Wandering, sway bars, alignment, ride height, oh my!!

[crah]

Originally Posted by jimkate

I understand. But before you spend a lot of money and do a bunch of work and/or make some serious changes, let me know what you're thinking of doing.

I've probably done it already, to no avail.

jimkate,

My next focus is on the tires. What tires do you have? I may have already asked you that in a previos thread.

I would still like to get this alignment situated though.

[Vanwill]

I think Jim (JimKate) has kindly summed up something that another poster more condescendingly suggested we were all guilty of—trying the same things over and over. Just about anything you’ve ever heard suggested as a possible cure has been tried…multiple times by multiple owners. And even in the cases of the RARE success, the “fix” that brought success to ONE member was the same thing that THREE others tried to no avail. Read every post you can find on every forum you can find for months...like I have. If there was a common denominator, a SILVER BULLET, someone would be selling it for an outrageous (but perhaps justified) profit. So, I’d say there is a really good chance no statistically significant number of owners will cure their problem with: Tires, Caster, Toe-In, Ride Height, Shock Absorbers, King Pin Replacement, Steering Stabilizer Devices, Steering Gear Adjustments, Tie Rod or Drag Link End Replacement, Lubrication, Wheel Bearing adjustment, Air Bag Replacement, Driving Techniques and so on, ad nauseum. After reading hundreds of posts, I’ve come to only a few conclusions.

1) Longer coaches consistently suffer less severe problems than shorter ones. But think about it, why SHOULDN’T that be true? If you are having trouble controlling the FRONT end of a vehicle, the closer the rear axle is to the front one, the worse the reactions are going to be.
2) The wandering problem is much more common in air-bag suspended coaches.
3) Wandering is nearly as common in new or very nearly new coaches as it is in twenty year old ones, so “fixing” worn parts probably is not going to help.
4) Tag axle coaches just DON’T wander.
5) Any change made to a coach to remove all possible play in its steering mechanism and linkage is likely to mitigate the problem. Likewise, any modifications that “stiffen” the suspension will likely mitigate the wandering. But “mitigate” is all it does. The owner can tell the “wander” is still there…just less of it. We have been treating the symptom…not the cause.

I have a theory grown from all the reading I have done, and from my own experience with a wandering 93 Dynasty. I think the problem cannot be easily fixed because it is not a matter of REPAIRING or ADJUSTING anything. The problem is that the design of the suspension/steering system is prone to wandering BY DESIGN. PERIOD. So any cure to the problem is going to be one that basically changes the way the suspension operates.

Some of you readily admit that you are not very mechanically inclined. Your input is just as valuable as those who think they are master mechanics. The data from those of you who have tried something that failed is just as valuable as that from those who tried something that “sorta” worked. But for those of you with some mechanical abilities and experience, I challenge you to do this—“think outside the box”. As our one brash poster suggested, why keep trying things that fail? Look at the suspension and the way it works. Note that it is an H-frame supported at four points…SUPPORTED by air bags and shocks, but not GUIDED by them. And the job of the front suspension is not just to “suspend” but to “steer”. Look at where the rigidity comes from, of that portion of the suspension which is used to steer the vehicle. Remember that if the part of the suspension that steers the vehicle is “rubbery”, then that is exactly the way the vehicle is going to “feel” going down the highway.

Does it sound like I have an idea for a solution? Yes, I do. I don’t care to disclose it at the moment and have to deal with flamers and nay-sayers. Only two people on this forum know what I’m thinking. (Be quiet, you two!) But I am working on fabricating the parts for the possible solution I want to try. It will probably be six weeks before I get to try it out, but I promise that when I do, you will hear about it. You will hear about it if it is an unqualified success. You will hear about it if it is a total flop.

In the meantime, those of you with mechanical abilities and experience—think outside the box. Forget “tweaking” small things. Look at the suspension DESIGN and see if you can find a reason it might not be rigid and stable like it should be. I’d like to hear your thoughts. And if I disagree with your thoughts, I’ll tell you WHY. I WON’T try to belittle you, your intelligence, or your abilities. So, if you have an idea that has not already been tried, let’s hear about it!

I’ll give you a clue as to what I’m thinking—there is a reason why some members have had miraculous results from adding sway bars…and for others they were just a waste of money. And it has little or nothing to do with preventing “sway”.

Van W. 93 Dynasty pulling one Harley

[crah]

Originally Posted by Vanwill

I think Jim (JimKate) has kindly summed up something that another poster more condescendingly suggested we were all guilty of—trying the same things over and over. Just about anything you’ve ever heard suggested as a possible cure has been tried…multiple times by multiple owners. And even in the cases of the RARE success, the “fix” that brought success to ONE member was the same thing that THREE others tried to no avail. Read every post you can find on every forum you can find for months...like I have. If there was a common denominator, a SILVER BULLET, someone would be selling it for an outrageous (but perhaps justified) profit. So, I’d say there is a really good chance no statistically significant number of owners will cure their problem with: Tires, Caster, Toe-In, Ride Height, Shock Absorbers, King Pin Replacement, Steering Stabilizer Devices, Steering Gear Adjustments, Tie Rod or Drag Link End Replacement, Lubrication, Wheel Bearing adjustment, Air Bag Replacement, Driving Techniques and so on, ad nauseum. After reading hundreds of posts, I’ve come to only a few conclusions.

1) Longer coaches consistently suffer less severe problems than shorter ones. But think about it, why SHOULDN’T that be true? If you are having trouble controlling the FRONT end of a vehicle, the closer the rear axle is to the front one, the worse the reactions are going to be.
2) The wandering problem is much more common in air-bag suspended coaches.
3) Wandering is nearly as common in new or very nearly new coaches as it is in twenty year old ones, so “fixing” worn parts probably is not going to help.
4) Tag axle coaches just DON’T wander.
5) Any change made to a coach to remove all possible play in its steering mechanism and linkage is likely to mitigate the problem. Likewise, any modifications that “stiffen” the suspension will likely mitigate the wandering. But “mitigate” is all it does. The owner can tell the “wander” is still there…just less of it. We have been treating the symptom…not the cause.

I have a theory grown from all the reading I have done, and from my own experience with a wandering 93 Dynasty. I think the problem cannot be easily fixed because it is not a matter of REPAIRING or ADJUSTING anything. The problem is that the design of the suspension/steering system is prone to wandering BY DESIGN. PERIOD. So any cure to the problem is going to be one that basically changes the way the suspension operates.

Some of you readily admit that you are not very mechanically inclined. Your input is just as valuable as those who think they are master mechanics. The data from those of you who have tried something that failed is just as valuable as that from those who tried something that “sorta” worked. But for those of you with some mechanical abilities and experience, I challenge you to do this—“think outside the box”. As our one brash poster suggested, why keep trying things that fail? Look at the suspension and the way it works. Note that it is an H-frame supported at four points…SUPPORTED by air bags and shocks, but not GUIDED by them. And the job of the front suspension is not just to “suspend” but to “steer”. Look at where the rigidity comes from, of that portion of the suspension which is used to steer the vehicle. Remember that if the part of the suspension that steers the vehicle is “rubbery”, then that is exactly the way the vehicle is going to “feel” going down the highway.

Does it sound like I have an idea for a solution? Yes, I do. I don’t care to disclose it at the moment and have to deal with flamers and nay-sayers. Only two people on this forum know what I’m thinking. (Be quiet, you two!) But I am working on fabricating the parts for the possible solution I want to try. It will probably be six weeks before I get to try it out, but I promise that when I do, you will hear about it. You will hear about it if it is an unqualified success. You will hear about it if it is a total flop.

In the meantime, those of you with mechanical abilities and experience—think outside the box. Forget “tweaking” small things. Look at the suspension DESIGN and see if you can find a reason it might not be rigid and stable like it should be. I’d like to hear your thoughts. And if I disagree with your thoughts, I’ll tell you WHY. I WON’T try to belittle you, your intelligence, or your abilities. So, if you have an idea that has not already been tried, let’s hear about it!

I’ll give you a clue as to what I’m thinking—there is a reason why some members have had miraculous results from adding sway bars…and for others they were just a waste of money. And it has little or nothing to do with preventing “sway”.

Van W. 93 Dynasty pulling one Harley

Interesting take and good summary. Looking forward to your development.

[crah]

Another observation perhaps others can use. I mentioned this in a previous thread but did not get much of a response. On some of the sway bar users with success (mostly the longer coaches) the front sway bar arms face forward. My sway bar arms face back towards the rear of the coach (due to the air tank being in the way). I questioned to myself on how effective this would be as it felt backwards. It seemed like if one was welding something and installing a gusset upside down.

[Papa_Jim]

,

Originally Posted by crah

jimkate,

My next focus is on the tires. What tires do you have? I may have already asked you that in a previos thread.

I would still like to get this alignment situated though.

The previous owner had installed a Goodyear brand tire. I changed them for Dunlop tires. This had absolutely no affect on the wandering situation.

Tire pressures, low, high or anything in between have absolutely no affect on the wandering situation.

I have had alignments done, minimum caster, maximum caster, 1/8" toe in, and believe it or not, 3/4" toe in, and finally 1/16" toe in. None of this had any affect on the wandering situation.

The 'excessive wandering' thread made me finally realize that none of these things has anything to do with this wandering situation. I believe that it has to be a serious structural design issue.

[VanDiemen23]

anti-roll bar installation direction does not matter. The direction they point is a matter of packaging - the location of the best mounting points combined with the best location and easiest connection for the vertical links. On my race cars I have U-bars that face forward, back, up, T-bars, torsion bars between the pivot axles of two a-arms, you name it. It's whatever works.

So in that Carroll Smith guide I posted:

"4) Loose or broken chassis member or suspension link mounting point - probably the most likely"

Now an 8-bag setup doesn't have a lot of controlled attachment between the subframes and the house - just the air bags (which squirm) and the rubber bushings on the shocks (that also squirm, and aren't designed to take a lot of side load. So it's likely that it acts like a regular suspension system with a couple of bad bushings.

So an appropriate fix to add rigidity without sacrificing a lot of ride quality would be to add panhard bars both laterally and longitudinally between each subframe and the house.

I'd guess the bars ought to be as long as possible with as much freeplay in the vertical dimension, and as little freeplay in the horizontal as possible.

[crah]

Originally Posted by VanDiemen23

anti-roll bar installation direction does not matter. The direction they point is a matter of packaging - the location of the best mounting points combined with the best location and easiest connection for the vertical links. On my race cars I have U-bars that face forward, back, up, T-bars, torsion bars between the pivot axles of two a-arms, you name it. It's whatever works.

So in that Carroll Smith guide I posted:

"4) Loose or broken chassis member or suspension link mounting point - probably the most likely"

Now an 8-bag setup doesn't have a lot of controlled attachment between the subframes and the house - just the air bags (which squirm) and the rubber bushings on the shocks (that also squirm, and aren't designed to take a lot of side load. So it's likely that it acts like a regular suspension system with a couple of bad bushings.

So an appropriate fix to add rigidity without sacrificing a lot of ride quality would be to add panhard bars both laterally and longitudinally between each subframe and the house.

I'd guess the bars ought to be as long as possible with as much freeplay in the vertical dimension, and as little freeplay in the horizontal as possible.

If I'm following you correctly, you are stating the direction of the u in the sway bar does not matter? I would think it would have better leverage near the ends of the frame compared to the middle. I may be off base but just asking. The rear sway bar connects the floating h frame to the house from the front of the rear axle to the rear house portion behind the axle. The front sway bar connect to my front axle (not the floating h frame) and faces back towards the middle of the coach and connects to the house behind the front axle.

As for you panhard suggestion, obviously they would have to be custom made for diesel pushers and placement would make more sense near the ends of the coach and not in the center. Again I may be wrong on all this but just trying to make sense of it all.

[crah]

A panhard bar design that could travel when airing down the airbags would be an interesting design challenge I would think.

[Happycarz]

The RR8S H frame is connected to the chassis via a 5 link system, including a Panhard bar, not just airbags and shocks.

[crah]

Originally Posted by Happycarz

The RR8S H frame is connected to the chassis via a 5 link system, including a Panhard bar, not just airbags and shocks.

Happycarz

Do you know if the longer rr8 chassis have more links than the shorter ones? Any change or location in the panhard bar? I will have to map mine out this weekend.

[nodine]

Originally Posted by crah

Happycarz

Do you know if the longer rr8 chassis have more links than the shorter ones? Any change or location in the panhard bar? I will have to map mine out this weekend.

The guys at Source have suggested to me that the panhard bars must be parallel to the ground when the coach is level and at ride height. Jim said some Monaco coaches experience bump steer because the panhard bars are not level when the coach is at ride height.

Bob

[walt2137]

Crah I see that the alignment has been covered but have you thought about your steering box it should be a Shepard M100PLG3, I had a 99 diplomat with the same wandering problem that had a Shepard M80 gear box the only thing that helped was the BlueOx Trucenter steering control our Dynasty does not have that wandering problem. On Tires I am running the 11R with no problem another advantage with this tire its easy to get a replacement on the road if needed. On the Ride height I show the 03 Scepter ride height at 9.25 and 10.5. Good Luck!

[sc3283]

I have watched this from the beginning and feel for you. I will say not to exclude tires.
I say this due to 30+ yrs in auto repair industry and handling issues with some cars and due to real hand experience with my 36' Dynasty. My Dynasty when buying last fall had perfect looking Bridgestones that were 10 yrs old. It did wander a bit and I was more comfortable being a 2 handed driver. This spring I replaced the Bridgestones with Firestone FS560+. The vehicle is a TOTAL different vehicle. Ride is far less harsh, and I can comfortably drive with 1 hand. So tires can make a major difference. (I don't work for Firestone and have NO gain in discussing Firestone except for my love to drive my RV now with them). Watching tire threads and having had a few GY brand tires in my past...If your coach was mine...frt tires would be swapped and not to a GY or Dunlop(GY owned) nor some chinese brand

[crah]

Originally Posted by walt2137

Crah I see that the alignment has been covered but have you thought about your steering box it should be a Shepard M100PLG3, I had a 99 diplomat with the same wandering problem that had a Shepard M80 gear box the only thing that helped was the BlueOx Trucenter steering control our Dynasty does not have that wandering problem. On Tires I am running the 11R with no problem another advantage with this tire its easy to get a replacement on the road if needed. On the Ride height I show the 03 Scepter ride height at 9.25 and 10.5. Good Luck!

Walt I am familiar with the Shepard box and I do not have that unit in my coach. I have the trw. That is correct on the ride height spec from Monaco. Unfortunately I have tried it for many miles with no change and that spec creates a giant void in my wheel wells that just does not look right. My current ride height is 9 in the rear an 8.75 in the front. There was no difference in the handling.