English French German Italian Spanish

Camshaft

Submitted by michel_vincent on Fri, 15/01/2016
Forums
Commando

hello everybody

I am rebuilding my 850 engine. Among other things, the camshaft will need replacing (an inlet cam was worn half way down). I have in my boxes of bits a Commando camshaft which has the same lift, but is stamped "P" on the near side cam, rather than "T", as the old one was. It is in good condition, so I think I'm going to use it. But just before I close the crankcase, does anybody know what that "P"stand for?

Submitted by john_holmes on Fri, 15/01/2016

Permalink

This has come up be before but can't find the post, can't remember there being any issues as long as you make sure you follow the rules on scrolled journals and bushes ie one must be scrolled at least, can be either or both but not neither.

Submitted by martin_freeman on Fri, 15/01/2016

Permalink

Dear michael,

Can't help with the P, however having replaced camshaft in a late 850 would suggest you check end float, mine had a good 1/8 and needed extra washer to make sure cam lobes and followers stay lined up properly.

regards Martin

Submitted by michel_vincent on Fri, 15/01/2016

Permalink

Thanks.

Someone on a French brit bikes forum mentioned a kind of case hardening called "parkerization" (hence the "P") and suggests such camshafts were made by Dunstall.

There is a washer, which has a chamfered face, and I suppose this goes towards the centre (the rev counter drive mesh), with the flat face against the bush. I suppose also that end float should be measured with camshaft sprocket in place, and nut tightened?

Submitted by jonathan_soons on Fri, 15/01/2016

Permalink

Previously Michel Vincent wrote:

There is a washer, which has a chamfered face, and I suppose this goes towards the centre (the rev counter drive mesh), with the flat face against the bush. I suppose also that end float should be measured with camshaft sprocket in place, and nut tightened?

That is exactly right. It prevents the worm gear eating the right side bush and the chamfer prevents the tach drive gear grabbing it. I recently dismantled one and made a note of this.

I don't know about end-float. I have never had to adjust it.

Submitted by patrick_hook on Sat, 16/01/2016

Permalink

I read somewhere that the 'P' simply meant that the cam was standard (I was checking because I have one too) - not sure what the 'T' refers to though!

Submitted by alan_elstob on Sat, 16/01/2016

Permalink

Hi Michel,

I'm surprised nobody has mentioned this. Unless you are comfortable with the provenance of the cam you may be better getting a new one.

My reason for saying this is that the original factory cams, especially on the 850'swere of inferior manufacture and generally tended to fail, often in a costly way, in less than 25k miles. I guess there are very few original ones in machines still being used. My own cam ( an original one) failed at about 24k miles rather inconveniently in northern Germany.

Apparently the factory wereaware of the shortcomings but because of there straitened circumstances at the times chose to do nothing about it.I had this confirmed by Norman White.

Regards.

Alan.

Submitted by michel_vincent on Sun, 17/01/2016

Permalink

Hello Alan

In fact, this camshaft I have is not off an 850: it is a Commando one, because it has the rev counter mesh on it, but it is also hollow and has the tangs to drive the camshaft breather, so it must be off a 1971 or so 750. (camshafts have the same characteristics on 750s and 850s). So hopefully, it was made before the factory were in "straitened circumstances"! Anyway, it's on the bike now, the crankcase is in the frame, and when the cylinder block comes back from the engineer's, I'll get on with it, keeping my fingers crossed!

 


Norton Owners Club Website by 2Toucans