Having removed and replaced my 20R timing chain I noticed the L/H guide (or as Toyota likes to call it “Damper #1”) creates a deflection in the chain at the top and bottom at the chain entry/exit. (Pictures) Inspection of the removed guides reveals the same issue - from wear/tear patterns - where the chain ate through the plastic bonded to the guide, resulting in a LOT of “chatter!” Obvs I don’t want the same to happen, and I can’t bend the guides, so I was thinking of redrilling the holes to allow a 2-3mm horizontal shift to the left to cure the deviations. Any other suggestions, and/or advice greatly appreciated!

Deflection at cam (top) gear

Deflection at bottom (crank) gear

Heavy wear at lower edge on old guide

Plastic eaten back to metal (lower edge) on old guide

 

could I ask how did you work it out

 

The newly acquired replacement guides would have presented the same deflection of the chain - so after taking a couple of calliper measurements of the interior of the cover, to make sure that some lateral adjustments could be accommodated, I used a Dremel with a “bullet-headed” grindstone to remove enough material from the guides existing bolt holes to allow me to slide it over a couple of mm. So after the chain has “bedded-in” to the plastic (which it is supposed to do), there’s no way that it will eat through to the metal, at the top or the bottom. Success! Rusty Bob now runs with a satisfying hum rather than the clatter of a bag of broken spanners! 😎