Norton Box Layshaft Gear

[medat727]

That picture above of the twin racer is one of my favorites, those pipes hand made from very thin walled tube by John Renwick himself I believe, same as the ones he made for Reg Bolton for his 1250 twin racer. I have held them in my hands and they are very light weight..........I'll see if I can put some pics on here of my latest Vin racer.........Norton framed, TTI box and so on.

Greg, your Norvin is a beauty, love to hear how she does on the track. Speaking of thin walled tube exhaust pipes, the quarantine has given me time to pursue this titanium header and reverse cone. It’s an exact copy of the 1 5/8” exhaust that I have run for the last two seasons but being so thin walled the ID is 1.57” as opposed to the stainless pipe that was 1.50” ID. Going down the road it seems to be an improvement but the dyno visit in one weeks time will confirm the performance, one thing for certain is that it is 2.5 lbs. lighter than the SS model.

 

[Mike 40M]

My main objection to the TTI box is that it don't fit in a Manx. Without milling off some or making new engine plates moving it up a couple of millimeters.

 

[Monkeypants]

Greg, your Norvin is a beauty, love to hear how she does on the track. Speaking of thin walled tube exhaust pipes, the quarantine has given me time to pursue this titanium header and reverse cone. It’s an exact copy of the 1 5/8” exhaust that I have run for the last two seasons but being so thin walled the ID is 1.57” as opposed to the stainless pipe that was 1.50” ID. Going down the road it seems to be an improvement but the dyno visit in one weeks time will confirm the performance, one thing for certain is that it is 2.5 lbs. lighter than the SS model.View attachment 35895

Very nice.
What is the wall thickness on the titanium pipe?
Any difficulties welding ?

Glen

 

[bmetcalf]

Is it commercial tubing with that ID?

 

[medat727]

The straight sections are 1.625” x .035” grade 2 titanium tube sourced through eBay, the trick was the 180 degree bend coming out of the head. To fabricate that radius in 1.625” tube was going to require multiple pie cuts welded together which is quite a bit of work, as it turns out, Yamaha builds a 450cc single cylinder motocross race bike that came stock with a factory built titanium header, that, while obviously being a metric dimension, is almost exactly 1.625” in diameter.

While you could probably flange the end of the pipe where it fits into the head and use a stock exhaust nut I was able to set it up as a slip fit with springs that works with an exhaust nut that was supplied by David Dunfey. When it came to the welding it requires the tube to be purged, we used high temp silicone plugs, barb fitting on one end for the supply line and just a hole in one on the other side, grade 1 filler rod and my welder says it’s actually enjoyable to weld.

I’ve included a picture of the Yamaha header, what I find interesting is that a modern 500cc performance single has the same pipe size as a 500cc single built in the 1940’s, coincidence?

 

[Pushrod Twin]

Reading the thread in the technical section with regard replacing the Comet Burman box with Norton box. I have one question which I didn't want to hi jack the thread with.
There are numerous mentions of the Norton layshaft gear roller bearing self destructing and therefore prudent to replace with a bush. Is this a well known/standard mod'when fitting to a big twin. I like to think my chopped motor hasn't got this far without the mod being carried out but am slightly twitched none the less.

Brian, if your Commando box does finally expire, when you rebuild it, you can help that bearing with a bit of extra support by mounting a bearing on the outer end of the sleeve gear .

 

[bmetcalf]

The welders at the dairy equipment company that I worked at just used masking tape to seal off the ends of the SS tubing for argon purge.

 

[medat727]

Definitely cheaper and probably just as effective.

 

[greg brillus]

Hi there Guy's, sorry don't wish to change this thread.......I'll probably start one on some racing bike theme........Yes I wanted to build a bike based on a true Vincent, and I do have the parts to do it. However, as I also have the bones of a new twin engine I wish to build that as a street bike........So that is why I bought a set of Comet cases and started to build a new engine to swap over for the 2 valve Jawa (ESO) engine that was in the racer I already had. I take a big interest in the all up weight of the machines as this gives a big advantage over heavy machines........This too was part of my reasoning for building a single racer rather than a twin, where the twin is much heavier and takes a lot more effort to stop. Before I stripped the bike it was 130 Kg's.......with the Vincent engine and many, many mods so far......minus the exhaust and the primary cover, it tips the scales at 120 Kg's at the moment. It all costs a damn fortune, and I think i'm completely nuts at times, but hey we all need our toys.......I always enjoy the challenge of it all.

 

[vibrac]

When I want to look up exhaust pipe manufacture the last place to look will be Norton gearbox threads