The BSA A7-A10 Forum

Technical => A7 & A10 Engine => Topic started by: Stu55Flash on 27.07. 2010 11:34

Title: Crank Roller Bearing Removal
Post by: Stu55Flash on 27.07. 2010 11:34
I need to re-shim the crank end float as this was 10 thou. I've ordered some shims. How do I remove the roller bearing as the shims go between it and the crank web? Do I need a bearing puller to wedge in? The crank and fly wheel where covered in sh1t and the sludge traps full see below.

The timing side crank journal is 1.3700" and round. The big end journals are 1.4566". I am taking it that these are standard size and have ordered some standard big end shells as the traps where that full and some copper is showing through in the shells.

Can you folks that have done this before let me know what you think of the measurements above and how to get the bearing off the crank

Thanks Stu.

Title: Re: Crank Roller Bearing Removal
Post by: MG on 27.07. 2010 12:10
Hello Stu!

For the small journal crank these values are STD:
   t/side:     1".374 - 1".3735
   big ends: 1".460 - 1".4595

-.010 would be:
   t/side:     1".364 - 1".3635
   big ends: 1".450 - 1".4495

So your t/side journal is somewhere in between (maybe has been reground once, just enought to make it round again).
The big ends however are way off. With this amount of wear it is time for a regrind to 0.10. They can't be round any more at this point, are they?
With a big end dia of 1".4566 you would have big end play of 4 to 4.5 thou probably, even with new shells, which is way too much.

How did you measure the journals? The only way to do it properly is with a good micrometer and measuring some points in horizontal and vertical direction.

You'll need an extractor for the roller bearing, there was a thread showing a home-made one once, but I couldn't find it anymore.
As you are doing a complete rebuild, I would consider fitting a new bearing anyway, so you might just as well hook the extractor to the roller cage or rollers and pull the bearing off.

Have you checked the play in the t/side bush? As you have the engine apart now, it might be worth considering getting a new one line-bored as well.

Cheers, Markus
Title: Re: Crank Roller Bearing Removal
Post by: A10Boy on 27.07. 2010 12:49
I fully agree with Markus.

You need a crank grind so may as well get the timing side journal cleaned up as well, then have a Lead Bronze bush made, fitted and line bored.

See this,1647.0.html (,1647.0.html)

His email is

good luck
Title: Re: Crank Roller Bearing Removal
Post by: Stu55Flash on 27.07. 2010 12:55
I measured it with a vernier caliper metric one then converted it. Before I split the crank cases there was no discernible play in either side of the crank or in the big ends. However I will take the readings again and dry fit it back together as it may have been full of thick oil that hid the wear.

Thanks Stu.
Title: Re: Crank Roller Bearing Removal
Post by: MG on 27.07. 2010 14:04
A vernier caliper, even a digital one showing 1/1000mm, is not the tool for the job, it's just not accurate enough.
It is possible to measure with an accuracy of +/- 2/1000mm or maybe even +/- 1/1000mm with a micrometer, but definitely not with calipers.
Title: Re: Crank Roller Bearing Removal
Post by: RichardL on 27.07. 2010 14:16

I'm thumb typing right now, so not easy to link you to the puller topic. Go up to the Search tab above and enter "dinosaur egg" (without the quotes; thank you, Groily). That should lead you right to the topic of my bearing puller. I'm not saying this is a difinitive solution, because, despite my duration and verbosity here, there are several members with much, much more experience. However, I haven't seen a bearing puller as crazy as mine. (I almost left out the word "bearing," but I didn't want to be misunderstood.)

Once the bearing is off, you will probably want to follow other advice from here to grind out some I.D. from an old bearing so you have an easy slip fit while working out how much shimming is needed. Be sure to check that the test bearing is the exact same height (within reasonable tolerances) of the final bearing.

Title: Re: Crank Roller Bearing Removal
Post by: Stu55Flash on 27.07. 2010 17:33
Now reassembled everything clean and dry. Good rattle on the big ends and timing side. So off to Rob Wardle this Sat. Getting the end feed thing done as well only £60 difference to the solid job. Not sure of the benefit on a cooking engine but combined  with the remote oil filter should give better longevity.

Thanks for the advice. - Stu