• Welcome to the website of the Vincent H.R.D. Owners Club.

    Should you have any questions relating to the Vincent H.R.D. Owners Club, or Vincent H.R.D. motorcycles in general, please contact Graham Smith, Hon. Editor and Webmaster by calling 07977 001 025 or please CLICK HERE.

    You are unrecognised, and therefore, only have VERY restricted access to the many features of this website.

    If you have previously registered to use this forum, you should log in now. CLICK HERE.

    If you have never registered to use this website before, please CLICK HERE.

E: Engine Alternative Pushrods

oexing

Well Known and Active Website User
VOC Member
#2
Arrow rods, no alu tubes ? And without steel end caps ? Aluminium has only one third of stiffness compared to steel, so I would never use same dimensions for copies like steel originals when stiffness is important. The tube types in my picture above work since more than half a century, no problems with more than double length.

Vic
 

oexing

Well Known and Active Website User
VOC Member
#5
Thanks for the idea about arrows-for-pushrods, I will get some for inspection. You cannot get alu tube material in high tensile basically so am interested what arrows are. 9 mm o.d. look good to me but I suspect the wall thickness to be minimal so guess I will keep the 10mm type with 2mm wall thickness tubing , available easily. Does someone actually run rods made out of arrows, what sizes ?

Vic
 

Robert Watson

Well Known and Active Website User
VOC Member
#6
These work well. I have run a set for maybe 50,000 miles. You have to grind a small relief for the adjuster end as they will contact the very bottom of the adjuster at full lift (and break a little bit off). They are fine in the follower cup. 20180716_070048_HDR.jpg 20180716_070059_HDR.jpg
 

Flo

Website User
VOC Member
#7
I can`t believe Aluminium arrows being a suitable start - after some recent consideration I tend towards fairly thin walled steel. Figures for coefficient of linear expansion are for any construction steel 12 to 13 * 10-6 mm/mm K to 16 * 10-6 mm/mm K for 18 8 (1.4301) while Aluminum alloys are typically in excess üf 23 * 10-6 mm/mm K.

The task of the pushrod is to withstand a buckling load corresponding to Euler case #2. Critical load (a force) is dependent on Young`s modulus and geometry. Buckling is a stablity problem, i.e. Since I have no robust data base i have assumed the original to be solid and max diameter being so that it can just be fed through the rocker.

see attached "0" approximation spreadsheet
 

Attachments

nkt267

Well Known and Active Website User
VOC Member
#12
Thanks for the idea about arrows-for-pushrods, I will get some for inspection. You cannot get alu tube material in high tensile basically so am interested what arrows are. 9 mm o.d. look good to me but I suspect the wall thickness to be minimal so guess I will keep the 10mm type with 2mm wall thickness tubing , available easily. Does someone actually run rods made out of arrows, what sizes ?

Vic
The thing about arrow shafts,they are rolled and welded not extruded.
The sizing for alloy arrows when looking at the listings is simple. Take 1916's for example:- the first 2 numbers (19) refer to the diameter in 64th of an inch ie 19/64"'s, the second 2 numbers (16) refer to the wall thickness in thou ie:- 0.016". X7's will be the highest tensile strength and Jazz or beginners arrows will be the lowest.
Also the bigger the diameter the stiffer the arrow, the wall thickness when shooting only affects the weight and therefore the distance/balistic arc.
https://eastonhunting.com/making-sense-of-arrow-spine/
the link will explain about 'spine' which is the amount an arrow will bend under testing for stiffness.
 

oexing

Well Known and Active Website User
VOC Member
#14
Thank you all for clarifications, as to arrows I guess I will stick to using common 10mm alu tubing, 2mm wall thickness - as used in Horex and many thousands of modern BMW flat twins. We do not need to discuss if alu or steel may be suitable. Alu types have proved to be perfectly allright for that purpose, even at TWICE the length of Vincent massive steel pushrods. I had a Vincent type and one Horex alu pushrod on my scales yesterday: The Horex type, in my picture no. 1 and 2 at the left, are just 8 grams more weight than the steel Vincent at HALF the length and no adjusters at these !! Ridgidity is super important with very long rods . Alu has only one third of stiffness to bending (english term ??) compared to steel with same dimension. Nevertheless the 10mm alu tubing has proved to be safe at 28 cm total length, Vincent rods are only 15 cm so I don´t see the faintest risk to going for alu here.
Main reason for change to alu -apart from weight saving- is thermal growth and steel is not a good idea in an all alu engine because when engine hot you see more valve clearance than is desirable. With excessive valve clearance you lose all of the minimal quieting ramps that is designed into the olde standard cam profiles. You cannot do much more than having nil play at cold state with steel rods and live with it. Negative clearance is not practical as no way to assess the amount. With alu rods you then have the chance to set some clearance when cold. But in this moment just thinking: Aahm, still no way to stick a feeler gauge anywhere for checking on a Vincent engine ??? So it is for setting nil at the adjuster screw and from this position backoff a fraction of a revolution - like 20 degrees - for working clearance with alu rods ?? Or else finger feel . . .
As to steel pushrods, in the R 69S sports type Earles BMW they picked ultra light thin wall steel tubing for pushrods, 10 mm o.d. at 0.50 mm wall thickness, brazed ball ends - super . BUT: These engines have cast iron cylinders and the rocker units sit on steel distance pillars deep down in the head, so only 20mm of aluminium up there plus the engine case containing the camshaft for temperature compensations in valve setting. When I skipped the cast iron barrels for alu types it was the same nil clearance game as with Vincents - no big deal, modern cam shapes with long quieting ramps there.
Looking at the photo samples of pushrods above, poor practice not to waist the ball ends. I do ball ends for adjuster screws or pushrods in times, no question , machining ball ends like here in my pictures, so never any troubles elswhere then.

Vic

P1040563.JPG


P1090189.JPG


P1050750.JPG


P1050740.JPG
 

clevtrev

Well Known and Active Website User
VOC Member
#16
Thank you all for clarifications, as to arrows I guess I will stick to using common 10mm alu tubing, 2mm wall thickness - as used in Horex and many thousands of modern BMW flat twins. We do not need to discuss if alu or steel may be suitable. Alu types have proved to be perfectly allright for that purpose, even at TWICE the length of Vincent massive steel pushrods. I had a Vincent type and one Horex alu pushrod on my scales yesterday: The Horex type, in my picture no. 1 and 2 at the left, are just 8 grams more weight than the steel Vincent at HALF the length and no adjusters at these !! Ridgidity is super important with very long rods . Alu has only one third of stiffness to bending (english term ??) compared to steel with same dimension. Nevertheless the 10mm alu tubing has proved to be safe at 28 cm total length, Vincent rods are only 15 cm so I don´t see the faintest risk to going for alu here.
Main reason for change to alu -apart from weight saving- is thermal growth and steel is not a good idea in an all alu engine because when engine hot you see more valve clearance than is desirable. With excessive valve clearance you lose all of the minimal quieting ramps that is designed into the olde standard cam profiles. You cannot do much more than having nil play at cold state with steel rods and live with it. Negative clearance is not practical as no way to assess the amount. With alu rods you then have the chance to set some clearance when cold. But in this moment just thinking: Aahm, still no way to stick a feeler gauge anywhere for checking on a Vincent engine ??? So it is for setting nil at the adjuster screw and from this position backoff a fraction of a revolution - like 20 degrees - for working clearance with alu rods ?? Or else finger feel . . .
As to steel pushrods, in the R 69S sports type Earles BMW they picked ultra light thin wall steel tubing for pushrods, 10 mm o.d. at 0.50 mm wall thickness, brazed ball ends - super . BUT: These engines have cast iron cylinders and the rocker units sit on steel distance pillars deep down in the head, so only 20mm of aluminium up there plus the engine case containing the camshaft for temperature compensations in valve setting. When I skipped the cast iron barrels for alu types it was the same nil clearance game as with Vincents - no big deal, modern cam shapes with long quieting ramps there.
Looking at the photo samples of pushrods above, poor practice not to waist the ball ends. I do ball ends for adjuster screws or pushrods in times, no question , machining ball ends like here in my pictures, so never any troubles elswhere then.

Vic

View attachment 22914


View attachment 22915


View attachment 22916


View attachment 22917
Using 10mm dia, you will most likely find the rod binding on the push rod tube.
 
Top