Pot joints. No, really.

Brian’s been working on the driveshafts. Rupert, like many Minis of humble origins, uses QL5000 universal joints on the inboard ends of the driveshafts, and CV joints on the outboard ends. QL5000 joints are cheap, but they’re too big to work with the exhaust headers we’re using, so we’ll have to replace them with modern CV joints. Here’s a QL5000 next to the CV replacement:
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Just one tiny issue: the old differential output gears need to be changed to suit the CV joint, and so do the driveshafts. Since we’re changing the diff output gears, we might as well rebuild the differential and choose a more suitable final drive ratio. Oh, wouldn’t you know it- the diff cage is worn beyond being rebuildable. Time for a brand new diff, thanks to our friends at MiniSpares.

This is where the problems start.

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That is not a happy face. While assembling the new final drive gear to the new diff cage, the first bolt pulled its threads out. “You overtightened it!” I say, and have a go myself. The workshop manual says tighten to 60 ft.lb. The threaded hole strips at about 30 ft.lb. Aargh! Looking at the remaining holes it appears the threads have been cut with a blunt or damaged tap- there’s galling everywhere.
Heli-coil to the rescue.
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Once the crappy threads on all of the bolt holes are replaced with Helicoils, the bolts easily tighten to 60 ft.lb without drama. Fingers crossed it all holds together in the car, or else we’ll just have to buy a race spec limited slip diff…

Oh, and “Pot Joint” is what all the workshop manuals call CV joints. The more you know!