Laydown Gearbox help

The N and M is on the later AMC gearboxes,this is for Norton and Matchless. Not on the laydown boxes.

Svein.

Previously paul_hibbit wrote:

I have an early Norton OHC International with a 4 speed laydown gearbox Pand I am trying to find some information on the gearbox. I was told the Norton gearbox should have a number beginning with an N. Mine has two numbers (1) GT202 V AF and (2) GB8 7617. can anyone help with identifying these numbers please ? any information on this gearbox would be much appreciated.

Paul Hibbit

It is from a March 1956 Dominator 99

Barry Stickland

Previously barry_stickland wrote:

It is from a March 1956 Dominator 99

Barry Stickland

Hi Barry. Long shot I know but from your authorative post I reckon that you know a hell of a lot about identifying gearboxes. Mine has only one set of stampings: GB8 7240, any chance that you could pinpoint that one for me. Thanks in anticipation. Ron.

GB8 is the laydown g/box from a Dommie 88 according to my lists, Ron.

Hope this helps.

George

What do you mean by 'an early ohc International'? That would be 1932 ish, and a laydown box from a Model 99 would not go in easily. Perhaps you mean an early featherbed International?

A gearbox to fit a featherbed has upper and lower lugs of the same width. An iron-lug frame needs a wider bottom lug, and a narrow, divided upper lug.

Do not assume that the shell contains the same internals as it started life at the factory with. For one thing, a twin has a longer mainshaft than a single, so will give primary chain alignment problems. Also, the ratios in a roadster laydown are much wider than International.

Paul

GB8 7240 is from an early March 1956 Dominator 99. The main casting can be of at least three types: GT100 (Not featherbed), GT202 (featherbed Dommie and Inter), GT186 (manx). All have different offsets. For much more details on the Laydown gearbox, I would suggest looking at Roadholder numbers 187 and 212.

Barry Stickland

Previously barry_stickland wrote:

GB8 7240 is from an early March 1956 Dominator 99. The main casting can be of at least three types: GT100 (Not featherbed), GT202 (featherbed Dommie and Inter), GT186 (manx). All have different offsets. For much more details on the Laydown gearbox, I would suggest looking at Roadholder numbers 187 and 212.

Barry Stickland

Sorry not to have thanked you earlier Barry, but I have only, just this minute, found your post whilst browsing info for laydown boxes. My main casting is GT202 and your dating info tells me that it is, more than likely, the original box. Many, many thanks. Ron.

Another thing to bear in mind is that the casing may contain a different gear cluster than its source suggests. You may have a Model 99 case with International gears, or anything else. You will only know if you start checking ratios or strip the box.

Paul