Pin of horror

Wierpig

Wierpig

Well-known member
UKGSer Subscriber
Joined
Aug 20, 2006
Messages
1,382
Reaction score
284
Location
merseyside
Drained my engine oil yesterday and found the " pin of horror " stuck to the sump plug magnet. This 10mm x 4mm steel pin , which our Bavarian friends hoped would stay in place but didnt really bother to secure properly, holds the front main bearing in place.The positioning of this bearing shell is critical, as pressurised oil is distributed through the various drillings and channels.
Its laughable that such an important part is secured by one free floating pin that is supposed to be secured by peening over the adjacent engine casing.
Anyway, Im about to pull the front cover off to have a look.
Any advice welcomed as Ive not done much work on these engines before ( most old bikes have been Triumphs) .
 
Look on it as an opportunity to learn more about airhead motors. Mikeyboy and Steptoe of this parish are the experts to go to for advice and help👍
 
Not much point in removing the cover as you won’t see anything.
It’s pretty much a full strip so you may as well pull the engine out to make it easier to work on.
You can’t remove the front bearing carrier without 1st removing the camshaft.
To get the camshaft out you need to remove the heads/barrels and cam followers.
If you remove the camshaft the oil pump drive is on the end so that will need refitting so the gearbox and flywheel need to come off.
 
mikeyboy said:
Not much point in removing the cover as you won’t see anything.
It’s pretty much a full strip so you may as well pull the engine out to make it easier to work on.
You can’t remove the front bearing carrier without 1st removing the camshaft.
To get the camshaft out you need to remove the heads/barrels and cam followers.
If you remove the camshaft the oil pump drive is on the end so that will need refitting so the gearbox and flywheel need to come off.
Click to expand...
Can you not just remove the camshaft drive gear, leave the cam in situ, and pull the main bearing cover and bearing off? Just looking at the parts diagram...
 
mikeyboy said:
Not much point in removing the cover as you won’t see anything.
It’s pretty much a full strip so you may as well pull the engine out to make it easier to work on.
You can’t remove the front bearing carrier without 1st removing the camshaft.
To get the camshaft out you need to remove the heads/barrels and cam followers.
If you remove the camshaft the oil pump drive is on the end so that will need refitting so the gearbox and flywheel need to come off.
Click to expand...
Bloody hell!!
 
Wierpig said:
Can you not just remove the camshaft drive gear, leave the cam in situ, and pull the main bearing cover and bearing off? Just looking at the parts diagram...
Click to expand...
I suppose you could.
How will you refit the sprocket,,it’s a press fit.(I wouldn’t be happy to use the back of the crankcase to support that much force)
If you get it back on ,how will you confidently set the correct clearance /float?
Sounds like more of a faff than it’s worth to me.
If you go down your route and find that the bearing shell has moved,you’d probably want to strip it further anyway.?
Personally I’d take the opportunity to strip and inspect the engine properly,
If all is ok it’s £50 on a gasket set,and a few hours work.
If you find any issues you’ll be glad you did it.
 
Im just assessing all avenues before proceeding.I prefer riding to spannering 😁
 
Being Totally Honest Its just like a game of Russian Roulette

If you sp[end the time and check / sort it Then you will have a blank chamber each time

If you choose to ignore then it's like a 6 chamber loaded with 3 random bullets i.e. 50 / 50

It could be there is enough wear on the interior that it will stay where it is simply because there is no real bite

But also there is a lot of weight resting on the nose bearing so it Might Turn / Might have turned Already

I had a cam chain kit to go in so I just cut the tops off two pins and removed the chain

Borrowed the BM club clam shell puller and pulled the drive gear off and removed the bushing housing that way

"BUT" when I was refitting I had the heat gun on the nose to get some heat into the front of the crank 15~20 degrees C so it does not soak up all of the heat out of the sprocket and make it jam halfway on ) , a good squirt of oil and slid the sprocket fresh from the oven straight on, It took a couple of goes, But resist the urge to hammer it the last bit!! Just pull it off, heat it a little more and be quicker next time And wrap it in an Old towel out of the oven to carry it to the garage

I did it on the ramp back end tied down, I removed the front wheel and forks to give me better access to the front casing and a straight run in when refitting

(Also and Important!!! Have a big tin of brake clear to scoosh it with prior to placement in the oven!! Remove all oil and SWMBO will be none the wiser ;) )
 
DrFarkoff said:
Being Totally Honest Its just like a game of Russian Roulette

If you sp[end the time and check / sort it Then you will have a blank chamber each time

If you choose to ignore then it's like a 6 chamber loaded with 3 random bullets i.e. 50 / 50

It could be there is enough wear on the interior that it will stay where it is simply because there is no real bite

But also there is a lot of weight resting on the nose bearing so it Might Turn / Might have turned Already

I had a cam chain kit to go in so I just cut the tops off two pins and removed the chain

Borrowed the BM club clam shell puller and pulled the drive gear off and removed the bushing housing that way

"BUT" when I was refitting I had the heat gun on the nose to get some heat into the front of the crank 15~20 degrees C so it does not soak up all of the heat out of the sprocket and make it jam halfway on ) , a good squirt of oil and slid the sprocket fresh from the oven straight on, It took a couple of goes, But resist the urge to hammer it the last bit!! Just pull it off, heat it a little more and be quicker next time And wrap it in an Old towel out of the oven to carry it to the garage

I did it on the ramp back end tied down, I removed the front wheel and forks to give me better access to the front casing and a straight run in when refitting

(Also and Important!!! Have a big tin of brake clear to scoosh it with prior to placement in the oven!! Remove all oil and SWMBO will be none the wiser ;) )
Click to expand...
Thanks for that.Ill definately be repairing it, I just want as much information as possible before I start. Ive not done any work on the engine beyond maintenance.
Did you remove the cam sprocket?
When you say you removed the bushing housing, was that the main bearing housing?
 
Wierpig said:
Thanks for that.Ill definately be repairing it, I just want as much information as possible before I start. Ive not done any work on the engine beyond maintenance.
Did you remove the cam sprocket?
When you say you removed the bushing housing, was that the main bearing housing?
Click to expand...
Okay So I am full of poop

I went out to check the spare engine as I stripped it before I sent the tool back

I removed the chain

Removed the exhaust headers and heads

Pushrods and slid barrels back so that I could pull them off with the pistons still in them N.B. support the Conrods don't let them drop and strike the cylinder opening!!!

Pulled the cam followers and then pulled the cam out I remembered after you said about the Cam sprocket (as it is the larger and covers the crank nose bush carrier So that you cannot get it past it

I chose to remove the cam intact as Miekyboy says above you really don't want to be hammering to get that cam sprocket back on (Oh and make sure that you engage the oil pump drive before you try and give it a damn good shove back into place !

The rest of the original description above is pretty straight forward But it is probably better to let some one who does more in depth mechanical work on airheads to do it for you

1727727652229.png1727727712394.png 1727728075525.png 1727728224931.png
 
Last edited:
DrFarkoff said:
Okay So I am full of poop

I went out to check the spare engine as I stripped it before I sent the tool back

I removed the chain

Removed the exhaust headers and heads

Pushrods and slid barrels back so that I could pull them off with the pistons still in them N.B. support the Conrods don't let them drop and strike the cylinder opening!!!

Pulled the cam followers and then pulled the cam out I remembered after you said about the Cam sprocket (as it is the larger and covers the crank nose bush carrier So that you cannot get it past it

I chose to remove the cam intact as Miekyboy says above you really don't want to be hammering to get that cam sprocket back on (Oh and make sure that you engage the oil pump drive before you try and give it a damn good shove back into place !

The rest of the original description above is pretty straight forward But it is probably better to let some one who does more in depth mechanical work on airheads to do it for you

View attachment 355306View attachment 355307 View attachment 355308 View attachment 355309
Click to expand...
Sounds like an engine out and strip and inspect...
 
If you’ve pulled so much off the engine already surely it would be easier just to take the remains out of the frame and do it on the bench?
 
All done.I left the engine in as its supported in the frame with no need for an extenal engine support.I took the front forks off for access.Pretty straightforward job really. But the cam followers were worn.And the cam pitted. So in went a Seibenrock cam and standard followers. 2 new exhaust valves, new timing chain and a set of rings. Over £1000 in parts so glad i didnt have to pay labour. Probably took me 20 hours.
Anyway, runs well now and the new cam is a great improvement.
The bearing hadnt moved and was in great condition so went back in.Pin loctited and peened properly.
 
I’m interested in the process you used. Can you outline the steps once you had the barrels off and the timing chest cover off?
 
Once the timing chest is off the bearing housing is visible.The chest needed warming around the outrigger bearing to free it off. Then remove the outrigger bearing with 3 leg puller. Split the timing chain and remove the crank sprocket ( heat and 3 leg puller.It was tight! Hardest part of the job). Ive since discovered thanks to the motobins airhead engine book, that the bearing housing will come off with the sprocket in place if you are careful.
I was replacing it anyway.
Then remove the exposed tappets with a magnet, undo the camshaft bearing bolts and remove the cam.As mine is a R100R, there is no keyway to the oilpump, just an easily locateable slot, so no re assembly issues, or need to remove gearbox and oil pump.
The crankcase needs to be warmed around the bearing housing as its a tight fit.Its quality engineering.
The housing can then be withdrawn.
The pin of doom was a good fit in the hole and the bearing hadnt rotated or worn so it was loctited in and peened over with a 3/8 punch.
 
I note you have used Loctite as well as peening the pin, something I would do.

I'd have been tempted to wipe a smear of Loctite 641 bearing fit around the bearing outer before aligning it in its housing with the retaining pin.

A good job you stripped it and rectified the pitted cam etc, a grand well invested plus your time, 20 hours is good going.
 
Wierpig said:
Once the timing chest is off the bearing housing is visible.The chest needed warming around the outrigger bearing to free it off. Then remove the outrigger bearing with 3 leg puller. Split the timing chain and remove the crank sprocket ( heat and 3 leg puller.It was tight! Hardest part of the job). Ive since discovered thanks to the motobins airhead engine book, that the bearing housing will come off with the sprocket in place if you are careful.
I was replacing it anyway.
Then remove the exposed tappets with a magnet, undo the camshaft bearing bolts and remove the cam.As mine is a R100R, there is no keyway to the oilpump, just an easily locateable slot, so no re assembly issues, or need to remove gearbox and oil pump.
The crankcase needs to be warmed around the bearing housing as its a tight fit.Its quality engineering.
The housing can then be withdrawn.
The pin of doom was a good fit in the hole and the bearing hadnt rotated or worn so it was loctited in and peened over with a 3/8 punch.
Click to expand...
Thanks that’s really helpful👍
 
I used loctite 638 on the pin and the camshaft sprocket.Its really high strengh ant sets quite quickly.
The front bearing shell was a secure fit and in good condition so I chose not to remove it as I would have had to replace it.
Its running really well now and Ive treated to some high zinc Valvoline 20/50!
 
Nippy Normans supply Touratech, Wunderlich, Desert Fox and many other makes of accessories.
You must log in or register to reply here.


Back
Top Bottom