Engine Rebuild (Part 12) - Joining the Engine and Gearbox

With the clutch and distributor tower fitted, I could reunite the gearbox and engine halves.

The engine had been split before: back in 1999 to deal with gearbox input shaft that sheared as the result of a vicious clutch snatch. That was what took my car off the road for all these years. The solution back then was to fit an alternative gearbox from a low mileage car. As the car was never put back on the road after that surgery, the replacement gearbox never really had a road test and remains an unknown quantity. It probably only ran another 3 or 4 miles after it was put back together again.......before I pulled it all apart again in 2016.

Engine about to be split: 25 September 2016

With this engine build now well underway, I was getting closer to finding out if that gearbox was any good.

The procedure for refitting the gearbox doesn't seem to warrant a mention in manual 814, but is covered (succinctly) in step 18 of Operation DX.100-2 in Manual 518. The thrust bearing refit is covered by step 23 of Operation D.330-3 in section 2 of volume 2 of Manual 814.

I refitted the thrust bearing. my car has the type with the 'eye' that fits over a guide rod. It took me ages to work out that the retaining clips are meant to go through holes in the clutch fork.

Thrust bearing eye mounted on guide rod

Gearbox bolts come in all shapes and sizes. Some hold clips to secure hydraulic pipes – so it’s important that they go back in the right places. This is where earlier reference photos come in handy!

Reference photo - 25 September 2016

Before zinc plating the bolts, I laid them all out, to make sure they were all accounted for and to work out which went where. The 'anti-tamper' bolts had been replaced with normal hex heads.

Gerabox Bolts - All Accounted For

 I also numbered their positions on the bell housing. 

Working out Bolt Positions.....

When I built my engine trolley earlier in the month (see other post), I had taken account of the need to accommodate the gearbox on it as well as the engine: it would become the platform on which the rest of the engine build took place before re-fitting.

Lots of room for the gearbox....

With the engine now on the trolley, and the gearbox innards complete, all I had to do was swing the gearbox back into place. Simple. In fact it was simple, but just tricky for one person to do on their own. Alignment of the two halves was crucial. Strapping the gearbox to the crane to achieve a level lift was fiddly and I used blocks of wood strategically placed to pad out the strapping to give me ’level’. It was frustrating when, thinking everything was lined up, the two halves would not mate. More than once I pulled the halves apart convinced something was blocking the way.

Aligning the gearbox and engine

In reality, it was probably just a slight mis-alignment of the end of the gearbox input shaft to the splines on the clutch plate. After several attempts the gearbox suddenly slid into place. Pinching a corner together with no more than finger and thumb I was able to put one bolt in place by a couple of turns. I didn’t force it as I was concerned about exact alignment and the risk of stripping the threads on the aluminium bell housing.

Bolting the Gearbox to the Engine

Working around the engine I put more bolts in place (with some threadlock) and gradually tightened each a little to pull the gearbox into position (it has two locating lugs). When I was happy I blocked up the gearbox end and l released it from its sling…..

Reunited - August 2018

There are three bolts that hold the starter motor in place – these also serve to hold the engine and gearbox together and I would fit these in due course.