The BSA A7-A10 Forum
Technical (Descriptive Topic Titles - Stay on Topic) => Frame => Topic started by: a101960 on 22.05. 2010 22:50
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Russell this is how I converted to taper roller head bearings. It is useful but not essential to have this service tool to knock out the original ball bearing cups (see image below).
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If you do not have access to this tool then a suitable drift can be employed. Hit the cup and work round the circumference as you as you hit it. If you do it this way the bottom cup is quite easy to knock out the top one less so because you will now be working from under the head stock. It is a bit like getting your left hand to do what your right hand normally does. There is also a cup to be knocked out of the top yoke. This easy enough just support the yoke to give some clearance.
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The fork stem cup is removed by using a cold chisel as a drift or even an old screw driver. Again just work your way round hitting it with a hammer as you go.
Putting all back together
The roller bearing cups are fitted to the headstock as in the image. I made two discs about 1/4" thick from some scrap metal. The discs were then drilled and a piece of threaded bar was used to pull the two cups into position. Doing it this way ensures that the cups pull into the head nice and straight.
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The Lower race was simply tapped into place on the stem with a piece of tube.
Points to bare in mind
This should be obvious, but make sure the cups are correctly orientated before you pull them in! Also make sure when you fit the steering stem race that the widest part of the bearing is face down. Do not forget to grease the bearings on assembly. I hope this helps. If there is anything you are unsure about let me know.
John
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John
Thanks very much for your excellent post, very helpful.
Russ
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what i did is spot welded a bar to the across on the old cup and cone then knock it out, a bit crude but did the job. i have taper roller cups and cons fitted to all my bsa's and it make life allot easer
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The Freezer / Oven system works for me gives just enough contraction / expansion so it all fits together easily.