Cheap Handling Fix (CHF)

[USTraveler]

I have been looking at the CHF solutions and can't help but think that there is some reason the design engineers wanted the sway bar connections in the outside hole rather than the inside. I keep thinking if I move the connections to the inside hole I would be defeating some design/safety issue. That being said, the CHF on the front looks like it is a nonstarter with my chassis. In order to move the connections I would have to raise the ends of the sway bar and that would move the inside holes further away from the ends of the rods that drop down from the frame. It looks like those rods are just too short to make the connection to the inside holes on the sway bar. The rods are already located forward of the sway bar and are slanted towards the sway bar to make the connection at the outside holes. I think the connection rods would be an inch or two short of the inside holes. On the rear sway bar the CHF could be done but I would have to lower the sway bar ends in order to connect to the inside holes. It looks like that is certainly doable without causing any additional issues. That's where the nagging design issue thought come into play. Perhaps I am over thinking this but I can't help but wonder why the connections are in the outside holes to being with. I can understand why there are 2 holes in the sway bars, which is probably to make the bars fit different chassis. If anyone has any design insights I would certainly be interested in seeing them. On another issue I'm looking at rear track bars and I see some connect from the frame to the sway bar bracket that is welded to the axle and some are connected from the frame to bolts on the differential housing. I think the latter would put a lot of stress on those bolts. Does anyone have any thoughts on which is the better approach?

[halfprice]

Originally Posted by USTraveler

I have been looking at the CHF solutions and can't help but think that there is some reason the design engineers wanted the sway bar connections in the outside hole rather than the inside. I keep thinking if I move the connections to the inside hole I would be defeating some design/safety issue. That being said, the CHF on the front looks like it is a nonstarter with my chassis. In order to move the connections I would have to raise the ends of the sway bar and that would move the inside holes further away from the ends of the rods that drop down from the frame. It looks like those rods are just too short to make the connection to the inside holes on the sway bar. The rods are already located forward of the sway bar and are slanted towards the sway bar to make the connection at the outside holes. I think the connection rods would be an inch or two short of the inside holes. On the rear sway bar the CHF could be done but I would have to lower the sway bar ends in order to connect to the inside holes. It looks like that is certainly doable without causing any additional issues. That's where the nagging design issue thought come into play. Perhaps I am over thinking this but I can't help but wonder why the connections are in the outside holes to being with. I can understand why there are 2 holes in the sway bars, which is probably to make the bars fit different chassis. If anyone has any design insights I would certainly be interested in seeing them. On another issue I'm looking at rear track bars and I see some connect from the frame to the sway bar bracket that is welded to the axle and some are connected from the frame to bolts on the differential housing. I think the latter would put a lot of stress on those bolts. Does anyone have any thoughts on which is the better approach?

The design issue of inside/outside hole has been decussed on irv2.com at great lenght. Do a seatch there and you can read for days.

Very few people disliked the chf and have gone back to stock. The majority would never go back to stock.

Rear track bar: the 18k chassis is the only one that attaches the to sway bar bracket. All others to the differential pumkin. I havent heard about any problem to either design.

The rear track bar is probably the best handling mod ive done to my 29m

Jerry

[jpmihalk]

The irv2.com forum conversations have some Ford people in them, basically the outer holes are the default positions from the factory. Since Ford has no idea what the frame final build or use will be, they just send them out as default and let owners or other companies make any changes. Keep in mind the F53 chassis are almost always stretched by MORryde prior to the RV house being built on it and the characteristics of that change cannot be overstated. The body becomes even a longer wind sail and will get pushed around by passing semis and wind even more than a simple box truck.

Thousands of owners have done the CHF and are very happy with it. We are very happy with the way our Hurricane rides now (and it is the only mod to the chassis that we have done.)

The other thing to check is to get your coach weighed and set your tire pressures accordingly. That also helps with the ride much more than you might think.

[USTraveler]

Thanks for the comments and insights. I had previously had the unit weighed and had adjusted the tire pressure appropriately. The tires were initially at 105 psi when I picked the unit up and now I have them at 84cpsi. That did make a difference in the handling. Based on the comments the track bar design that connects to the sway bar bracket is the longer of the track bar designs so that sounds like the way to go for the best results. When I was under the unit I didn't notice any add on Beams to the chassis frame. That doesn't mean it hadn't been stretched but if it was it was a pretty decent job. I still have concerns about the CHF but will probably try it on the rear when the weather warms a bit. I just can't see how the front CHF can be done unless I get longer rods to connect the frame to the sway bar. I always think that just because something has always been done doesn't necessarily mean that it is the right thing to do. Thanks again for the comments.

[jpmihalk]

Originally Posted by USTraveler

I still have concerns about the CHF but will probably try it on the rear when the weather warms a bit. I just can't see how the front CHF can be done unless I get longer rods to connect the frame to the sway bar. I always think that just because something has always been done doesn't necessarily mean that it is the right thing to do. Thanks again for the comments.

I will be honest - when we did our front CHF, the rods were pretty close to their limit when finally connected. But this is also what gives the ride its stiffness. The sway bar had to be lifted up to almost a 45 degree angle to line the holes up. The rear CHF was not nearly as much of an angle but was a little harder to do because of the removal and repositioning of the bolts and the mount in a limited space.

As a former Navy Surface Warfare Officer (driving ships for a living) the best thing about the CHF is the limit of the house whipping back and forth during turns and rough roads and the cabinet and pantry doors being forced open by the momentum of the side to side rocking. Without the CHF, we had the pantry flying open on a regular basis and things stored higher up had a tendency to go flying (missile hazards, in Naval parlance.) With the CHF, we don't worry so much about them any longer. Of course, we have also added some safeguards to keep the doors from opening anyway (bungee cords and hooking a wire in front of the pantry baskets to the wall prior to departure.) My first ship was an LST - a big flat-bottomed ship designed to beach and deliver Marines directly ashore - and it was simply awful in rough seas. Many lessons were learned from that experience that apply to our new RV life. I just hope I never have to learn how to walk on the walls of our RV!!

[SuperD]

Your 31S is on the same chassis and only slightly longer than our 29M. I have almost 7000 miles since doing the chf and would not change back, better handling makes it worth the time it takes to change. If you try it and don’t like it you can always change back, but as Jerry said, very few do. There is a lot of discussion and history on iRV2 concerning the chf and 95+% is positive, there is input from Ford engineers who also recommend the chf.

[USTraveler]

Thanks for the additional info. I don't feel like such a lone ranger now. Just FYI, Phil_T on the RVForum replied that Hellwig makes adjustable end links for sway bars and they can be bought from Amazon, Summit Racing, among other places. I think I am going to look into those for my front sway bar. It looks like they have versions with different adjustable lengths (8"-11", 11"-14", etc).

[tnedator]

Originally Posted by USTraveler

Thanks for the additional info. I don't feel like such a lone ranger now. Just FYI, Phil_T on the RVForum replied that Hellwig makes adjustable end links for sway bars and they can be bought from Amazon, Summit Racing, among other places. I think I am going to look into those for my front sway bar. It looks like they have versions with different adjustable lengths (8"-11", 11"-14", etc).

That's the most frustrating part of the CHF discussion, is the back and forth as to whether the existing end links are ok or need to be replaced.

It seems like for years people were doing them with factory end links, but now recently the movement is to replace them.

[SuperD]

I have read the majority but not all the posts on iRV2 and have not read of any failures. Jerry put the plates on his coach but I haven’t and don’t feel the need for them or extended links, everything seems to work fine as it is.

[USTraveler]

I did the CHF on the rear and looked more closely at the front. The end links for the front sway bar measure 11" from bolt to bolt and if I lift the sway bar to try to connect to the inside holes I would need end links that are 12 to 12 1/2 inches in length. I didn't measure the distance without having to lift sway bar but that could be an option. I would guess that the end links would have to be about 14 to 15 inches in that case. The end result is that the existing end links are too short and I am not sure the expense of longer ones is worth it. I'm thinking it may be better to just get a steering stabilizer. I have read that getting the toe in adjusted so that it is greater helps the handling but I wonder about that increasing the tire wear. I haven't test drove the unit yet since the CHF so have no report on differences there. I'm waiting for a day when there are no high wind warnings and the temps are above freezing.

[SuperD]

Originally Posted by USTraveler

I did the CHF on the rear and looked more closely at the front. The end links for the front sway bar measure 11" from bolt to bolt and if I lift the sway bar to try to connect to the inside holes I would need end links that are 12 to 12 1/2 inches in length. I didn't measure the distance without having to lift sway bar but that could be an option. I would guess that the end links would have to be about 14 to 15 inches in that case. The end result is that the existing end links are too short and I am not sure the expense of longer ones is worth it. I'm thinking it may be better to just get a steering stabilizer. I have read that getting the toe in adjusted so that it is greater helps the handling but I wonder about that increasing the tire wear. I haven't test drove the unit yet since the CHF so have no report on differences there. I'm waiting for a day when there are no high wind warnings and the temps are above freezing.

Many people, myself included, have done the front with no adverse effects. Remove the links, raise the swaybar and reattach, it’ll work just fine without extended links.

[halfprice]

Originally Posted by SuperD

Many people, myself included, have done the front with no adverse effects. Remove the links, raise the swaybar and reattach, it’ll work just fine without extended links.

I agree with dave. I would say the majority of the chf done are with the stock links. The only reason I added the plates is because I could. $20 to buy the plates and my friend welded and drilled the holes. All the plates or longer links do is lower the sway bar to a level angle. If my friend couldnt weld the plates mine would be stock.

Jerry

[USTraveler]

Ok. I'll go through this in more detail. The end links for the front sway bar are not hanging straight down but are angled toward the rear of the MH to connect to the outside holes of the sway bar. In that position they cannot connect to the sway bar inside holes because they are not long enough. The ends of the front sway bar are angled up to enable the end links to connect to the outside holes of the sway bar. If the sway bar and the end links are allowed to swing freely the ends of each would swing in an arc. At some point in the arc the ends of the end link and the sway bar would be at their closest point. At either side of that closest point the ends would move further away from each other. If I remove the end link from the sway bar and swing the sway bar up I am moving the inside hole further up the arc and away from the end link. If I push the end link back towards the sway bar it is also moving further up the arc to its' closest point to the sway bar. Unfortunately the sway bar has moved beyond its' closest point to the end link and is now moving away from the end link. There is no point in the arc of either the end link or the sway bar at which the inside holes of the sway bar will be able to connect to the end link. It really doesn't matter how many other people have been able to do this on their chassis because on mine it is physically impossible to do it, for the reasons stated above. Sorry guys.

[jpmihalk]

One other item to note - the vehicle must be parked on level ground or else you may NOT be able to reach the sway bar holes. You can't use the leveling system, the suspension must be at rest and level. Anything else can cause a situation where one side may reach and the other doesn't or where the front is leaning down and the back won't reach.

[halfprice]

Originally Posted by USTraveler

Ok. I'll go through this in more detail. The end links for the front sway bar are not hanging straight down but are angled toward the rear of the MH to connect to the outside holes of the sway bar. In that position they cannot connect to the sway bar inside holes because they are not long enough. The ends of the front sway bar are angled up to enable the end links to connect to the outside holes of the sway bar. If the sway bar and the end links are allowed to swing freely the ends of each would swing in an arc. At some point in the arc the ends of the end link and the sway bar would be at their closest point. At either side of that closest point the ends would move further away from each other. If I remove the end link from the sway bar and swing the sway bar up I am moving the inside hole further up the arc and away from the end link. If I push the end link back towards the sway bar it is also moving further up the arc to its' closest point to the sway bar. Unfortunately the sway bar has moved beyond its' closest point to the end link and is now moving away from the end link. There is no point in the arc of either the end link or the sway bar at which the inside holes of the sway bar will be able to connect to the end link. It really doesn't matter how many other people have been able to do this on their chassis because on mine it is physically impossible to do it, for the reasons stated above. Sorry guys.

Both the sway bar and the link have to move. Sway bar moves up and the link moves back. They will line up. Usually a bottle jack, or any kind of jack you have, is needed to move the sway bar up. And the bottle jack is definitely needed to do the other side after the first bolt is attached.

Wish you lived by me I would help you out with it. It takes about 15 minutes to do.

Jerry

[halfprice]

Originally Posted by halfprice

Both the sway bar and the link have to move. Sway bar moves up and the link moves back. They will line up. Usually a bottle jack, or any kind of jack you have, is needed to move the sway bar up. And the bottle jack is definitely needed to do the other side after the first bolt is attached.

Wish you lived by me I would help you out with it. It takes about 15 minutes to do.

Jerry

Im sure you have seen pics but heres a couple more

[Yvonnemarc]

I guess the key to remember is this chassis is used on everything from 24 to 37 ft rigs. Ford sets the chassis for a standard setting as they don't know which house will go on which chassis. Thats where you come in. The coach maker has better things to think about than which holes the sway bar is using. I know that sounds crappy and it is depending which size rig you have. But if I'm the manufacturer and it's "safe" the way Ford sends it I'm letting the eventual owner make the modification to his liking.

[LockChuck92]

Originally Posted by halfprice

Both the sway bar and the link have to move. Sway bar moves up and the link moves back. They will line up. Usually a bottle jack, or any kind of jack you have, is needed to move the sway bar up. And the bottle jack is definitely needed to do the other side after the first bolt is attached.

Wish you lived by me I would help you out with it. It takes about 15 minutes to do.

Jerry

Jerry is spot on here. This is exactly what I had to do as well. The bottle jack did the trick on raising the sway bar into position. I felt the same way! I remember thinking, "these *#%^ things aren't going to line up!" But, for lack of a better term, you gotta manhandle the links and pull them down into position. Then use a persuader (ball peen hammer) to persuade the bolts into the holes. On mine, it looked at first like the leaf spring was going to prevent me from reinstalling the bolt through the link and the sway bar. In all honesty, I got mad at the dang thing, and knocked the #%^* out of it with the hammer. Whaddya know?!? It went right in! I was definitely frustrated because I expected a 15 minute fix; mine was anything but! But it can be done. Best of luck to you, and keep us posted!

[Wrpt58]

Just to throw another kink into the discussion, I only re-adjusted the rear sway bar endlinks and left the front as they were, mainly because I didn't like the angle the front endlinks were going to be at. I "prefer" the endlink to sway bar angle be as close to perpendicular as possible.

The plates Jerry added mitigates this angular problem pretty well, from what I could see.

I've driven my 29M about 7-8 K miles since then and haven't had any ill effects from leaving it that way. Actually, I like it better now, for sure.

From suspension/engineering POV, stiffer Rear Sway bar should throw a little more weight on the front axle, and add just a little oversteer, maybe.
Check this website for basic Sway bar (ARB, Anti-Roll Bar) tuning thoughts.
anti-roll bar (sway bar) - iRacing.com Wiki

Given the $$ and opportunity, I will probably go with Sumo Springs all around first (Control the suspension travel during roll events), then work the Front Sway bar endlinks. After that, I will look at the Saf-T-Steer, then lastly the Track bar if needed.

As you can see, Personal Preference factors pretty highly in the realm of Steering and Suspension mods.

Just my 2 cents.

[Chance]

Originally Posted by Wrpt58

....cut....

Check this website for basic Sway bar (ARB, Anti-Roll Bar) tuning thoughts.
anti-roll bar (sway bar) - iRacing.com Wiki

.....cut.....

A couple of good points were made in that article, even though caution should be used when applying race car dynamics to motorhomes. The basic theories apply the same, but the reason for making modifications is so different that they may not apply or make sense.

The first point I'd like to iterate is that anti-roll bar stiffness goes up by diameter^4 assuming they are shaped the same an made of steel. It's really easy to fall for marketing hype and overdo stiffness. When average buyers don't know this, they won't think they are getting their money's worth unless they see a huge size difference.

The second point which addresses original question, and as an engineer I've mentioned many times, is that anti-roll bars do reduce suspension compliance. As the article states, you should really want the least amount you actually "need", not the most you can get "cheap" just because you can.

If a driver needs added roll stiffness then they need it, but while it may not cost anything monetarily, it will cost some in suspension compliance. It has to, there is no way around it. Ford could make anti-roll bars much stiffer for practically no cost, but they have to weigh all pros and cons, which includes how the vehicle rides.

Tuning advice

Just like spring rate, you want to run as soft an ARB as possible while maintaining sufficient control of the car and body roll and the proper handling balance. Softer settings lead to more compliance and more grip on that end of the car. They also tend to be slower responding and easier to drive, but stiffer settings can be more stable and faster responding.

Front:
(1) Stiffer: Will increase overall car stability (reduces roll) and shift the car’s balance toward UNDERsteer (push), thus allowing the driver to be more aggressive with the steering. The compromise can be on bumps and/or braking. A stiffer front bar will reduce compliance, so when one tire hits a bump the entire front axle will be affected through a loss of overall grip.