LCGB Forums

Can anyone please tell me what size and pitch the thread is on a series 3/gp lambretta fork stem?

M10x1.5 (x35mm long bolt) if memory serves me

If you mean the large thread - which seems likely - a commercially available bearing lock nut (SKF KM series) KM6 has the correct (identical) thread which is M30 x 1.5.

I have used them in the past with the matching lock-washers, but care must be taken in avoiding anything snagging on the castellated tags. For making a thread dressing tool, they would be ideal...

Warkton Tornado No.1 wrote:If you mean the large thread - which seems likely - a commercially available bearing lock nut (SKF KM series) KM6 has the correct (identical) thread which is M30 x 1.5.

I have used them in the past with the matching lock-washers, but care must be taken in avoiding anything snagging on the castellated tags. For making a thread dressing tool, they would be ideal...

That’s great, thanks very much. Looking to fit taper bearings to the top race and looking at options for locking it in place. Already sussed out the locking washer but was unsure on the lock ring. Have measured everything else and just waiting on the steel to arrive before machining.

gaz_powell wrote:M10x1.5 (x35mm long bolt) if memory serves me

Opps thought you ment the clamp....

Following the top tapered bearings use, been looking myself but can't find tapered bearing small enough.. assuming you will have to machine top cup to hold bearing and possibly a shim to fit between stem and race??

AL BARKER wrote:Following the top tapered bearings use, been looking myself but can't find tapered bearing small enough.. assuming you will have to machine top cup to hold bearing and possibly a shim to fit between stem and race??

It’s done using drawings that Ian from Taffspeed gave me years ago. Only thing I had difficulty sourcing was the top bearing dust shield but that’s used on lots of Chinese bikes and scooters so a source has been found.

do you want them CADing up so that everyone else can make use of the drgs/sketches?