Rear Knocking Noise - Possible Aftermarket ARB/Droplink Allignment Issues? - NA

Hi everyone, just joined the owners club and this is my first post so apologies in advance if I’m putting this in the wrong place or anything like that.
Anyway, my car has developed a knocking noise in the last few days. It sounds like it is coming from the OSR corner (could just be due to me sitting on that side however) and it seems to be quite random when I hear it, sometimes it will happen a few times in succession, other times just once or twice, and I think it may be slightly worse when cornering. I’ve checked that it’s definitely not anything like a calliper bolt missing or just a loose bolt somewhere in the suspension.
The only areas that have recently been touched on the rear of the car are the camber/toe adjustments during a 4-wheel allignment and the anti roll bar was swapped for a Whiteline adjustable one. Now, it’s just been to a mechanic and he seemed to think the new ARB wasn’t the correct fitment as the droplinks are fairly angled in order to reach the holes (pictured below). I ordered the bar from BOFI Racing and it was definitely the NA bar.

Are these angles too much, and even so, would it cause the knocking noise? I’ve heard from a friend with a 5 today that the bar does have a specific orientation, which I’ve probably done wrong as I’m sure you will all let me know - before you judge me too harshly, the bar that came off before it was some weird DIY fully tubular design with no angles to it, that even MX5 specialists said they’d never seen before! But even if I were to rotate the bar, the angle of the ends are so minimal I can’t imagine it will make much difference at all?
Thanks in advance for your help :slight_smile:

The top joint of the drop links is definitely “off” you’re not able to tighten the nuts anywhere near properly due to the severe angle where the drop links attach to the ARB. Also, how low have you got the car overall? The Meister suspension looks to be wound down into the bottom of the units quite a bit?
I would be in touch with BOFI, perhaps with clearer pictures and see what they have to say. To me, it looks like the ends of the ARB need to be aligned further out to reduce the angle on the joints (read ‘bent’ outwards)

Just to add, the ARB’s are the same for mk1/2/2.5

The car isn’t tooo low, there’s still a fair gap in the arches - I just left them set to what they were out the box, can’t quite remember what the measurements were now. Although I am planning on raising it soon as I’ve fitted a lower front chassis brace which tends to scrape over aggressive speed bumps.
Looking at the pictures again, it does look as though just flipping the ARB around might help a fair bit? But I also agree that overall the bar looks as though it should bend out more than it does. The pictures of it on the BOFI website do look fairly symmetrical though :thinking:

Yes does look ‘flat’ in the pics so turning it round probably won’t make a deal of difference :thinking:


I’d say it looks as though there is a slight angle. I’ll probably turn it round once I have access to my tools and send a prayer to the car gods that it really is just as simple as that, somehow I don’t quite think so though :sweat_smile:

The ends of the ARB are supposed to be level with the ground when the suspension is loaded up? I.e. car sat on the ground. As you have adjustable droplinks, might be worth checking this out too.


Yeah I did have the droplinks wound down a lot more than in the pictures so the bar was level, but the mechanic that just had the car wound them up because he thought that might help - evidently not

Is this ARB sided, ie is it possible to install it upside down ?

Honestly I’m not too sure? If it is then it definitely isn’t immediately obvious. I recently watched Donut Medias video on youtube where they fit new ARBs and during the rear one they mentioned how it has a specific orientation, although their bar looked a hell of a lot more angled than the whiteline one I’ve got.


I would expect a drop link to work so the joints are centred in wishbone and ARB for most of their travel.

This looks so wrong, the rose joint housing will be knocking/jamming on its axle. I’ve zoomed in to it to highlight it.

IF the mounting flat on the ARB for the drop-link bolt is slightly angled from vertical, same as the spring, and the bar is upside down, then that might explain it.

However, if the flat is not angled, but simply vertical to the ground, then the ARB is not satisfactory

Whatever has been done, I don’t expect those rose joints to survive for long.

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Well it’s funny you say that. The last ARB that was fitted to the car had a very weird setup that I’ll show in some pictures below (Ignore the tape measure).

As you can see there is a portion of metal that sticks out from the original mounting that is clamped down with a U-Clamp and the droplink attaches to that. My assumption was that this was fitted due to odd dimensions of that bar, but seeing as that droplink is also at quite a hefty angle, I suppose there is a slight chance that there has been some dodgy welding going on. :thinking:

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Looks like the lower drop link mount has been “moved” outwards cf. 7.13 here

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You may well be right. That seems so bizarre and I’m struggling to understand why that would be the case - especially as it’s not like they were lined up very well with the last setup either.
I’ll still have a go at just rotating the bar round when I get a chance to see if it makes any difference and I’ll post an update (fingers crossed), otherwise I guess I’m looking at either new arms or another welding job :sweat_smile: