CONTEXT
For context I own a 2005 Mini Cooper R50 automatic w/ ~200,000 miles. I got it at ~160,000 miles and had no idea about the infamous CVT. It's my first car and I take good care of it now...the first couple of years not so much, I was clueless. I've replaced failed brakes, missing trim, parking brake cables, calipers, rotors, hoses, the chrome hatch handle thing, there is a lot of rust around the car, ABS module gone bad, the computer throws up codes like the Matrix loading screen--the list goes on. CVT Transmission has its quirks but it's been solved with draining and refilling or topping off the oil. Engine still good, I replace the oil every ~3,000 miles.

2 months ago I was looking for a donor car for parts. I got tired of sourcing for cheap parts online, figured I would save with something cheap from an auction.

Last month I purchased this used 2006 Mini Cooper w/ ~150,000 miles and a bad transmission from a public auction for ~$800 taxes and fees included. Cosmetically the car is in good shape, no rust is a huge plus, labels and stickers on everything, original parts, clean interior, seats are in great condition, LED headlights, the cluster even has a clock! I scanned all the modules using INPA and Ancel BM700, everything checked out (I'm writing this a month later i can't remember off the top of my head. if there were 1 or 2 codes it wasn't serious enough to remember)

2006 Mini Cooper R50 (base) automatic w/ 149,900 miles

I have 2 options:
1. Rebuild the bad CVT transmission (worst case: I learn something and junk it; best case: I end up with 2 R50's..............................that sounded much better in my head)
2. Swap the bad CVT with my good CVT. The "newer" Mini is in much better condition cosmetically and computers check out. I would use my "old" Mini as the donor.

DIAGNOSIS
On the test drive, I get about 3,000-4,000 rpm at about 10-15 mph. Is this what a transmission "slipping" feels like? RPM's just shoot up but not much speed.

screenshot from a video I took showing 3,500rpm at 15mph but it hits 4,000rpm

video link: https://www.youtube.com/watch?v=bmjzzn8ofFU

I drained some tranmission oil from the check plug and it came back dark pink, held up against light it was just pink. I don't know if the previous owner changed it before or after the CVT transmission failed, but the oil seemed new. I checked the speed sensor connected on top/behind the transmission and it seemed like someone has already been there. Tape was cut and replaced. The way I see it I have a couple options:
1. Replace the transmission oil and filter
2. Replace the transmission speed sensor
3. Reset CVT adaptations in addition to 1 or 2
4. Pull out the transmission and begin inspecting

one more thing I'm working on compacted gravel

 

How are your manual transmission skills ? If you can drive 3 pedals, a conversion to manual is a much better idea. The CVT is a compromise at best.

 

i can't drive manual but i can learn, this is an option i will consider!