Hi Bill, and others
I have heard of the 'drill' test. You need the transmission to be
complete so the drill chuck will fit the input shaft. It would not be
easy to just test the OD since you might have a problem keeping the oil
in and a problem finding a drill chuck to fit the mainshaft !.
But IMHO ( having dismantled "one or two" of these ) the best way to
check a "J" type is to split it in half at the brake ring ( the small
center casting ) and check the condition of the clutch linings.
Beware, even an Overdrive in bad condition might pass the 'drill' test.
The linings can be pitted or worn quite badly and the overdrive will
still work...for a while...
I have at least 4 in this condition taken from working cars that are
sitting in my garage. I'm sure they would pass the drill test.
Remove the sump plate and check the filter and magnetic strip for nasty
bits. You could also check the internal filter if you have a tool able
to remove the plug. The state of the oil in the transmission should also
give a few clues of overall condition. Check the magnetic drain plug.
The nasty bits stuck to this may also been going through the overdrive.
If what you've found is all o.k., you've only destroyed 3 gaskets that
probably needed replacing anyway.
These units are not difficult to rebuild a home providing the linings,
gear teeth and solenoid are o.k. and you have suitable bearing
extraction tools.
Three bearings, Four gaskets, 2 "O" rings and a rear seal and maybe a
oil filter will do it in most cases.
Hope this helps
( Hey ! a techo message for all those complaining about the lack of them
:-) ... )
Peter Cebalo
73 Spitfire Mk IV ( with "J" type )
Auckland New Zealand.
>
>
>Greetings,
>I may be purchasing an OD unit soon. I recall a thread about testing the
>unit using a drill to obtain sufficient RPM and then activating the solenoid
>with a 12V battery. Is anyone familiar with this operation? Does anyone
>know the correct length of the J-type OD driveshaft?
>Thanks Bill
>
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