R107 Flex Disc and Driveshaft Center Bearing: Vibration Fix

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A vibration that comes in at a certain speed, or a clunk on take-off, often comes from the driveshaft rather than the wheels. On the R107, the rubber flex discs and the center support bearing are the usual suspects.

Symptoms

• Vibration around 35–50 mph or under acceleration
• A clunk when shifting into Drive or Reverse
• A shudder on take-off
• Visible cracks in the rubber disc at the transmission output or the rear of the shaft

How to inspect

1. Raise the car safely on stands.
2. Look at the front flex disc where the driveshaft meets the transmission, and the rear disc at the differential on cars that have one.
3. Check for cracks between the bolt holes, bulging or separated rubber.
4. Check the center support: the rubber around the bearing should be intact, not torn or sagging.
5. Grab the driveshaft near the center support and move it: excessive play means a worn bearing or carrier.

Replace both discs and the center support?

If the car has unknown history, I replace both flex discs and the center support together. They have aged the same way, and the labor overlaps. Kits that include discs, center support and hardware are available from specialist suppliers.

DIY outline

1. Mark the driveshaft and flanges so it goes back in the same position (balance matters).
2. Remove the exhaust sections and heat shields if they are in the way.
3. Loosen the center support and the driveshaft clamping nut.
4. Remove the flex disc bolts.
5. Slide the shaft back to free it from the disc; on some cars the shaft comes out to replace the center bearing.
6. Fit new parts, align the marks, and tighten bolts to spec.

Hardware notes

Use new nuts and bolts where specified; many are self-locking. Tighten the bolts with the nut, not the bolt head, if the manual says so.

Cost

Parts are moderate. Shop labor is a few hours, more if the center bearing needs pressing. It is a good job to combine with engine mounts.

Quick answers

• Can a flex disc fail suddenly? A badly cracked disc can come apart; inspect regularly.
• Will balancing the wheels fix this? Only if the wheels were the cause. See shimmy and vibration.
• How long do flex discs last? It depends on age and use; inspect them whenever the car is on a lift.
• Can I replace only the front disc? Yes, if the rear and center support are good.