The BSA A7-A10 Forum

Technical (topic titles must be descriptive) => A7 & A10 Engine => Topic started by: cosmikdebriis on 08.03. 2012 21:05

Title: Timing side bush and re grind....
Post by: cosmikdebriis on 08.03. 2012 21:05
I know this question must get asked over and over and believe me I have searched the forum but opinions seem to change...

I need to replace the bush and grind the crank on the timing side and just wondered what the current thinking was?

I've seen a bush on eBay for forty quid...

http://www.ebay.co.uk/itm/BSA-A10-A7-Ariel-Huntmaster-Main-bearing-crank-bush-/320845708054?pt=UK_Motorcycle_Parts&hash=item4ab3e4fb16#ht_500wt_1413

Ideally I'd like to buy a bush and ship the bush and crank and cases? to someone who knew what they were doing.

Alternatively I could go for a needle roller conversion?

By the way. I assume whoever reams the bush will need the cases as well as the crank?

If someone could help with likely prices and where to get it done, I'd be very grateful.

I'm south coast Bournemouth if anyone can think of someone local but I'd rather pay and ship than get a rubbish job done ;)

Thanks in anticipation...

Title: Re: Timing side bush and re grind....
Post by: bikerjohndavies on 09.03. 2012 08:14
I use a chap called Gary Bowden of Bowden Auto Engineering, Redfield Road, Patchway, Bristol. BS34 6PJ Telephone: 0117 9693355. He is very good with classic motorcycles and will just grind the crank journal until it is fit to use rather than take it down in 10 thou steps. He then reams the bush to fit. He would need the crank and cases.
Title: Re: Timing side bush and re grind....
Post by: Goldy on 09.03. 2012 08:56
The timing side bush is fitted to the crankcase half and then the cases bolted together.The most important thing is that the timing side bush is  INLINE BORED. Here the machine shop need to set up the cases on a vertical milling machine or vertical borer. The setting up needs to be done with the crankcase mouth and drive side bearing diameter as the datum. The bush is then bored through to the correct diameter.  The term reaming refers to the use of a reamer for opening up a bush such as a small end bush and this cannot be done with the timing side bush. It is probably best if the machine shop has some motorcycle experience, but the main thing is their machine shop capability. All the best Goldy.
Title: Re: Timing side bush and re grind....
Post by: andy2565 on 09.03. 2012 10:04
if you went along to ray fishers shop in christchurch,he would recomend a local engineer.
Title: Re: Timing side bush and re grind....
Post by: cosmikdebriis on 09.03. 2012 16:21
Thanks for the replies guys and I've found someone locally to do the job.

As a matter of interest though, as I always like to know how things are done...

I'm assuming they place the clutch side crank case flat on the table of the milling machine and bore vertically down through the bush?

As such. Should they require an old bearing in the drive side to help with alignment?

Wish I had a milling machine. got a lovely lathe but no room for any other toys. *sad2*
Title: Re: Timing side bush and re grind....
Post by: Goldy on 09.03. 2012 17:40
They can either clamp it down on the clutch side as you say or fit the mouth of the crankcase on  a 90 degree table block. Don,t leave the bearing in, they will line up to the housing wall.