timing advance bushs

[ANLAF]

That's a good job there, Carbon. I am not an engineer, so how does it work when you've 'stopped' that crack by drilling, and then drilled it out? I take it that preserves the integrity of the metal.

Anlaf

 

[TwoManyXS1Bs]

Hey, ANLAF, g' mornin' mate. You brits come on board just like the rising sun.

'Stop drill' is an old, proven method to prevent cracks from lengthening/migrating, especially effective on plexiglas. Like the old 'tear the phonebook in half' trick, shear/stress is concentrated at an extremely tiny zone, the very tip/end of the crack. By drilling a hole there, being sure that the end of the crack is drilled out, forces the shear stresses to be distributed over the larger hole edge, and the crack stops progressing...

 

[ANLAF]

That's another neuron or two now linked up in my brain storing up all this new engineering information - tell me, will 'stop drill' help me with my window?

Look what happenEd spontaneously yesterday to the inside layer of my double-galzed window.

Anlaf

 

[peanut]

T tell me, will 'stop drill' help me with my window?



Anlaf

guess thats a new sealed unit Anlaf ouch. You should check the structural integrity of the door frame (ie see if it twists )or your new sealed unit will go the same way .

I don't know ......I go away on a 3x day break and look what happens !...... I miss all the drama.

Bad luck Carbon ..I feel for ya mate. its the sort of damage I do all the time, though in my case its due to losing my patience and just wacking something .

Now I'm back i'll have to catch up on ya build thread

 

[ANLAF]

Peanut - conservatory has shifted. Just inspected, and seen a gap in the roof panels. Oh! my - quick, insurance claim before the first fall of snow and the grizzly bears start their prowling.

Anlaf

 

[jd750ace]

Hey, ANLAF, g' mornin' mate. You brits come on board just like the rising sun.

'Stop drill' is an old, proven method to prevent cracks from lengthening/migrating, especially effective on plexiglas. Like the old 'tear the phonebook in half' trick, shear/stress is concentrated at an extremely tiny zone, the very tip/end of the crack. By drilling a hole there, being sure that the end of the crack is drilled out, forces the shear stresses to be distributed over the larger hole edge, and the crack stops progressing...

Great explanation. I will add that a stop drill in, and of itself does not constitute a repair, but an arresting measure. We still stop drill cracks today to terminate the load path that runs along the edge of the part, and a reinforcing patch is applied to further reduce the stress in the cracked member and effectively carry the load.
Attached is a pic of a typical stop drill in sheet metal.

What we have with the cam is a relief channel which serves the same function. It is reinforced by the ATU nut on the outside and the bushing on the inside, so the direct stresses in that area are exceptionally low.

 

[Brian902]

ANLAF, on the 80 up bikes that had the TCI there are no bushings in the cam. So there is no old bushing to compare to.
On installing the bushes for the Pamco, If you found that it was going in hard I might think to use a Dremel tool with a thin cut off blade and cut a slot in the bushing. Like the bushing for the clutch push rod. This will let the bushing compress to a slip fit. After all the rod won't be spinning in the bushing like it does with the points and advancer.

XSLeo, I'm not sure what you are talking about here. The ATU rod never spun in the bushing ever. It simply rotates the whole assembly at camshaft speeds and the rod rotates in the bushing the amount the ATU advances and retards. That's why a little moly grease every 5 years will make both shaft and bushing last the life of the bike. That statement is just totally wrong.

Anyway Carbon, you are the MAN. Watched your video and hoping you will allow me the privilege to use your idea for bushing removal. Awesome! Never would have thought of that one.

I think the elusive flying object might have been a bronze bushing shard or something left in the extension you were using as a drift.

And the idea of mounting the ATU whether it is needed or not, for those who have the other ignitions systems, supports the cracked shaft and eliminates any further failure.

Good recovery!

Happy Motoring!

 

[XSLeo]

When I said "spins in the bushings" I didn't anything about it spinning faster than the cam or spinning more or less than the ATU moves it.
With the ATU it spins a small amount. About 28 degrees. With the Pamco E-advancer it doesn't spin at all. The e-advancer cap that you replace the ATU with locks the rod to the cam.
My apologies if this confused you.
Leo

 

[TwoManyXS1Bs]

...With the ATU it spins a small amount. About 28 degrees...

Actually about 14 degrees, to get about 28 degrees at the crank.

Boy, I hate nit-picking, especially on Sunday mornings....

 

[ANLAF]

But you are right, TwoMany - one degree at the cam is two at the rotor/PMA. That's a vital piece of understanding when timing - as I found... hmmm! eventually.

Nit-pick away, my friend, and keep us on our toes.

Anlaf

 

[ANLAF]

Brian902, the bush I was referring to was the bush provided by Boyer for my electronic ignition. Boyer doesn't require the mechanical advance mechanism, so there is all the room in the world for this type of bush. As you can see, I would have to be very strong to drive this baby in there and split the cam shaft end-thread.

Anlaf

 

[I am Carbon]

Thanks Guys for the help and the good words too.
Hey Leo, No sir I am not confused.
I understand the weights provide the advance to the ignition.
And the rod spins with the cam
thanks again for all YOUR help Guys!
I goin for a ride have a good day later Guys

 

[peanut]

Peanut - conservatory has shifted. Just inspected, and seen a gap in the roof panels. Oh! my - quick, insurance claim before the first fall of snow and the grizzly bears start their prowling.

Anlaf

thank god for insurance. Key to insurance claims is to convince the assessor that it was a 'one off event' with no prior warning . i used to work for Norwich Union and Sun Life

 

[ANLAF]

Peanut - thanks for that. I'll be on the phone tomorrow (I have the rest of the day to myself, feet up in the garage, just cleaned the bike, done the brakes - come on ThreeBond, arrive in the post before this wonderful early autumn weather goes. How's the work going on yours?

Anlaf

 

[peanut]

took 3x days off down in Cornwall in our campervan . Spent a day paddling down the river Fowey taking pictures of birds and wildlife . brilliant...

Looking forward to getting stuck in tomorrow and finish the bike off ready for the MOT.
Good luck with yours

 

[ANLAF]

Three days of relaxation is as good as two weeks. I have a VW T4 I use as my camper - and the seats come out so it easily takes my bike.

I'll have to get round to sorting out those rusty bits.

Anlaf

 

[roselenore]

Newb here. I'm reading this thread trying to find the answer w/o asking. No luck. This is my first engine teardown on a '79, and am trying to remove the camshaft. I have removed the locknut but what in the %@&$ holds the advancer plate onto the camshaft? I've lightly tapped CCW in the hope it screwed off like the locknut. No joy. What am I missing?

 

[I am Carbon]

It should come off after taking the nut off.
there is a locating pin it might be hung up on
I made videos of top end tear down.

 

[roselenore]

I'll check it out. Thanks

 

[pamcopete]

I didn't know there was a Labyrinth Seal
The kit for 80s-84 only comes with 3 bushes .
the directions say to put 2 bushes into the right side of the cam.
And only one bush in the left side which leaves room for the Labyrinth Seal
Right now there is a space and the advance rod rides only a few MMs of the bush.
Looking at the cam for my #1 engine is has bushes and Labyrinth Seals, one of each in both ends.
So what does the Labyrinth Seal do in this case the bush does not?
is it just wider?
Is see on the other cam the Labyrinth Seals come out to the edge of the cam.
Two bushes together don't quite make it to the end.
A guy would think the Pamco kit would come with the correct parts.

Carbon,

The reasons for only three bushings instead of the factory setup with two bushings and two labrynth seals are:

1. The PAMCO rotor does not produce any torque at all on the advance rod, so the extra support and lubricating feature of the labyrinths is not necessary.
2. Only one bushing is needed on the PAMCO side due to #1 above.
3. Two bushings are needed on the advancer side. The inner bushing holds the locating pin so it will not fall into the cam hollow.
4. Having just three bushings reduces the possibility of the advancer rod binding due to misalignment of the bushings during installation.
5. Eliminating the labyrinths reduces the cost as well. (Three brass bushings: $4.50 X 3 = $13.50. Two brass bushings plus two labyrinths = $4.50 X 2 + $5.50 X 2 = $20.00

Your method for removing the stuck bushing as shown in your video was pure genius.