The BSA A7-A10 Forum

Technical => Frame => Topic started by: Housewiz on 03.11. 2012 22:16

Title: Tach Drive Preference
Post by: Housewiz on 03.11. 2012 22:16
I have seen most photos of SR tach drives mounted to the timing cover.  In one book I saw a tach drive mounted to the oil pump fitting where the book said that was a very good way of identifying a SR or RGS. 

When the time comes I find a tach, what's the preferred place to hook it up to a '58 SR?

As the bike has the nacelle headlight speedo, thanks for any comments on what tach to look for also.

Steve
Title: Re: Tach Drive Preference
Post by: trevinoz on 03.11. 2012 22:32
Steve,
                The tacho drive was mounted on the timing cover until 1959.
From 1960 it was mounted on the inner timing cover and driven from the oil pump.
Pre 1960 tacho is 2:1 chronometric and post is 3:1 reverse chronometric.
Trev.
Title: Re: Tach Drive Preference
Post by: wilko on 03.11. 2012 23:04
There's a maggy type one on ebay at the moment.
Title: Re: Tach Drive Preference
Post by: Housewiz on 17.11. 2012 23:24
Trev,

I like the hidden tach cable on the later SR's - could I install the tach drive like that on my '58 or would it not bolt up?

Tanks,

Steve
Title: Re: Tach Drive Preference
Post by: trevinoz on 17.11. 2012 23:46
Steve,
                You would need the late model inner timing cover and the oil pump with the tacho drive tang plus the bits and pieces for the drive, not to mention the 3:1 tacho.

Trev.
Title: Re: Tach Drive Preference
Post by: Housewiz on 18.11. 2012 01:22
Hey Trev,

Too much work with that idea.  I am having enough trouble finding basic missing parts now.

Next time around I'll be looking for a newer SR - maybe one that isn't such a Frankencycle like the one I'm currently working on.  Great education though - no complaints. 

Thanks,

Steve