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A vibration in an R107 is usually easiest to diagnose by noting when it happens: at what speed, under what load and whether you feel it in the steering wheel, the seat or the brake pedal. Here is how I narrow it down.
Start with when and where
- Steering wheel shake at 50–70 mph: usually front wheel balance, a bent wheel or a tire problem.
- Seat or floor vibration at 40–60 mph: often rear tires, rear wheel balance or driveline.
- Vibration under acceleration: driveline: flex discs or center support bearing, or engine mounts.
- Vibration when braking: warped or uneven brake discs, or worn suspension parts.
- Vibration at idle in gear: engine mounts or an engine misfire.
Tires and wheels first
- Check the tire pressures.
- Look for bulges, flat spots and uneven wear. Old tires that have sat for years can develop flat spots or internal belt separation.
- Have the wheels balanced on a good machine, ideally a road-force balancer.
- Check the wheels for bends or damage. The Bundt and 15-hole wheels need hub-centric balancing.
Brakes
A pulsing pedal and steering shake when braking means the brake discs have uneven thickness. Measure them or replace them. Also check the front wheel bearings for play.
Driveline
A vibration under acceleration that changes when you lift off the throttle points to the driveline. Inspect the flex discs and center bearing, and check that the driveshaft was refitted with its marks aligned after any work.
Front suspension
Worn ball joints, tie rods or control arm bushings can cause a shimmy, especially over bumps. See ball joints and front end.
Engine and mounts
A vibration at idle in Drive that goes away in Neutral points to collapsed engine or transmission mounts. A misfire feels like a rhythmic stumble at all speeds; check the ignition first.
Quick answers
- Can old tires cause vibration even with good tread? Yes, age-related separation does.
- Will an alignment fix vibration? Usually not. Alignment fixes pull and wear, not shake.
- Why does it vibrate only at one speed? Balance and tire issues often appear at a specific speed range.
- Is the steering damper related? A weak damper can make a shimmy worse but rarely causes it.
- Can a bad flex disc cause a shake? Yes, especially under acceleration.
- Do I need a road-force balance? It helps find tire and wheel problems a normal balancer misses.
