Cam followers - Andover to the rescue?

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SteveA said:
The issue then is a business one, you need in your example 3 times the stockholding, of visibly identical parts, or visibly marked parts, if you include +5 thou variants that is 6 types, you need to create and manage your stock by variant part number. And so do your dealer network!

And you need to complete your R&D and testing on all variants.

It may not be an aerospace application but we are talking aerospace complexity and parts management, guess what cost that comes with!
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Or, only produce/sell one 'breed' of camshaft. Then you can have just one type of cam follower to match.

(No doubt I've missed the point as to why there are three different materials used for Norton camshafts.....)
 
oldschool said:
Or, only produce/sell one 'breed' of camshaft. Then you can have just one type of cam follower to match.

(No doubt I've missed the point as to why there are three different materials used for Norton camshafts.....)
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They are trying (very admirably) to cater for the entire market place, including uncouth folk who fit other makes of camshaft.

It’s a mix of trying to serve the market and also protect themselves I think. If they don’t make followers to suit all cam types in common use... and their followers fail when used with ‘the wrong’ cam... their followers will still get ‘blamed’.
 
Fast Eddie said:
They are trying (very admirably) to cater for the entire market place, including uncouth folk who fit other makes of camshaft.

It’s a mix of trying to serve the market and also protect themselves I think. If they don’t make followers to suit all cam types in common use... and their followers fail when used with ‘the wrong’ cam... their followers will still get ‘blamed’.
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Thanks Eddie; that sounds reasonable.

However, if AN can sell a camshaft and a set of followers which have been proven to work together, they may persuade other buyers to opt for the complete package from AN.
If choice of materials is the key to solving the problem, presumably AN could make available other camshaft profiles in the 'right' material, for those of us who may want something for the track.

It could certainly improve 'couthness' within the Norton community.....:)
 
oldschool said:
Thanks Eddie; that sounds reasonable.

However, if AN can sell a camshaft and a set of followers which have been proven to work together, they may persuade other buyers to opt for the complete package from AN.
If choice of materials is the key to solving the problem, presumably AN could make available other camshaft profiles in the 'right' material, for those of us who may want something for the track.

It could certainly improve 'couthness' within the Norton community.....:)
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Please consider those who may well have a camshaft they are happy to use and re-use but need to replace the followers!

Currently flat followers are around £400 a set and a cam around £250. The revised followers are likely to be more as noted above.

As a retired rather than practicing engineer I do recall a design principle of changing one thing at a time.

I wonder if getting a new supplier to reliably make the existing type of follower, with the inset foot, and then experimenting with various metals on these before moving to a one piece design would be an alternative stragegy.

The old issue of losing the foot was pretty much eliminated with these!

Madnorton may have said this wasn't viable, but AN have a long way to go on this one, revisiting the options may be worthwhile?
 
Two piece tappets, if you can find someone to grind them then there is the cost, and yes, I have asked numerous grinders here and in Germany. The process loss rate is large, gas quenching does not work consistently, so a two piece though still possible is not viable. If you cast a tip that would work, then you can cast a one piece.

We now have physical data obtained from Jim, and some of the worlds hard facing experts both sides of the Atlantic will be looking at them with a very modern and very modern and expensive read, 6 figures, microscope to see what has happened.
 
comnoz said:
Really, the Maney steel pushrods that were in my racebike for years and are now in my streetbike are lighter than the original aluminum pushrods. I haven't pulled them apart to see what the wall thickness is.
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Here are the weights of 2024 alum pushrod tubing alum vs steel

alum 3/8 x .058” = 32 grams per foot

4130 3/8 x .035” = 58 grams per foot

4130 3/8 x .028” = 47 grams per foot

Note that stock finished intake pushrods are only 8.15" long

A stock Norton intake pushrod is 32 grams (pre 1975). 2024 alum alloy pushrods are about the same.

Alloy-Tech 4130 steel pushrod with steel ends - 50g

Post 1975 stock pushrods might be heavier (solid?). I haven't weighed them.

The 2024 alum intake pushrods I make are less than 32 grams.


Lets us know exactly what your steel intake pushrod weighs so we can get the facts straight.
 
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The only set I have is in my engine.
They were slightly lighter than a stock pushrod but heavier than Ken's pushrod. That's as close as I can get at this time.
 
From the Steve Maney website:

"Being made from chrome molybdenum tube, my pushrods are at least 30% more rigid than aluminium, titanium and carbon fibre types. They are also lighter than standard pushrods."​

I've used the Steve Maney pushrods with my ultra short stroke 750 Norton. This USS had a nominal redline of about 8,350 with regular excursions to 9,000 rpm (man that motor loved to rev) without a problem.
 
Maney inlet pushrod = 48g
Ken’s of same length = 33g

Anyone got a stock one to weigh?

Am I correct in thinking that original Norton pushrods were hollow, and that new AN pushrods are solid... and heavier?

If so, and if we’re comparing what can be bought new, we should really weigh a new one
 
Fast Eddie said:
Maney inlet pushrod = 48g
Ken’s of same length = 33g

Anyone got a stock one to weigh?

Am I correct in thinking that original Norton pushrods were hollow, and that new AN pushrods are solid... and heavier?

If so, and if we’re comparing what can be bought new, we should really weigh a new one
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It depends on the year.
Early twins were 20 grams.
Old Commando intakes are just over 32 grams.
As I recall late models were almost twice that much but I don't have one here to weigh.
 
Dances with Shrapnel said:
From the Steve Maney website:

"Being made from chrome molybdenum tube, my pushrods are at least 30% more rigid than aluminium, titanium and carbon fibre types. They are also lighter than standard pushrods."​

I've used the Steve Maney pushrods with my ultra short stroke 750 Norton. This USS had a nominal redline of about 8,350 with regular excursions to 9,000 rpm (man that motor loved to rev) without a problem.
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Pushrods are not "one size fits all" The best rod for the application depends on the cam design and what you are doing with it.

On the spintron I have seen more valve control problems caused by light, springy, aluminum pushrods than I have from heavier steel pushrods -when you are using cams with aggressive ramps.

The lightweight pushrod compresses on the aggressive opening ramp and springs back over peak lift causing valve train separation.
 
"The lightweight pushrod compresses on the aggressive opening ramp and springs back over peak lift causing valve train separation."

Thats exactly what the NASCAR people discovered and they got more power that way. Everyone started using springy pushrods if they wanted to win. Later on they just bumped up the cam lobes and went to stiffer pushrods.

Springing over the top might actually reduce wear on the nose of the cam????

Just got these weights by email:

O.E. standard length AN alloy inlet from around 2007:
45.8g but it may be solid, 9.53mm diameter in the middle


RGM standard length steel inlet
69.0g 9.53mm diameter
 
Agree Comnoz. A very general rule is stiffer is better. Modulus of elasticity is a big factor in pushrod design both for durability (resistance to buckling) and improved valve motion control, ultimate strength, not so much. There is also very trick stuff out there with metal-ceramic composites and more, somewhat eclipses what we (those actually manufacturing and testing) are trying to do here - keep lifter feet from falling off or scuffing up.

Aluminum has roughly 1/3 the stiffness of that of steel. Another way of looking at it and disregarding buckling, for a given stiffness of steel pushrod, one would need roughly three times the cross sectional area of aluminum to get the same stiffness for a given load.

The application I was referring to above (750 USS and steel pushrods) worked well with an N480 race cam amongst other bits. We don't want to get derailed here and should keep the perspective here and that is - "lifter durability for the masses in road going engine conditions and maintenance intervals". Racing is in some ways, a whole different kettle of fish.

So why did Norton and other bike manufacturers choose aluminum pushrods? I don't know. I doubt it was all about avoiding valve loft. Could it be that aluminum pushrods are easier and cheaper to manufacture? Subject of another thread.
 
Dances with Shrapnel said:
Agree Comnoz. A very general rule is stiffer is better. Modulus of elasticity is a big factor in pushrod design both for durability (resistance to buckling) and improved valve motion control, ultimate strength, not so much. There is also very trick stuff out there with metal-ceramic composites and more, somewhat eclipses what we (those actually manufacturing and testing) are trying to do here - keep lifter feet from falling off or scuffing up.

Aluminum has roughly 1/3 the stiffness of that of steel. Another way of looking at it and disregarding buckling, for a given stiffness of steel pushrod, one would need roughly three times the cross sectional area of aluminum to get the same stiffness for a given load.

The application I was referring to above (750 USS and steel pushrods) worked well with an N480 race cam amongst other bits. We don't want to get derailed here and should keep the perspective here and that is - "lifter durability for the masses in road going engine conditions and maintenance intervals". Racing is in some ways, a whole different kettle of fish.

So why did Norton and other bike manufacturers choose aluminum pushrods? I don't know. I doubt it was all about avoiding valve loft. Could it be that aluminum pushrods are easier and cheaper to manufacture? Subject of another thread.
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I would say aluminum pushrods are a good choice for a motor with easy lift rates working near the original RPM range. And sometimes even higher RPM's if you watch the lift rate.

But if your opening the valve with a big hammer you probably should have a steel nail....
 
comnoz said:
But if your opening the valve with a big hammer you probably should have a steel nail....
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Spin a cam designed for X rpm range at 1.5X rpm range and you've just more than doubled the valve train loads due to acceleration (2.25 times)


Agree on adequacy of aluminum in many applications. My question is really why did they choose aluminum? My hunch is overall cost to produce.
 
Dances with Shrapnel said:
Spin a cam designed for X rpm range at 1.5X rpm range and you've just more than doubled the valve train loads due to acceleration (2.25 times)


Agree on adequacy of aluminum in many applications. My question is really why did they choose aluminum? My hunch is overall cost to produce.
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I don't know about the price.

But aluminum pushrods do run quieter. When you run aluminum pushrods and an iron barrel the lash goes close to zero when hot.
 
JS
I went through this with you some time ago, but since you've raised it again, I'll repeat what I said back then.

Size for size, a steel tube in 4130 is heavier than one in 2024 aluminum, and has greater resistance to buckle under the same load.
It's co efficient of thermal expansion,CTE, is also lower.

To increase resistance to buckle, either increase the overall diameter, or increase the tube wall thickness, or shorten the tube. Doing all 3 at once gets the max benefit.

But what have pushrod characteristics to do with cam follower tests ?
 
Steve did tell me that his pushrods require in an iron barrel half the clearance of alloy . So if you want to run a 4s or other big cam then you will get a quieter motor .
 
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