ET: Engine (Twin) ET38 Valve Circlip Install Tool, Collet Types and Pushrod Info

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oexing

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Hi Roy,
your pushrods alu or stainless ? Alu tube, any kind, is perfectly suitable in this application, Vincent types are very short, so no worries here. It is not the problem of straight load along the tube but the lateral motion at ends as these do a fraction of a circle together with the lever cups below and above. So at high speeds this is a sideload onto pushrods really and critical with long types as in BMWs and Horex, at 28 cm (280mm) compared to some 15 cm in Vincents. In this respect the E-module ( in English used, the stiffness under loads ?) is a factor, alu got one third of E-module compared to carbon steel. Stainless steel is a bit less E-module than carbon steel but we like the extra heat growth of factor 16 in stainless, carbon steel is 12 and alu is 24, so twice from steel. When this stiffness (correct term here? ) of material is critical you get a tube with three times wall thickness more than steel tube for same strength for side loads and bending.
Aliexpress got lots of nice thin wall stainless tubes at next to no money, or carbon steel if you prefer. I would not be willing to drill all tubes from solid rounds.
The problem of pushrods grinding on shrouds is the result of a design fault as the seal recesses in engine case do not lign up with the follower cup by at least one mm. Am I really the first to see the flaw ? That is why I did the excentric seal holder with small o-ring in it . The shroud can be shortened to end just above the end of the counterbore, no need to be any longer. An o-ring is nicer to have for shroud seal, some alignment range is in this and easier to slip in and out with a little lube. So in the end the 10x2 mm alu tube works allright with the Andrews Mk2 , 29 gr weight only ! Certainly 10 mm don´t drop through the rocker thread but this is no big deal to assemble pushrods first before you put heads over them - nothing I´d care much.

Vic
8x1 stainless tube

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oexing

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Is there a tool to get the wire out of the groove when disassembling ?? Lots of fingernails or rather not . . .

Vic
 

Bill Thomas

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A tiny screw driver is what I use to get them on and off,
Like a lot of things, There is a bit of a knack to doing it,
More so with Vincents.
 

royrobertson

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Just to clarify my previous posts, my pushrods are stainless with hardened steel ends and I made them this way as thick wall stainless tube was not available to me in 1986. The tatty drawing dates from then.
The ET46 pushrod tubes are anodised aluminium. I purchased them in a job lot of parts from Malcolm Attrill in 1986 as well. They have been trouble free since.
Roy
 

delboy

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Out of interest, I went looking for my notes on the the standard Stainless ET43 Pushrod and my wonderful filing system means I can only find odd bits!

Modern instruction sheets [1998 from Paul Richardson's original manuscript.] Up until Feb. 1950 Silver Steel used for pushrods with hardened ends.
PEI. Motorcycle Engineering "Stainless steel rod 0.280" dia with integral work hardening ball ends"
PEI MPH Stainless Steel 18-8 Austenitic high co-efficient of expansion 0.000018" per deg.C.
Know Thy Beast; Work hardening 18-8 Stainless steel. [in the back pages it refers to EN58BM]

I'm no metallurgist, but for the Stainless pushrods it seems to point to EN58BM which seems to be 304 Stainless.

I have come across the odd one over the years [literally only the odd one] that has quickly worn it's balls. OW!
I put it down to rogue pushrods made from incorrect grade of stainless.
99% of pushrods I have encountered have behaved perfectly.
Clevtrev has made many perfect Pushrods over the years, perhaps he can share his wisdom on the correct grade of Stainless?
Regards, Delboy.
 

vibrac

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I grabbed my 3 rods out of my spares box they could have been from anywhere but as usual time was pressing and they looked OK. never again! at least a stroke with a file, or new ones from Vincent Spares
 

oexing

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Thanks Vincent, nice idea. But still the wire clip idea was b.s. , just a complication when other standard collets would have been simple to assemble and take out.
What material were the spring caps in Vincents, got no originals ? If alu,they may have produced collets in own company, with a wider angle taper for reducing loads in caps, possibly ? But still the typical collets like in other bikes could have been just as easy to fabricate - no good reason .
"Work hardening" is a myth, there is nothing like that in stainless steel. You notice high cutting forces on a lathe when the carbide tip is the wrong type or blunt. Once you stop feeding for a second you feel extra force to get going again. This is really what you may call "work hardening" but nowhere near to min. 50 HRC you need on pushrod ends.
So when deciding on stainless you look for types for hardening the ball ends by torch heat, no other way to have real hardness on stainless. There are some types suitable if you can get them:
1.4034 is a 13 percent carbon/chrome steel, thermal expansion is only factor 11, so no benefit of selecting it.
1.4109 is a 16 percent carbon/chrome steel, again, expansion is like carbon steel - no choice .
1.4125 , a 17 percent carbon/chrome steel, expansion 11 - no choice.
1.4110 , a 13 percent carbon/chrome/Mo steel, expansion same as above.

In effect, when no nickel is in the alloy you see no extra expansion in stainless steel. So your choice is only to get common stainless and have ends welded up with hard material - or have hardened balls pressed in tubing.
So after all I am still pleased to have gone the 10x2 mm alu tubes plus hardened balls pressed in . No real need to have the chance to feed them through the adjuster thread as I have demonstrated with the first engine , just you drop the rods down onto followers first before putting the head onto the lot. And yes, due to a faulty position of counterbores for shroud seals - min. 1 mm offset - you got to fabricate some adapter with o-ring in it -no big deal.

Vic
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