(Some of these are copies of manuals available at:
Austin Healey Laycock de Normanville
Volvo J Type Overdrive manual
"J" Type Overdrive Fitting - Nelson Riedel
Quantum Mechanics Information on Overdrives
Instructions on fitting a J
Overdrive (from Ian Roslian, NZ)
1/ make sure oil is drained,
Remove lid/remote 8 bolts 1/2' AF spanner.
2/ with screwdriver select 3rd or 4th gear and also reverse gear.
3/ trans should now be locked so undo nut holding on flange at rear and remove
4/ remove speedo drive gear from side of tailhousing.
5/ undo bolts holding on tailhousing and remove housing.
6/ remove speedo drive gear off mainshaft, also circlip holding on large
7/ remove front clutch bearing carrier, 4 bolts. Inside bell housing, goes over
8/ remove small plate at front, covering layshaft hole, 2 bolts.
9/ remove plate at back, retaining layshaft and reverse gear shaft.
10/ push out layshaft, push from front with screwdriver, out back.
11/ Drive mainshaft forward through large bearing, this will push out input
shaft, (do not let it drop on your foot.)
12/ remove rear bearing off mainshaft, mainshaft will now lift out top of trans
with gears on it.
13/ remove front circlip off mainshaft and take off gears and bush,s.
14/ put all these gears onto the mainshaft I supply, and assemble trans opposite
of stripping down.
15/ fit overdrive adapter on to back of trans, then making sure the cam lines up
with the cam follower hole, push on overdrive. Turning flange all the time until
overdrive slips on easily, (do not force it ).
Reading this might look confusing , but when you get started it will all be
Here's some details on the J
Overdrive I purchased from Ian Roslian.
What I received:
1) J O/D
3) Angle Drive (I asked him to add this, at extra $$$)
4) Lockout switch
5) Early type mainshaft
Middle, from left: Lockout switch, gasket, angle drive, solenoid
Here's a closeup of the ID plate:
Serial numbers are: 28/115873 / 007305
Close up of speedo angle drive, and where it fits on the O/D: