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MG MGB Technical - overdrive solenoid removal

My overdrive takes a second or two to engage and someone on here said to clean the solenoid out. As the gearbox is nearly ready to attach I feel I should do this whilst it's out of the car. Am I going to have any suprises when I start to remove screws/plates etc, like springs pinging out and disappearing into the far corners of the garage? The gearbox is currently stood on end on two blocks of wood supporting the bellhousing. I pressume I only need to remove the plunger and give it a clean along with the bore of the solenoid. Its a Laycock unit.
Steve Church

I assume that you are talking about the '68 and later LH OD units. The plate is secured with 4 machine screws and when removed, the solenoid, plunger and ball will come out. There are no springs or other surprises here. Clean the burrs off the perimeter of the plunger. If it looks like mine did, you'll be amazed that the OD worked at all. Before re-assembling, take a small drift, with a dab of grease on the end and place the solenoid ball in the grease. Insert it into the OD cavity and tap it lightly with a small hammer. This will renew the seat that the ball rests on. Clean off the ball and re-assemble the unit as it came apart. The only replacement part, that you are likely to need, is a new solenoid plate gasket. RAY
rjm RAY

May or may not make a difference. There are selective shims in the pressure relief valve assembly that control speed and sharpness of engagement. That *does* have springs and things, but nothing that should ping across the workshop, see here http://www.mgb-stuff.org.uk/gearstext.htm#oilchange
PaulH Solihull

Hmmm. Does this bit just need cleaning then Paul. Or am I best to leave alone. Looks like an aweful lot of bits there. Suddenly that one or two second delay doesn't seem so bad!!

I've removed the solenoid and plunger. The small ball is still in it's seating. Presumably I don't need to remove it.
Steve Church

Cleaning both may not make any difference, there is a similar ball in the relief valve and the pump that may need reseating as well, and a worst case scenario of gunge in the passages. But if the oil, filter and relief valve are clean that is perhaps less likely.

Watch the ball doesn't drop out while unattended! I put a clean bowl under mine just in case as the one in the relief valve didn't.
PaulH Solihull

This thread was discussed between 10/04/2012 and 12/04/2012

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