E39 M5 - suspension knocking noise when warm, and slow...?
Discussion
Hopefully someone might be able to help with a diagnosis...
I have a 2001 M5, currently on about 75k, and is completely standard.
A knocking noise has appeared, on what I think is the front left corner. I can't be 100% once it's echoing about the interior, but I'm 80% sure. It started last September, being very subtle, and has slowly got worse. I had a main dealer oil service done in December, and it got a full bill of health.
When the car is cold, it's fine. Braking, turning, speedbumps, accels, forward/reverse, full lock, it's totally silent.
If I drive it slowly, as in city centre type traffic, the noise slowly appears as an almost continuous hard vibrational knock, increasing with time to a very loud crescendo. The closest I've heard to it was when I had a loose front topmount nut on a solid mounted trackday E36.
If I then drive at high speed, like a motorway, the sound diminishes. Once I come off the motorway and start trundling it reappears. It almost seems like it's related to heat buildup in the suspension or the brakes.
At standstill, at any time, there's nothing when revving the engine, so I'm reasonably happy the mounts and front subframe are ok.
I've not yet managed to isolate it to a particular manoeuvre, so it doesn't seem to be worse or better when braking, turning in a particular direction, or anything else. However, I'm going to try some light left foot drag-braking when it does it to see if that changes anything. I also want to do some on-handbrake checks to see if there's anything with the propshaft centre, or the diff mounts.
I've been doing a light front end refresh on it, the 4 lower arms are about 6000 miles old, both front wheel bearings, ARB dropmounts and strut top mounts are about 3000 miles old, and all spent about 2500 miles being silent before this happened.
I've done a light inspection, nothing is damaged or loose, no missing spring coils, nothing appears to be rubbing or moving. I torque-checked the caliper and the easily accessible bolts, all OK. The disc is old, but comfortably above minimum thickness.
So, it's a bit baffling. Other than throwing some new discs and stuff like pitman arms and track rods at it, I'm out of ideas. However, why pitmans or track rods would be affected by heat, but seemingly have no response change during steering is slightly odd.
If you read all that, any ideas or thoughts?!
I have a 2001 M5, currently on about 75k, and is completely standard.
A knocking noise has appeared, on what I think is the front left corner. I can't be 100% once it's echoing about the interior, but I'm 80% sure. It started last September, being very subtle, and has slowly got worse. I had a main dealer oil service done in December, and it got a full bill of health.
When the car is cold, it's fine. Braking, turning, speedbumps, accels, forward/reverse, full lock, it's totally silent.
If I drive it slowly, as in city centre type traffic, the noise slowly appears as an almost continuous hard vibrational knock, increasing with time to a very loud crescendo. The closest I've heard to it was when I had a loose front topmount nut on a solid mounted trackday E36.
If I then drive at high speed, like a motorway, the sound diminishes. Once I come off the motorway and start trundling it reappears. It almost seems like it's related to heat buildup in the suspension or the brakes.
At standstill, at any time, there's nothing when revving the engine, so I'm reasonably happy the mounts and front subframe are ok.
I've not yet managed to isolate it to a particular manoeuvre, so it doesn't seem to be worse or better when braking, turning in a particular direction, or anything else. However, I'm going to try some light left foot drag-braking when it does it to see if that changes anything. I also want to do some on-handbrake checks to see if there's anything with the propshaft centre, or the diff mounts.
I've been doing a light front end refresh on it, the 4 lower arms are about 6000 miles old, both front wheel bearings, ARB dropmounts and strut top mounts are about 3000 miles old, and all spent about 2500 miles being silent before this happened.
I've done a light inspection, nothing is damaged or loose, no missing spring coils, nothing appears to be rubbing or moving. I torque-checked the caliper and the easily accessible bolts, all OK. The disc is old, but comfortably above minimum thickness.
So, it's a bit baffling. Other than throwing some new discs and stuff like pitman arms and track rods at it, I'm out of ideas. However, why pitmans or track rods would be affected by heat, but seemingly have no response change during steering is slightly odd.
If you read all that, any ideas or thoughts?!
The bigger V-engined e39s are renowned for suspension leg top-mounts making a noise that sounds like what you say.
Easy fix if you use the weight of the car to compress the spring, undo the top-mount, lift the car, change the top-mount, then slowly/carefully lower the car back down, making sure the shock top and spring go where they should.
Easy fix if you use the weight of the car to compress the spring, undo the top-mount, lift the car, change the top-mount, then slowly/carefully lower the car back down, making sure the shock top and spring go where they should.
It does sound like the centre tie rod. One of the ball joints on the centre tie rod is located close to a part of the exhaust system so there is accelerated wear due to heat cycling. Doesn't readily show up during inspection with a pry bar etc.. Typical symptoms are noises etc only after about 30 mins driving. If the centre tie rod has not been replaced before I'd start further investigations there.
If are going to replace the centre tie rod then probably best to change the left and right tie rods as well if they're original. The whole tie rod assembly - left, right & centre - can be removed from the car as a complete unit if you're careful. New pitman & idler arm probably worth doing (or at least replacing the one critical bush) 'while you're in there'. Oh, the joys of M-car ownership!
If are going to replace the centre tie rod then probably best to change the left and right tie rods as well if they're original. The whole tie rod assembly - left, right & centre - can be removed from the car as a complete unit if you're careful. New pitman & idler arm probably worth doing (or at least replacing the one critical bush) 'while you're in there'. Oh, the joys of M-car ownership!
Ah, inner track ball joints, nice call. The track rod ends seemed sturdy on the hub, but I didn't specifically lever against the track rod to drag link ball.
However, it would seem appropriate given its position relative to the headers and it's a hard knock, rather than the softer thud from a knacked bush.
The pitman is nicely visible in a cut out of the right side arch liner, so getting at the bush in it shouldn't be the worst thing ever...
I'll get on it as the next job, here's hoping...!
Cheers!
However, it would seem appropriate given its position relative to the headers and it's a hard knock, rather than the softer thud from a knacked bush.
The pitman is nicely visible in a cut out of the right side arch liner, so getting at the bush in it shouldn't be the worst thing ever...
I'll get on it as the next job, here's hoping...!
Cheers!
tting suspension and associated bushes 
Can anyone offer advice I have a 2016 BMW 116d F21 Sport 41000 miles which has a knocking / vibration which can be felt through the steering at low speeds but only seems to occur in hot weather ? the issue became apparent during the hot weather this summer I booked the car in to my local BMW dealer Ocean at Falmouth for investigation the diagnosed that the vehicle had worn wishbone suspension bushes tracking out of alignment and feathered tyres worn unevenly . I had both suspension arms replaced tracking geometry done and Two new tyres Cost not including Tyres just under £700
all seemed well untill last couple of days had hot weather around 27 c and the problem is back just as bad starts of with slight clonking but gets worse over speed bumps ect
I have wondered if this is a steeering rack or top suspension mount issue going to have to take it back to the dealer again but somewhat anoyed having paid for new suspension arms and the problem stll not rectified
any advice gratefully recieved
all seemed well untill last couple of days had hot weather around 27 c and the problem is back just as bad starts of with slight clonking but gets worse over speed bumps ect
I have wondered if this is a steeering rack or top suspension mount issue going to have to take it back to the dealer again but somewhat anoyed having paid for new suspension arms and the problem stll not rectified
any advice gratefully recieved
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