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Driveshaft lock nuts

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  • Driveshaft lock nuts

    There have been a few methods of trying to keep the driveshaft lock nuts tight on competition vehicles, with modern tyres and good suspension a road car driven enthusiastically can produce side loads on the hubs that can flatten the soft tab washer. Once the tab squashed it releases the torque on the threads, torque is thread stretch like a tension spring the turning of the nut pulls on the threads and adds tension which keeps things tight. If you lose this tension due to the soft tab the hub will rock slightly on the splines fretting away at the tab. On competition vehicles this can get so bad if not checked and the hub can put a side load on the nut which is transferred to the threads, this breaks the thread off at the root and you lose a wheel. People have tried split pins but the split pin does not stop the nut from rotating, it will prevent it coming off but will not lock it in position at the required torque to keep all mating surfaces tight and square to each other. I have some aircraft spec locking nuts that do away with the tab and do not come loose.

  • #2
    Mike, you supply these nuts correct ? feel free to add an image and a cost / contact details so folks know where to get these upgraded parts.

    Standard nut and lock tab washer solution is £9.50 a side so £19 a pair currently from Bob or he has a castellated nut and special washer for £40 a set.

    As it is castellated it is perhaps expecting a split pin.

    If you have a solution feel free to list it Mike, same for the upgraded ignition components.

    Note for readers : Membership is required to buy from Bob at The Imp Club Spares Service.
    / John


    • #3
      Yes John i can supply these nuts, proven on a few race and rally cars now. I have used them for 15 years and never had one come loose. Will need to get a list together of the parts i can do, currently turning all my raw material into useful parts so when things get back to normal all i have to do is buy the components i do not make such as the poly bushes etc so can provide a better lead time on items. I am still working on JDU 9 till 5 on my days off trying to get as much done as possible just in case the real job gets silly and my shift pattern changes! I give myself 2 hours each morning on my own stuff.


      • #4


        • #5
          Ooooooh hmmmm. I might well be keen on getting hold of your nuts Mike I need to re-check my Imp and look into making sure I have no issues in the future once running more torque through the driveshafts. I'm currently looking at driveshaft options for my Subaru box and wondering about changing out the bearings and half shafts for Subaru leone 4wd cv items that will then match my transaxle better.
          However- if I keep the stock halfshafts I'd like to upgrade the nuts!



          • #6
            Nice to hear from you Alex, things seem to be going well on the megabuild lovely work. Will be interesting to see the outcome of the drive shaft mods if they go ahead as I reckon you will be putting a "little" bit more torque to the wheels.

            Skipping the men, nuts topics

            / John


            • #7
              Cheers John. I've been a bit quiet on the Imp front because busy building a mezzanine, prepping housetruck for sale etc. But that's another story whereas this thread is all about Mikes nuts....


              • #8
                those ones are quite big as well

                Same here Alex, winter getting a grip on us good and proper now so have loads of outside stuff to nail on the head (well nail gun down fence line) but so cold now its only 3/4 hours a day and taking forever

                Plus got some servo controller designs to finish off as well as some really cool and interesting photonics stuff using some cool bits from Hamamatsu

                Will be back on DDG when things leay off.

                Good luck with the mezz, can never have enough storage and I love the updates on the engine, cant wait to hear it purr, the flat engines are just so elegant .
                / John


                • #9
                  I seem to recall seeing one of the racing guys at a previous National Weekend had drilled and tapped the splined outer half of the driveshaft to accept a modern (rather large) Torx bolt to eliminate the use of a nut completely. Does anyine know if this approach is a good idea?


                  • #10
                    You are correct this was an idea from Andy Jones of Shrigley engineering (the best man to build you an imp engine in my opinion) We have discussed this and we both like each others ideas. My argument of my system V his was mine is easier and you are not removing material from the driveshaft when you drill and tap. Both systems have had Zero failures that we know of.