Christmas tree/mainshaft inner bearing track replacement

[AlG]

I am building up a tuned engine with new bearings. I am considering replacing the inner track for the christmas tree that sits in the back of the case. Anyone know what measurements I should take to decide if it actually needs doing? And then how to actually extract the track? The old Lambretta workshop guide recommends an extractor tool 59350. Anyone done this?

AlG

[HxPaul]

First make sure that the bearing surface of the cluster is not worn in any way.Then fit a new bearing into the race in the case (fit it dry)Insert the cluster and see if you have any side to side play,if not its ok to use,if there is play your race needs replacing using the tool and heat,or a bar the correct diameter and lots of grease.

[steve t]

May as well change it if you've got engine in bits might regret not doing it later

[Fast n Furious]

Measuring the wear in this outer track is difficult to do without the proper gauges.
Usual rules apply........ When replacing a bearing, replace it all. If there is any wear in the bearing surface of the mainshaft then these can be reclaimed by specialist suppliers like MB.
Be wary about bearing outer tracks that are made in godknowswheristan, as these can be out of tolerance from the off.
When using the drift and grease method to remove the track, be sure to have the casing properly supported under the track so you don't punch through the casing.
Sticky's manual offers basic advise on how to do this.

[AlG]

Many thanks all. I will compare against a few combinations of cases, mainshafts and bearings to decide if it is worth doing. Scootopia does a kit that makes it cheap enough to invest in and be sure of the quality.

Al

[holty]

last one of these i changed, i found an old lambretta big end pin from an af race crank, welded up the hole in the middle and filled the track with grease and used the big end pin as a drift, hitting it with a hammer soon removed the track, not as hard to do as i expected.

[steve t]

I used a 16mm 3/8 socket and extension I put the extension into the wrong end of the socket filled the race with grease and tapped the old race out using the hydraulic force of the grease ( it's an old fitters trick I was shown as an apprentice) anything round and a good fit will do it as mentioned by holty

[dscscotty]

The track is 22mm so as mentioned a solid 22mm crank pin is ideal, however my preferred method is to use bread in the track instead of grease!

[rossclark]

The track is 22mm so as mentioned a solid 22mm crank pin is ideal, however my preferred method is to use bread in the track instead of grease!

Pan or Plain?

[steve t]

The track is 22mm so as mentioned a solid 22mm crank pin is ideal, however my preferred method is to use bread in the track instead of grease!

Brown or white

[Fast n Furious]

Just make sure its wholemeal. It'll keep regular then.

[dscscotty]

White is best!
https://www.youtube.com/watch?v=00OlG5E8vLk&t=106s