Layshaft mount, Oil leak, Alternator alignment

Continuing the rectification work after test running and then removing the engine... 

The layshaft bracket I made a long time ago was a bit of a shambles. Firstly, it wasn't sitting flush when bolted on as one bolt boss on the engine block is actually 1mm lower than the others, as indicated by this piece of 1mm steel sheet and a ruler edge. I made this bracket years ago and never picked up on this before!

The bolt hole positions in the original design were also slightly misaligned, and the middle bolt was impossible to get a socket onto as it was too close to a brace piece that I had welded on.

I used my 3D printer to design and print a series of prototypes to get the bolt hole positions/design perfect. There's approx 20 hours of printing amongst these pieces.

The final layshaft bracket design (3D printed) :

I provided the CAD files to a local steel company to get some new 8mm steel pieces laser cut, then welded everything together.

Old bracket (note the proximity of the centre hole to the vertical piece) :

The new bracket has an additional bend to provide clearance to the bolt holes, and not does have any horizontal brace pieces as I figured that there is no axial movement of the layshaft that needs to be accounted for. 

Once the two pieces of the new bracket were TIG welded together, I also welded on a 1mm washer on the back of the bracket to allow for the difference in that third bolt boss height on the block.

I had to confirm whether the oil leak I had previously seen running down the gearbox plate was from the rear main seal. I removed the gearbox, clutch and flywheel to inspect it however I didn't have anyone to help me hold the flywheel ring gear while undoing the flywheel bolts so I made a simple flywheel locking tool for this.

Once the flywheel was off I found the leak was not from the rear main seal, but weeping from the RTV gasket between the sump and and block so I had to drain the oil, remove the sump and old sealant and degrease everything. After this photo of the cleaned sump was taken, new oil resistant RTV sealant was applied and the sump refitted.

When reinstalling the clutch, I couldn't find my clutch alignment tool so I 3D printed a simple piece with a 21mm OD shaft and used that instead.

The alternator bracket I made a long time ago didn't have the alternator properly aligned which ended up causing the belt to move side to side while the engine was running. I wanted a much more accurate way to align both crankshaft and alternator pulleys and I ended up making multiple one-off tools for this task. The first tool was a length of steel rod that I machined to fit some standard 608 bearings.

With the bearings are pressed against the crankshaft pulley, the other end of the rod indicates the pulley centreline.

In this case, it was able to indicate a ~1.5mm misalignment over approx 330mm (less than 0.5 degrees)

I also made a second tool to maintain the distance between the pulleys the same as the original alternator mount but mainly not allow any twist/tilt angle between the pulleys. This tool has a semi-circle machined on either end (for a snug fit over the two 4PK pulleys) with a slide mechanism in the middle. This was all welded whilst clamped down to my workbench so the tool itself did not twist.

Using the above tool in combination some 3D printed spacers that sat against the cam wheel and over alternator pulley, I hoped that would be enough keep the alternator in the correct alignment while the new alternator mount was tack welded together.

The new mount with some additional bracing :

Once the mount was completed I rechecked the alignment with the steel rod/bearing tool and the result was no misalignment, but to be 100% certain I refitted the engine and alternator in the Mini. A slight hiccup here though - the starter motor decided to stop working. I purchased a brand new starter motor which ended up being smaller and massive 30% lighter (4.3kg vs 2.8kg) than the 30yr old OEM motor. 

Once the engine was started and test run up to 3000-3500rpm, there was zero lateral movement of the alternator belt. There was a lot of hours of work put into this single alternator bracket but it was worth it to get the alignment spot on, especially with the engine running to just over 7000rpm.