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Titanium con-rods ?

Discussion in 'Norton Commando Motorcycles (Classic)' started by acotrel, Jan 18, 2018.

  1. acotrel


    Jun 30, 2012
  2. lcrken

    lcrken VIP MEMBER

    Mar 15, 2009
    Do you mean Arrow Ti rods specifically, or just Ti rods for Commandos? I bought a pair of Crower Ti rods for a Commando around 20 years ago. It turned out that the small end weight of the rod was only a little less that a steel Carrillo rod, so I didn't see much benefit in it. I think they cost me $600 for the pair. Today, you can get a more modern design Ti rod, and I'm guessing that the small end weight would be significantly less than for a comparable strength steel rod. If you can't reduce the reciprocating weight, what's the point of paying for a Ti rod. The Arrow design looks like it should be significantly less than a similar steel rod, so might be worth it. Carrillo will make Ti rods to order, but they are pricey. As I recall, the last time I talked to them about it, which was probably at least 10 years ago, the dealer cost was about $600 each, and they wanted a minimum order of 8. I'm sure it would be much more painful now.

  3. RoadScholar

    RoadScholar VIP MEMBER

    Dec 28, 2008
    I had a customer walk-in looking for some Commando stainless; we got talking, and I'll cut to the chase. He works at a small mechanical research facility on the 128 belt way. I asked him what he was engaged with and he told me that a European F-1 team had commissioned his company to develop powder metal connecting rods; we ran out of time and he left.

    Is this a new application for powder metal technology? Would connecting rods made this way have the potential to be lighter that Ti? stronger? Engine failure in F-1 is pretty rare, so all I can think is that the advantage must be lighter weight; interesting, but way out of my limited expertise.
  4. htown16

    htown16 VIP MEMBER

    Apr 29, 2009
    Technology has been around for a while. Both Chevy and Ford use powder metal rods on their high performance engines. Also fractured caps. Seems there is only one aftermarket maker, Howards. Technology is probably too costly to design and produce small batches. Doubt we will see any Norton rods soon.
    Last edited: Jan 18, 2018
  5. Fast Eddie

    Fast Eddie VIP MEMBER

    Oct 4, 2013
    What does ‘powder metal’ mean and how is a rod produced in this way?

    FWIW, most automotive OEMs use the fractured cap method.
  6. SteveA


    Dec 20, 2011
    Norman White told me he had run Ti rods (probably many years ago now), I understood the advantage was the ability to run a very close squish clearance.
  7. Deets55

    Deets55 VIP MEMBER

    Oct 3, 2013
    I believe the process is “sintering”


    I’m not 100% sure, but I have heard it called that before..
  8. htown16

    htown16 VIP MEMBER

    Apr 29, 2009
  9. BritTwit


    Aug 25, 2009
    A little off topic, but related.

    I recently read an article in Aviation Week & Space Technology about new metal additive processes using 3D metal printing that use metal powders to build turbine blades for jet engines. The porous powder is covered in a very thin coat of resin. Then the particles are deposited or printed in layer by a 3d printer.
    I laser partially melts the resin around the metal particles in layers, one layer after another until the object (turbine blade) is completed. The completed object is referred to as a “green” part. The green part is then heated in an over to fuse the metal powder into a single component part that finally composes the completed part.

    Aerospace companies claim that turbine blades manufactured in this way have superior metallic crystal structure and have greater resistance to fatigue.

    Tomorrow is here.
    Nater_Potater likes this.
  10. acotrel


    Jun 30, 2012
    That is very interesting - the metallurgy involved with titanium is very strange. It tends to grow in size as it is machined, so it is difficult to get on-size and it work-hardens a lot. My only interest lies in reducing reciprocating weight - so lighter pistons and con-rods - con-rods which don't allow the top end to pop off when revved too hard. The squish-band is important, but most other old British twin cylinder motors don't even have squish bands. There are other ways of achieving squish - the squish-band does not have to be horizontal. In two-valve Jawa speedway motors it is an angled part of the combustion chamber.
  11. gripper


    Dec 3, 2010
    Reducing the reciprocating weight in an engine is good for the stress levels but if you weigh 18 stone yourself, that is the place to do your tuning. I think Dani Pedrosa weighs about 10 stone soaking wet. Saying that, the late David Jefferies TT racer was a big lad and managed to get round the IOM at record speeds. In that case his weight may have kept the whole plot on the ground and hence keep the power on longer when rival were getting airborne
  12. Nater_Potater


    Apr 7, 2013
    Dodge has been using powdered metal/fractured caps in their production 5.7l V8 hemis since '03. I have one in an '04 Durango, and it's snappy!

  13. hobot


    Oct 19, 2005
    Ya do know that JSMotorsports steel rods are lighter than factory and has useless oil hole obliterated. When ya get to level that rods actaully matter Alu is perferred for the shock absorption which is definitely an issue to Norton cranks can cases brutalized by maniacs. TC told me he'd try to shift at 8000 but too comonally couldn't in time till over 8500+ with Norton rods and cast iron flywheel. I'm holding out for graphene impregnated ceramic 3D printing if someone else don't beat me to it on heads to cranks.

    There's other composites with strength and hi flow heat transfer so obsolete engine might best those still lugging around cooling systems. If can make 2 hp per cubic inch then only hooking it up will limit the thrills.
  14. hobot


    Oct 19, 2005
    Much as ignorantly denied - when a Norton is making more than 1 hp per cubic inch, such as fogging out on proof of 65 hp 12.24 1/4 m factory Combat power, it must be running/tolerating some detonation. Its these shocks that alu bests other materials for protecting bearing brindaling and case cracking crank jump rope flexing. So how ya/we known ya gained anything but technical expense bragging rights beyond dyno room artificial performance?

    Literally cut my Norton teeth on '68 RIGID\VIBE
    mount P!! Ranger built dedicated track only dragster 10.5 sec 1/4 m 2 yr National champion with big chrome kill button to tap/shift when the needle hit 9000 rpm marked by distinct red finger nail polish - which age 19 not knowing better hardly ever exceeded over few year dominating any/everything private to gov't able to be tagged in public. So forgive my lack luster feedback on supposed upgrade quests that ain't up to speed of 40+ yr ago.
    Last edited: Jan 19, 2018
  15. acotrel


    Jun 30, 2012
    I always try very hard to change up before my 850 motor reaches 7000 RPM, because I always have visions of a piston popping off the end of an aluminium con-rod. In most push-rod motors, the valve gear and cam profile are usually the things that limit the usable revs. I don't believe that is the case with the Commando engine.
  16. Madnorton


    Jun 9, 2008
    Powder rods - blanks are cheap and quick to make to a more accurate tolerance thus less machining, so used by the mass OEM, usually heavier than they need to be due to powder technology.
    Ti rods - light and strong but very expensive, need to be perfectly made from flawless stock.
    Steel rods - Heavy, strong massive fatigue life, last for ages.
    Alu rods - very light, relatively strong - above powder size foe size, but not Ti or Steel, cheap.

    With the small end, with the above you have what you have, cap is the area that needs to be lighter which would be kinder to the whole set up.

    Irrespective of all the above, worn small end and / or incorrect piston and ring fitting will destroy a rod before it fails itself.
  17. acotrel


    Jun 30, 2012
    Jawa speedway engines often have aluminium rods. I don't know why, but I still don't feel comfortable with the thought.
  18. splatt


    Jul 14, 2008
    [QUOTE="Fast Eddie,

    FWIW, most automotive OEMs use the fractured cap method.[/QUOTE]

    Never seen an older engine using this method, only ever 2 stokes manly outboards, is this the way new engines are being built, it must mean there is no machining on a con rod at all
  19. Fast Eddie

    Fast Eddie VIP MEMBER

    Oct 4, 2013
    Never seen an older engine using this method, only ever 2 stokes manly outboards, is this the way new engines are being built, it must mean there is no machining on a con rod at all[/QUOTE]

    Not sure what you mean about ‘no machining’... maybe we’re talking about different things?

    Normal procedure is thus:

    Blank, one piece forgings have the big end rough bored. The area where the big end caps are to be ‘split’ is weakened with a laser. The big end cap is then split via inserting and expander which ‘cracks’ off the cap.

    The rod machining is then finished off, big end final machining, little end and cap fixing bolts.

    It’s easier than making two separate components. It also affords a better ‘join’ when clamped together as the two components really ‘bite’ together. And it’s (of course) impossible to fit the wrong caps or fit them the wrong way around.

    I don’t know when the process started or became mainstream, but it has been like this for 25 years that I know of.