The R107’s rear suspension and differential sit in a subframe (also called the rear axle carrier) that is attached to the body through large rubber mounts. When those mounts age, the car can clunk, wander and feel loose at the rear.
Symptoms
- A clunk from the rear when accelerating, braking or going over bumps
- The rear feeling like it steers itself on uneven roads
- Wandering at highway speed
- Uneven rear tire wear
How to inspect
- Raise the car safely and support it on stands under the body.
- Look at the subframe mounts: they sit where the subframe attaches to the body on each side.
- Check for cracked, split or oil-soaked rubber.
- With a pry bar, gently lever between the subframe and body: movement in the rubber, or the metal sleeve shifting, indicates a worn mount.
Parts kit
Kits that include both mounts and the necessary hardware are available from Mercedes and specialist suppliers. Replace both sides together.
Replacement outline
- Support the subframe with a jack and a wide support.
- Disconnect components that restrict movement: exhaust hangers, brake lines or the parking brake cable if needed.
- Remove the mount bolts and lower the subframe slightly.
- Remove the old mounts; they can be stubborn and may need pressing or careful cutting.
- Install new mounts with a suitable lubricant as instructed.
- Raise the subframe and tighten the bolts to the factory torque with the car at normal ride height if specified.
Torque figures quoted on forums vary; use the factory manual for your car. One BenzWorld discussion cited about 45 Nm for some bolts, but confirm before you tighten anything.
Cost
Parts are moderate. Labor at a shop can be several hours because of access and stuck bolts. It is often done together with the differential service or rear suspension bushings.
Quick answers
- Is “rear axle carrier” the same as “subframe”? Yes, on the R107 it is the same part.
- Can worn mounts cause a vibration? They can let the driveline move enough to cause vibration; also check the flex disc.
- Do I need an alignment after? It is a good idea to check rear alignment after any subframe work.
- Are polyurethane mounts a good idea? They reduce movement but increase noise and vibration; most owners stay with rubber.
