noise when going over rough surfaces - like a tennis ball in a cup

[wilkius]

Hey folks, I'm looking for ideas on where this noise might be coming from.

When I go over rough surfaces such as crossing an intersection, but not big bumps, I get what sounds like a tennis ball in a cup sort of sound. It's not metallic, but does feel a little hollow and could be like a knocking. I can't seem to get a decent recording of it.

I've just replaced my front struts, mounts, bearings, bumps stops, outer tie rod ends and sway bar links as well as the rear shock mounts and shocks (Bilstein B4 all around). The noise seems to have started after that replacement but as far as I can tell, everything is torqued. I checked my subframe bolts and sway bar mount bolts and they are tight. The noise started before I replaced the tie rod ends.

Sometimes when I hit a bump it will do the tennis ball rattle when the front hits AND the rear hits the bump. Other times, it seems to be more just the rear. I'm completely deaf in one ear and so I can't tell AT ALL where the sound is coming from specifically although it seems like if I go over bumps on the left side of the car the noise is more common.

Looking for ideas on what to check. It's been suggested I have a bad shock (that sounds a bit like the "log" thing that a lot of MK7 GTI folks have had) but the cure for that is Bilstein B4s.

I'm stumped and with all the torque to yield bolts, troubleshooting can get expensive so I'd like to have a laundry list of things to check to find this once and for all. Thank you!!

 

[nokivasara]

It's really difficult to locate sounds even with 2 good ears but if it is from the rear I'd check the shock mounts, especially if you can pin point that it happens when the shocks are extended when going over pot holes and such.
Or maybe if you're lucky it could be just the exhaust heat shields.

 

[RIP TDI]

If you reach a dead end and/or your wit's end, this might be helpful to narrow down the possible causes. They have more elaborate wireless models, but this more reasonably-priced model would probably be cheaper to buy than farming out the job to a local shop that has one of the "professional" models.

 

[wilkius]

If you reach a dead end and/or your wit's end, this might be helpful to narrow down the possible causes. They have more elaborate wireless models, but this more reasonably-priced model would probably be cheaper to buy than farming out the job to a local shop that has one of the "professional" models.

This looks like a wonderfully geeky solution that isn't outside the realm of me buying... as you say, when I'm totally at wits end! I love that someone has built a product like this.

It's really difficult to locate sounds even with 2 good ears but if it is from the rear I'd check the shock mounts, especially if you can pin point that it happens when the shocks are extended when going over pot holes and such.
Or maybe if you're lucky it could be just the exhaust heat shields.

I did replace the shock mounts but they could be faulty for sure - and aren't expensive to replace. I'll check the heat shields - I know I had two missing clips missing from the mullfer area and fixed those but didn't think to check the rest.

 

[nokivasara]

If the shock mount is not tight enough on the shock it will make a thump sound going through bumps. But now that I read the OP again it doesn't sound likely to be the mounts. So the noise is mostly when going through smaller bumps or rough patches, not in big bumps or pot holes?
Chasing a noise is so frustrating! I once had a Peugeot van and it had a bad wheel bearing, I was sure it was the right side rear wheel, turned out to be front left!

 

[wilkius]

Yeah it's been quiet on larger bumps. Just rough, twitchy type terrain.

BUT as an update - I swapped out a rear shockt and mount for the original and so far it's quiet. I left the bellows and the top cap off as it's temporary to test this setup (I had lowered the bellows to see if it was it rubbing on the strut previously. Not sure if the shock or the mount were to blame, but it did seem like the shock had more lateral play than I'd expect.

I had replaced OEM with Bilstein B4 shocks and Febi Bilstein shock t mount (FCP Euro FEB-45717) which matches the shock mount part number that came off my car (and back on...)

I'll update again. It's such a big help when reading a thread and a conclusive answer is found rather than the post dying.

EDIT: replaced "Strut" with "shock" because duh.

 

[wilkius]

Replaced both sides to OEM and the sounds are gone.

Looking at the parts that I bought that just came off - I may have installed the incorrect shock in the first place. In Canada, Highline TDIs were equipped with "sport suspension" and I assumed that would have only been springs but I think the shock is different as well. Can't look up a Highline TDI from the usual suspects parts suppliers so I bought the "SEL" version which I understand is standard suspension in the US. I don't think Bilstein make a B4 for the "sport" suspension with torsion beam rear axle for Mk7 Golf. I looked up the part I put in (B4 19-230-542) and it does show up as sport suspension for TDI 2.0 in the UK.

OEM part number for the shock is 5QM513049B and it really doesn't pull up any aftermarket options.

Tomorrow's project will be to temporarily fit the Bilstein shocks with my original mounts and see what happens.

If anyone has insight here, it's appreciated.

 

[wilkius]

UPDATE -

It's the mounts that were the issue. I installed the new shocks on the old mounts and it was golden silence.

Upon inspection, the OE mount has a little lip inside the hole where the shock goes. My Febi Bilstein one did not have that lip. Other than that they were pretty much identical to my eye.

So I'm going to order another round of the torque to yield bolts so it's all done correctly and this project is wrapped.

 

[nokivasara]

UPDATE -

It's the mounts that were the issue. I installed the new shocks on the old mounts and it was golden silence.

Upon inspection, the OE mount has a little lip inside the hole where the shock goes. My Febi Bilstein one did not have that lip. Other than that they were pretty much identical to my eye.

So I'm going to order another round of the torque to yield bolts so it's all done correctly and this project is wrapped.

Great find! I wonder why the Febi parts were different, I've used Febi for years and been perfectly happy with their parts.

 

[wilkius]

I had been happy with their parts as well and have a number of them on my "less fuel efficient" car.

Here are pics of the differences...
Febi

Febi.jpg

• wilkius
• Oct 1, 2024

OE

OE.jpg

• wilkius
• Oct 1, 2024