Ford's Stance on CHF

[ehunt]

I attended a session from Ford at our Tiffin owners rally today, they had an FAQ slide on the CHF fix with their official stance. Hadn't seen this posted so thought I would share. The following is from the Ford reps slide, capitalization included.

Q. Can I move the torsion bar attachment to the unused hole on the bracket, with the goal of increasing torsion resistance and thus reducing sway?

A: CAE analysis shows the system would be stressed beyond its design limits if this hole is used to stiffen the suspension. FORD DOES NOT AUTHORIZE OR RECOMMEND THIS MODIFICATION!

The "unused hole" is a left over from the time when there was a support for the sta-bar bolt. The support was not needed and removed but the hole was left.

[marjoa]

WOW. Very interesting.

OK, that's FORD's official stance. Maybe for warranty reasons or for real chassis and suspension stress control studies and results. Who knows. Not sure what CAE analysis stands for. I'm thinking..........Oh, OK Computer-aided engineering, but I don't care. I'm not an engineer nor want to be one. Maybe FORD's just covering their butt, I don't know.

I'd like to know if this was their position on using CHF on front & rear, or just front...or what?

What I do know from being on this forum for some time now and being a CHF user myself and reading the many, many users that have implemented this mod—with good long lasting results—I'm sure this post will go miles and miles with replies from online RV self made engineers and beyond. This post IMO may be a record breaker in replies.

I'm really interested to hear from my friend Tejay and other CHF crafters and testers on this FORD's official position.

I'd also like to know more about this previous "sta-bar bolt" thing. I know nothing about this.

Thanks for that post Ed.

[F4Gary]

What will it over stress other than maybe the rubber sway bar bushings.

[Dav L]

Originally Posted by F4Gary

What will it over stress other than maybe the rubber sway bar bushings.

More likely the links. Especially when they aren't sized correctly and the sway bar is at a steeper angle than intended to the link.

[EdInArk]

I just keep looking at how many years and how many people have done this successfully with no trouble.

As for stressing it, the sway bar is essentially a very large torsion spring. What we're doing is shortening the effective length of the lever making it move farther with any given movement and twisting that spring more. Maybe they think it could be stressed by twisting it farther than they designed it to flex.

I'm sure someone will come along shortly and explain that far better

[TeJay]

Lets see!!!! John Mckinley implemented the CHF in the summer of 2010. I believe he has well over 40,000 or maybe 60,000 miles on the CHF and all is well in OH. We have over 40,000 miles (August of 2014 until the present) on our RV and nothing has prematurely failed. That's NOTHING!!!

For over 10 years hundreds maybe thousands of owners have implemented the CHF and we have heard of none prematurely failing in any way shape or form. We all recognize the squeaky wheel gets all the grease. When bad things happen folks let others know and they do it loudly and endlessly. Well John and others are still waiting.

About the only consistent failure in the sway control area has been Fords fault. This has happened to many RV before they might have done the CHF.

Often times they discovered the loose or missing bolts, bent, broken or missing brackets when they were investigating the sway system so they could do the CHF.

To this day FORD still does not recognize nor admit they have done anything incorrectly. That's the front SB brackets coming loose on NEW and OLDER units.

Well documented and recognized here on this forum.!!!! Yes if yours fails (warranty) and you take it in Ford will fix it. The problem is few recognize when it fails. Remember the supposed catastrophic accident that is going to happen when the sway control system breaks? When the brackets fail it's usually out of warranty.

What say you FOMOCO ????

We all have known or read about vehicles that have multiple holes in the SB arm designed to allow sway control as needed by the owners.

"The "unused hole" is a left over from the time when there was a support for the sta-bar bolt. The support was not needed and removed but the hole was left."

The above statement makes absolutely no sense. Has anybody ever seen any stock bolt placed in the inner hole prior to doing the CHF?? How could one possible add a bolt and support brace to that hole and still allow the SB to do its job???

And last I doubt Ford or any manufacturer is going to endlessly place a hole anywhere that is never going to be used. The inner hole has been punched in the SB front and rear since at least 1999. They don't drill, punch or stamp holes just for the fun of it. That would save them some $$$$ and I'm sure they'd do it for just that reason.

The steeper angle created by the CHF was addressed by extending the links. Some say it's not necessary yet some say it might over stress the system. It's one or the other. Many to be on the safe side fixed the angles with any one of 2-3 methods. We all recognize what they are.

[Ohiomike]

Ford should be ashamed of themselves for putting such a terrible handling product on market. Jim McKinley designed a better fix than their engineers and software could come up with. Maybe they should have done a better suspension from start. As usual some guy from Cincinnati has to fix their mistakes. Hahaha

[tderonne]

Of course both holes have been used in the past. The second hole was for the "Z-bracket" - or whatever Ford called it.

Funny thing is, I think Ford has approved of the change before. Probably mentioned in the CHF thread somewhere.

(I made the change in 2009 to my motorhome. I've since swapped to a larger swaybar from the 24K/26K GVWR chassis on my 20.5K. About 50,000 miles total for me.)

Edit:
Here's one thread where a retired Ford suspension engineer said it's ok. Maybe that's what I was thinking of. Not Ford.)

Another:
This thread someone called the motorhome hotline about the warranty implications.

[hohenwald48]

There are many fixes for many manufacturer shortcomings on many vehicles. That's what the vehicle "accessory" industry is all about. The CHF simply addresses something inadequately addressed by Ford by using existing parts and it has a long and successful history.

Having said that, I do believe there are some Ford chassis configurations where the CHF is inappropriate. Back when the anti sway bars were straight there seemed to be no problem. Now that Ford has begun using bent and formed anti sway bars there are some interference issues coming up regarding anti sway bar contact with differentials and brake drums.

It's up to each owner to determine if the CHF is appropriate for their particular chassis and configuration. I don't think we can simply state the CHF is a valid solution for all configurations. Nor can Ford simply state it is an inappropriate fix for all configurations. I doubt a single Ford public presenter has all the facts as other Ford reps have stated there is nothing wrong with the CHF.

Who knows what configuration challenges may come with the new F-53 chassis?

[blueridge-fl]

Did anyone at the presentation ask what the design limits were? Is the limiting factor the links, the brackets, the bushings or the bar itself? Also, CAE is only one aspect of verifying the integrity of a change. Has Ford ever performed any road/track testing of the CHF mod?

Also, the timing of this proclamation is interesting given that Ford has beefed up the SBs on the new chassis. Saying that the CHF is bad might increase the motivation for buyers to move to a newer unit.

[Waiter21]

I wouldn't expect anything less from Ford, I;d do the same. Why would they sanction this and open themselves up to liability for a modification that they have no control over..

[glen_423]

So CAE stands for Computer Added Engineering. Which is a way off doing computer analysis to measure stress, loads and strain on a part or a system of parts. It has been around for like 40 years

The “z” bracket is an anti rotation device to prevent the bolt at the link from coming loose. At some point someone at ford must of determined that the Z bracket was not need or the link attachment system was change so the bracket was no longer needed

Because of the legal system in the US you should never find any OEM engineer giving you the OK to make any modifications over what is released by the OEM.

I am surprised that someone who represents Ford stated that this change was even evaluated at Ford. Moving the attachment to the other hole location is a big change when it comes to the loads on the anti roll bar system It does not surprise me that this change would not pass Ford’s standards

[Dav L]

Originally Posted by glen_423

The “z” bracket is an anti rotation device to prevent the bolt at the link from coming loose. At some point someone at ford must of determined that the Z bracket was not need or the link attachment system was change so the bracket was no longer needed

I think the Z bracket is there to provide a 'box' structure to the sway bar link pivot. To keep the bolt from bending. It doesn't do anything for rotation. The bolt and bushing don't pivot (when tight). The only flex is in the rubber bushing that allows for pivoting.

If CHF is done correctly, I don't see any issue based on the number of folks that have done it and no reported incidents.

What is right? The length of the link is adjusted to keep the sway bar at the Ford standard inclination when the RV is settled on it's suspension. This can be achieved by purchasing adjustable links, by purchasing TeJay plates or home fashioned by welding sufficient strength extensions to the stock links.

That the sway bar links never suspend the axle when the axle is dropped.

That the sway bar links never prevent the axle from topping out when completely compressed.

That the sway bar never contacts the chassis or axle or pumpkin during full stroke and full articulation.

All bushings are in good shape.

The Z strap (if used - recommended) never contacts the sway bar link during full stroke. If the sway bar links are the right length, this shouldn't be a problem.

All bolts are loctited and torqued to spec.

[EdInArk]

Originally Posted by Waiter21

I wouldn't expect anything less from Ford, I;d do the same. Why would they sanction this and open themselves up to liability for a modification that they have no control over..

Exactly.