Cheap Handling Fix

[TeJay]

First of all the Ford chassis is a truck chassis. If we were talking about a TT or 5'ver chassis then yes I'd be worried. Since they are built on the, "Edge of Destruction" (Thin frames). The Ford is designed for heavy duty work. Exactly how much that means is probably anybodies guess and I believe that is what is driving this latest concern just some guesses.

Look at it this way!!!
As we drive down the road we are subjecting the chassis to a lot of unwanted movement. The manufacturer wants to control the movement but still give a decent ride. So we have: bumps, dips, SWAY, undulations, wind gusts or just strong winds and lateral frame movement. All that makes the ride and handling lousy. The same movement is also being imparted onto the frame and everything else attached to it.

We could remove the springs, shocks, and stabilizer bars and attach the front axle and rear differential solidly to the frame. Then we'd call it a "Buckboard" and we know how that would ride.

The secret is to manage or dampen the unwanted energy by converting it into a different form of energy and that form is HEAT.

So we add back into the system: leaf springs, bushings, shocks and a SWAY control system in the form of a torsion bar which is nothing more than a straight spring being twisted at either end by a link attached to the frame.

All of these added devices change the energy of motion being created as we travel down the highways and byways of this country into heat energy which is then dissipated into the air.

If any one of these items is removed the energy that it controlled has to go somewhere. Yes some of the other items will absorb it but for how long and how well. Eventually that energy will be imparted somewhere and that somewhere will be the frame which over time will be negatively effected.

So in reality the SWAY control system is controlling or dampening coach movement and therefore not allowing or controlling the flex of the frame.

The SB (SWAY control system) helps to reduce or prevent frame flex!!!

[rssj]

What that guy said! Excellent explanation.

[Insane938]

X2

[Hudsoner]

Originally Posted by EdInArk

Well, that worked for me.

Did not work for me. The links hit the springs under different driving conditions (my son, the Ford mechanic who is taking care of my motorhome discovered hit marks on the springs and the links).
The plates corrected this.

[twinboat]

Originally Posted by TeJay

The SB (SWAY control system) helps to reduce or prevent frame flex!!!

This is not true on uneven surfaces.

When a MH sways ( leans ), the sway bars fight it, by transferring the energy to the opposite side. The sway bar on the compressing spring side is attempting to compress the opposite side spring. That's what they do.

Put 1 wheel on the curb and that wheel wants to, thru the sway bar, pull the other wheel up with it.

Put a scale under each front wheel. Have 1 scale on a set of 2" blocks. You will get more weight on the blocked up scale and less on the one on the ground, then if both were on the ground.

That causes frame flex. Put enough sway control and the suspension is no longer independent, side to side. That will cause a rough ride and frame flex on uneven ground.

Proof of this is the fact that you can't do the CHF on unlevel ground.

Off roader remove sway bars, in rough terrain. The don't want to limit, right to left, suspension travel and cause a wheel to lift off the ground. That will decrease traction and flex the frame.

[Hudsoner]

Originally Posted by twinboat

Off roader remove sway bars, in rough terrain. The don't want to limit, right to left, suspension travel and cause a wheel to lift off the ground. That will decrease traction and flex the frame.

You are correct here! That is the reason why my modified Jeep has detachable sway bar links!

[jharrell]

Originally Posted by TeJay

All of these added devices change the energy of motion being created as we travel down the highways and byways of this country into heat energy which is then dissipated into the air.

If any one of these items is removed the energy that it controlled has to go somewhere. Yes some of the other items will absorb it but for how long and how well. Eventually that energy will be imparted somewhere and that somewhere will be the frame which over time will be negatively effected.

So in reality the SWAY control system is controlling or dampening coach movement and therefore not allowing or controlling the flex of the frame.

The SB (SWAY control system) helps to reduce or prevent frame flex!!!

Springs are NOT dampeners shocks are. Springs store energy shocks convert it to heat.

The sway bar is a spring HOWEVER when you do the CHF or get thicker bars it is LESS of a spring. That is it gives less and resists flexing more. The SAME energy is imparted over LESS distance INCREASING force. Sway bars REDUCE travel resisting body roll. More of the energy imparted into the frame to resist the roll.

The links on the sway bar are attached to the frame, the closer you move them as in the CHF the less leverage they have and the more force per inch of travel is imparted to the frame. If the front wheel hits an uneven bump while the rear are on level ground either the suspension flexes to compensate or the frame wants to twist to compensate, the stiffer the sway bar is the less the suspension will give in that situation and the more the frame will see.

I am not saying this will cause a problem, it hasn't for my MH and we don't generally offroad, but it does apply even when going over driveway entrances etc just to a lesser degree.

Here are exaggerated pictures that may help explain the effect:







You can get a good explanation in detail here: suspension - Effects of sway bar stiffness on rough, uneven roads - Motor Vehicle Maintenance & Repair Stack Exchange, which is where I got the pics. To deny the CHF makes suspension stiffer and transfers more to the frame is denying well understood physics.

As I have said before would your ride get harsher if the sway bar didn't flex at all? Of course it would, I hope everyone gets that. Why then would you think making it flex less would not?

[jharrell]

Here is another one, again exaggerated compared to a MH. In which pic is the frame under more stress and more likely to be twisting?

The top is sway bar connected, the bottom disconnected:



The more the suspension flexes, the less the frame does.

[pfritz]

I have about 25k on the CHF with Helwig links. I am based in the west, strong winds they call tripical storm in the SE ( been there thru a few H's) My background is alignment and front end work to 18 wheelers, and vibration expert for cars, alas, many years ago.. not all is forgoten.. the chf WORKS but to me has consequence, ie, hard ride... It may be did not really feel the ride when first new, but as a retired vibration expert I do feel the CHF, however, only on bad roads.. I drove admitly stupid ito thr super storm last week, I went 30 miles and called it quits, 80+ gusts 50 plus steady.. should have stayed in port another day.. My rig drove pretty thru it all.

[TeJay]

Good responses and I will take some time later to study more. We are at a CG so have things to do.

My quick response:

jharrell, Yes I do know that a leaf spring does not dampen. The shocks dampen the springs oscillations. Yes I also know that a torsion or SB is a spring. I've worked on Chrysler's before. However reading carefully I meant that leaf springs will heat up as they flex. They have to if they are going to follow the laws of physics. The shocks convert/dampen the spring oscillations dampening into heat energy.

Not sure comparing our RV's to rock crawlers is a fair comparison. We have not read nor heard of anybody having issues with to much frame flex after the CHF. That's also why I still believe that the CHF does not make the ride harsher.
While there is something to what is being said I just don't believe we are creating an excessive amount of SWAY control which will cause frame stress beyond what the frame can handle. In addition the ride is not getting harsher. Those of you who do the rock crawling do over stress your vehicles and can see the results.

How many folks who are currently using not 2 but three SB's and two of the new after market ones are heavier than the stock Ford SB's do you need to tell you that the ride is not harsher after adding those SB's + doing the CHF?????

We just MAY NOT yet be in the world of a, "Rock Crawler".

We arrived in LR, AR yesterday heading East. The winds coming down were coming out of the NE and fairly strong and we had a lot of rain. Lots of truck traffic and could have driven all the way with one hand.

[jharrell]

Originally Posted by TeJay

jharrell, Yes I do know that a leaf spring does not dampen. The shocks dampen the springs oscillations. Yes I also know that a torsion or SB is a spring. I've worked on Chrysler's before. However reading carefully I meant that leaf springs will heat up as they flex. They have to if they are going to follow the laws of physics. The shocks convert/dampen the spring oscillations dampening into heat energy.

So I am using academic terms to describe a spring and damper. In the real world there is no perfect spring or damper. All springs are less than 100% perfect at storing energy and convert some amount to heat. Usually a very very small amount, your are right though that leafs are one of the least efficient springs and convert more of the energy to heat through stiction between the leafs. This was taken advantage of in the old days before modern shocks in wagons and what not. The leafs where so bad they did act like a shock to some degree, not in the smoothest way mind you but it did work.

I believe the springs on the F53 have poly slip pads between them to try and reduce this effect as much a possible, because today with good modern shocks you want them doing as much of the dampening as possible.

Most modern cars have gone to coils as they have basically zero stiction.

Originally Posted by TeJay

Not sure comparing our RV's to rock crawlers is a fair comparison. We have not read nor heard of anybody having issues with to much frame flex after the CHF. That's also why I still believe that the CHF does not make the ride harsher.

Why is it not a fair comparison? This is not a binary on/off issue, does an RV see the magnitude of forces a rock crawler does? No of course not, it does see the same forces though just to a lesser degree when say going over a curb, but also a RV can't take the same force a rock crawler can either. There are plenty of stories of RV's popping a windshield going over a steep curb or jacking up wrong. RV's see less of the same force, but need less for bad things to happen as well. One can be applied to the other, the forces are smaller but they are the same forces.

I had hoped showing you the exaggerated Jeep would make it easier to see what a sway bar does as it not as visible when occurring on the RV, instead you just reject it outright as though there is no comparison whatsoever, denying the obvious.

Originally Posted by TeJay

While there is something to what is being said I just don't believe we are creating an excessive amount of SWAY control which will cause frame stress beyond what the frame can handle. In addition the ride is not getting harsher. Those of you who do the rock crawling do over stress your vehicles and can see the results.

Again I did not say it will OVER stress anything, only that the stress is greater the stiffer the sway bar system. I have the advantage of a electronic disconnect on my Jeep. With a button I can remove the sway bar from the system and put it back, when disconnected it is immediately less harsh on any uneven road surface, it rides nice and plush, its great up until you go into a turn and the whole jeep dives and rolls.

I keep trying to get you to do the thought experiment. If more and stiffer sway bars are always better why don't they just do rigid axles links that don't flex at all? Take it all the way to the maximum expression of your conclusion. The axle would only go straight up and down, no articulation, no sway. Why are sway bars adjustable? Why would you make them softer if harder is always better as you keep proposing?

The answer is obvious, there must be a trade off, whats good in one situation is worse in others so they are tune-able. What is the trade off? What gets worse the stiffer the sway bar gets? If you know the sway bar is a spring, what happen to your ride when you put stiffer springs on a car? Why wouldn't you put the stiffest springs you can find, why have springs at all?

Originally Posted by TeJay

How many folks who are currently using not 2 but three SB's and two of the new after market ones are heavier than the stock Ford SB's do you need to tell you that the ride is not harsher after adding those SB's + doing the CHF?????

They may not feel it, and that's great, if it doesn't bother you weld the axles solid, you will get no sway whatsoever ultimate evolution of stacking bigger and bigger sway bars.

If you measure with say an EVM on the same road before and after CHF you will get higher numbers after, doesn't mean you will feel it in your butt, someone else however may, everyone's different, some are more sensitive to sway than vibration some the other way, which is why its great it adjustable from the factory and relativity easy to take it further if you want.

Again I did the CHF and I like it and hasn't caused any issues with my MH, the sway was really bad from the factory and I think the stock setting is too soft for modern top heavy RV's for most people. I do cringe going over uneven drive curbs etc though as I know my sway bar is pushing harder back against my frame than stock to keep the axle straight and that huge windshield is creaking.

[alank]

by jharrell:
Again I did the CHF and I like it and hasn't caused any issues with my MH, the sway was really bad from the factory and I think the stock setting is too soft for modern top heavy RV's for most people. I do cringe going over uneven drive curbs etc though as I know my sway bar is pushing harder back against my frame than stock to keep the axle straight and that huge windshield is creaking.

Couldn't agree more with the statement above, and every thing else said about stiffer sway bars inducing more flex in the frame and coach body.
I also did the CHF and extended all the frame links, I think 3 1/2' front and 2 1/2" rear if memory serves.
There are a lot of members that just don't have a good understanding of mechanical applications and are posting statements that are not accurate which makes it very difficult for those that want to learn about improvements that can be made to their motorhome.

[calebh]

i am sure this has been brought up before but i dont want to go through 300 pages to find out. yesterday i was under the mh messing around and i unhoked the tie rods that connect the frame to the sway bar. my thought was that there must be some reason the mh rides like crap after the chf and i am thinking i may have found something. the sway bar stock has no lube and with all my strength (age 35 240lbs not bad shape) i could not move it in the bushings. i unbolted it and pulled off the bushings and lubed everything really good with bearing grease and reinstalled. no joke i could move it with one hand up and down with little more than 10 lbs force. when you add the crazy angle that the sway bar and the tie rods are in the chf configuration and the fact that the sway bar was practically locked up in the bushings there may have been some contributing factors there. i have not driven it yet but next will be the rear bar as soon as i have time.

[TeJay]

calebh,

What you discovered I'm sure is a contributing factor to the proper movement and operation of the SWAY control system. Actually very little has been discussed concerning the lubrication of those bushings.

You have a 32' Thor but don't mention the year. Starting on the 2012 chassis or 2013 coaches Ford started using the polyurethane material for those SB bushings. It is 10X's better than the stock rubber.

Would be a good idea if you don't have the poly material to replace it. Do a Google search under the phrase (Ford bushings Skuterdude). He has good prices and a good product.

When you do that job there is a special poly lube that is compatible with the poly bushings. Regular grease is not recommended for the stock rubber or for the poly. Amazon.com has it because it does not seem to be easily available at local outlets. I do believe that Skuterdude supplies you with some poly lube with the bushings.

Also all the SWAY control attaching bolts (front and rear) should be re-torqued and blue lock tight used as added insurance. A fair number of coaches have reported finding those especially rear SB brackets loose, bent or missing.