Square 4 Mk2 belt primary drive

[klaus gerhard]

A friend asked me if it's possible to convert the primary drive of his Mk2 to a belt drive. His main goal is to fix the leaks in the chain case. Has anyone done this modification before? Any tips are welcome.

Thanks, Klaus

[Chris Sealy]

The engine shock absorber would have a hard life without lubrication. Also the crankshaft oil seal would have to be in perfect condition.
It would be easier, and certainly more cost effective, to fix the leaks.
Cheers, Chris.

[Roger Gwynn]

Most belts are too wide to fit within the case without a spacer but there are belts that will fit, you have often seen my Caroline, she has a belt drive but I changed the clutch to one with a shock absorber as the one on the crankshaft is no longer there. The other advantage of a belt drive is that, once adjusted at doesn't wear. As Chris says, cheaper and easier to fix the leaks or use chain spray.

[nevhunter]

I think the belt tension would put extra Load on the gearbox sleeve gear Bearing and the Cush drive is a necessary part of the whole picture and needs some Oil or chainlube directed at it regularly to keep it Happy. Nev

[paul.jameson]

The late David Jones fitted belt drive to his Mk II successfully but needed to change to a Norton clutch and to extend the splines on the mainshaft by welding to suit. He made a new primary cover in place of the Ariel original. Somewhere in the deepest depths, I may have photos.

[RenzoLuigi.b]

Want to fix leaks? Pour chainsaw oil into the crankcase. It forms a film inside the crankcase that prevents leaks without compromising lubrication.
Renzo

[Roger Gwynn]

Don't use the tension in a belt as recommended by the makers, as Nev says it will knock out the gearbox bearings rapidly, but tight ish is OK, I've done 10's of thousands of miles on mine. Spec and pics available or show and tell at a rally.

[klaus gerhard]

Thanks for the valuable information.