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Born Again Cars

Gearbox here we go!

4/10/2010

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It's been a busy few days! This update will take you through the gearbox rebuild, and the re-assembly of the engine (head block and gearbox). After this I have another exciting update to take you through as I've had the excitement of getting the shell back from the shot blasters. So I can show you a few interesting bits and pieces that will definitely need some attention!

But first things first, "The Gearbox".

Having split it from the bottom of the engine before reconditioning the block and bottom end, the first job was to completely strip all the components and assess them for wear.
Although I found a missing thrust washer on the crank for the primary gear, which explains some of the whining noise, I still need to make sure there are no other maladies deeper inside the box itself.

The first of those maladies became evident very early on, the outer input shaft (1st motion shaft) bearing was starting to disintegrate, that is the plastic carrier for the rollers was in pieces, luckily the rollers were still in place and there was no sign of damage to the shaft, so a new bearing, complete with the race that sits in the clutch housing was sourced.
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Gearbox Internals Ready for Cleaning and Inspection
Once all the parts were removed (see pic) the inspection continued. The baulk rings all appear fine, very little wear (confirmed by the fact that there were no gear selection issues when driving the car). The other bearings were also all ok, until I got to the ones inside the lay-shaft (2nd motion shaft), they were showing quite a bit of pitting and I know they are a Mini weak link, so I've replace both of those too. Otherwise, all the gears are fine, the shafts don't have any wear either. the selectors, detent springs and detent balls just needed to be dug out of the sludge in the bottom of the casing (here’s an obvious tip, make sure you have all the exits covered when you put an airline into the hole to help move the stuck detent balls! if not the best that will happen is you will be showered in oily sludge but that will seem minor if you get shot by a ball that you have missed!)

Once apart everything was cleaned thoroughly (good old Nitro Morse to the rescue once again), the empty casing also had a jet wash before being thoroughly dried.
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Re-assembly started with the selectors, just a little grease on all the moving surfaces is enough, after all everything will be submerged in oil down here in the bottom of the sump well before the engine is started.

Then the output (or 3rd motion) shaft is re-assembled. It's worth knowing that unless you're changing the big primary shaft bearings the Mini gearbox can be re-build without the need for a press. This is becaues the gears and syncro hubs are retained by an ingenious spring and plunger arrangement in the base of the shaft splines, it's a bit of a fiddle to assemble, but it works really well. I guess it's a system that's too expensive in today's manufacturing world (it requires a drilling in the shaft, a spring, ball, plunger and special washer, as opposed to a press fit) but it certainly makes re-conditioning a doddle.
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Selectors reassembled
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1st gear going onto the output shaft
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The complete output shaft (gears and syncro hubs)
So once the shaft is back together, it's time for the major re-assembly to begin, making sure to trap the oil pick up strainer into the casing before the lay shaft is fitted (it's a big job to fit if you forget it and find it on the bench at the end!)

Once it's all back together it's ready for re-assembly to the block then the whole assembly gets turned back up the right way and the head can go on!

With nice clean aluminum clutch casing and gearbox married to the shiny green block and head, it's all starting to look rather special! (even if I say so myself!)
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Cylinder Block and Bottom End.

4/4/2010

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So here we go with the Cylinder Block and bottom end.

I've stripped the assembly completely, and then finished the cleaning process by removing all the old paint from the outside and all the oil staining from the inside with Nitro-Morse (yep, the stuff you use for stripping paint off your banisters!)

There was one nasty surprise. When removing the clutch and flywheel assembly, the "C" ring and washer that is supposed to retain the primary drive gear on the crankshaft was missing completely! Just not there? It appears this has allowed the gear to move in and out on the end of the crank shaft which in turn has bashed the thrust washer that sits behind the gear into pieces, which are now sitting in the bottom of the sump! Fortunately neither the gear or the crank are damaged, but I wouldn't mind guessing it's what was causing the extra whining noise, as it can't have been meshing properly with the idler gear? Hopefully it hasn't damaged anything in the gearbox. (in Mini's you might know, the gearbox sit's in the sump below the engine, sharing the same oil and in this case the same debris!)

Luckily that was the only surprise. The other - more expected - areas that needed attention were the Main bearing shells, they have been replaced, the bores which needed a flexi hone, and a corresponding new set of piston rings. Oh yes and the cam followers are worn enough to require replacement too.

On the up side, the cam shaft itself is hardly more than run in, and that goes for the big end bearing shells and the timing chain as well. I think this points to the engine having been opened before (this is also evident by the used tab washers throughout). But why someone would replace a cam shaft and not the followers is beyond me? (Although apparently not beyond someone that forgot to fit the 'C' ring and washer on the end of the crank? Enough said). The pistons, now the lacquer has been cleaned off look like new, as do all the other smaller components and covers etc.

I've bought a new oil pump new timing chain tensioning rubber rings and a selection of new nuts and bots as a matter of course.

As you can see in the pictures below, not only has the engine bottom end been stripped, cleaned and inspected, it's actually all back together again and looking resplendent in it's original BMC green engine enamel paint.

Next job is the gearbox, where the strip down is well underway, so I'll update you on that very soon.

Thanks for looking!
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Cylinder Head

4/4/2010

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It’s all going on now!

I’ve decided to tackle the engine re-build in stages, I’ll do the Cylinder Head first, then the Block and finally the Gearbox. This means I won’t fill the whole garage with a ton of bits in one go!

So as you can see from the Pic’s the head is already nearly finished, Removing it from the engine was pretty simple. I’ve kept the rocker shaft together, and poked the push rods through a piece of cardboard with numbers on to keep them in order.

I’ve then removed the valves (the springs needed a little tap with a plastic mallet to free them from the retainers), but other wise they cam out without issue.

The stem seals, basically little ‘O’ rings on these early cars, are all either badly perished, very hard or missing completely, which nicely explains the whiff of oily smoke on start up. Fortunatly the gasket set comes complete with a nice new set.

The valves and valve seats are all fine, they’ll needed lapping in again of course, but there are no burn marks or pitting. I’ve decided to keep the seats that are in the head, so will need to continue to run with the lead fuel additive, partly to keep the originality and partly because there is nothing wrong with the original parts, so I’m using the “if it isn’t broken don’t mess with it” rule.

One thing that will need fixing though, is one of the spring seats. The head has obviously been in bits before and has had a washer used in place of one of the seats, which, because it’s not hardened has badly deformed. So I’m trying to source an original part, but it’s not proving that easy!

The rest of the valves are however back in place and it’s had a coat of the proper BMC Green Engine Enamel/ Along with the rocker cover it now looks smart and new.

So… next up is the bottom end, Cylinder Block, Crank and pistons
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Busy Busy Busy!

3/31/2010

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The engine as you can see is out, dismounted from the subframe, cleaned and ready for stripping.

Nothing too untoward found, probably the most major problem to fix under the bonnet is going to be the wiring. The original loom has been rather cut and shut. It’s been converted to use an Alternator instead of the original Dynamo and voltage regulator, but the wiring work leaves a bit to be desired!

So more jobs for the list!

The good news is, ther subframe and front suspension all look just fine, with the exception of the discs and pads that will need to be replaced with new.

First things first though, and that’s to strip the engine to make sure all is well inside. I’m hoping it won’t reveal too many surprises, it was running well when I bought the car. It actually drove about 150 miles home without any major issues. But there was a little oily smoke on start up and there is definitly excessive whine from the gearbox even by Mini standards.
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    Rob Russell.
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