[widetyres]

I've had a knocking noise when driving over rough surfaces, and managed to investigate this properly last night.

The knocking could easily be replicated with hands at 3 & 9 o'clock on a lifted wheel - rocking the wheel left to right would repeat the knocking noise (see video for how this sounds here: https://youtube.com/shorts/MJ_thPXHqnk). The edge of the tyre was probably moving in/out about 5-8mm in total.

I thought it was the control arms at first, and whilst those do need replacing IMO, the noise wasn't coming from them. To be honest, it was very tricky to trace the sound (especially with my duff hearing!!!, but even my wife struggled to pinpoint it). But through a process of elimination, I was pretty convinced it was coming from the steering rack!!! OMG I was thinking, this is going to be expensive!!!

Anyway, I found a thread on the net for non-M cars that mentioned tightening an adjuster, so thought I would give that a go. Whilst on those cars a special 3-pronged tool was required, my 2016 OG M2 has a plain 17mm nut at that location (see photos for location).

It didn't need much adjustment. I probably tightened it initially 1/16th of a turn, but the knocking was still present. Then I tightened it until I couldn't tighten it anymore, then backed off a bit (this was probably a further 1/8th of a turn), and the knocking was gone!!!!

Before putting it all back together, I turned the car on, and checked the steering - it was so heavy!!!! It felt like a lorry without power steering!!! It took a few attempts, but I adjusted it so that the knocking/movement was gone, but the steering wheel was still easy to turn.

Happy days! No play or knocking, and no need to buy a new steering rack!!!

Pics:
1) Shows the location of the adjuster on the steering rack (the top of a rubber bung within the nut can be seen at the end of the ratchet handle - this rubber bung did not need to be touched) - this is on the driver's side of the rack on UK cars, or the passenger side for other regions.
2) Shows the 17mm socket installed and ready to tighten - you will need a universal joint due to the angle.

[widetyres]

As it happens, I did take a pic of the nut (very blurry though as not much room):

[atlas]

Thanks for the photos! Excuse my ignorance but I assume this is under the car?

[widetyres]

Originally Posted by atlas

Thanks for the photos! Excuse my ignorance but I assume this is under the car?

Yep, and you'll need to take the undertray off as well.

[widetyres]

Stumbled across the below thread - loads of people with F80/82 have experienced knocking following lowering of their car (mine is lowered to MPSS height recommendations) and they also eventually traced back to needing to adjust the steering rack tension:

https://f80.bimmerpost.com/forums/sh....php?t=1637057

https://f80.bimmerpost.com/forums/sh...1422771&page=2

[warrenw]

Reading the threads you provided someone said:
There has been some discussion in other threads about adjusting a bolt on the steering gear to take up slack and eliminate play. (Some people claim this fixed their issue, at least temporarily)

Don't. My friend who works for Bosch in steering gear development said not to touch that bolt, that there's a specific procedure for setting the preload and doing it yourself could cause heavy wear and screw things up. Take it to the dealer if you think the steering gear is an issue.

Any ideas what that procedure might be...?

[widetyres]

Originally Posted by warrenw

Reading the threads you provided someone said:
There has been some discussion in other threads about adjusting a bolt on the steering gear to take up slack and eliminate play. (Some people claim this fixed their issue, at least temporarily)

Don't. My friend who works for Bosch in steering gear development said not to touch that bolt, that there's a specific procedure for setting the preload and doing it yourself could cause heavy wear and screw things up. Take it to the dealer if you think the steering gear is an issue.

Any ideas what that procedure might be...?

Thanks for highlighting. When I found that thread I also saw comments that there is no BMW procedure for this - I did have had a search on ISTA and can't see anything. This would essentially mean that most BMW garages would specify a new rack, which is big bucks out of warranty. Although it does seem that a couple of people have had it adjusted by more competent dealers.

If you over-tighten it, I can certainly imagine that it would wear quickly. From further reading, this nut it what tensions the rack and pinion gears together. With mine, I left it as loose as possible, but with pretty much all the knocking gone (I still could hear a very slight noise, but didn't want to leave it too tight).

As I'm out of warranty, it's a four figure bill or that bit of DIY - I'll risk the latter!!!

When I get some more time, I will try to find some Bosch instructions - had a quick look, but all I can find so far is older ZF rack instructions: https://www.e90post.com/forums/showthread.php?t=1820855
- you can see from the 2nd post that the procedure is very detailed!

[warrenw]

I fixed my issue by rebuilding my Ohlins. It could also be that some things were getting loose and reinstalling the suspension tightened those again. But either way, both those together fixed my issue.

[Rumbloki]

Shouldn’t tie rod ends with bump steer adjustment take care of any steering rack issues caused by lowering? At least when installed before damage is done.

[Tetsu69]

Originally Posted by widetyres

I've had a knocking noise when driving over rough surfaces, and managed to investigate this properly last night.

The knocking could easily be replicated with hands at 3 & 9 o'clock on a lifted wheel - rocking the wheel left to right would repeat the knocking noise (see video for how this sounds here: https://youtube.com/shorts/MJ_thPXHqnk). The edge of the tyre was probably moving in/out about 5-8mm in total.

I thought it was the control arms at first, and whilst those do need replacing IMO, the noise wasn't coming from them. To be honest, it was very tricky to trace the sound (especially with my duff hearing!!!, but even my wife struggled to pinpoint it). But through a process of elimination, I was pretty convinced it was coming from the steering rack!!! OMG I was thinking, this is going to be expensive!!!

Anyway, I found a thread on the net for non-M cars that mentioned tightening an adjuster, so thought I would give that a go. Whilst on those cars a special 3-pronged tool was required, my 2016 OG M2 has a plain 17mm nut at that location (see photos for location).

It didn't need much adjustment. I probably tightened it initially 1/16th of a turn, but the knocking was still present. Then I tightened it until I couldn't tighten it anymore, then backed off a bit (this was probably a further 1/8th of a turn), and the knocking was gone!!!!

Before putting it all back together, I turned the car on, and checked the steering - it was so heavy!!!! It felt like a lorry without power steering!!! It took a few attempts, but I adjusted it so that the knocking/movement was gone, but the steering wheel was still easy to turn.

Happy days! No play or knocking, and no need to buy a new steering rack!!!

Pics:
1) Shows the location of the adjuster on the steering rack (the top of a rubber bung within the nut can be seen at the end of the ratchet handle - this rubber bung did not need to be touched) - this is on the driver's side of the rack on UK cars, or the passenger side for other regions.
2) Shows the 17mm socket installed and ready to tighten - you will need a universal joint due to the angle.

Hi,
Thank you very much for elaborating.
When you did this fix, did you need very high torque to turn this bolt?

I have similar noise since I changed suspension.
I asked my mechanic to turn this bolt but he said he couldn’t turn because bolt is too sticky. I want to know if this is because the bolt is just rusty or actual mechanical stop.

[widetyres]

Originally Posted by Tetsu69

Hi,
Thank you very much for elaborating.
When you did this fix, did you need very high torque to turn this bolt?

I have similar noise since I changed suspension.
I asked my mechanic to turn this bolt but he said he couldn’t turn because bolt is too sticky. I want to know if this is because the bolt is just rusty or actual mechanical stop.

Hi. I recall it being a bit stiff to move initially.

The threaded disc that the nut is bonded to/part of, compresses a spring that tensions a thrust piece; if it was tightened to the point of being a mechanically locked, then you would struggle to move the steering wheel.

I recommend that your mechanic uses a chalk pen to mark the current position of the threaded disc, and then slackens it off to break any corrosion, then tries to tighten further. Doing this means that there is no way that he can cause any damage.

[Tetsu69]

Originally Posted by widetyres

Hi. I recall it being a bit stiff to move initially.

The threaded disc that the nut is bonded to/part of, compresses a spring that tensions a thrust piece; if it was tightened to the point of being a mechanically locked, then you would struggle to move the steering wheel.

I recommend that your mechanic uses a chalk pen to mark the current position of the threaded disc, and then slackens it off to break any corrosion, then tries to tighten further. Doing this means that there is no way that he can cause any damage.

Thank you!
Your explanation and advice are very reasonable and I will try as you described!

[Rub1con76]

I follow this thread.
Got some knocking also, but my ohlins shocks get rebuild now.
So hope that will solve the knocking

[widetyres]

Originally Posted by Rub1con76

I follow this thread.
Got some knocking also, but my ohlins shocks get rebuild now.
So hope that will solve the knocking

Yep, shocks can knock as the bushings wear, so worth checking it. My AST's did that, but that was after the steering rack correction.

You can check for a worn bushing by jacking up a corner and trying to wobble the shock - the feel of the knock is usually quite obvious.

Hope you get it sorted!