|"Moving" part on the left attaches to the seat back, "fixed" part on the right attaches to the seat base.|
The adjuster comprises 2 parts, the "moving" part which is fixed to the back of the seat, and the "fixed" part which is attached to the seat base and on which the adjusting arm is attached (it goes through the centre of the "moving" part).
On the fixed part of the adjuster there are three internal cams with toothed edges which are held by a spring loaded triangular plate against fine teeth on a ring on the moving part, but those teeth have worn flat in places so the seat gives way if I lean backwards. The lever releases the spring allowing the cams to disengage with the ring and the seat back can then move forwards or backwards.
The main spring, which causes the seat back to fold forward when released, is mounted on the opposite side of the seat and is completed independent from the adjuster.
|Teeth on the locking ring worn smooth at the most used seat back position|
|Toothed cams which mesh with the locking ring|
I've effected a temporary fix to the reclining mechanism.
The mechanism can be disassembled by turning the 4 eccentric locking heads using vice grips until the 2 sections come apart. The adjuster arm will need to be straightened a small amount so that it can slip through the moving part (clamp the mechanism in a vice, slip a piece of pipe over the arm and lever gently).
I reconstituted the ring teeth using a hammer and cold chisel to give the cam teeth something to bite on.
|Shims fitted under the toothed cams|
I slipped a large washer (not shown) on to the "R" pin to provide something meaty to pull on and when the seat needs to be tilted forwards, it's very quick to pull out the pin, just like a grenade.
|An "R" Pin to hold the seat back in position|
Of course this fix doesn't take the place of a properly functioning mechanism but it works fine for the time being.
I suspect the damage was caused in the 1/2 million km that our Oka had done before we bought it, especially if the lever wasn't fully released before reclining the seat, allowing the teeth to grind over each other. It first failed several years ago and we do use the mechanisms quite often to provide access behind the seat but without abusing them.
Dirt build up probably doesn't help and once the teeth don't mesh fully, they start slipping, which will only escalate the wear problem.