nappy time?

I think you owe somebody an apology....

gemini5362 · 12-15-2013, 07:13 PM

I am glad so many people are worried about early tire wear out. Most of the people I see talking about tires talk about them having to be replaced because of age. I know that is why I replaced the front two on my unit when I bought it. They had about 30,000 miles and not much appreciable wear. I guess the previous owner probably weighed each individual tire every 3rd Tuesday of the month and had a sophisticated program that kept track of everything in the cargo area and had it all weighed to the individual gram and variable gram weights to add to make sure everything was balanced. I imagine he kept the tanks empty when he traveled and only drove 5 maybe as much as ten miles between service stations and filled up until diesel was coming out of the filler spout every time he stopped. He lived in Hot Springs, Arkansas which has a horse race tracker so he probably had the official from their way all passengers and add weight to the chairs or sofa to make sure that everything was balance.

Of course he might have done what I do which is just basically put diesel in and drive it. If my tires only last for 6 years instead of 8 I will just buy new ones and regret not taking better care to balance the loads better

targaboat · 12-16-2013, 08:08 PM

Yes, I owe some on here an appology. Others ??

I still stand on the following: Check and adjust the ride height if necessary to make match the factory specs. Also, if your axles and tires are within their rating, then go drive and enjoy your unit.

If you are having to discuss the situation on the Forum, you need to take your unit to a service center for you really do not have the knowledge to do your own work.

ImagineIF · 12-16-2013, 09:29 PM

Just a few things.

-- Tire pressure should be the same on all tires on the same axle.
-- MINIMUM tire pressure is set by the tire manufacturer and is based on the heaviest wheel position on the axle.
-- Tire pressure guages may or may not be accurate.
-- There is no reason why you can't run with more tire pressure than the weight would recommend as long as you don't exceed the maximum pressure. The only potential down side is the center if the thread may wear sooner than the outter thread.
-- Underinflation is dangerous, tire heat increases, excessive strain is placed in the sidewalls, most blow outs are due to underinflation.

Given this information, you might want to do as I do. I inflate my tires 10 psi iver the minimum recommendations. I have a Matco DT-4 tire pressure gauge and I personally checked its calibration. Any tire shop should let you check your gauge.

ahicks · 12-17-2013, 07:12 AM

Quote:

Originally Posted by targaboat

Yes, I owe some on here an appology. Others ??

I still stand on the following: Check and adjust the ride height if necessary to make match the factory specs. Also, if your axles and tires are within their rating, then go drive and enjoy your unit.

If you are having to discuss the situation on the Forum, you need to take your unit to a service center for you really do not have the knowledge to do your own work.

Wow, you really are a fountain of information aren't you? You actually believe what you just wrote? You visit forums like this one because you already know everything about topics you visit/are being discussed? You don't visit to learn something new on occasion? Or share something you know with somebody struggling for a basic comprehension?

MANY of us are quite capable of picking up enough information through an INTELLIGENT conversation, one that "supports a thoughtful exchange of knowledge, values and experience" (see the top of the page) to effectively trouble shoot or work on many problems encountered in systems we may not have a basic understanding of going into it? If nothing else, it may develop a level of understanding that might help prevent being ripped off if we decide to get the repair work done?

Bashing somebody trying to develop knowledge is counter productive. All that will lead to is people afraid to write and ask questions for fear they'll be stomped on by some wannabe pro. Enough of that, and you have a failing forum. Not exactly in the best interest of all involved.

The same goes for those expressing ideas/concepts we might not agree with?

I'm sorry. I see stuff like this happen and it irritates the heck out of me - this time to the point I had to say something. -Al

BFlinn181 · 12-17-2013, 09:15 AM

To jimbo2013, (the OP) I hope when all the smoke clears you will pay attention to the facts, not the fiction and hyperbole. If you don't notice any leaning or sagging, your ride height may be O.K. I'd cut a dowel or stick to correct height, go park on a level, hard surface and check it anyway. It would take a noticeable lean or squat to influence your weights like you had. While the pennies and a board was a nice illustration, no RV has a frame stiff as a board, it would take major differences to cause such imbalance. If ride height is O.K. or adjusted, check compartments, cupboards and closets for any gross overloading or concentration of weight in one area or side. NOW you are ready for a return to the scales. If measures don't add up, question the scale operator and ask to try again. Once you have reasonable, averaged weights, adjust tire pressure to the higher weight/pressure recommendations for each axle. Drive and enjoy. There will be no disaster if a 50 lb kid or dog moves from one side to the other.

targaboat · 12-18-2013, 06:29 AM

ahicks, here is a web site with lots of info on RV upkeep you might be interested in.

Care | Dicor Products | Official Website

The OP has received several valid answers to his tire inflation problem so we , the forum has full filled that mission. The answers to the load distribution answer is where he received way too many answers some of which are wrong. My concern is how is he to sort all of that out and arrive at a correct solution. My answer to that is take it to a professional of find a private person whom he trusts know the correct answers.

I sincerely hope this clears up your confusion.

ahicks · 12-18-2013, 07:21 AM

Thanks for the link targaboat. Not sure how any information supplied within that link is relative to the subject at hand, but nice of you to be so helpful?

As an ex RV service manager in a largish RV dealer for 19 years, pretty familiar with RV maintenance. However, I don't know everything there is to know! I'm willing to listen to new ideas, and enjoy discussing those I find interesting in an intelligent manner. I'm also generally capable of sorting the wheat from the chafe when collecting information I'm looking for - just like the majority of the people participating in these forums?

That said, my point has been made. I won't bore anyone following this further. -Al

jimbo2013 · 12-18-2013, 10:07 AM

Not confused I'll re-weigh it again with some of the advise I received here and report back.

Shoptech · 12-18-2013, 10:27 AM

Working as a technician at Henderson's Line-Up, I have weighed a few(hundred) coaches with and without air suspension and ride height and leaning definitely affect weight distribution (transfer). However I have seen many coaches with diagonal weight differences even with proper ride height. I would verify ride height adjustment and relocate compartment loads according to the weights and then simply use the heavy side of each axle to determine tire pressure.

Kuzzy · 12-18-2013, 11:18 AM

Quote:

Originally Posted by jimbo2013

Not confused I'll re-weigh it again with some of the advise I received here and report back.

As a quick note here. When you put your front axle on the scale and stop, put the transmission in neutral then release your brakes. This will unload the suspension and the weights should change slightly. Be careful not to roll while reading the weight. Do the same with the rear.
Cheers
Dave

targaboat · 12-18-2013, 11:42 AM

Does anyone know the exact configuration of the OP's coach? I have owned two DPs with air ride. One was a heavier coach, more the age of the OPs coach and it had three vales, two on the rear axle and one on the front. That means that the rear valves set the roll angle and the rear height. The third valve supplied the two front bags which control the front height. Since each front bag has the same air pressure the loads on the front wheels would be equal. It had independent front suspension. This would also mean that loads on the rear tires would be a function of the weight locations within of the coach.

The second coach was almost identical in size, weight and power of the OP coach. It also had air suspension and between rest and travel mode height deference was about 4 inches. It had a solid front axle. It also had in front steel springs which was supplemental to the air bags. I have no idea what it had on the rear for springs beside the bags. I also do not know how many air valves there were since I never did any work on that area of the coach. However, with the combination of front springs, bags and leafs, there was no way any of the loads on the tires could be equal.

Does anyone on here know the exact configuration of the OP's coach? With this detail we can give real meaningful detail of what the OP should do from here on his situation.