Advice on a non-rotating pushrod

[Real Rocker]

Rotating pushrods

Hello Piggy Wig, If my fading memory serves me correctly the cause of big end failure after the rebuild was that the crankshaft Quill broke off. Defective? not centred correctly? I don`t know. That quill & its purpose has always been a mystery to me. Just another part to go wrong. I am not aware of any other engine designs that require this device.

 

[sidmadrid]

J.A.P., Velocette. sid

 

[BlackLightning998]

Read Classic Bikes this month and Rick Parkington...

In the magazine Rick had a similar problem with a Velocette this month - and only found the problem by accident before he put the whole thing back together with the damaged end off the quill still inside!!

S

 

[Real Rocker]

Crankshaft Quill

I am sure several people know of an accurate way to locate the quill & confirm it is in the correct position .I.E. dead centre of the drilling. Please advise of any tips because for years the thought that the quill might be being worn away again has worried me. Dell Boy.

 

[clevtrev]

I am sure several people know of an accurate way to locate the quill & confirm it is in the correct position .I.E. dead centre of the drilling. Please advise of any tips because for years the thought that the quill might be being worn away again has worried me. Dell Boy.

First, I would ask what that quill was made from?
Impossible to put the quill in anywhere else but the right place. Dowels in the cover are there for that reason. There are plenty of mainshafts out there with the hole NOT in the centre of the shaft, which might be the reason for your demise. Or the quill was bent, or maybe just suffering from old age.

 

[piggywig]

Big end quill

Real Rocker,
Note your more detailed info regarding the b/end trouble.Not really the fault of the re-builder!
I have a bronze? quill well worn on one side in the old parts box that did much service before seen, by chance. No doubt all the wear took place very quickly which removed the excess or out of true portion, and all continued to function happily.
By all means drop by while in Oz, I'll introduce you a part worn quill and a well stocked wine cellar.
Col.

 

[nkt267]

I'll introduce you a part worn quill and a well stocked wine cellar.
Were on our way,start pulling the corks

 

[Tom Gaynor]

Answer for real rocker

Oil has to be conveyed to the timing side mainshaft somehow, and since the shaft rotates, and the castings don't, a seal needs to be contrived between the two. Most manufacturers used a seal that bore on the outside of the shaft (like the BSA Gold Star). Irvine used the considerably more elegant method of injecting the oil via a quill that, because it didn't touch anything, had zero friction, and zero wear. He "threaded" the outside of the quill so that oil trapped inside the gap would move towards the big-end, not away from it. This idea, known later as a labyrinth seal, was adopted by those no-hopers Yamaha to isolate the crank-chambers on their unsuccessful TZ series of racers.........

 

[dave g6xnc]

Quills

I have never seen a quill with any "thread" on it at all, if you read Richardson it states that there may be signs of "rubbing" on the quill but this is just bedding in and is of no consequence. I not know that yamaha
had many problems with racers ( apart from Ducatis!" they always seemed to go pretty quick!.) Velo's also have a quill, another design by Mr Irving and these were always pretty good.
dave gs.( Living in the world of shaft drive)

 

[stumpy lord]

hi all,
to call it a thread is probably a bit of an over statement, more like a shallow spiral grove, but every quill that I have had has had this feature.
norm.