Author Topic: A10 Timing side main bush/bearing  (Read 9397 times)

Online Butch (cb)

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Re: A10 Timing side main bush/bearing
« Reply #30 on: 04.11. 2013 12:48 »
Hmmmm. So points of note then:

I thought that the softer material always wore the hard one? My understanding being that any contaminants stick in the soft stuff and then wear the hard stuff. So to some extent a harder material bush should be better?
(My sister has proven this with different grade gold in her engagement and wedding rings).

The whole point of 'white' metal bearings is that there is no direct metal to metal contact. The important aspects here being good oil pressure and clean oil.

Except, as noted, when we're kicking over with near zero oil pressure. So an easier starting bike should give better engine life?

I'm running a return side filter and magnetic sump plug, and change oil fairly regularly. I've no clue what my bush is made of - though it's only done around 2.5k miles since it all went together ... some 3 or 4 years ago. At 53, though not necessarily expecting to make old bones, at that level of usage I wasn't really expecting to split the cases again.

Warning - observations made by this member have a 93% unreliability rating.

Of Bikes; various, including ...
'58 Iron Head Flash Bitza

Online RichardL

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Re: A10 Timing side main bush/bearing
« Reply #31 on: 04.11. 2013 15:35 »

It seems you and I are on parallel tracks with the work on our A7s. I am also in the midst of trying to un-sieze my pistons and, before long, will need my timing-side bush replaced.

I thought I had previously asked  where you're located, but it seems not. I am in the western suburbs of Chicago and a local automotive machine shop (Custom Engine Service, Aurora, IL, ph: (630) 844-1071) has worked out very well for me.

C.E.S. just did the timing-side bush on my A10. I explained what I wanted, provided the new bush and left him the Haynes manual (doubt that he needed it). As far as I'm concerned they did a top-notch job. He says it's 0.001" clear and I believe it. I told him I thought that the journal needed to be ground, but I was wrong and he told me all it needed was polishing out the high spots of some scratches, thus, foregoing the money.  Sooo much better than the last time it was done by a Brit bike specialty shop whom I don't name in open forum (PM me if you want that story).

Now, don't expect to get a receptionist answering the phone, these folks are all shop and no frills except for, apparently, having every kind of machine needed to work on internal combustion engines and wicked skills. (Crank and cam grinding; welded journal buildup, spray metalizing, magnafluxing, balancing, line boring, etc, etc, etc.) Oh, did I mention the price, in my opinion, was quite reasonable? No, I don't own the place or have any relatives working there, but I hope they remain in business as long as I am still working on engines.

Richard L.
Plan on signing up for the world-wide 2020 DISTINGUISHED GENTLEMAN'S RIDEon September 27, 2020. This year it's a solo or pillion ride in dapper attire. Watch website at for details.

Offline Bsa Nut

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Re: A10 Timing side main bush/bearing
« Reply #32 on: 05.11. 2013 03:13 »
Hi all, I've heard it mentioned on this site that the bronze timing side main bush wears the crankshaft main journal and the lead bronze two part ones are the ones to get. What does everyone think? Where can you get the NOS ones. Thanks in advance for comments.

I've gotten OEM BSA bushes from Baxter cycles in Iowa...they may have a few more on the shelf. ;)

Online bsa-bill

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Re: A10 Timing side main bush/bearing
« Reply #33 on: 05.11. 2013 11:12 »
Only fitted two both supplied by the Brothers Brum (C&D Autos) solid PB I think and being one size can be machined to fit the crank so as been said already the crank does not need to be taken down in ten thou steps.
So I've limited experience but no bad experience, only thing of note I've heard is the two part ones can separate (peg shears) resulting in one part moves within the other and the oil holes get out of sync -- not good.
Also should mention I've no connection with C&D Autos other than always receiving good stuff and advice, and the stuff usually is with me next day
All the best - Bill
1961 Flash - stock, reliable, steady, fantastic for shopping
1959 Rocket Gold Flash - blinged and tarted up  would have seizure if taken to  Tesco