FRONT SUSSPENSION (passenger side) SNAP sound (1994 E320)

[August Forster]

Hello!

Help needed to find out the source of the front passenger side noise. First it started as a snap sound coming from the right front tire when after driving I was parking and making complete stop and slight wheel turn. Sound occurred exactly when I stopped. This happens consistently and what is started to happen today is kind of a dull sound (as if you would try to push against plastic material like under shield) which happens every time I start to accelerate after stops (traffic lights, for instance). No sounds while driving what's so ever.

Worth to mention that couple of months ago replaced front shocks and shock absorber rubber parts on the top (do not know the name) and tie rods assembly (L+R), drag link, drag link damper, idler arm bushing (all parts from MB except shocks - Bilstein). Also worth to mention that I started having steering wheel vibration while breaking at higher speeds (140-150 km/h). Steering wheel vibrates in general at higher speeds as well, but that's I'm almost certain due to steering box wear (259000 miles on odometer).

Thank you very much in advance!

 

[August Forster]

I have just checked the the suspension components - found nothing. However, break pad material is about 4mm left (changed exactly a year ago). I hope this is the culprit. Because, the noise happens at starting the move after a stop and then disappears. And no sounds/noises while driving at all.

 

[TerryA]

@August Forster,
While you’re in there check that the bolts holding the shock to the spindle are properly torqued. On my old 300E I had a snapping sound after I had installed new Koni Red Shocks. It turned out that I had not torqued the attachment bolt high enough even though the torque wrench read the proper torque number. After re-torquing the snap never came back. I can’t remember the torque value it’s been too long. I’m thinking 85ftlbs.

Just check it out.

Good Luck

 

[August Forster]

@August Forster,
While you’re in there check that the bolts holding the shock to the spindle are properly torqued. On my old 300E I had a snapping sound after I had installed new Koni Red Shocks. It turned out that I had not torqued the attachment bolt high enough even though the torque wrench read the proper torque number. After re-torquing the snap never came back. I can’t remember the torque value but it’s been too long. I’m thinking 85ftlbs.

Just check it out.

Good Luck

Thank you very much! I actually feel like that this dull "pushing against a plastic" comes somewhere from that area - high just under the hood on the right.

 

[geraniumtr]

FYI here are the torque specs for the front strut "pinch" bolts per the FSM:

pinch bolt, M12 size is 110nm, M14 is 200.

lower 2 bolts, 110nm.

I used some blue Loctite on them.


Regards,

Peter

 

[gsxr]

Help needed to find out the source of the front passenger side noise. First it started as a snap sound coming from the right front tire when after driving I was parking and making complete stop and slight wheel turn. Sound occurred exactly when I stopped. This happens consistently and what is started to happen today is kind of a dull sound (as if you would try to push against plastic material like under shield) which happens every time I start to accelerate after stops (traffic lights, for instance). No sounds while driving what's so ever.

Worth to mention that couple of months ago replaced front shocks and shock absorber rubber parts on the top (do not know the name) and tie rods assembly (L+R), drag link, drag link damper, idler arm bushing (all parts from MB except shocks - Bilstein).

As mentioned above, double check that all the suspension component fasteners are torqued to spec. If the noise started after all this work, it's probably not coincidence.

Also worth to mention that I started having steering wheel vibration while breaking at higher speeds (140-150 km/h). Steering wheel vibrates in general at higher speeds as well, but that's I'm almost certain due to steering box wear (259000 miles on odometer).

Steering wheel vibration is almost certainly not from steering box wear. #1 suspect is wheel balance. If you didn't have them Road Force balanced and at least under 20 lbs of measured force (preferably under 10 lbs)... do that first. Details in this link.

 

[nocfn]

Worn strut mounts up top as well, especially if your torque has not been maintained below.

 

[luckymike]

What about that area at the A-pillar that can fail/crack and cause a noise?

Or, what about the vertical sway bar mount? Mine snapped but actually, I heard that over bumps. You say no sound while driving. I'd still check them.

 

[August Forster]

Worn strut mounts up top as well, especially if your torque has not been maintained below.

strut mounts are new // and I actually ended up braking one of the three studs of that mount while attempted to torque them to 85flb // but I guess I took it wrong 85flb was referred to the strut shaft not to the strut mount nuts.

 

[August Forster]

What about that area at the A-pillar that can fail/crack and cause a noise?

Or, what about the vertical sway bar mount? Mine snapped but actually, I heard that over bumps. You say no sound while driving. I'd still check them.

sway bar is intact // but the sound is like rubber/plastic rubbing // Snap happens only when I park and only pull back

 

[August Forster]

FYI here are the torque specs for the front strut "pinch" bolts per the FSM:

pinch bolt, M12 size is 110nm, M14 is 200.

lower 2 bolts, 110nm.

I used some blue Loctite on them.


Regards,

Peter

Thank you! Those three bolts are tight.

 

[August Forster]

What about that area at the A-pillar that can fail/crack and cause a noise? Or, what about the vertical sway bar mount? Mine snapped but actually, I heard that over bumps. You say no sound while driving. I'd still check them.

thank you for the response, but I do not know what "A-pillar" is, unfortunately. // Yes no noise or sounds while driving AT ALL. The noise only appears while starting the motion and that's it.

 

[gsxr]

strut mounts are new // and I actually ended up braking one of the three studs of that mount while attempted to torque them to 85flb // but I guess I took it wrong 85flb was referred to the strut shaft not to the strut mount nuts.

YIKES! That was WAY over spec for the 3 strut mount nuts. Were you following the factory manual? Spec is only 20 Nm (15 lb-ft). FSM job 32-0100, see Installation Note on step #8, click here. Nothing has a spec of 85 lb-ft (115 Nm).

sway bar is intact // but the sound is like rubber/plastic rubbing // Snap happens only when I park and only pull back

If the sound only occurs when applying the brakes at low speed, it could be the pads clicking in the caliper body.

Next thing to check is the ball joint... that's more difficult to do though...

 

[August Forster]

YIKES! That was WAY over spec for the 3 strut mount nuts. Were you following the factory manual? Spec is only 20 Nm (15 lb-ft). FSM job 32-0100, see Installation Note on step #8, click here. Nothing has a spec of 85 lb-ft (115 Nm).

Yes, I know! I told myself before applying that much tightening that this doesn't seem to be proper... but, however, kept on turning the torque wrench // I did follow the specs for the three main bolts, the strut mount I did by feeling (gut-n-tight).

 

[August Forster]

YIKES! That was WAY over spec for the 3 strut mount nuts. Were you following the factory manual? Spec is only 20 Nm (15 lb-ft). FSM job 32-0100, see Installation Note on step #8, click here. Nothing has a spec of 85 lb-ft (115 Nm).



If the sound only occurs when applying the brakes at low speed, it could be the pads clicking in the caliper body.

Next thing to check is the ball joint... that's more difficult to do though...

Thank you for the steering wheel vibration explanation! These technical advisors at MB are either bunch of idiots who knows nothing, or they do know but simply want to rip-off from you. About three months ago I put all new tires ordered them from Denmark, because was searching and wanted to get something close to what I used to and had very good experience for 7 years, which is Good Year Eagle Sport A/S 195/65R15 91V. But these are no longer available in this size. All Goodyear Eagle Sports in this size are in lower load speed rates 91H or T - 4 times different retailers sent me wrong tires. This is how I ended up ordering tires from Europe. I found Dunlop Sport All Season in Denmark available in 195/65R15 95V (even better load rating). Cost me just under $700 with FedEx.

So, after installing new tires I had a terrible steering wheel vibration even ad mid speeds. The car was almost undrivable. Took to MB for the alignment - vibration remains the same. Then ordered from MB tie rod assemblies, drag link, damper, idler arm bushing kit, struts and strut mounts. Took again to MB for the alignment after replacing all these. At picking up the car I asked the "advisor" if the vibration is completely gone, for which he replied that it's gone partially. I asked why because I replaced everything, and for this my so called adviser went "did you replace the steering box?"... I mean I'm not a complete fool, I understand the approximate cost and values of different types of parts, and I knew that something like steering box wouldn't be a relatively inexpensive purchase. But these people at MB lays out these things so easily and swiftly as if they offer you to buy a couple of pounds of potatoes.

Anyways, thank you very much for the prompt responses and advises!
God bless you all gentlemen!

 

[gsxr]

Based on what you describe... it sounds like you definitely need to get all 4 tires Road Forced. Hopefully they can all be "force matched" to at least below 26 lbs (which miiiight be adequate with stock 15" wheels). The lower the RF number, the better.

Put the best one on front/left position, next best front right, third left rear, worst (highest RF number) on the right rear. This helps keep vibration as far from the driver seat as possible. It's possible to have a defective brand new tire that is out of spec (unbalanced, out of round, etc) that cannot be balanced correctly. Since these tires were ordered from overseas, let's hope that's not an issue.

BTW, this also assumes all 4 wheels are straight & true. The Road Force machine can check the wheel for lateral & radial runout. This is typically done if a wheel won't balance well, or if there's a visible hop / wobble when spun on the machine.

 

[August Forster]

Based on what you describe... it sounds like you definitely need to get all 4 tires Road Forced. Hopefully they can all be "force matched" to at least below 26 lbs (which miiiight be adequate with stock 15" wheels). The lower the RF number, the better.

Put the best one on front/left position, next best front right, third left rear, worst (highest RF number) on the right rear. This helps keep vibration as far from the driver seat as possible. It's possible to have a defective brand new tire that is out of spec (unbalanced, out of round, etc) that cannot be balanced correctly. Since these tires were ordered from overseas, let's hope that's not an issue.

BTW, this also assumes all 4 wheels are straight & true. The Road Force machine can check the wheel for lateral & radial runout. This is typically done if a wheel won't balance well, or if there's a visible hop / wobble when spun on the machine.

Yes, I will definitely follow up with RF. I actually had doubts about the tire shop which installed/balanced the new tires. I was watching them doing the work, and they look really unprofessional. The rims are not perfect, considering they are original. But I didn't spot any significant deformations, however I will examine again.
Thank you immensely!
My hat off!

 

[August Forster]

Gentlemen,
I will come back with the results soon. Please do not think that I forgot to follow up.
Thank you very much, everyone!

 

[August Forster]

Gentlemen,
As you may remember from the previous post the original problem started as a snap noise from the front passenger side wheel. And if you remember I mentioned the steering wheel vibration on mid-to-high speeds. The problem is in the brake system. That snap sound transformed into a clunk noise every time a depress the brake pedal, so without any doubt it was faulty brake caliper. I ordered from MB rebuilt parts (except the pistons) and cleaned the inner of the piston pots, reassembled with red rubber grease, bled new DOT 4 fluid.

However, unfortunately all these efforts failed. Instead I started to have more pronounced clunk noise every time I push on brake. One of the pistons from the passenger side caliper had chipped off from it's surface chrome coating approximately 4x3 mm in size (attached photo). The problem most likely is complicated by the high chances that the brake rotor on the passenger side is also ruined by the faulty caliper (I'm assuming the vibration of the steering wheel caused by this problem).

So, next step will be to install calipers. I was considering to install better performing calipers and rotors from E500. While browsing internet/ebay I found that E500 and R129 front calipers are the same models. My reasoning is that if the W124 steering knuckle is standard for E320 and other models including E500, then I can directly (without any adapters) install calipers and rotors from E500 or R129 (SL 500) onto E320. If anyone knows answer to this question please let me know.

Thank you in advance so much!

 

[August Forster]

I think I have found the answer to the question. Someone has already installed Brembo calipers from SL500 without adapters and 334mm rotors onto E320/W124.

 

[TerryA]

YIKES! That was WAY over spec for the 3 strut mount nuts. Were you following the factory manual? Spec is only 20 Nm (15 lb-ft). FSM job 32-0100, see Installation Note on step #8, click here. Nothing has a spec of 85 lb-ft (115 Nm).

@gsxr,
I said I wasn’t sure when I mentioned 85 lb/ft and after checking your FSM job 32-100 above the bolts 11i at the base of the strut are 110 Nm the 11k pinch bolt to 11u nut is also 110Nm that’s 81.12 lb/ft

These were the bolts I was referring to. It’s been probably 20+ years since I did that job.

lol

 

[gsxr]

As you may remember from the previous post the original problem started as a snap noise from the front passenger side wheel. And if you remember I mentioned the steering wheel vibration on mid-to-high speeds. The problem is in the brake system. That snap sound transformed into a clunk noise every time a depress the brake pedal, so without any doubt it was faulty brake caliper. I ordered from MB rebuilt parts (except the pistons) and cleaned the inner of the piston pots, reassembled with red rubber grease, bled new DOT 4 fluid.

However, unfortunately all these efforts failed. Instead I started to have more pronounced clunk noise every time I push on brake. One of the pistons from the passenger side caliper had chipped off from it's surface chrome coating approximately 4x3 mm in size (attached photo). The problem most likely is complicated by the high chances that the brake rotor on the passenger side is also ruined by the faulty caliper (I'm assuming the vibration of the steering wheel caused by this problem).

I may be missing something here, but the snap/clunk noise you are hearing, and steering wheel vibration, likely have NOTHING to do with brake calipers or brake rotors. You can keep replacing brake components but it will probably be a waste of money.

So, next step will be to install calipers. I was considering to install better performing calipers and rotors from E500. While browsing internet/ebay I found that E500 and R129 front calipers are the same models. My reasoning is that if the W124 steering knuckle is standard for E320 and other models including E500, then I can directly (without any adapters) install calipers and rotors from E500 or R129 (SL 500) onto E320. If anyone knows answer to this question please let me know.

Yes, you can use larger brakes from the R129, but the 334mm Brembos shown in your photo will also require 17" (or larger) wheels. It's a nice performance upgrade, but unnecessary with only 220hp on tap from the M104.

 

[gsxr]

...I started to have more pronounced clunk noise every time I push on brake.

There's a factory TSB about a clunking noise when braking, along with a higher torque spec for the 4 large eccentric bolts for the LCA (lower control arm) pivots. I'd check all 4 of those and torque to the new, higher spec.

...I'm assuming the vibration of the steering wheel caused by this problem).

Do you still have steering wheel vibration? Did you ever get all 4 wheels/tires Road Forced as described above?

 

[August Forster]

There's a factory TSB about a clunking noise when braking, along with a higher torque spec for the 4 large eccentric bolts for the LCA (lower control arm) pivots. I'd check all 4 of those and torque to the new, higher spec.



Do you still have steering wheel vibration? Did you ever get all 4 wheels/tires Road Forced as described above?

I do still have vibration and I haven't done the RF balancing so far.
What makes me think that it's brake caliper is that when I brake at high speeds, let's say, I hear that dub-dub-dub-dub-dub...
How to check those eccentric bolts? The car should be sitting on it's weight while torquing these bolts and it will be quite difficult for me since I have only a floor a jack.

 

[August Forster]

There's a factory TSB about a clunking noise when braking, along with a higher torque spec for the 4 large eccentric bolts for the LCA (lower control arm) pivots. I'd check all 4 of those and torque to the new, higher spec.



Do you still have steering wheel vibration? Did you ever get all 4 wheels/tires Road Forced as described above?

I think you might be right suspecting the control arm bolt issue. I will tighten them and will see what happens. Thank you so much again!

 

[August Forster]

There's a factory TSB about a clunking noise when braking, along with a higher torque spec for the 4 large eccentric bolts for the LCA (lower control arm) pivots. I'd check all 4 of those and torque to the new, higher spec.

Hi,
Could you please provide with the link to that TSB. I went to MB for the alignment and despite my request to torque the eccentrics to a higher spec, they said "we can do only factory torque". May be if I provide official recommendation from MB they would agree.
Kind regards!

 

[gsxr]

Hi,
Could you please provide with the link to that TSB. I went to MB for the alignment and despite my request to torque the eccentrics to a higher spec, they said "we can do only factory torque". May be if I provide official recommendation from MB they would agree.
Kind regards!

See page 2, this is directly from the FSM.

https://www.500eboard.co/forums/misc/Manuals/Servicev3.2/W124/w124CD2/Program/Chassis/Prog_Repairs/FrontAxle.pdf

 

[August Forster]

See page 2, this is directly from the FSM.

https://www.500eboard.co/forums/misc/Manuals/Servicev3.2/W124/w124CD2/Program/Chassis/Prog_Repairs/FrontAxle.pdf

View attachment 180229

Yes! The problem solved! It was rear eccentric bolt nut on the side where the noise was coming from. The nut was loose because of the oil leak which I was aware of for quite some time. When I started to turn that nut it almost didn't have any torque. The entire surface of the control arm bushing was soaked with the engine oil (attached the photo).
I'm very happy that this issue is solved! No snap, no creaking sound - all gone! Thank you very much for the help! I do appreciate it very much!
P.S. Still have dub-dub-dub-dub.. sound while brake at high speeds and when slow down it transforms into uneven oscillating brake force.

 

[gsxr]

Awesome - glad the noise is fixed!

Uneven oscillating brake force is most likely from deposits on the rotors. Usually this is difficult to fix without installing new pads + rotors.