Cam followers stellite inserts

Status
Not open for further replies.

pierodn

Joined
Nov 10, 2012
Messages
3,154
Country flag
Hi.
Both intake cam followers stellite inserts, of a 1971 commando (unmolested engine with 30.000 km. done), came off damaged fortunatly only the camshaft.
The bike had a good oil and oil pump worked well with a good pressure.
Have you never had or seen this accident?.
Why it can happen?.
Thank you.
Piero
 
I have half a stellite tip break off after rebuilding an engine, fortunately I head the rattle and was able to strip the engine before the camshaft was damaged. No, I don’t know why it happened, but those tips are very hard and very brittle and easily cracked
 
I don't recall hearing or reading about any pattern or batch of the stellite faces failing; they seem to be infrequent and very random...
 
Had it on a BSA B40 cam follower with stellite feet, almighty clatter from the rockerbox so stopped, when home replaced the follower and no problems so very random covers it.
 
For the cam longevity yes, it resets the stellite back to being flat after taking a wear pattern that matched the old cam, think of it like re-honing for new rings.
 
I had the Stellite pad come off of a lifter once at Daytona on a Commando race bike. It did quite a bit of damage to the camshaft, rods and crankshaft. Still, I agree with Paul that it seems to be a fairly rare occurrence. FWIW, it was an original factory lifter, not one of the aftermarket replacements.

Ken
 
I had a stellite pad come off of a single lifter too. I went for a short ride one day on my test loop route. I pulled into the driveway and while idling the bike started going "clack, clack, clack...." I shut it off instantly. Yes, this was just another reason to pull the head and barrels to see WTF is wrong this time.

When I pulled the cylinders, I didn't look at the underside of the barrels right away. Instead I looked into the bottom end and one lobe of the camshaft had this hunk of metal sitting in place right on top of it... I thought WTF is that? Then I looked at the followers and saw one of them was missing it's pad. Bingo, it made sense. The stellite pad delaminated.

Thankfully Jim Comstock hooked me up with a new pair of lifters. He also answered my questions about how these things are made because I wondered about just repairing my single delaminated lifter. I was told that they are oven brazed and it's not a process I could do in my home oven.... Yes, I'm that crazy...

Anyway, I sent him my damaged lifter pair, and Jim fitted a new pair of lifters to my barrels from a thousand miles away. That Jim is a smart man. I did that repair early last summer and my bike has run perfectly since then. Needless to say, I've been very lucky with my bike, but if it even makes a clunk or an internal engine noise I don't like, it comes apart, so I have made my own good luck being vigilant.
 
A couple of years ago while I had the engine running at lowish revs on the centre stand it suddenly sounded as if it had a large ball bearing rattling around the crankcase. Perfectly all right one moment and terrible the next moment, with an unstressed engine running. Glad it was not reving on the road at the time because it turned out that the hardened pad had come off one of the (original) cam followers. Ruined the camshaft and took a small gouge out of the camshaft trough but no other damage.
I seem to remember reading somewhere that cam followers are now made with the hardened pad extending, mushroom shaped, into the body of the follower so that if it detached it would not come right off. Don't know if this is correct or not, or if it is even possible to make them like that!
 
Some discussion at the link below on possible cause and effect of Stellite delamination from the lifter body. At the link scroll down to the image of the delaminated lifter and read thereafter to the end of the thread to follow the discussion.

https://www.accessnorton.com/NortonCommando/about-time-for-the-spintron.18787/page-15

I also recall a thread where Comnoz replaced a delaminated lifter with a new (recently manufactured) lifter having the Stellite pad “keyed” into the lifter body prior to furnace brazing, thereby decreasing the likelihood of delamination from the lifter body. However, at this juncture I cannot locate that thread and do not recall the vendor that was supplying this improved version of the lifter. Perhaps others here might direct us to that thread or recall who the vendor was.
 
WZ507 said:
Some discussion at the link below on possible cause and effect of Stellite delamination from the lifter body. At the link scroll down to the image of the delaminated lifter and read thereafter to the end of the thread to follow the discussion.

https://www.accessnorton.com/NortonCommando/about-time-for-the-spintron.18787/page-15

I also recall a thread where Comnoz replaced a delaminated lifter with a new (recently manufactured) lifter having the Stellite pad “keyed” into the lifter body prior to furnace brazing, thereby decreasing the likelihood of delamination from the lifter body. However, at this juncture I cannot locate that thread and do not recall the vendor that was supplying this improved version of the lifter. Perhaps others here might direct us to that thread or recall who the vendor was.
Click to expand...

New lifters from Andover are spigotted. They do not loose the pad anymore.
Highly recommended, to bad they're not inexpensive. Jim
 
Hi All.
Rebuilt the engine.
New cam, new cam followers, new piston, new valves, guides, rebored barrells, new Fag superblend, new distributor chain and tensioner, and new other.
The bike started well and run great for 200 km.
But, to day, suddendly a thunder, and the bike swithched off.
No more valve timing,using kick start valves firm so that I have thought that the distributor chain was cutted off.
Keep out the timing cover, and with great surprise i have seen that the “Crankshaft Pinion” (not new) was broken in three parts!.
I know it is easy to change but remain the question why it happened!
Easy to solve, but have the valves met against the pistons?.
Let me know yours.
Thanks.
Piero
 
99.999 percent sure it would have bent at least one valve.

Not sure why the gear broke, but I will say those gears are made of the finest cheese available. jim
 
Perhaps the shape of the stellite pad affects the cam's lift profile and thus the loads involved when the cam moves it ? There are two different radius followers used in Triumph motors. The race cam is used with the bigger radius followers.
 
You’ve been huffing that stale Ethanol out of that seeley tank of yours again. Jerry has a triumph forum just for you. Why don’t you go over there to talk Triumph dare I say, while we continue with Norton’s over here.
 
I haven’t.

I’ve seen gears in other applications break when they’ve not meshed correctly. I had a Vincent kick start gear break into three pieces due to this.

I could also imagine that if the gear was too tight on the crank, it would be under great stress to break as you describe, effort required to fit it could have caused the damage if the fit was too tight.

So, either a meshing issue... a foreign body getting between the gears... or a tolerance issue between shaft and gear. Would be my hypothesis.
 
pierodn said:
Hi.
Have you never seen before such gear break?.
Piero
Click to expand...

Yes, The factory gears are made of poor quality metal and then they are hardened to the consistency of glass. They wear well -but any kind of shock will break them easily.

I suspect that if they would have had a decent gear on the crank back when they attempted the electric starter it probably would have worked. Jim
 
Status
Not open for further replies.
Back
Top