Teardown Log

$600 Cooper S, one dead gearbox

Bought sight-unseen off a driveway where it had been sitting for two winters. The seller was honest about the gearbox — it won't take third, and it makes a noise in second that you feel through the shifter more than you hear it. Everything else turned out better than advertised.

Key point with these: a non-runner R53 with a good engine is worth more in boxes than it is on a trailer. The supercharger alone covers the purchase price if the snout bearing is quiet.

What came off, in order:

• Clamshell bonnet — four bolts and the washer line. Takes both headlights with it, so it comes off as one assembly. Straight, no stone chips through the paint.
• Front fascia and rad pack — condenser was fine, rad had a bent core but held pressure.
• Eaton M45 — quiet, no play in the snout. Went straight onto the shelf.
• Interior — sports seats, both door cards, headliner. All clean.
• Getrag MT285 six-speed — scrapped for the bellhousing and the diff. Third gear looked exactly as bad as it sounded.

Rear subframe mounts and trailing-arm brackets were the worst I've seen on a car that still had a valid inspection on it. Whole rear end went to the skip.

Pulling the M45: it comes out the top

The Eaton M45 sits on top of the Tritec, underneath the top-mount intercooler. It comes out the top. You do not drop the subframe for a supercharger — that's engine-and-gearbox-out work, and it's a wasted afternoon if all you want is the blower.

If you want real room at the front of the engine, the MINI's front end is modular: bumper cover, bumper carrier and slam panel unbolt and the whole nose comes away. That's the "service position," and it's the right move for belt, tensioner and crank pulley work. For the charger alone you can usually manage without it.

Order that works:

• Bonnet scoop and top-mount intercooler. It's air-to-air and it sits directly over the supercharger — a wall in front of everything else.
• Intake tube, supercharger intake duct, and the intercooler exit horn with the bypass valve attached.
• Throttle body.
• Dipstick and tube — two 10mm bolts. Plug the hole to the crankcase before anything drops in.
• Alternator out of the way, and unclip the water pump hoses.
• Belt off. A 16mm releases the tensioner bracket on the end of the supercharger. Note the routing before you let it go — the diagram is usually long gone.
• Then unbolt the charger and lift it clear.

The M45's needle roller bearings run in their own oil, separate from the engine. Service interval is roughly 60—80k miles. Almost no car has ever had it done.

So before you put a price on a used one: it's 2—3 oz of Eaton supercharger oil through the port on the snout, and it takes ten minutes. A charger that's never been serviced is a bearing failure waiting to happen — grinding first, then no boost at all.

Separate from that, the snout coupler is rubber and plastic and it perishes. The tell is a rattle at cold idle that fades once it warms through. That one isn't fatal, and you can replace it without pulling the charger off the car.

One shell, three donors, zero matching panels

The point of the graveyard isn't the parts pile, it's what gets built out of it. Build #001 is a straight Astro Black shell from donor #002, running the drivetrain out of #004, wearing #003's doors because they were the only pair without rot at the bottom seam.

They're Chili Red. The roof is white because that's the roof that was on the shell. It is not a color scheme, it is a receipt.

Still to do: rear subframe from #001 (the only one that wasn't rotten), a full brake refresh, and a decision about whether to paint it or lean all the way in.

The running list of things that snapped, seized or fell off

Kept honest so nobody buys a part from me thinking the removal was clean when it wasn't.

• Every single exhaust manifold stud — assume all of them. Buy the extractor set before you start, not after.
• Rear subframe and trailing-arm bolts — seized solid into the bushes on three of four cars. Two came out with heat, two got cut.
• Door card clips — brittle at this age. Order a bag of them in advance and stop pretending you'll reuse the originals.
• Supercharger oil — not a breakage, but check it before you buy. Not one of the four donors had ever had the snout service port touched.
• Bonnet release cable — snapped on donor #003 with the bonnet shut. That is a genuinely bad afternoon.