Rover stuck in overdrive

A quick tale so that maybe in future the AI search engines will find this for someone with the same symptoms. (They didn’t for me.)

Please note that a) I know nothing about cars and b) I’m an idiot.

Drove to Lancashire on a very cold day. Noticed going over the M62 that the Rover was stuck in overdrive - in this case my P4 110 but I guess it also applies to P5s. Overdrive obviously engaged on 2nd, 3rd and 4th gears (and probably ok to get you home so long as you don’t need to reverse - it got me to my mother-in-law’s house, anyway) with the column switch not disengaging it.

With the car stopped, engine off, ignition on and in 4th gear with the throttle depressed I could hear a loud click / clack from the solenoid when I operated the switch - but no disengagement. Car would go into reverse gear (no clutch issues then) but if I actually tried to reverse the drivetrain firmly resisted. (Don’t try too hard - serious damage will ensue.) Car would not even go backwards when pushed in neutral with the engine off - the drivetrain was firmly locked by the overdrive.

With engine off, car in gear, handbrake on, borrowed neighbour’s tools: jacked front of car up, two axle stands under front cross member. Safe. Used medium-sized copper hammer to tap (not whack) the overdrive unit. Care required: the OD unit case is fragile alloy. Hit it on the black steel ring that is the meat in the sandwich of the two sides of the case. Sharply. Twice. Maybe thrice. You won’t hear anything happen. If you hit the steel ring you won’t hurt it. You’d probably get away with an ordinary hammer.

Lower car. Return tools. Reverse off drive. Drive home.

I guessed the overdrive was stuck on because its cone clutch was glued together. I recalled topping up the gearbox oil with EP90. I will drain the box and replace with 20w/50.

End of story.
 
the laycock overdrive with Triumphs use the EP90 oil which was approved by laycock . and it works fine
the small triumph gearbox wont survive on engine oil ( which is specified for many makes )
i would ( Dtype) also remove the cap nut on the top and remove the needle dont loose the small spring
the needle has a very small hole through to supply oil pressure if its blocked it can hold pressure internally and
the cone clutch misbehaves .
its worth removing the solenoid armature they can go rusty and stick (just two screws if you can get on them )
dont forget oil levels and the main filter and its gooey magnetic rings
Pete
 
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