C219 W219 W211 Arnott Strut Top Mount Bolts Sheared - Wow

[DanB8]

Hi All,

I was having a go on the car again today and whilst I was cleaning in the engine bay I found the O/S top mount bolts for the front suspension strut have sheared off completely. I'm totally shocked (no pun) and have never seen this before.

C219 W219 W211 Arnott Front Strut Top Mount Bolts Sheared Off

• DanB8
• Oct 23, 2017

A picture of a fairly new right hand side (O/S) Arnott Air strut. Notice that the three top...

C219 W219 W211 Arnott Front Strut Top Mount Bolts Sheared Off

• DanB8
• Oct 23, 2017

A picture of a fairly new right hand side (O/S) Arnott Air strut. Notice that the three top...

The strut is a pretty new Arnott item (not sure of the exact age of the strut but it looks like its less than 2 years old).

Apparently, according to Arnott, I need a new strut.

I think almost anything is serviceable so I hope to be able to remove the strut, disassemble the top mount, drill out the bolts, reinstall new ones but I'm finding it near impossible to find pictures of the struts disassembled, exploded diagrams of the struts etc. Arnott are not very helpful (I'm on it today) or forthcoming with information.

Are these items serviceable? Has anyone ever done this? Can I replace the top mount bolts? I thinks so because the bolts has a torx fitment similar to the strut piston (to hold it steady).

If anyone has any info or advice it would be much appreciated.

Cheers

Dan

 

[Will]

Hi Dan,

Might be wrong but I’d have thought they would be captive studs and not bolts that could be replaced.

Are they torx head on the end? Look like hex to me. They have the hex head on them so you can hold the stud whilst installing the nut and torque it to spec.

Looking at the markings on the nut (looks like they have a dacromet type coating) I suspect someone has installed them with an impact gun and overtightened them, hence stretching the stud and causing it to snap.

Might be possible to remove the old stud but I suspect it will be part of thr whole top mounting of the strut and will need to be replaced (unless you can get an engineering place to fit new ones, precisely welding etc if strong enough)

 

[renault12ts]

You'd think Arnott would be more than a little interested in this.

You could suggest to them that you'll be going on all the MB forums you can find to see if this has happened to anyone else. Indeed any forum for any car where Arnott supply aftermarket struts.

 

[DanB8]

Thanks for the replies chaps.

Will, yes you are correct. The head is a hex fitment not torx (I didn't have the bit in front of me when I typed this out) and that is what led me to think I could remove the remnants of the stud (I'm not good with correct technical terms but knew it wouldn't be a standard bolt) and install new ones. Hopefully I can do this without stripping the strut down.

I hoping the studs won't be the captive type due to the hex to hold it/insert when manufacturing. I imagine/hope them to be the type of stud similar to this but not for wheels. https://www.demon-tweeks.co.uk/performance/wheel-nuts-bolts/grayston-conversion-stud

I thought captive studs gripped the material they are installed into and wouldn't need a way to hold them steady but I'm not qualified to say. I'll hopefully be able to shed some light on the situation. If they are captive and I can't strip the top mount down it looks like it's a new strut.

Renault21ts, I would have thought Arnott would have been more helpful due to the lifetime warranty they have. I didn't ask for a free replacement as I know it's a "limited' lifetime warranty but would have thought that because they issue a lifetime warranty if you buy the item yourself they would have helped me a bit as a goodwill gesture. All I wanted was a bit of help/info on whether I could change the studs, if the struts are serviceable, etc. They said they can't be serviced and a new strut is the only way.

In all fairness to Arnott, it was probably some trigger happy mechanic with an impact gun who stretched the bolts and not down to quality of construction. I just thought they would have been a bit more helpful like "yes mate, you are able to strip down the strut enough to replace the studs, which are this type of stud, and maybe we can sell you some" but they don't have to I suppose. It would have been a big help though.

I'll hopefully get them off the car and start the repair over the weekend.

 

[Major774]

I think it’s just the quality, clearly not up to the task.

I have used impact guns, torque wrenches etc on many OEM suspension (various car brands), the OEM parts just feel solid. Just try and see what you can get back from them (hopefully something), then change to back OEM for your safety.

 

[Will]

I think it’s fair to say that Arnott have quite a good reputation generally, they’ve sold loads of these all over the world and quite a few UK cars have these installed.

What’s the torque setting for the front top mounts? I bet it’s not a lot, even a cordless 1/2” impact gun can exert 500+Nm of torque quite easily. If MB wheel bolts can break I wouldn’t be surprised to see a small stud like that go.

FWIW, I’ve got Arnott struts on my car (fitted by previous owner) - no issues!