The BSA A7-A10 Forum

Technical => A7 & A10 Engine => Topic started by: Chrisf1 on 01.07. 2008 21:38

Title: A10 tacho drive
Post by: Chrisf1 on 01.07. 2008 21:38
Hi again everyone I have yet another problem with my A10 café racer. I purchased a new tacho drive to convert my oil pump which was easy enough to do but when my engine builder assembled it he told me it is not for an A10 it is for an A65, A10 oil pump tacho drives are no longer available but being a handy chap he made a spacer plate to fit and enable it to work which it does as it should, the problem I have is that I cannot get it oil tight and having no knowledge of A65?s and not much more about A10?s. It is a problem I really do not want such a pretty bike pi####g oil from the front of the engine! I am told this is quite a common conversion is there anyone out there who has done it, I think the problem could be an oil seal around the drive shaft I will not know until I collect the bike tomorrow if it has one at all or even if it is meant to have many thanks I will be away until Thursday night but any suggestions appreciated. Thanks Chris
Title: Re: A10 tacho drive
Post by: trevinoz on 02.07. 2008 22:55
Originally the A10 had a very fine O ring fitted to the shaft close to the cable end and I think the A65 had an O ring fitted in the base of the shaft housing. On my A10, I bored the housing base to take an O ring. From memory the O ring had an o.d. of 3/8" and was a snug fit on the shaft.
If you fit an O ring and seal the housing to the crank case you should  get a good result.
Title: Re: A10 tacho drive
Post by: dpaddock on 06.07. 2008 21:01
Another solution, which could give a more mechanically artful look to the cafe image, is to mount an external right angle tach drive box (65-9164) to the outer timing cover (676-712) as was done on the SF, RR and SR thru 1959. This will definitely eliminate any oil leak at the cable drive.
Title: Re: A10 tacho drive
Post by: dpaddock on 06.07. 2008 21:04
Correction: the timing cover p/n is 67-712.
Title: Re: A10 tacho drive
Post by: trevinoz on 06.07. 2008 23:12
The problem with doing the timing cover set-up will be the different ratios of the tacho drives. Oil pump - 3:1.  Timing cover - 2:1.