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Hollow Tappet Adjusters

Discussion in 'Norton Commando Motorcycles (Classic)' started by acotrel, Sep 9, 2019.

  1. acotrel

    acotrel

    Joined:
    Jun 30, 2012
    When I was racing a Triumph, I used hollow tappet adjuster screws which I think I bought from Wassell, They took a hex Allen key when being adjusted. The nuts supplied with them were aluminium, however I used steel nuts cut down a bit. - I was wondering if anyone is using similar in a Commando, even though lightened and polished valve gear is not usually a priority unless you use a dramatic cam or habitually over-rev.
     
  2. lcrken

    lcrken VIP MEMBER

    Joined:
    Mar 15, 2009
    I've used them for years in most of my race engines. I don't usually bother with them for the street bikes. RGM still sells them, and probably other suppliers. I used them with the aluminum nuts with no problems.

    Ken
     
  3. comnoz

    comnoz VIP MEMBER

    Joined:
    Dec 10, 2008
    After loosing an aluminum nut on my racebike I went to cut down steel nuts.
    Lucky I caught it in time.

    I have seen a few others who have lost the aluminum nuts with disastrous results.
     
    SteveA likes this.
  4. Fast Eddie

    Fast Eddie VIP MEMBER

    Joined:
    Oct 4, 2013
    I use alloy nuts, but like Jim says, I see them as a weak spot. I keep a few sets in stock and change them quite regularly.

    I would really like titanium nuts, that would be the perfect compromise I think. Can’t find any though...
     
  5. Onder

    Onder

    Joined:
    May 11, 2010
    Have some run up then.
     
  6. gtiller

    gtiller VIP MEMBER

    Joined:
    Nov 5, 2012
    I was told that the Dural nuts are for race use and should be changed at least every season because the threads get sloppy.

    533EE8DF-BAF3-4139-B6A6-2D8CA51FC3F1.jpeg
     
  7. Bernhard

    Bernhard

    Joined:
    Apr 20, 2011
    Very easy to make, titanium nut bars size is obtainable;

    Nylon & Alloys, Address: Unit 1500, 145-147 Boston Rd, London W7 3SA

    https://www.bing.com/maps?&ty=18&q=...023418113531~&cp=51.505226~-0.334738&v=2&sV=1

    Also, https://www.motorcycleproducts.co.uk/about_us.php
     
  8. phippsy

    phippsy

    Joined:
    Dec 28, 2013
    Well if someone wants to start making them put me down for a set ! Beyond my engineering expertise
     
  9. Triton Thrasher

    Triton Thrasher

    Joined:
    Feb 10, 2009
    Mine must have done 70,000 miles by now. If they got sloppy I’d probably notice when doing the clearances.
     
  10. acotrel

    acotrel

    Joined:
    Jun 30, 2012
    Putting threads on titanium is not straight forward. I was there when my friend was making the top and bottom bolts for my TTI box. As you take a cut, the threads grow, so you are always making allowances for the growth. Getting the threads on size is difficult. You might be able to use hex titanium bar, drill it and tap the treads, then try the nuts on the adjuster and feel if they turned too loosely - but it might be a bodge job with a bit of risk. I wonder if the aircraft industry uses titanium nuts ?
    My engine bolts are titanium, but I use them with UNF steel nuts. They were out of shelf-life components for the F/A 18 Hornet. I had them shortened by a shop which specialises in working with titanium.
     
  11. acotrel

    acotrel

    Joined:
    Jun 30, 2012
    I understand your comment - it is not easy. The other thing is that if titanium cops a hammering, it changes dimension very quickly. I had an 8mm titanium bolt holding a bracket - after three race meetings, it had necked down to about 6mm, from being loose. - Makes me wonder about titanium connecting rods. And the rod bolts in Porsches
     
    Last edited: Sep 10, 2019
  12. Time Warp

    Time Warp .......back to the 70's. VIP MEMBER

    Joined:
    Dec 3, 2012
    Titanium is odd stuff, this was a all Ti TL1000S fuel tank pivot made around 2007 with a self supporting rear cowling unit to suit it. (No one clicked to the name on the box but I bet the A man will)


    Pn6.JPG

    Pn5.JPG

    It was a low stress part and still bulky enough to most likely never fail, threaded stressed parts are something else.
    I believe stress risers in titanium are to be avoided, I have made Ti bolts but never for something that if it failed might be a drama.

    Would a Ti adjuster locking nut even be worth it without a Ti spring retainer ?
    The adjuster locking nuts are little more than half nuts so you never know what is out there off the shelf.
     
    Last edited: Sep 10, 2019
  13. SteveA

    SteveA VIP MEMBER

    Joined:
    Dec 20, 2011
    You don't necessarily notice progressive 'sloppiness'.....one day you notice a sliver of aluminium, that used to be a thread, poking out!

    Put me on the titanium nut set purchasing list! The cost of the cutting/threading tools would need to be used on more than a set of 4 to be a worthwhile return. They are not a 'standard' thread size.
     
  14. Bernhard

    Bernhard

    Joined:
    Apr 20, 2011

    I must confess that I have never taped threads on titanium, and judging by your comments I suspect that if true they use special ground taps to counter the expansion of this metal.

    Re;" I wonder if the aircraft industry uses titanium nuts ?" -they use all sorts of lightweight materials.

    Said website does Aero quality nuts ;

    http://www.teknipart.co.uk/en/catalog/alloys/titanium/nuts/t0501
     
  15. SteveA

    SteveA VIP MEMBER

    Joined:
    Dec 20, 2011
    They use light nuts by design shape rather than material choice!

    ARP 12 point nuts are representative of aircraft nuts.
     
  16. SteveA

    SteveA VIP MEMBER

    Joined:
    Dec 20, 2011
    Yes they do, but often remain oddly conservative, I recall looking at an A380 tailplane structure in a factory in Madrid.

    It was constructed mainly of carbon fibre, but each component was more or less a replica of the equivalent part in sheet or billet aluminium. Constraints are normally the test and qualification regime for civil aircraft.

    In the military training aircraft factory I worked at in Italy the use of composites involved more adventurous shapes and fewer individual parts!
     
  17. Bernhard

    Bernhard

    Joined:
    Apr 20, 2011
    The billet aluminium would be more likely aircraft quality and where necessary be heat treated to give it the same added strength as steel.
     
  18. acotrel

    acotrel

    Joined:
    Jun 30, 2012
    As I said, I wonder about titanium when it is subjected to a lot of stress cycles. Titanium nuts on tappet adjusters might grown in dimension and loosen. I think when Titanium bolts are used on Porsche con-rods, the racing teams might control the number of cycles they do by replacing them regularly. When you machine titanium, two things happen - the material work hardens and each cut has to be made by getting under the hard layer - and the material sort of flows as it is cut, so you end up with a slightly bigger dimension than you calculated for.
    I think Arrow titanium con-rods with Jim Scmidt's light pistons would be very good in a Commando racing engine.

    https://shop.arrowprecision.com/
     
  19. SteveA

    SteveA VIP MEMBER

    Joined:
    Dec 20, 2011

    Norman White showed me JE pistons he had had made that are very similar to JSMs JSM made pistons and told me he had used titanium rods at one point and had got the squish down to a few thou......

    Most things have been done at some point!
     
  20. lcrken

    lcrken VIP MEMBER

    Joined:
    Mar 15, 2009
    I once rebuilt a Commando 872 cc engine with Nourish one-piece crankshaft, forged Omega pistons, and Crower titanium rods. It had been originally built with .020" squish, and in racing use the pistons had hit the head hard enough to break the crankcases. I rebuilt it with .040" squish and new cases, and it never had that problem again. It's very risky to try to push the limits of squish clearance in any Commando engine.

    Ken
     

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