Sprinter 2019 Alert - Rear Sway bar

[Travelino]

Maastor,
I agree with the bolt length. I read one possible reason for the shorter bolt, is that the locking flange nut is most effective if not threaded on a longer bolt, as the bolts friction locking tends to weaken as you run it up further along on a bolt.



But then too, both of mine have come off on their own. Mercedes replaced the first one with another that was 65mm. When I found the second bolt missing, I replaced it with a temporary bolt, SAE flange style, because I was not able to find the metric bolt locallly.


But I did go online and the closest I could find was 70mm, like you got and so they will be used to attach the Helwig tow bar, hopefully tomorrow. I think with the locktite they will be fine and will have more threads showing after putting them on.

[rosspam]

Originally Posted by Travelino

I have a 2020 Tiffin Wayfarer on a 2019 Sprinter 3500 chassis.
I have about 10,000 miles on it, since I bought it new at the end of May of this year.


On our first major trip, on the last leg of that trip, the driver's side bolt that attaches the rear sway bar to the chassis frame vertical support came out when we used our leveling jacks. When we got home, we had our local Mercedes dealer replace the nut and bolt. The passenger side nut and bolt were checked by both myself and the dealer and were snug. This all happened around 5,000 miles. I decided this was a fluke at the time.


This past week, we had the passenger's side nut and bolt come out. I don't know exactly where it happened, so I don't have either the nut or the bolt. Now, I don't think this is just a one-up incident, but perhaps a design problem.


We find our Wayfarer has a lot of side to side sway anyway, but I can tell you if one side of the sway bar detaches, it is down-right dangerous, with excessive sway in wind, or even on a surface that has some dips.


I noticed that the 2019 Sprinter sway bar attachment is different than previous year models. The prior models have a "U" shaped vertical leg that attaches to the frame and the end of the sway bar. I attached a picture of a prior 2019 model I found on the web. In this case, the sway bar rides on the "shaft" of the bolt. The 2019 models, eliminated the "U" in the attachment leg and now the two components, the end of the sway bar, and the end of the support piece are simply bolted together. The fasteners are a flange bolt and a flange locking nut. In reading about the locking flange nut, I learned that its the torque force of the nut against the surface that is primary in keeping it from detaching. I am concerned that these two pieces being attached this way, are in constant motion and may be a cause for the nut to come loose.


I am hoping that those of you that have a 2019 model Sprinter, can take a look at your rear sway bar and see if they are still snug. Also, mine were attached so the nut is to the outside, that is facing the wheel and the bolt is on the interior side. Please let me know if your setup is the same way.


I do plan to make additional inquires about this and will let you know what I find out. I'm also considering a Helwig sway bar for better control, but for the 2019 model, the new Helwig sway bar uses the same attachments provided by Sprinter, so if this is a problem it would also effect the Helwig.


Picture 1 is a pre-2019 Sprinter showing how the support arm is attached (gotten off the web). Picture 2 is my driver's side with the replacement bolt that Mercedes installed. Picture 3 is my passenger side after I found this side also lost its bolt last week. I temporarily installed a bolt and nut till I can get the proper nut and bolt from Mercedes.

Notice washers on either side of bushing in this roadmaster install on sprinter from etrailer. This makes better sense. They use longer bolt and nylon lock washer

[rosspam]

Found theses fasteners on line.Attachment 274476

[rosspam]

Originally Posted by maasthor

in my own UNprofessional opinion, the bolts on these appear a smidge short. only a thread or two showing. why is that? I ordered some high strength bolts in same size as factory (M12 x 1.5) but 70mm long instead of 65mm. there appears to be no reason a few more threads cant be showing. or am I mistaken? Thinking they will hold better...?

Upper bolt protrudes a couple of threads giving split beam lock nut plenty engagement. Standard MB lower bare has a thread. I am going with new flange bolts 70 mm and conical lock nut (dot of blue loctite) on my lowers.

[f14av8r]

After seeing these reports I checked my chassis. Lo and behold, one of the sway bar screws (passenger side) was missing. I pulled the other screw off to get the proper sizes, headed for Ace Hardware, and bought some replacements. I replaced both sides. The stock screws are too short or, as others have guessed, they were removed and then not torqued properly when reinstalled. I might have Mercedes replace them with stock next time I go in for service but, for now, I'm pretty happy with the fix. I used 70 mm screws, washers on each end, and nylon nuts. Note that the stock screws and nuts have an integral flange so, if you use the stuff available at the hardware store you'll need to add washers to get an adequate bearing surface.

I used 10.9 12-1.50x70 Hex Head Cap Screws, 12-1.50 Fine Thread Lock Nuts and 12 mm Flat Washers. See the photos.

No surprise, the ride is vastly improved with the sway bar reattached!

https://randyking.smugmug.com/frame/...=2&clickable=1

[rosspam]

Originally Posted by rosspam

Upper bolt protrudes a couple of threads giving split beam lock nut plenty engagement. Standard MB lower bare has a thread. I am going with new flange bolts 70 mm and conical lock nut (dot of blue loctite) on my lowers.Attachment 274684

Finished replacing sway bar lower bolts. Bought extras.

[f14av8r]

Originally Posted by rosspam

Finished replacing sway bar lower bolts. Bought extras.Attachment 274795Attachment 274796Attachment 274797

I like Ross' approach best, I'm just not sure it is necessary. The grade 10 hardware from Ace is probably just as good and less difficult to obtain. The real bottom line here is that Mercedes should set this right. We are just avoiding having to deal with the dealer, and all that involves!

[Travelino]

I wish that those of you that have found your sway bar bolts missing or loose would call Winfield and report it. I originally pointed out this problem and sent Tim Tiffin a letter about it. When I checked back more recently with tech support, they indicated they hadn't seen the problem. I had asked them to check 2020 units coming in for service. They would have more clout with Mercedes than each of us. It appears to be a problem.


I also went and bough replacement bolts and nuts from the same company as pictured in the envelope, but 70mm long. It was less hassle and cost than driving all the way in to the Mercedes dealer.


I just installed the Hellwig sway bar that I ordered and used the new bolts and nuts on it, rather than the Mercedes sway bar. I need to write up a review of my initial impressions. I'll start a new topic on the subject soon.


I'll call it something like "Installing Hellwig sway bar on my 2019 Sprinter.

[KanzKran]

Originally Posted by Travelino

I just installed the Hellwig sway bar that I ordered and used the new bolts and nuts on it, rather than the Mercedes sway bar. I need to write up a review of my initial impressions. I'll start a new topic on the subject soon.

I’m looking forward to reading it.

[Flarpswitch]

I was looking around for info on sway bars because our 2016 chassis seems a bit more squishy than our 2008, the later being no problem at all. Then I came across this problem. My question is this: are the bolts just unthreading and falling out or are they breaking off. If they are breaking, I would think it is because the load on the bolt is exceeding the shear strength. The U shaped mount distributes the load in two places while the new design loads in only one. Am I reading this right?

[f14av8r]

Originally Posted by Flarpswitch

I was looking around for info on sway bars because our 2016 chassis seems a bit more squishy than our 2008, the later being no problem at all. Then I came across this problem. My question is this: are the bolts just unthreading and falling out or are they breaking off. If they are breaking, I would think it is because the load on the bolt is exceeding the shear strength. The U shaped mount distributes the load in two places while the new design loads in only one. Am I reading this right?

The screws are not failing in shear. That just isn't a likely failure mode in this application. The stresses just aren't there. I'm fairly certain that the problem here is one of two things. The most likely is that Tiffin disassembled this structure to facilitate their uplifting and did not properly reinstall and torque the screws. That allowed the nuts to become loose and back off. The other possibility is that Mercedes installed screws that are too short and thus the nuts backed off the screws. Frankly, I suspect the former. But, fortunately, the fix is simple. Longer screws addresses the later and properly torqued installation addresses the former.

I'm looking forward to visiting with Tiffin about this at the Sarasota rally later in the month.

[rosspam]

Originally Posted by Flarpswitch

I was looking around for info on sway bars because our 2016 chassis seems a bit more squishy than our 2008, the later being no problem at all. Then I came across this problem. My question is this: are the bolts just unthreading and falling out or are they breaking off. If they are breaking, I would think it is because the load on the bolt is exceeding the shear strength. The U shaped mount distributes the load in two places while the new design loads in only one. Am I reading this right?

A number of folks have found nuts loose, so shear failure unlikely as f14av8r said.

[KanzKran]

Originally Posted by rosspam

A number of folks have found nuts loose, so shear failure unlikely as f14av8r said.

Most prevailing-torque type locknuts are single use items, and won't hold as well once removed and reinstalled. That includes nylon-insert types (so-called 'aircraft nuts'), and deformed steel, like with the dimple in the side or deformed thread. Or those with the little nylon button inside (don't remember what they're called).

They may still have adequate holding, or they may not, but they won't have as much residual torque as when first installed. Some folks have speculated that they were removed and reinstalled at some point, maybe by the up-fitter, which would make sense. Or it's confirmation bias on my part.

For such an application, I'm surprised they're not castellated nuts with cotter pins.

[Travelino]

The nuts loosened and fell off, then the bolt worked its way out. The bolt was not sheared off. When the first one fell off,, Mercedes replaced it and checked the torque on the other side, but 5,000 miles of so after, it too fell off. I now put on 70mm bolts, versus the original 65mm bolts and new nuts when I installed the Hellwig sway bar. sorry I haven't written that up yet, but will soon.


When I talked with Tiffin, they said they checked with the people that put on their Sumo springs and they do not remove the sway bar bolts. I can't see why Tiffin would be removing them. Also a non Tiffin owner said they had the same problem.