It was time to sort out the driveshafts for the Mini which involved joining the inner CV at the Toyota gearbox to the Mini outer CV at the wheel hub. The cost of a getting a workshop to fabricate the pair of custom one-piece intermediate shafts (axle shaft piece between the inner & outer CV) was prohibitive at around $800 so I chose to use the technique which I seen with various engine swaps. The Toyota & Mini intermediate shafts will be cut and welded together to make a custom length shaft. As long as you don't abuse the drivetrain, I've seen this method provide a reliable solution. But how do I determine the required length of the shafts?
After a quick consultation with a CV joint workshop, I had a key piece of information - I was advised that the ideal lateral position of the tri-bearing in the inner CV housing (plunge-joint) is in the middle of the housing, while the car was at normal ride height.
To measure the required shaft lengths I needed to fit the inner and outer CV joints on the car but have a mechanism to measure the distance between them. I used a section from an old adjustable tent pole for this task but then I need to replicate the shaft ends. I machined some plastic pieces on the lathe to the same lengths of the splines at the end of the driveshafts. In the photo below, the top shaft is from the Mini - where a thick circlip limits how far the splined section can be inserted into the outer CV joint. The lower shaft is from the Toyota Starlet.
The plastic pieces were pressed into the tri-bearing (left joint in the photo below) and outer CV (right joint in the photo below) and with tent pole pieces inserted into these plastic ends, the adjustable-length driveshaft was complete.
With the upper & lower arms, wheel hub, outer CV and inner CV housing fitted to the car, and the wheel hub jacked up to simulate a normal ride height, the tri-bearing was pushed half way into the inner CV housing and a mark made on the tent pole then held in place with a hose clamp.
I wasn't sure how much the inner CV joint would move as the wheel moves up and down so to make sure that the tri-bearing wouldn't disconnect or bottom out in the inner housing, I first raised the wheel hub (same as lowering the car). The tri-bearing position was okay at this point and barely moved outward.
I then dropped the wheel hub to simulate the car being jacked up. In this state, the driveshaft bottomed out in the inner housing but the wheel would never be this low when driving anyway.
With everything removed from the car, the required length was measured and the process repeated for the passenger side.
Drivers side 270mm
Passengers side 290mm
After a quick consultation with a CV joint workshop, I had a key piece of information - I was advised that the ideal lateral position of the tri-bearing in the inner CV housing (plunge-joint) is in the middle of the housing, while the car was at normal ride height.
To measure the required shaft lengths I needed to fit the inner and outer CV joints on the car but have a mechanism to measure the distance between them. I used a section from an old adjustable tent pole for this task but then I need to replicate the shaft ends. I machined some plastic pieces on the lathe to the same lengths of the splines at the end of the driveshafts. In the photo below, the top shaft is from the Mini - where a thick circlip limits how far the splined section can be inserted into the outer CV joint. The lower shaft is from the Toyota Starlet.
The plastic pieces were pressed into the tri-bearing (left joint in the photo below) and outer CV (right joint in the photo below) and with tent pole pieces inserted into these plastic ends, the adjustable-length driveshaft was complete.
With the upper & lower arms, wheel hub, outer CV and inner CV housing fitted to the car, and the wheel hub jacked up to simulate a normal ride height, the tri-bearing was pushed half way into the inner CV housing and a mark made on the tent pole then held in place with a hose clamp.
I wasn't sure how much the inner CV joint would move as the wheel moves up and down so to make sure that the tri-bearing wouldn't disconnect or bottom out in the inner housing, I first raised the wheel hub (same as lowering the car). The tri-bearing position was okay at this point and barely moved outward.
I then dropped the wheel hub to simulate the car being jacked up. In this state, the driveshaft bottomed out in the inner housing but the wheel would never be this low when driving anyway.
With everything removed from the car, the required length was measured and the process repeated for the passenger side.
Drivers side 270mm
Passengers side 290mm
Nice work mate 👍
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