Gearbox removal.

[Keith Clements]

I was getting bored with php programming so went down the garage and removed the gearbox (again) from the SA. This is the one that Scott and I rebuilt after it locked solid at Goodwood when PP was driving it. It was making a noise and the oil colour was not good.

So here are the steps which are made considerably easier with the chassis modification.


1. Remove the sump guard, 4x 1/2AF nuts on U bolts and 2 tie wraps that are cut. Note how wood shock absorbers are placed.





2. 4x 7/16w (spanner size not bolt thread!) Layrub bolts. Mark orientation and position and keep nuts and washer on bolts. Mark orientation and position of layrub with respect to gearbox output flange and prop shaft flange.






3. Remove 1 set screw and 2 bolts 1/4W on gearbox support


4. Remove 8 bolts 7/16W on chassis tube connectors.




5. Unscrew speedo cable, remove clutch rod split spin with needle pliers and clevis pin.




6. Release gearbox selectors at steering column end, one with 2BA spanners the other with flat screwdriver.


7. Release reversing switch plate - two 3/16W nuts with socket.




8. Remove two top nuts and two nuts inside clutch housing securing gearbox with open ended spanner.




9 Remove the gearbox carefully making sure to pull out without straining the input shaft. Support the box using a transmission support. Let the box down slowly, the engine will drop also which makes it easier to pass the output flange past the prop shaft flange. Also take care not to catch the selector rods. The clutch race and finger will drop. Make sure the phosphor bronze bush is still in place in the crankshaft.





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[Keith Clements]

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Following on from removal of Peter's gearbox, I selected a gearbox previously rebuilt to replace it.
I needed to make a new locking tab for the end of the gearbox selector so this was formed with tin snips, small square file and needle nose pliers. A ball peen hammer was used to peen over the square shaft that I had filed onto the end to hold the lock tab.


The 2 BA nut was fixed with thread sealer (Loctite).


The balls were coated with molybdenum grease and a split pin inserted. Note the split pin was just opened up enough to prevent it coming out during normal use but is easy to remove.


Some oil proof paper was cut out for the gasket. A spare clutch housing was used to form the gasket, but it could be done in situ. The two bolt positions were marked with a copper hammer.


A punch of the correct diameter was selected to punch the holes for the bolts.



The wedge end of a tack hammer was used to mark and cut the edges of the gasket whilst holding the paper firm on the housing.




A small amount of silicone sealer was run around the brass dome and the end of the rectangular gear selector rod box (the bottom part of in the image above, but normally on the right with the box upright). The gasket was placed on the gearbox.


Note the brass dome must be accurately positioned to allow the clutch actuating ball to press on the gearbox face.


The rear support bush was checked to make sure it would just rotate (the clutch bell housing might crack if it does not!) Washers wre added or removed to make sure this was correct.


The selector balls were greased.


The clutch release bearing and operating fingers were positioned. This is best done with the clutch operating shaft connected with the clevis pin.



The position of the ball in the socket was checked.

[Keith Clements]

Having stripped three gearboxes at the Resto show it was interesting to see the differences between them.
Here I concentrate on the 1st and Second synchro selector.

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I had three different ones, the top is from the Jowett box the bottom two from Meadows.


The sliding gear sleeve has one hole that goes right through so that the lock plunger can engage with the mainshaft.
The Jowett sleeve has a recessed hole to locate the spring.


The dogs are quite different and must be very precise as the amount of interference to lock the assembly is quite small. Any wear and the synchro will not stay in. The Meadows is on the left.

As the sleeve moves to engage synchro it then locks once the dog has meshed with the synchro ring.

All Meadows parts have numbers applied with electric pencil.


Care is needed and a ring compressor helps to put the 5 springs and balls and the plunger in.