Rebuilding the D-Type Overdrive Part 3

The parts showed up a few days early, which was a nice surprise! This is the continuing saga of rebuilding the gearbox and overdrive from a 1964 Triumph Spitfire. In this video, we put the back half of the overdrive together (including a trick for reassembling the uni-directional clutch). Don't forget to subscribe so you can easily find our other videos!

[@jabberwockytdi8901]

The manual says put the bearing on the annulus 1st and that way you don't load the bearing from outside to inside race while pulling/pressing the annulus in or risk overloading the thread on the annulus. The bearing is a tight fit on hte annulus but I've found if you heat the housing with a heat gun the annulus with it's bearing and speedo gear etc will push in with a light tap with a hammer handle in the center of the annulus.

[@midwestmotoring]

Good tip, thanks!

[@TimCook-mq9nv]

Have you tried using thick grease instead of the rubber band? I frequently do this on loose bearings and it works well. A bit messy but less fiddly.

[@midwestmotoring]

Unfortunately, that won't work. The uni-directional clutch is spring loaded, so the pressure will force it to twist out of position and the bearings will still fly out.

[@cgignac5444]

Are you not afraid by inserting your annulus by installing the flange that your rear bearing can get out of his final position since nothing is retaining it? Otherwise very interesting.

[@midwestmotoring]

Good question! The bearings aren't retained in the housing by anything other than a press fit... BUT... the flange doesn't press against the housing. It just gets drawn farther onto the shaft until the end of the splines. Therefore, there are no forces that would be pushing the bearing out. Instead, it's more of a "pinching" force that push the 2 bearings closer together. Think of it like this: Replace the annulus with a piece of threaded rod and a nut and washer at either end. As you tighten either of the nuts, the space between them shrinks, pushing everything in the middle closer together. That's the same thing that's happening with the annulus, which effectively presses it into the bearings without changing their position in the housing. I hope that helps! Let me know if you have more questions.

[@cgignac5444]

@@midwestmotoring Thanks for the response. So the flange is against the washer and the rear bearing and doing so force the 2 bearings into their locations. That make sense. Correct me if I am wrong.

[@midwestmotoring]

I think technically it's against the annulus itself, since it can only go as far as the splined portion. Otherwise it would put a load on the bearings if over tightened. Either way it doesn't contact the casing at all so no worry about moving a bearing in the wrong direction.

[@cgignac5444]

@@midwestmotoring correct me if I am wrong. The front and rear bearings are a tight fit on the annulus shaft and lighter fit (not as tight as on the shaft) on the OD casing. When you screw the nut on the flange it has to exercise a pressure on something for the annulus to go in. If it is not on the casing, I believe it is on the rear bearing. I hope I am not bothering you too much with this discussion...

[@cgignac5444]

And I believe it is ok because you have pressure on the rear bearing from the annulus shaft and opposite pressure on the same bearing from the flange. And both at the same level, the inner bushing. So no problem.