Thursday, 27 April 2023 / Published in BMW, Lanoguard, Restoration

BMW 320i Convertible Lanoguard, Bump Stop and Bearing replacement

The BMW E90 series (saloon) also spawned the E91 (Estate), E92 (Coupe) and the E93 Convertible which we feature here.

BMW E93 Convertible outside our workshop

The E93 convertible was BMW’s first model to use a retractable hardtop, instead of typical fabric roof of its predecessors. The E93 was one of first retractable hardtops in its price range. The E93’s side windows are 30 percent larger than its E46 convertible predecessor, resulting in a 38 percent increase in visibility.

The BMW 3 Series convertible unlike many in its class feels solid and stiff on the road, with no hint of scuttle shake. Due to the complicated rear suspension it has excellent driving dynamics.

Our customer was concerned about a difference in height between each side of the car, he’d had some springs replaced before, and then one had broken just outside warranty. After getting them replaced again, he still noticed that occasionally, one of the wheels would appear to be much higher in the wheel arch than it should be.

When we got the car up in the air to begin stripping out the wheel arch liners and the under trays, we spotted the problem. It was twofold, firstly he’d had two new rear dampers fitted but someone had decided not to fit the bumpstop and dustcover! Secondly the rubber spring pad on the side which was a little lower, was squashed out of shape.

Let’s take a look at what we found with the arch liners and under trays removed..

e93 3 series corrosion on inner sill — 3 Series corrosion on inner sill

corrosion by heatshield fixing — Corrosion by heatshield fixing – the reason it’s corroded here is they attached an aluminium heat shield in between steel body and steel plate *before* the underbody protection was applied (galvanic corrosion)

corrosion by heatshield fixing 2 — Corrosion under the heatshield fixing – with the plate removed you can see how the underbody protection was applied by a robot after this was assembled.

corrosion by heatshield fixing 3 — The corrosion under the heatshield fixing is worse on the other side

Stage 1 clean back to good metal — Stage 1 – clean back to good metal

apply gravitex stone chip protection — Apply gravitex stone chip protection – Protects against stone, chips, salt, damp and rust – this is an excellent product with a high build formula, for gratuitious use of this product see this restoration

heat shied repair completed with a coat of lanoguard — Heat shield repair completed with a coat of Lanoguard

rear suspension and underfloor after coating with Lanoguard — Rear suspension and underfloor after coating with Lanoguard

front wheel well after lanoguard treatment — Front wheel well after Lanoguard treatment – notice the brake discs? Guess how you fix them easily? A few heavy emergency stops cleans them up and restores brake system performance – if you get judder discs need replacing. Always make sure there is nobody behind.

Missing bump stops and worn bearings

As mentioned at the start the car was missing rear bumpstops and dust covers, bump stops are a vital component in the modern car. Removing them is dangerous. The wheel can easily travel too far and ultimately you could go either coil bound or metal to metal on the damper. Both could result in a roll over in extremis.

missing bumpstop replaced with BMW genuine parts — Missing bumpstop replaced with BMW genuine parts and a nice coating of Lanoguard to protect the wheel well

Nearly all the bushes for the BMW E90-93 are available on the aftermarket, often in upgraded Polyurethane. However the one key wear bush on this chassis on the rear is not. It is only available from BMW. It often gets missed on an MOT even when the wear is considerable. On the road it causes serious instability particularly at high speed.