Exhaust Crankcase bolt size please?

[Donnie]

So, got series 2 casings which don't have the hole under the casings for the exhaust to bolt into and apparantly it's a well known fact that if you don't use this then your bgm clubman will fail, apparantly. Ive never seen anyone advertise these exhausts advertise them as series 3 only but there you go!

So, Im planning on drilling and tapping said block of aluminium but am unsure of the depth of hole, obviously I don't want to go through, but want enough to ensure a good grip. Anyone know offhand?

[Donnie]

Never mind, I forgot about an old series 3 casing I had under the bench so Ive answered my own question, ie the M8 hole is approximately 20 to 22 mm deep.

However, it does not help at all because not only did innocenti add this for the exhaust bolt, they actually added a whole block of aluminium on the casings, so my idea of drilling and tapping one of the 13mm x 13mm blocks on the underside is completely out the window as the brackets about an inch away

[Scooter Paul]

A period modification was to drill and tap this block and then use the bracket from the later silencer that had been removed by drilling out the spot welds and repositioning it and using appropriate sized nuts and bolts.

[Donnie]

hmmmm yes could be doable I suppose, found this on the Lambretta Club USA http://www.lambrettaclubusa.net/forums/ ... m-exhaust/

[maddogmadox]

Another option is to make yourself a small bridging bracket between the original bracket on the exhaust and the aluminium block you are tapping.
this is what i did on mine. a small bit of flat bar 3mm- 4mm thick and about 25mm wide bent to shape with a hole drilled at each end and bolted to the exhaust and to the engine case block .
solid as a rock if you use a decent bit of bar and take the time to shape it to be a snug fit

[Donnie]

I've ended up selling it, shame as good pipe but tired of things being sold as Series 1 2 and 3 when in fact its really only suitable out of the box for series 3 :-/