335d – Rear suspension refresh

For some time now I’ve known that things weren’t okay at the back of the 335d. Even unladen, the car appeared to have been lowered, slightly more so on the left than the right. When unladen, I’d occasionally feel it hit the bump stops, and there was always more post-bump oscillation than I’d associate with a healthy pair of shock absorbers.

I’ve dug around for photo evidence of the car unladen and this is the best I could find. I’ve adjusted the image levels to help make it easier to perceive the detail of the black tyre in the dark wheel arch. It’s fairly clear here that the rear looks lower than the front.

Silver 335d showing rear suspension lower than front

The ride height alone wasn’t a problem for me. Some may even suggest lowering the front in sympathy! Yet the crashing around when laden was a problem, and the crazy oscillation over bumps at speed was frightening at times, so something needed to be done.

Over the last couple of weeks I’ve gathered some parts from BMW and Euro Car Parts (ECP).

ECP 2x Bilstein Shock Absorber @ £61.74 each (PN 635110585)
ECP 2x Sachs Coil Springs @ £60.44 each (PN 627112290)
ECP 2x Febi Bilstein Top Strut @ £6.39 each (PN 609111050)
BMW 2x Rubber lower shock mount @ £41.90 each (PN B33.52.2.406.287)
BMW 2x Shock top bump stops @ £18.32 each (PN B33.50.6.773.629)

So that’s £377.58. I’ve a couple of regrets here. First, I could have bought the Rubber lower shock mounts from ECP at a lower price had I been more organised. Second, I should have bought BMW’s “Repair kit, support bearing” PN which would have included the new top strut mounts, and provided some other new rubbers and plates around the upper mount point.

With all that out of the way, this is what the haul looked like:

335d next to all listed parts laid out on a driveway

Here’s a close up of the parts for one side:

New shock, spring, shock top, top mount, lower mount and bolts

Now I’m not going to do a full how-to here, as there are many great videos already on the web. Here’s a good one about the shocks:

And another for the springs:

Overall, especially with the help of these videos, I found it a civilised job. The first phase inside the car was a great opportunity to give everything a good clean and clear out various compartments.

335d load bay with panels removed to expose top mounts

Old versus new springs and shocks:

335d outgoing spring and shock next to new parts

I took this photo after removing the shock and spring from the left side. There’s no great difference between the springs when not under load, but perhaps the newer one will be stronger under compression. The outgoing shock was obviously knackered: much easier to compress than the new part, and near zero enthusiasm to return to a neutral position.

I’m annoyed I didn’t photograph the shock top bump stop, as it turned out to be very degraded.

New parts on the car – very satisfying indeed!

New shock and spring fitted to 335d

It now sits more level, and is nice and firm, supple and reassuring over bumps. Most pleasing!

Close up of the rear ride height with new shocks and springs fitted.

Side view of whole car on new shocks and springs

As an encore, I changed the car’s oil too. It’s always nice to know that’s been done properly with an old-fashioned sump drain, while the oil is warm, and replaced with proper oil (Castrol Magnatec 5W-30 BMW LL-04). The car has only done 3,000 miles since it was last serviced in September 2017, so this interim change is just there for peace of mind.

335d with bonnet up and two 4l bottles of Castrol Magnatec 5W-30 LL-04

All in all, a very satisfying day.

335d and 330d in front of house

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