Cheap Handling Fix

[TeJay]

Tim,

What you experienced has been reported dozens of times. Every MOD beginning with the CHF will affect each RV differently based on the many variables. It's kind of obvious what those variables are starting with with length, chassis weight, floor plan, lengthy overhang, tire sizes, the builders weight distribution etc, etc.

Most of these variables are not in our control. We can change how we load our personal stuff. We can add fresh water which may help.

The MODS we add are in out control but they will affect the ride & handling differently. We have always recommend starting with the cheap and easy ones and evaluate after each MOD or change. The prudent thing to do is to start with an alignment no matter if the unit is old or new. A good alignment always begins by checking the tire pressures but never use the side wall pressure unless you are loaded to the max. Use the pressure listed inside the MH as your starting point

Then do the CHF front and rear. Then start with the more costly ones and we have recommended a rear Track Bar (TB) since it has received many positives in past years. The next is usually a front steering stabilizer with either an external or internal heavy spring to assist in centering and resisting steering wheel changes as a result of outside forces like winds.

If an RV is older shocks would be next since they also assist with sway, bounce, porpoising and in general the over all ride quality.

[Cheeseman1]

Thoroughly enjoyed my test drive today after installing the Super Steer rear Trac Bar. Tire pressure is appropriate. New alignment has been done. CHF front and back completed. And now the rear trac bar. Test drove after each step and definitely could feel the better tracking and far less tail wag was noticed after EACH step. It won’t be my normal driving speed, but today all felt comfortable to the point where I was very relaxed and tooling along at 75mph! Looking forward to more extensive drives on future trips.

[TeJay]

Mark,

Ya gotta love it when a plan comes together!!! For those to young to remember that's a quote from Mr. "T". Pleased it has worked as planned.

Just a side note on two MODs that you didn't try and that's Sumo Springs and Air Bags. I'm sure Sumos add more sway stability based on the fact they are somewhat progressive. The more they are loaded down the more they resist further compression. That means more sway control but it does not help the ride quality.

I have a good friend who won't drive some roads that we travel when we are both going to the same camp ground because his ride quality is that bad. He added Sumo's on all corners. I mentioned air bags but he's got over $1,000 invested in Sumos and is reluctant to spend more $$$$. He has not changed his shocks to Koni's.

Several have responded positively when air bags are added instead of Sumo's. That includes myself in that group. If you do air bags the Sumo's have to come off. Adding the AB's will cushion the road bumps and ruts but it won't make it an air ride system. An air ride system will either remove one end of the leaf spring or at least use softer springs so more of the ride is handled by the bags.

I'll again state this fact. AB's gave us about 5% to 10% improvement in the ride quality. I have also stated this before. If we get even a 5% improvement I'm OK with the $$$ spent.

Adding AB's is only about $650 while adding an air ride is in the many thousands. I believe I read about $14,000 for just one axle. If it cost that for both axles you've got the cost of a DP and the added cost of diesel fuel and increased expensive service/maintenance.

[Cheeseman1]

TeJay,

Thanks the heads up on further alternatives to better the ride performance. At this point we’re going to put some miles on ‘er and see how we like it. Hopefully all will seem ok, but if the ride is too stiff then I envision doing some of the things you mentioned.

FYI — A-Team George Peppard - I love it when a plan comes together. Mr T- I pity the fool!�� I’m old enough to remember!

[TeJay]

Mark,

Thanks man I didn't remember the name of the show, "The A Team." Ahhh the memories back to a simpler time.

[woodbender]

Hello Gents, this is my first post here.

First, a big thank you to John McKinley and the rest of the 'A' Team for so thoroughly analyzing this modification. (I just yesterday did the CHF on my new Thor 31' ACE.)

There is a lot of backing and forthing on the subject of the longer links in the front. The angle of the front sway bar seems like it would benefit by longer links, at least visually, but I'm just guessing about any functional difference.

Is there a consensus on this topic?

Is there a functional difference by installing longer links?

Thanks again, everyone, for all the work you've put in to inform guys like me about this.

Lon aka Woodbender

[jharrell]

Originally Posted by woodbender

Is there a functional difference by installing longer links?

Longer links soften the sway bar by increasing the effective lever arm. In the end with longer links you have about half the effect of the standard CHF without longer links.

I have done the math a few times its about 750 lbs-inch spring rate for front stock config, 1250 lbs-inch standard CHF, 1000 lbs-inch extended links.

John McKinley has run the standard non extended version for nearly a decade without issue, I have run mine for 3 years and 20,000 miles this way. The only thing to pay attention to is any contact the sway bar might make as the suspension moves, typically in the rear if you have a park brake in front of the diff.

Consensus? Its lever physics, here is the sway bar calculator: Sway Bar Rate Calculator | GTSparkplugs measure and plug in your sway bar numbers, the A dimension will change with with angle between links and bar.

[woodbender]

Thanks for the quick reply. I am (obviously) not an engineer, so please pardon my ignorance.

Seems to me that by changing the location of the link connection on the sway bar, we, as you say, change the length of the lever thereby stiffening or softening the ride accordingly.

My question is not about the sway bar lever length, but about the length of the link - the part that connects the sway bar to the frame.

Seems to me that part's length may or may not effect the function of the sway bar - to affect the ride one way or the other - but I don't know.

Just looking at the angle of the sway bar, seems like it points upward toward the frame more than it should. The longer links would move the sway bar 'lever arms' downward so they're more horizontal.

That would 'look better' to me, but would the more horizontal sway bar effect it's functionality in any way?

Thank you for your patience since I'm aware this topic has been discussed repeatedly.

Perhaps this is a different but corollary question - Is there any reason (other than cost, hassle, etc.) to NOT install longer links?

[jharrell]

Originally Posted by woodbender

Thanks for the quick reply. I am (obviously) not an engineer, so please pardon my ignorance.

Seems to me that by changing the location of the link connection on the sway bar, we, as you say, change the length of the lever thereby stiffening or softening the ride accordingly.

My question is not about the sway bar lever length, but about the length of the link - the part that connects the sway bar to the frame.

Seems to me that part's length may or may not effect the function of the sway bar - to affect the ride one way or the other - but I don't know.

Just looking at the angle of the sway bar, seems like it points upward toward the frame more than it should. The longer links would move the sway bar 'lever arms' downward so they're more horizontal.

That would 'look better' to me, but would the more horizontal sway bar effect it's functionality in any way?

Thank you for your patience since I'm aware this topic has been discussed repeatedly.

Perhaps this is a different but corollary question - Is there any reason (other than cost, hassle, etc.) to NOT install longer links?

I have posted similar diagrams before and I am trying not to come off as belittling but this in high school physics and I have had to argue here so much its gets tiring:



Pay very close attention to the lever arm length as depicted, the more angle the shorter the lever arm.

The lever arm length is the "A" dimension in the sway bar a calculator it is effected by connection point AND angle! The shorter this length the stiffer the bar.

So yes it effects its functionality, it adjusts the sway bar just like the hole does!

[woodbender]

Ok, I think I'm starting to 'get' what you're saying --

Is it fair to say that leaving the bolt location in the sway bar in its 'soft' position and only shortening the link so that the sway bar 'lever' points more upward toward the frame, the lever length would shorten and the ride would stiffen?

I really do appreciate the physics lesson. (I never took physics in High School. )

[jharrell]

Originally Posted by woodbender

Ok, I think I'm starting to 'get' what you're saying --

Is it fair to say that leaving the bolt location in the sway bar in its 'soft' position and only shortening the link so that the sway bar 'lever' points more upward toward the frame, the lever length would shorten and the ride would stiffen?

I really do appreciate the physics lesson. (I never took physics in High School. )

Yes again both where the link connects AND the angle change the lever arm, it just so happens the standard CHF does both at the same time, by lengthening links you remove half the effect. Note the link connection point changes both "A" and "C" in the calculator, while the angle only changes "A", "C" accounts for the bars arm flexing as a spring too.

If you just shortened the links which changes angle without moving holes you would also stiffen the bar a certain amount, if you changed the connection point on the frame to change the angle without changing link length again you would stiffen the bar.

[woodbender]

Most interesting....

Amazing how informative your answer is... thanks once again for your patience with this..

Gets me thinking... (I'm like that) with a link that's adjustable in length, you would be able to fine tune the ride, right? ... hmmmm.....

Ok one more question... a hypothetical if you'll indulge one:

Let's say in a turn, the link pulls on the sway bar until the lever end of the bar aligns with the link to form a straight line... it essentially 'bottoms out'.

Wouldn't this potentially strain the assembly beyond it's design strength? (And eventually break something?)

[jharrell]

Originally Posted by woodbender

Most interesting....

Amazing how informative your answer is... thanks once again for your patience with this..

Gets me thinking... (I'm like that) with a link that's adjustable in length, you would be able to fine tune the ride, right? ... hmmmm.....

Ok one more question... a hypothetical if you'll indulge one:

Let's say in a turn, the link pulls on the sway bar until the lever end of the bar aligns with the link to form a straight line... it essentially 'bottoms out'.

Wouldn't this potentially strain the assembly beyond it's design strength? (And eventually break something?)

Yes you could use an adjustable length link to fine tune, but normally that sort of fine tuning is not worth the effort.

If the sway bar and link form a straight line it turns into one long link with infinite sway control until it breaks ( "A" becomes zero and spring rate goes to infinity).

This will not happen in practice as you will need to extend the suspension far enough where the shocks will also run out of length and stop and the force from the sway bar will continue to rise resisting the body roll. That after is its job to prevent the axle from articulating in a turn.

If you lift your front end with jacks the axle will drop evenly and the sway bar will straighten out without resistance and you can see how far you can go before it hits 180 degrees. On the F53 you will notice the front bar contacts the leafs before this happens stopping further droop.

Here is a picture of my sway bar links with standard CHF with the front wheels off the ground, it drops about 3 1/2" before bar contacts leafs. Your RV would probably be close to tipping over with 7" total roll to worry about the links straightening:

[woodbender]

I will add my voice to the 'WOW-what-a-difference' crowd.

After I did the CHF last Saturday, yesterday I took her (new 2019 Thor 31') on her first excursion on some winding and rough roads and also a bit of freeway driving. Most of that time I was flat-towing our 3500lb Honda CRV.

Handling without the toad was immeasurably improved. She drove like a glorified pick-up truck!

Handling with the toad was actually better than driving the coach alone prior to the CHF.

I tip my hat to everyone who's contributed to doing this. Two hours and no new parts. Doesn't get any better!