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MG MGB Technical - OD B's

Hi All

Got to work on the OD transmission. Pulled the solenoid and when it was tried outside the car it bairly had the power to hold the plunger in. Figured the secondary coil was gone.

Took it apart and found there are a set of points in the solenoid (the brits sure did love using points). A simple cleaning with 600 sandpaper and realigning the point and tada, back in business. In fact, transmission shifts even better that ever.

Here is a picture of the points.

BEC Cunha

Good info! Those things are pretty bomb-proof.
Steve Simmons

Actually the primary coil was being affected. This is a high-current winding to pull the solenoid in. Then the points open and disconnect that to leave just the secondary winding connected, which is low current and just enough to keep the solenoid in. FWIW.
Paul Hunt 2

Thanks Paul. Gives me a better understanding of the operation. So initial is primary winding to snap the plunger back and then the points open. I assume the little nipple in the base of the plunger sleve pushes the points open at that point and the low voltage keeps the plunger pulled back.
BEC Cunha

Well done and thanks for the image. I currently have my D type overdrive apart for a rebuild. New bearings and o'rings throughout + a complete cleanout. Just having a few issues getting the spacer washer correct - a little bit of preloading to the bearings when applying the final torquing to the flange nut. Anyone had much experience with setting up the clearances in the annulus assembly?

C Brennan

This thread was discussed between 13/10/2007 and 18/10/2007

MG MGB Technical index

This thread is from the archive. The Live MG MGB Technical BBS is active now.