Tach drive housing with oil seal

1974 850 Mk2.

Went to fit a tacho drive housing with oil seal (067254), so removed the old housing without the seal, pulled out the drive gear and removed the o-ring to replace with a new one (061282), scrapping it in the process. I noticed the new o-ring was bigger than the old one



I checked on the AN site and only then did I realize that my drive gear is scrolled (061089/S) and so the smaller o-ring that I need is 065203 (which is listed for a Mk3 Elec Start) and also that my drive gear is unsuitable for the housing with oil seal.



I think my options are to either modify my original housing to accept the oil seal and order the smaller o-ring or buy a new tach drive gear (065201 - not scrolled), but the route I think I'll go is to order 061089 from RGM (£24.90 +vat). It mentions that the o-ring sits on the shaft though I can't see a recess for one on their image.


A bit more of a palaver than I thought it would be.

Cheaper to go buy a full O ring kit from a auto parts shop, i have a complete metric and imperial O ring kits in my workshop just for replacing any size O rings i need for anything.

You don't want the earlier scrolled one , you want the later solid shaft one .
Mine has fitted a seal , not an o-ring . Can't recall the number , it presses into place .
Another important consideration is to fit a crankcase reed valve .
Do all 3 and the tach drive will never leak again .
I eventually , with evolution , fitted the Smiths electronic instrument option , that reads off of one coil . The tach drive gets a cover plate , sealed up permanent now .

Torontonian said:

You don't want the earlier scrolled one , you want the later solid shaft one .
Mine has fitted a seal , not an o-ring . Can't recall the number , it presses into place .
Another important consideration is to fit a crankcase reed valve .
Do all 3 and the tach drive will never leak again .
I eventually , with evolution , fitted the Smiths electronic instrument option , that reads off of one coil . The tach drive gets a cover plate , sealed up permanent now .

Click to expand...

Plus there is no cable!
Mike