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

[crah]

Originally Posted by VanDiemen23

Caster is self-centering and too much contributes to phase lag in steering. Toe in creates straight line stability while toe out creates instability (quicker response to turn-in).

When I got my beaver it had 15 degrees of caster - so much that the shop couldn't fix it in the time allotted by my appointment, I had to bring it back. What the excessive caster was doing was making my directional changes significantly lag the stimuli I was trying to correct for - "chasing my tail".

After taking the excessive caster out and putting on a saf-t-plus (which provides a significant centering force from the two springs) the majority of my wander went away.

I have a 30'DP which doesn't have enough weight on the nose and is susceptible to weathervaning. What I've learned with race cars is the manufacturer's specs are just a starting point. Everything else is what works for you. There are no disasters here except for tire wear.

In your case I'd reduce caster and add toe. As far as wind is concerned, the higher the coach is the worse off you are, so lowering the coach might be a good start. to get more weight on the nose, lower the front or raise the rear. Since these are solid axles, playing around with ride height doesn't affect the alignment and can be adjusted in your driveway via the air bag linkage. Just measure and take good notes so you can go back to the beginning.

Sway bars - well on a vehicle with solid axles and air bags, I'm not sure they are doing much for you. their job is to resist the roll and put weight on the uphill side, but there's no compliance in the suspension, and the air bags oare trying to compensate anyway. I'm not saying they don't work, but they induce other characteristics. I'd take one of the links off and try to get it right again with alignment and ride height, and add the bar later.

By the way, a front bar induces oversteer and a rear bar induces understeer, all things being equal. When you do an alignment, especially with corner weights, you need to disconnect the sway bar. when you hook it up at the end, it should not be pre-loaded. If it is, either the bar is bent or something is very wrong.

Thanks for the input. As for the caster recommendation to reduce, how would you know I have too much caster? You may be right but don't understand how you could guess. 15 degrees of castor seems pretty extreme and probably even be visible looking below. I will find out my before settings. As for your take on the sway bars, the air bags diesel coaches don't come with sway bars as you already know. However their are a select few Monaco rr8 chassis members that have them with significant highway handling improvement. Most air ride diesel coach owners can't buy sway bars as it's not a common off the shelf item. As for the preload, etc I will make sure all adjustments are made during the alignment. I plan on being there the whole time. I did have preload on the fronts when I installed them as my driveway leans a bit. I pulled one side of the bar down with good might and installed the bolt. The test ride made no difference at all though. I will have the shop check everything. Again thanks for your insight. I've researched all reasonable solutions and am empty handed at this time.

[crah]

Originally Posted by nodine

I am still thinking the steer tires may be your problem. I would go with a 275 if it will work on your rim. I once traded a dually truck for a brand new dually truck. Same brand, just went to a newer model. The old truck drove like a dream but the new one wandered and drove me crazy. I took it back and they said the alignment was to spec. Long story short, after a few weeks it stopped wandering. My guess is it was the front tires and they finally wore to a good track. Don't forget to check the torque on the front wheel bearings.

I almost forgot. If your rear tires have much flex in the side wall that will cause a tremendous affect on the front. The heavy engine out back will move from side to side causing a force to be applied to the front. You will have to compensate by moving the steering back and force which just makes things worse as that force gets transmitted back to the rear and here we go again. I do remember you said your tires had a lot of sidewall flex.

Bob

Bob

It may very well be the tires. With my luck it will be the last item I end up working on. The tire size I have on there already is the 275/79/22.5 which matches what size came stock. I planned on upsizing to the 295/80/22.5 or 11rs. Not sure how much difference is in size with the 11rs. The local tire shop only has 11r on Bridgestone.
You are right on the side wall flex. It may be normal and may not. I have no way to compare unless someone here wants to give their coach a back and forth push near their entry door and see how much their sidewalls flex. The current tire has a 2008 date code and are the Goodyear g168 rsa load range h tire. I'm not quite certain how many plys they are but I believe they are true Long haul tires. That will be my next move if this fails.

[crah]

Wow couple of typos above. Tire size is 275/70/22.5 and Goodyear g169 rsa. Darn smart phones.

[JimM68]

Screw the smartphones.

Change the front tires

You've put up with this for far too long....

Bearing in mind my daily driver is a wrangler tj.....
And my previous moho was an f53....

My 08 knight is smooth, easy, and relaxing. Much more pleasant to drive than my jeep. Night and day compared to the ferd moho....

Keep at it, u can doit....

[rpasetto]

Crah, Two suggestions: Call Monaco Tech Support and ask for ride height specs again. Give them your coach # and if they respond with specs different from the manual ask for an explanation. Do same with alignment specs. It could be the manual is in error.... could be that Monaco revised alignment specs for the RR8S chassis your coach rides on. (By the way, we also tow an Enclave).

Good luck.

Secondly, make sure you get a "complete" alignment ... steer and drive axle, to be sure.

[Coached]

After three alignments what makes you think it's the alignment? Take it on the road and let go of the steering wheel at speed - does it drive straight or wander? Easy way to rule out alignment problems. Put the right front steer tire on the left front and vice versa then try it. This will tell you pretty quickly if it's the tires? If they both check out then it isn't alignment or tires so save that money. I'd be checking all the mechanical parts at this point and the air suspension, especially the part that HR claims "automatically" adjusts ride height as you drive. I owned a coach on that chassis and you need a shop or Dealer that is familiar with the Roadmaster set up or is willing to work with Roadmaster (by phone?) while working on your coach. Make sure all components are tight and right in your steering components and axles. If you rule all these considerations out and still want an alignment make sure it includes "boxing" the frame ie. aligning the rear axle with the front to ensure the unit is actually tracking properly on the road. If the rear axle is out of line it will really mess up your driving.

[Automobilist]

I know how not fun a wandering coach can be.

To tag along with the good advice "VanDieman" and others made, make sure your tire pressures are dialed in.

Don't bother with a pressure gauge. Get a laser / infrared temp gauge. $50 or so at Sears, etc. Drive enough to get the tires fully warmed. Jump out and take heat readings as quickly as you can. Take readings three places on the tread; each outer point, and the center. If the center is hotter, lower the air pressure. If the edges are warmer, increase the air pressure. You basically want even temperature across the tire tread. (NOTE: RV's only, not generally suitable for race car set up...)

This method helped immensely with mine and other coaches I've helped with.

Ed

[crah]

Ok here is the latest update and I hope this answers most questions as well. My coach still wanders after my latest trip and alignment. I've listened to a lot of input from others and do appreciate the advice. Unfortunately the advice is all over the place and sometimes contradicting. I understand the problems of diagnosing a problem with someone else's coach through a forum. If I could make it clear that I am sincerely thankful for everyones input. I want to provide constructive feedback hoping it will help others that may be going through the same thing. One thing that I do realize is that there is no one answer to all wandering solution.

I had my coach aligned again on Thursday. To answer one posters question on why an alignment again is that I've never had a print out and had some doubts. What is the magic alignment spec? If it was so simple, you would think they would publish those specs. This time around, this shop let me stay in their pit during the entire alignment and watch and ask questions. The alignment tech seemed pretty experienced. The first thing he did was check the ride height at all 4 positions. He used a very large pair of adjustable channel locks and checked every suspension bushing for looseness. Then he finally lifted one steer wheel at at a time and checked for loose wheel bearings. Finally he set up his alignment gear at all 4 wheel positions and gave me a snapshot of the current alignment spec and gave me a rundown of what he wanted to change. I gave him my full history of the problems I was having and what he wanted to change didn't really match what I've been hearing from this forum. He wants the toe to be closer to neutral (maybe a 32nd). It was close to a 16th at the time. I told him should he toe be more closer to 1/8 and he said it will follow the ruts. He adjusted the passenger side caster higher close to 6-1/2 degrees and left the driver side cater at 5.1 degrees explaining they do this to adjust to the crown. (I may be off on those numbers a little). I have the printout in the coach that i will upload tomorrow. These adjustments made no noticeable difference to the handling. I already know many will chime in saying 1/8 tie in, etc, etc. I don't believe that will make a difference based on my experience so far. I would really like to see someone else's printout if anyone wants to volunteer. I will provide some more info and feedback tomorrow. As mentioned previously, tires will be my last resort but at this point my opinion is that it won't make a difference. I'm sure I can get the alignment guy make the alignment changes I originally suggested but what are the true real numbers?

[rpasetto]

crah, It appears you've had the alignment done. I see details of the front alignment records; and that the tech checked the ride height. Not sure what Monaco's specs for this coach are but, assuming that alignment is now "in spec", I can think of two things which may improve your wander situation:
1- If you have the steer tires swapped left-to-right and you notice a change in steering characteristics, e.g. a drift to the left becoming a drift to the right that may be indicative of a tire problem.
2- There's no mention about rear axle alignment; as a few others on this thread have suggested, a 4 wheel alignment is likely to help.

Good luck.

[ahicks]

crah, those specs sound like the ones used by some shops doing the Chev P30 (Gas!) MH chassis? Did you ask where he got them?

Now that you've had a chance to try his specs, with no difference, maybe you could ask that he try more toe in just for grins?

The 0 toe in theory is used on a lot of later model cars and pick-ups - it's about minimizing drag for increased gas mileage as I understand it..... I'm REALLY struggling to believe that 0 spec isn't going to to more inclined to follow the ruts more than one with 1/8" toe in...

[Coached]

somebody way, way smarter than me said something about the definition of insanity is doing the same thing over and over and expecting a different result? You keep trying an alignment without knowing that it's the alignment is my point? If you swap the steer wheels like I suggested you'll know right away whether it's tires and if you let the coach "steer itself" at speed you'll know if it's the alignment? There are many moving and fixed parts that are absolutely critical to drive style and I think they should all be eliminated or at least examined before continually trying to align your way out of this? At least this latest Guy checked bushings etc. - maybe you have a bad wheel or some other component? You stated that you 'already know' that swapping the tires won't make a difference? How do you know that or do you just want this to be an alignment problem, period? I've been here and done this and my coach is going back to Indiana next Monday so that Spartan can replace the steering box - one year after I started complaining about wandering, then it will be aligned again. No offence but an open mind is often allot less costly than an open wallet?

[greystroke]

Originally Posted by crah

I'll try to respond to all in 1 post.
greystroke-I had the Safe T Plus on the coach for a year. I took it off about a month or so ago. Made no difference at all.
.

Thanks a bunch. Saves a lot of money I was thinking about putting out.

I have a steering adjustment although I don't think anybody wants you to adjust it beacause it is not accessible without removing the generator. Friend down the street had the same chassis and he could get to his adjustment. He adjusted IAW AcccessFreightliner and it did not help his wandering.

So I can't wait for you to post your solution.

Just had a blowout on the front tires. They were steering tires. The new tires seem to handle a little better. Maybe my imagination.

[wetdog]

I had wandering problems. Tried alignment a couple of times, they didn't do the job. It was time to have front wheel bearings packed. I decided to change over to wet hubs. First trip out I noticed a difference in handling. It sure is nice to not have to struggle driving on the highway. The tech who did the switch told me that the right wheel bearing was a little loose. Hope this helps. later wetdog

[Papa_Jim]

I am now of the firm belief that this wandering problem cannot be solved with alignments and add on steering stabilizers. I believe that some Monaco coaches are built with a structural flaw in the floating frames that causes wandering. If you have one, hang on tight, cause it's never going to get better, cause no one, including Monaco, knows exactly what the problem is, or how to fix it.

I have personally exhausted all avenues in this regard. I followed a thread called 'excessive wandering' of a disappointed soul with a brand new Monaco that is wandering and, to date, Monaco and Josams cannot solve it.

I also read that the president of Monaco RV took his family on a trip in one of his company's brand new coaches, and he was very unhappy with the handling, saying that he couldn't lift one hand off the steering wheel long enough to have a drink of water.

So, we can take small comfort in the fact that we're not alone.