Cam Followers

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Actually JBW is a rather poor glue as does not chemically bind to surfaces only by mechanical grip to surface texture. The hi temp version also goes kinda soft/pilable over a few 100'F.
 
Hope that I don't stir things up too much since I am not an expert but it is my understanding that :-

1) Original engines would do 80,000 miles before major overhaul
2) Original camshafts were case hardened (again I believe this to be to do with carbon content in the steel, if it was all high carbon content it would be very hard but brittle so it has a lower carbon content and then somehow carbon must be somehow diffused into the surface with heat)
3) Original cam followers were case hardened
4) Aftermarket billet camshafts that are sought after are not case hardened, when I asked a particular supplier. The answer is that they will never do a high mileage in a classic or even on the track.
5) If you can grind it down then the tool has to be alot harder than the surface and if you can 'wear it away' that easily then so can the other surface.
6) The only way is to machine the surfaces with high carbon content (brittle) tools and then case harden the softer metal to make it durable.
7) Most aftermarket parts are not up to the same standard as the original which of course were matched and are certainly no longer available.

Lets face it, these bikes are no longer asked to be everyday transport for Police and the general public.

Like us all, most of them are not what they once were :oops:

As I said, I am not an expert on this stuff, it's not my field, so please correct me if I am way out of line, but this was always my understanding.
 
Engie said:
Hope that I don't stir things up too much since I am not an expert but it is my understanding that :-

1) Original engines would do 80,000 miles before major overhaul >It happens occasionally with good care<
2) Original camshafts were case hardened (again I believe this to be to do with carbon content in the steel, if it was all high carbon content it would be very hard but brittle so it has a lower carbon content and then somehow carbon must be somehow diffused into the surface with heat) >pre Mk3 850 were case hardened<
3) Original cam followers were case hardened > they were brazed stellite , no case hardening<
4) Aftermarket billet camshafts that are sought after are not case hardened, when I asked a particular supplier. The answer is that they will never do a high mileage in a classic or even on the track. > they do not need to be case hardened to do high milage, lubrication is the key<
5) If you can grind it down then the tool has to be alot harder than the surface and if you can 'wear it away' that easily then so can the other surface. >case hardened parts are normally ground to finished dimensions<
6) The only way is to machine the surfaces with high carbon content (brittle) tools and then case harden the softer metal to make it durable.
7) Most aftermarket parts are not up to the same standard as the original which of course were matched and are certainly no longer available. >sometimes true -sometimes it's the other way around<

Lets face it, these bikes are no longer asked to be everyday transport for Police and the general public. >I must not be "general public"

Like us all, most of them are not what they once were :oops: "nailed that one" :? Jim

As I said, I am not an expert on this stuff, it's not my field, so please correct me if I am way out of line, but this was always my understanding.
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"Most aftermarket parts are not up to the same standard as the original which of course were matched and are certainly no longer available"

I would have to disagree with this. Andover Norton parts are as good or better than originals. Aftermarket US made camshafts are preferred over originals as the quality control is better as it relates to surface hardening. It's a known fact that many 850 original camshafts did not get a complete hardening process and went flat.

Cam followers aren't hardened, they have stellite welded to the portion that rides on the camshaft.
 
Russ,

One thing you might think about is getting a read on the cam. Put it back in the cases, mount up the cylinders with the tappets installed and measure the lift with a dial indicator. You can leave out everything else, all you need to get is the lift. I don't think that MkIII's were the only ones to have iffy cams. The pictures look like there might be something going on. How many were miles on that motor?
If the cam is really gone then the question about resurfacing the tappets has answered itself, you gotta do it if you're going to put in a new cam. Megacycle has a fixture specifically for these tappets, they can do flat surfaced in addition to the radius for their cams. I don't think it was too expensive when I did it a long time ago.
 
rpatton said:
Russ,

One thing you might think about is getting a read on the cam. Put it back in the cases, mount up the cylinders with the tappets installed and measure the lift with a dial indicator. You can leave out everything else, all you need to get is the lift. I don't think that MkIII's were the only ones to have iffy cams. The pictures look like there might be something going on. How many were miles on that motor?
If the cam is really gone then the question about resurfacing the tappets has answered itself, you gotta do it if you're going to put in a new cam. Megacycle has a fixture specifically for these tappets, they can do flat surfaced in addition to the radius for their cams. I don't think it was too expensive when I did it a long time ago.
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I have the cam and lifters here. The cam is good. The one crooked lifter has been fixed and he is good to go. Jim
 
Yes, the cam checked out OK. So it is going back in.

Russ
 
I find this an interesting discussion so i'll carry it on although the op"s problem is solved. I'm also no expert, for example my 1st intro to stellite was on chainsaw bars when i was 16. All the old timers worshipped stellite tipped bars which were easily recognized by the bright silver bead on the edge. This left an impression on me that stellite was one of THE hardest metal surfaces known to man and until recently I considered the Norton cam to be considerably softer than the stellite tipped lifter.

Engie said:
Hope that I don't stir things up too much since I am not an expert but it is my understanding that :-

1) Original engines would do 80,000 miles before major overhaul
I wish! but then I always enjoyed taking the bike apart as much as riding it so never got to find out.

2) Original camshafts were case hardened (again I believe this to be to do with carbon content in the steel, if it was all high carbon content it would be very hard but brittle so it has a lower carbon content and then somehow carbon must be somehow diffused into the surface with heat)
See EN 32 B steel tech (what stock Norton cams are made from) here:
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http://www.westyorkssteel.com/en32.html

Engie said:
3) Original cam followers were case hardened
Norton cam followers have a stellite pad brazed on the contact area. Stellite has it's own inherent strength as an alloy and is not hardened otherwise. Stellite comes in a variety of blends therefor the hardness varies somewhat.

4) Aftermarket billet camshafts that are sought after are not case hardened, when I asked a particular supplier. The answer is that they will never do a high mileage in a classic or even on the track.
A billet camshaft is one that is turned from a solid steel bar stock. The grade of steel will determine the type of hardening process used to finish the cam ie: "case hardening", nitriding, etc. The other method used to make cams is casting which is one of the best ways. Some shops will regrind this type of cam but not billet cams. Cast or chilled iron cams are known as blanks. Hard alloy steels suitable for nitriding are comparable to chilled iron cams in quality and reach above HRC 60. It sounds like your supplier was being a bit evasive or didn’t want to enter into a long conversation. There are different types of hardening processes but the whole advantage to billet cams is the profile exists in the CNC program, not in a casting mould. This allows for easier modifications to the profile at the expense of greater maching costs. For short runs it’s the only way. Anyone going to the trouble of turning biliet cams should be using steel grades suitable for nitriding instead of case hardening which is maybe what your supplier meant.

5) If you can grind it down then the tool has to be alot harder than the surface and if you can 'wear it away' that easily then so can the other surface.
On a hardness scale it just has to be harder, not alot harder and no one said it was easy.

Here is an interesting hardness comparison chart from the web:

Cam Followers



6) The only way is to machine the surfaces with high carbon content (brittle) tools and then case harden the softer metal to make it durable.
That would be the most affordable and productive method and therefor most practical. Know where you want to go in the end, then take systematic steps to get there. However chilled iron cams and stellite tipped lifters are still re-surfaced after the fact when practical.

Comparison chart of tool steel and abrasives:
Cam Followers


7) Most aftermarket parts are not up to the same standard as the original which of course were matched and are certainly no longer available.
New and better processes and better alloys are constantly emerging. After 40 years a lot of folks have identified the weaknesses and created marked improvements to the design. In design, cams and lifters are matched by the hardness of their materials. Andover still supplies many original parts.

Lets face it, these bikes are no longer asked to be everyday transport for Police and the general public.

Like us all, most of them are not what they once were :oops:
HEY NOW WAIT A MINUTE!!! Unfortunately some yahoos are not content to have and ride a beautiful classic machine that will putter along for 80,000 miles. Some yahoos have to push them beyond their original design by adding higher compression, bigger valves, higher lift cams, lighter components and on and on... Dam yahoos anyhow, they've been fiddling with Nortons for a 100 years now.

As I said, I am not an expert on this stuff, it's not my field, so please correct me if I am way out of line, but this was always my understanding.ditto for me too and thanks for posting Engie, I'd love to watch the process used to make an original Norton cam.
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rvich said:
Yes, the cam checked out OK. So it is going back in.

Russ
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Russ,
You must be living right. I'll bet your toast always hits the floor jam side up too! :D
 
It's better to be lucky than good!

Some bits of this bike amaze me as to how incredibly untouched by time they are, and other bits, just completely worthless. I tore down the swingarm pivot and removed the isolastics from the cradle in the last few days (getting it ready for paint). The swingarm pin looks like it has never been installed in anything and the isolastics will still rebound into my hand when I bounce them off the work table from about 16 inches. How do you explain that?

Russ
 
Wow RennieK, I am awe inspired, I would really like to know all that stuff and have a garage full of machine shop tools, lathes, grinders, boring bars, milling machines etc, (She, who must be obeyed, has other plans) I knew there was a lot to it.

I don't really want to hijack rvich's thread though, because at the end of the day this thread is about getting his cams and followers sorted.

I hope we have made him aware that it may not be as straight forward as it may first appear and it may be best to replace both with quality stuff.
 
rvich said:
It's better to be lucky than good!

Some bits of this bike amaze me as to how incredibly untouched by time they are, and other bits, just completely worthless. I tore down the swingarm pivot and removed the isolastics from the cradle in the last few days (getting it ready for paint). The swingarm pin looks like it has never been installed in anything and the isolastics will still rebound into my hand when I bounce them off the work table from about 16 inches. How do you explain that?

Russ
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It's funny what you come across when you get into an old bike. I think it's a combination of how they were used and maintained before they were laid up and then how they were stored for all the years till you get them. The one doesn't always reflect the other very well. I'd rather find a bike that's surprisingly nice on the inside, even though it's probably a wash as far as how much money you wind up spending. Between the engine and the frame stuff, it's proof that the Gods must like you. They've been maintaining a convincingly indifferent attitude towards me as far as bikes go up to now. Go figure.
 
Engie said:
Wow RennieK, I am awe inspired, I would really like to know all that stuff and have a garage full of machine shop tools, lathes, grinders, boring bars, milling machines etc, (She, who must be obeyed, has other plans) I knew there was a lot to it.

I don't really want to hijack rvich's thread though, because at the end of the day this thread is about getting his cams and followers sorted.

I hope we have made him aware that it may not be as straight forward as it may first appear and it may be best to replace both with quality stuff.
Click to expand...

Go ahead and hijack this thread. If you notice it was originally posted in July, then reserected when Comnoz posted the result of surfacing my follower. Whether or not we have it sorted it, a plan has been made, put into action and pretty much followed. Don't worry, I still have more bits that I will be trying to figure out.

Russ
 
This is a question about the the valve train geometry so I hope it's related to the thread. It has to do with sideloading of the tappets by the pushrod, which seems to be necessary for things to work. Here goes. The rocker arms are located on the spindle by a spring on the inside and a thrust washer on the outside. There has to be some amount of outward push on the rockers to keep it against the thrustwashers or the arm would be moving across the spindle, the springs aren't that stiff. Are the cups on the tappets directly lined up under the balls on the rockers or are the tappets moved in a little so the rockers get pushed out against the thrustwashers and stay put? If that's so do the tappets get canted in their bores and cause uneven wear on the faces, and maybe the cams too? Does the fact that the spindles and the cam aren't parallel come into play at all?
I've used bronze spacers instead of springs before but on this build I used the springs.I haven't noticed any more or less noise or troubles with the springs.
Thanks
 
Dunno if they didnt call them ' thackery ' ? springs . Leave wear marks from the end in the end of the Rocker ,
and then go ' click click ' . so they all said . Which suported a trade in replacement spacers , which were suypposed to be
hand lapped to give about 10 thou endfloat for the rockers .

You see ancient rocker arms with a worn rebate from the spring end . Typical on pre-historic Triumphs like olde ridgid era stuff .After a few times ' around the clock ' .
 
rpatton said:
This is a question about the the valve train geometry so I hope it's related to the thread. It has to do with sideloading of the tappets by the pushrod, which seems to be necessary for things to work. Here goes. The rocker arms are located on the spindle by a spring on the inside and a thrust washer on the outside. There has to be some amount of outward push on the rockers to keep it against the thrustwashers or the arm would be moving across the spindle, the springs aren't that stiff. Are the cups on the tappets directly lined up under the balls on the rockers or are the tappets moved in a little so the rockers get pushed out against the thrustwashers and stay put? If that's so do the tappets get canted in their bores and cause uneven wear on the faces, and maybe the cams too? Does the fact that the spindles and the cam aren't parallel come into play at all?
I've used bronze spacers instead of springs before but on this build I used the springs.I haven't noticed any more or less noise or troubles with the springs.
Thanks
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As far as I have been able to tell they are lined up. So no push either way. I have also built them with spacers and with springs and never seen any difference. Jim
 
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