Considering a suspension refresh

[molgrips]

I drove to Nottingham and back on Friday and on much of the M5 and M42 the road surface is rough. On anything other than completely smooth roads I could feel the grain of the road surface through the steering wheel, and the edges of every imperfection.

My car is a 2013 CLS with 18" wheels and Goodyear Eagle tyres at 8mm. I would expect a more muted feeling from the road. I feel as if it's got a bit worse in recent months but it's obviously hard to be sure and those roads are not ones I drive often.

Given the age of the car I'm considering replacing all the bushings. A big job of course but I've done it before on another car and I think I can handle it. There doesn't seem to be any other handling problems or noises.

Has anyone else done this and improved the ride quality? Do I need to replace the lot or should I target certain bits (e.g. that big lower bushing at the front or the top shock/strut mounts) Much of the car needs a good coat of rust proofer underneath so I'll be able to do that at the same time.

Thoughts?

 

[TeddyRuxpin]

I've done it at the front of my W212, so should be similar/the same. It's not an easy job, especially on a driveway without a lift, impact gun, heat.

I wouldn't say the ride quality is improved per se, I think that's more down to the shock/damper and the springs being healthy. I don't have any knocking anymore, though, and the steering is more direct (new tie rod ends). All lemforder parts.

I also changed the rear sway bar drop links (10 min job per side) which solved a strange swaying feeling.

Don't underestimate the cost either...! Just control arms, tie rod ends, drop links (front and rear) alone with no labour is probably £600+. I can't quite remember the tally in the end.

I haven't done the shocks, springs, or the any of the rear control arms...

 

[molgrips]

Last time I did it I bought bushing alone and pressed them out with an eBay cheap press. That part was a total nightmare. I swore I'd buy complete arms next time. And yeah, I know it's going to cost.

I changed the shocks for Bilstien B4s about 6 months ago. I didn't do the top mounts on the rear or the strut mounts at the front.

 

[TeddyRuxpin]

Oh! How was it after the B4s? why did you change?

I'm guessing that if you found it necessary to change the shocks, the bushings will be done too. Are you going to do the top mounts too, this time around?

I think the W212 as the same layout as your car, so I should be able to point you in the right direction. Finding the torque settings can be a big pain the ****. There are two large control arms (one with separate ball joints), drop links and you may as well do the tie rod ends as you're going to have to get the tracking done anyway.

I'd say that the 'rear most' control arm (with the separate ball joints), ARB drop links and tie rod ends are easy, but the biggest, front most control arms are the trickiest. Having said that one of my tie rod ends was so seized it needed a good load of heat for ages, thankfully somebody was able to help.

Yes, just buy the full arms, Lemforder via Autodoc works out the best, wait for a 38-41% discount day. I rented a lift for a day near London, as it makes it much easier. I can see you're in Cardiff - there used to be a place in Caephilly that rented the ramp by the hour/day, but they seemed to have stopped doing that now post-covid.

Remember you have to torque the main control arm bolts while the car is level/on the ground, so it's tricky to do with a big torque wrench on your drive way with 1 foot of space in the air. Luckily the place I rented had an impact gun and heat - as well as a mechanic that could help. I ended up paying for 1 hour of his time to help get the work done in 1 day.

Curious to any info people can give on changing the rear arms, nobody seems to mention those...

 

[molgrips]

New shocks on a 9 year old car go a long way towards restoring the comfy ride of a new car. In thos case, not quite far enough. Previously I did bushings first and then shocks so it's possible that you need both to restore that new car feeling.

The B4s were better than the Sachs that came on the car, probably because they were new, but they are I think a little firmer. Which I think suits the car better. The front would dive a lot over speed bumps, but it doesn't now.

 

[Bobby Dazzler]

Could it be the B4s are firmer which is causing the sensation you feel through the steering wheel?

Surprised that you feel it on the M5 and M42, but not on local roads. Perhaps it’s frequency relating and something is resonating?

 

[TeddyRuxpin]

I think B4 is supposed to be OEM - B6 are the sportier ones?

Not sure about SE vs sport suspension however..

 

[molgrips]

Shock firmness would affect the ride over bumps, but I'm happy with that. It's the buzz of the actual road surface.

 

[Bobby Dazzler]

Shock firmness would affect the ride over bumps, but I'm happy with that. It's the buzz of the actual road surface.

Vibration or “buzz” sounds like a secondary ride issue, which is influenced by the dampers, bushes and the relationship between the dampers and bushes. Working out which will not be straightforward. Being precise about when you started feeling these sensations might help.

Did you drive on these stretches of the M5 and M42 before you changed the dampers, and if so did feel the buzz then, and if you did how was it compared to now? Do you experience anything similar on any other stretch of road, and if so how was it before changing the dampers.

Unless you can switch back to the old dampers and drive the same route in the same conditions then it will be difficult to be conclusive. Replacing the bushes may help if they are they are indeed the cause, and if you believed the suspension to be tired then it is probably worthwhile regardless.

Given that you mention feeling the buzz through the steering wheel then there is also the possibility that a component in the steering system is tired and/or has failed, and needs to be replaced. It would be worth paying close attention to the steering before change the bushes.

You mentioned that your tyres have 8mm, so when did you change them relative to noticing the buzz and changing the dampers? What’s the date code on the tyres? Tyres with a manufacturing defect - or hard due to age/UV degradation - can result in high frequency vibrations.

If you’re not able to replicate the sensation on any other stretch of road, and you only noticed it after replacing the tyres, then I would suggest the tyres are amongst the front running contenders. I would expect issues with steering or bushes to manifest in a broader range of conditions.

Good luck getting to the bottom of it. It could caused by one or more of many things, and only occurring in specific conditions will make it trickier to diagnose. It will require a comprehensive refresh or a little bit of luck. Perhaps one to live with until becomes more obvious more often.

 

[grober]

Vibration or “buzz” sounds like a secondary ride issue, which is influenced by the dampers, bushes and the relationship between the dampers and bushes. Working out which will not be straightforward. Being precise about when you started feeling these sensations might help.

Did you drive on these stretches of the M5 and M42 before you changed the dampers, and if so did feel the buzz then, and if you did how was it compared to now? Do you experience anything similar on any other stretch of road, and if so how was it before changing the dampers.

Unless you can switch back to the old dampers and drive the same route in the same conditions then it will be difficult to be conclusive. Replacing the bushes may help if they are they are indeed the cause, and if you believed the suspension to be tired then it is probably worthwhile regardless.

Given that you mention feeling the buzz through the steering wheel then there is also the possibility that a component in the steering system is tired and/or has failed, and needs to be replaced. It would be worth paying close attention to the steering before change the bushes.

You mentioned that your tyres have 8mm, so when did you change them relative to noticing the buzz and changing the dampers? What’s the date code on the tyres? Tyres with a manufacturing defect - or hard due to age/UV degradation - can result in high frequency vibrations.

If you’re not able to replicate the sensation on any other stretch of road, and you only noticed it after replacing the tyres, then I would suggest the tyres are amongst the front running contenders. I would expect issues with steering or bushes to manifest in a broader range of conditions.

Good luck getting to the bottom of it. It could caused by one or more of many things, and only occurring in specific conditions will make it trickier to diagnose. It will require a comprehensive refresh or a little bit of luck. Perhaps one to live with until becomes more obvious more often.

Following on from BD's comments- have you tried experimenting with slightly different tyre pressures? Tire ride characteristics are influenced by sidewall stiffness /construction and tyre pressure which can alter from manufacturer to manufacturer. As a general comment many car manufacturers advise running higher pressures than required to improve fuel consumption figures and this can give rise to the sort of affects your are experiencing.

 

[molgrips]

Thanks folks. The car came with 19" wheels which were clearly stiff and sporty. The road buzz was not especially obvious at the time but of course it was harsh over bumps and the tyres themselves were rather noisy at the back (P-Zero). So I changed the tyres for new Goodyear Eagle F1 Asymmetric 5 about a year ago and it was smoother and quieter. I then replaced the shocks, but I didn't change top strut mounts.

The problem is that these things are very subjective. On Friday it was fairly late, a long drive, and it's possible that I simply noticed it more. Or that those roads are particularly rough - that was the first time I'd been that way in this car. Or, it's possible that I did something wrong fitting the shocks, possibly with the strut mounts at the front. I opted not to change those at the time, now I am thinking perhaps I should have. It's a fairly straightforward thing to replace.

The tyres are at 32psi which I think is fairly low for such a large car anyway.

I don't know if the vibration in the steering wheel is because the vibration is being transmitted through the steering, or it's being transmitted to the car and the wheel is just resonating.

I don't know what an MB at this age should be like but I felt a bit more stressed than I thought I should be due to noise and vibration. In September I drove back from Scotland for longer and I didn't experience the same problem, but I came down the M6 rather than the M42.

 

[Bobby Dazzler]

Which section of the M42 was it?

 

[HB]

Could it be the B4s are firmer which is causing the sensation you feel through the steering wheel?

Surprised that you feel it on the M5 and M42, but not on local roads. Perhaps it’s frequency relating and something is resonating?

Bobby I have the B4s on our 350. They’ve done 10 k miles and all I can say is that they are superb. Great ride and control with no harshnes.

 

[HB]

Oh! How was it after the B4s? why did you change?

I'm guessing that if you found it necessary to change the shocks, the bushings will be done too. Are you going to do the top mounts too, this time around?

I think the W212 as the same layout as your car, so I should be able to point you in the right direction. Finding the torque settings can be a big pain the ****. There are two large control arms (one with separate ball joints), drop links and you may as well do the tie rod ends as you're going to have to get the tracking done anyway.

I'd say that the 'rear most' control arm (with the separate ball joints), ARB drop links and tie rod ends are easy, but the biggest, front most control arms are the trickiest. Having said that one of my tie rod ends was so seized it needed a good load of heat for ages, thankfully somebody was able to help.

Yes, just buy the full arms, Lemforder via Autodoc works out the best, wait for a 38-41% discount day. I rented a lift for a day near London, as it makes it much easier. I can see you're in Cardiff - there used to be a place in Caephilly that rented the ramp by the hour/day, but they seemed to have stopped doing that now post-covid.

Remember you have to torque the main control arm bolts while the car is level/on the ground, so it's tricky to do with a big torque wrench on your drive way with 1 foot of space in the air. Luckily the place I rented had an impact gun and heat - as well as a mechanic that could help. I ended up paying for 1 hour of his time to help get the work done in 1 day.

Curious to any info people can give on changing the rear arms, nobody seems to mention those...

Teddy hope you’re well. The B4s are tremendous, I thoroughly recommend them.

 

[molgrips]

Which section of the M42 was it?

I came from Nottingham so I think all of it down to the M5 which also felt rough.

 

[Bobby Dazzler]

Bobby I have the B4s on our 350. They’ve done 10 k miles and all I can say is that they are superb. Great ride and control with no harshnes.

I’ve only ever heard hood things about them.

 

[SnowBear57]

Oh! How was it after the B4s? why did you change?

I'm guessing that if you found it necessary to change the shocks, the bushings will be done too. Are you going to do the top mounts too, this time around?

I think the W212 as the same layout as your car, so I should be able to point you in the right direction. Finding the torque settings can be a big pain the ****. There are two large control arms (one with separate ball joints), drop links and you may as well do the tie rod ends as you're going to have to get the tracking done anyway.

I'd say that the 'rear most' control arm (with the separate ball joints), ARB drop links and tie rod ends are easy, but the biggest, front most control arms are the trickiest. Having said that one of my tie rod ends was so seized it needed a good load of heat for ages, thankfully somebody was able to help.

Yes, just buy the full arms, Lemforder via Autodoc works out the best, wait for a 38-41% discount day. I rented a lift for a day near London, as it makes it much easier. I can see you're in Cardiff - there used to be a place in Caephilly that rented the ramp by the hour/day, but they seemed to have stopped doing that now post-covid.

Remember you have to torque the main control arm bolts while the car is level/on the ground, so it's tricky to do with a big torque wrench on your drive way with 1 foot of space in the air. Luckily the place I rented had an impact gun and heat - as well as a mechanic that could help. I ended up paying for 1 hour of his time to help get the work done in 1 day.

Curious to any info people can give on changing the rear arms, nobody seems to mention those...

Where abouts in London did you hire the lift?

 

[TeddyRuxpin]

It was a place called Ramp Garage, it’s just outside the M25 not far from Hillingdon. It’s at 9 o’clock of the m25. Not glamorous but a nice and helpful owner: https://m.facebook.com/100063722673639/

 

[molgrips]

I went under the car to check the subframe which slight surprisingly isn't particularly rusty at all considering that some other parts are, like the diff. But I had a good prod at the bushings and the ones that were proddable (the big sub-frame ones) seemed smooth and rubbery as you'd expect. I couldn't check the condition of the small ones in the suspension arms, and whilst there's a bit of aluminium corrosion around them there's no reason to assume they've aged worse than the other bits of rubber under there. The exhaust mounts and propshaft coupling were also looking good. The big hydro mounts on the front also looked good - no leaks. So maybe it's not worth a refresh just yet.

I did check the tyres though and it turns out that I hadn't reduced the pressures after I increased them for some towing at Christmas. I put them back down and that seems to have helped a bit. It's not blissful silence, but it's not vibrating. I suspect it was a combination of higher pressures, rough roads and a little excessive speed that were making the vibrations felt.

 

[molgrips]

Driving around on the M4 today between Bristol and Cardiff and the vibration is bad, now much worse than it used to be. I can feel the grain of the road through the car and the steering wheel, it's really quite unpleasant. It rather feels as if something is loose. The tyre roar is also pretty loud. Our other car, a cheap Nissan Leaf not known for its quality, is much smoother and quieter.

I think I'll start with top strut mounts, as I did not do those when I changed the shocks. This way I can figure out what is the most important by trial and error. I'm guessing the ones with the biggest bushings make the most difference...