Has anyone replaced the gearbox input shaft bearing?

[DaveKennedy]

Hi all,

I have the gearbox out of my Series 3 and want to replace the input shaft bearing, which is noisy. (A new clutch disc and release bearing are going in too.)

Has anyone done this job?  I'd like to understand which parts have to be removed to get at the bearing and the workshop manual/parts drawings don't make it clear, not clear to me anyway. It looks like all the gear control rods have to be removed but I don't want to end up with springs flying out unexpectedly!

Dave.

[lancianut666]

Anyone? If you get stuck I know someone who has just had a gearbox in bits so will be able to talk confidently about it so get in touch.
Clarkey

[DaveKennedy]

Will do. Thanks Jim.

[DaveKennedy]

Updating this now my gearbox is back in and working.

Removing the input shaft bearing turned out to be tricky. It's tight in the gearbox housing but much tighter on the shaft.

To remove the bearing without totally disassembling the gearbox, I had a special tool made by a local machine shop. It was a collet type puller where the collets fitted into the snap-ring groove on the bearing. They used the new bearing as a template.

Once the tool was made the steps were:

- drive the input shaft forward enough to get access to the snap-ring groove (with the front and rear supports removed you can drive the output shaft forward, which will push the input shaft and bearing forward)
- use the puller to pull the bearing off the shaft. (In my case the bearing came apart leaving one of the inner journals on the shaft and I had to use a separate puller to get that off.)
- drive the input shaft (and gears and output shaft) back, at least 8mm further back than their correct position. This will allow the input shaft to be removed completely. (the output shaft will automatically be put into the correct position when you replace the rear support and insert the locating pins)
- remove the input shaft and put it into a freezer for 12 hours
- prepare a support arrangement so that the end of the output shaft and the gearbox housing can both be supported when you are driving the bearing on (I put a steel plate against a wall with the end of the shaft against it then used timber packing to support the housing)
- heat the new bearing (I put it in a bag in boiling water for 20 minutes)
- get the input shaft out of the freezer and into position, being careful to get the roller bearing and locating frame in the right place
- drive the output shaft forward until the input shaft is in the correct position
- make sure the output shaft and gearbox housing are both firmly supported
- take the bearing out of the hot water and drive it onto the cold input shaft (I put a disc of 5mm steel with a hole drilled in it against the bearing, then used a very large box spanner and a club hammer)
- fit the snap-ring before getting the bearing into its final position. Use the LH threaded locking nut to finally locate the bearing against the shoulder on the shaft.

Dave.

[lancianut666]

You deserve a medal Dave for doing all this!
Clarkey

[DaveKennedy]

If I’d known what was involved I don’t think I would have started!
Fortunately the old bearing was actually bad as we believed, and there is now a very low level of bearing noise with the box in neutral and the clutch engaged. It was very noisy before.

[Mikenoangelo]

and I thought the Augusta box was tricky - well done .
Mike

[richardlewis]

Hi , was wondering about my car, the buzzing noise... what did yours sound like ? I thought it might be the same thing ....