Is yawing or tail wagging normal for Class A mortorhomes? How much?

[John From Detroit]

Gary back in 2005 I was told here in this very forum to install a Rear Trac Bar.. Still I went with a Davis Tru-Trac FRONT track bar.

And I must say I'm very pleased with the result...    I do agree with you.. my "Common Wisdom" is simply what I was told, here, a decade ago.   

Fact: When I first drove Detroit to Lost Wages (2006 Jan) it was a relief to park the Motor home and drive the Chevy Lumina APV

Then I returned, had the trac bar and a Blue-Ox Tru-center installed over-summer and made the trip again about Thaniksgiving.

When I finally dropped the towed and drove it,, Man was that car hard to drive compared to the motor home.

Same Motor Home,, Same car,, Same driver.. Only difference was the Trac Bar and steering stabilizer.

So now you know why I recommend them.

 

[Gregg]

Sometimes I can over research something but did a little more reading on this site and back a few years ago there were a lot of responses that indicated the Safe-T-Plus was not as highly praised as it seems to be today.  Actually from what I read, a single track bar, either front or rear, but a few needed both was the recommendation.  Hopefully the change in Safe-T-Plus is more road proven experiences and not marketing.  I will try to keep an open mind and post back. 

 

[Gary RV_Wizard]

Gary back in 2005 I was told here in this very forum to install a Rear Trac Bar.. Still I went with a Davis Tru-Trac FRONT track bar.

And I must say I'm very pleased with the result...    I do agree with you.. my "Common Wisdom" is simply what I was told, here, a decade ago.

I think you could find an example of almost any advice here, John. Not sure that makes it "popular wisdom", though.  I know I've been promoting the front track bar for 15 years (since I installed my first one), but that was mostly because the Davis Tru-trak was the original, widely available device. The Supersteer rear track bar came along later.

I'm not arguing against track bars at all. Just questioning whether there is any consensus on this forum that rear is recommended vs front.

 

[Gary RV_Wizard]

I'm not a big fan of the Safe-T-Plus (and I have used one in the past) or the similar Steer Safe. Most of the reason is that people tend to install them for the wrong reasons. Its main function is that of a safety stabilizer for blowouts. Anti-rut tracking and yaw prevention are only incidental to what it does and (in my opinion) it has only a modest effect on them. If any.  Having installed one and being disappointed in the result, I set out to learn more about the causes of yaw and wheel rut-tracking. To me, it was evident that a steering wheel centering device was not going to address the fundamental problems, but a panhard rod would help a lot. The steer devices will, however, help with bump steer and blowout control, and thus have a value of their own.

You can make your own judgment now that you are installing a Safe-T-Plus, so I hope you will report back once you have some experience with it.

 

[Dragginourbedaround]

Sometimes I can over research something but did a little more reading on this site and back a few years ago there were a lot of responses that indicated the Safe-T-Plus was not as highly praised as it seems to be today.  Actually from what I read, a single track bar, either front or rear, but a few needed both was the recommendation.  Hopefully the change in Safe-T-Plus is more road proven experiences and not marketing.  I will try to keep an open mind and post back.

Gregg,
Before going the expensive route did you four corner weigh your rig and adjust the weight to try and even it out at all four corners? Did you adjust  the tire pressures to the mfg tire/psi tables, without adding any extra psi?

Might not work for your mh, but worked for mine and it saved me a lot of moola. 

 

[Gregg]

Gregg,
Before going the expensive route did you four corner weigh your rig and adjust the weight to try and even it out at all four corners? Did you adjust  the tire pressures to the mfg tire/psi tables, without adding any extra psi?

Might not work for your mh, but worked for mine and it saved me a lot of moola. 

Honestly no I have not.  Did set the tire pressure to what the supplier suggested but will check the manufacturer chart to make sure he did not make a mistake.  The interior upgrading is not quite complete so will have to wait on the weight balancing check.  Whew all of these variables is starting to take some of the fun out of RVing. 

 

[blw2]

I'm not a big fan of the Safe-T-Plus (and I have used one in the past) or the similar Steer Safe. Most of the reason is that people tend to install them for the wrong reasons. Its main function is that of a safety stabilizer for blowouts. Anti-rut tracking and yaw prevention are only incidental to what it does and (in my opinion) it has only a modest effect on them. If any.  Having installed one and being disappointed in the result, I set out to learn more about the causes of yaw and wheel rut-tracking. To me, it was evident that a steering wheel centering device was not going to address the fundamental problems, but a panhard rod would help a lot. The steer devices will, however, help with bump steer and blowout control, and thus have a value of their own.

You can make your own judgment now that you are installing a Safe-T-Plus, so I hope you will report back once you have some experience with it.

I have done a fair bit of research on this topic, not first hand experimentation mind you.... but researching online, discussing with alignment "experts", etc....
Gary, it seems that your advice of the panhard rod is very likely the one solution that most closely addresses the real problem that a lot of these coaches see....
BUT
in almost every case it seems to be the very last thing that anyone tries.... and even the one thing that never gets done.

I find this interesting that all of this is such a puzzle.

I sure do wish that  had the funds and the time to buy all three of the popular aftermarket solutions for my coach
and try them each individually to verify the results
(panhard rod, beefier sway bars, and steer centering device)

 

[Gregg]

TheNewhalls brought up a good point and missed his original post.  Thanks for reiterating it.  The tires that were installed actually were a load rating higher than what came on my unit originally.  Tire dimensions exactly the same.  The re seller's pressure recommendation was considerably higher than what was posted by Ford.  I was assuming that was because of the couple of extra ply on the tire but just read that load rating no longer has anything to do with ply but more about the amount or quality of steel in the ply.  Will try and drop it down to the manufacturer's sticker.  It is only air and a few gallons of gas to add or remove one assignable cause to the overall problem.

Note: I do not have any real previous experience with the handling of the RV.  The original tires were 10 years old and did not take it out at highway speeds until I put some new tires on it.

 

[fijidad]

I have done a fair bit of research on this topic, not first hand experimentation mind you.... but researching online, discussing with alignment "experts", etc....
Gary, it seems that your advice of the panhard rod is very likely the one solution that most closely addresses the real problem that a lot of these coaches see....
BUT
in almost every case it seems to be the very last thing that anyone tries.... and even the one thing that never gets done.

I find this interesting that all of this is such a puzzle.

I sure do wish that  had the funds and the time to buy all three of the popular aftermarket solutions for my coach
and try them each individually to verify the results
(panhard rod, beefier sway bars, and steer centering device)

I've posted this before, but the first thing I did was inquire on this forum about how to fix this problem on my '94 Itasca 32-footer. Gary suggested the track bar; I purchased and installed one from Super Steer and the result was an amazing improvement in the handling of the rig. We drive in some tough winds here in So. Ca.; Santana winds from the east can be brutal, but this track bar makes it all very manageable. So....what Gary said.

 

[Charlie 5320]

Are you talking about the anti-roll (anti-sway) bars? Different thing than a panhard rod (track bar). Thickness doesn't matter for a panhard rod - it just has to be strong enough not to bend. It's not a torsion device like the anti-roll bars, where the diameter is roughly proportional to the torsion it exerts.

I know the difference, and stated what it was. I don't have a track bar and don't need one. The very large stabilizer bars must work.

 

[Mc2guy]

I owned a '08 F53 with a 35' coach.  The rear trac bar is the correct fix for your problem as it is primarily the lateral movement allowed on the longer rear leaf springs that causes the problem AND as you have already identified, the F53 has a factory front trac bar.  I installed one and it immediately and effectively mitigated the tail wagging.  Nothing eliminates push from passing vehicles, but steering correction was 90% reduced.  Here is a link to my install/review: 

http://www.rvforum.net/SMF_forum/index.php/topic,21357.msg205163.html#msg205163


To an earlier poster discussing the F53 frame strength as the driver for wheelbase, you are incorrect. All commercial chassis place their axles based on load distribution.  A rear engine diesel chassis has more weight toward the rear of the coach, and therefore, in order to place the axle in a position to properly balance weight, the axle is place further back.  A Gas front engine chassis is the opposite, since the front axle is bearing the weight of the engine, the rear axle must bear be placed further forward as to not over burden the front axle with the weight of the "house".  That doesn't mean a manufacturer can't still overburden a chassis, only that there is an inherent reason for the wheel base differences between a front and rear engine chassis.

 

[John From Detroit]

I think you could find an example of almost any advice here, John. Not sure that makes it "popular wisdom", though.  I know I've been promoting the front track bar for 15 years (since I installed my first one), but that was mostly because the Davis Tru-trak was the original, widely available device. The Supersteer rear track bar came along later.

I'm not arguing against track bars at all. Just questioning whether there is any consensus on this forum that rear is recommended vs front.

Well Gary,, as I said, when I was researching Trac Bars a decade ago,, I do not recall anyone recommending a front bar only...  (I may have missed your post) but there were many telling me "Rear"

Well.. I ordered and got surprised, it's a front.. and it works great, so as I said, I can not argue with you as to the value of a front track bar but at least 5 folks told me "Put on a rear first" back then...

Thinking about how things work.. I actually think a front bar is the better idea.  But the explanation is something I can not type.. I have to draw a picture.  The rear axle in this house is far too close to center of body.

 

[Gary RV_Wizard]

I know the difference, and stated what it was. I don't have a track bar and don't need one. The very large stabilizer bars must work.

A bigger anti-roll bar does indeed help - no doubt about it. Just wanted to clarify that is what you meant, since you appeared to be commenting on the size of your anti-roll bar vs the size of Gregg's panhard rod. Maybe I misunderstood the comment...

 

[Gary RV_Wizard]

The tires that were installed actually were a load rating higher than what came on my unit originally.  Tire dimensions exactly the same.  The re seller's pressure recommendation was considerably higher than what was posted by Ford.  I was assuming that was because of the couple of extra ply on the tire but just read that load rating no longer has anything to do with ply but more about the amount or quality of steel in the ply.  Will try and drop it down to the manufacturer's sticker.  It is only air and a few gallons of gas to add or remove one assignable cause to the overall problem.

There is some misinformed thinking here.

A higher load range in the same size just means the tire can handle a higher pressure and heavier load.  At lower weights, the required tire inflation will be exactly the same as for its lower-range sibling. Since your load (weight) did not change, the air pressure required also did not change. Changing the load range has no little or no effect on the tire pressure, whether recommended, minimum or optimum. The tire seller gave you plain bad advice (not unusual, sad to say).

The RV makers recommended pressure would have been for a fully loaded (max weight) RV. If you have a lesser load on either axle, the optimal pressure may be less, but the recommended is still ok. Maybe just a bit rougher riding, but probably not much difference. If the tire seller recommended a much higher pressure and they are a higher load range, odds are strong that the tires are way overinflated for the actual load. At the very least, go back to the RV recommendation, but why not invest $10-$15 in a scaled weight (axle by axle or wheel corner by wheel corner). Then check the tire load tables.

 

[Gregg]

There is some misinformed thinking here.

A higher load range in the same size just means the tire can handle a higher pressure and heavier load.  At lower weights, the required tire inflation will be exactly the same as for its lower-range sibling.  ....... Then check the tire load tables.

That is what I was afraid of.  OK will drop it to the manufacturer's recommended pressure.  Once I have everything done inside, then will head off and get the actual weights per corner. 

Based on all this new information, I may have jumped too quickly with the Safe-T-Plus purchase and would have been better off investing in a rear Track bar.  We will see and will post if I can tell any difference.  I will try to give feedback on overall improvement beyond just the tail wagging.  Glad it is still summer to give me some time to add each and evaluate incrementally.

 

[blw2]

That is what I was afraid of.  OK will drop it to the manufacturer's recommended pressure.  Once I have everything done inside, then will head off and get the actual weights per corner. 

Based on all this new information, I may have jumped too quickly with the Safe-T-Plus purchase and would have been better off investing in a rear Track bar.  We will see and will post if I can tell any difference.  I will try to give feedback on overall improvement beyond just the tail wagging.  Glad it is still summer to give me some time to add each and evaluate incrementally.

Gregg
I wouldn't consider a loss though.  I figure the safetplus adds something to the equation to help, and may even be a great thing for blowout and bump-steer correction that it provides.

 

[Peteyboy]

For what it's worth,,, we went from a R-Vision 28 foot gasser in February, to a 38 foot Itasca gasser on the F53 chassis.  The difference on the road is night and day, from handling, ride and when a big truck passes us.  Have no idea what the differences are underneath the rigs, but driving is a WORLD of better.

 

[legrandnormand]

For what it's worth,,, we went from a R-Vision 28 foot gasser in February, to a 38 foot Itasca gasser on the F53 chassis.  The difference on the road is night and day, from handling, ride and when a big truck passes us.  Have no idea what the differences are underneath the rigs, but driving is a WORLD of better.

The main difference are the tires, you were probably running on 19,5 compared to 22,5 inches and the wheels were at that time way inside the body of your old R-Vision !
I bet that you had a Chevy chassis under that R-Vision.

 

[Peteyboy]

The main difference are the tires, you were probably running on 19,5 compared to 22,5 inches and the wheels were at that time way inside the body of your old R-Vision !
I bet that you had a Chevy chassis under that R-Vision.

Sure did, and that 8.1 engine was awesome !

 

[Gregg]

Gregg
I wouldn't consider a loss though.  I figure the safetplus adds something to the equation to help, and may even be a great thing for blowout and bump-steer correction that it provides.

If you watch the video, it claims to improve the passing of a semi so even if it helps a small amount it is worth it. Like Gary and yourself mentioned, it is a side benefit.  Hope to never have to test the blow out benefit.