Harley Jackshaft

Question Random grind when starting (Harley jackshaft pinion strongly hits the clutch´ ring gear) – Heritage Nostalgia 1993
My Heritage Nostalgia 1993, usually starts nice and strong, but sometimes when starting (engine either being both cold and warmed up) the jackshaft pinion hits the clutch ring gear and on second try it starts ok. Other times sounds and starts at the same time (seems the teeth hits a little, then engage before starting). This happens randomly but it´s very annoying when it does. Two years ago, I had the following parts replaced by a mechanic: new starter motor, new jackshaft pinion and new clutch ring gear. However, this happened from day one, very sparsely, as it´s still happening now. Being the starter motor brand new, don´t know what can be the cause. Electric system checked.

Answer You say it has been a problem from day 1. You mean, like, 1993? You need to determine if you are chasing an electrical issue or a mechanical problem. If your battery is weak, or low quality, you may be lacking amperage. That is the muscle in a battery. You might have an alignment issue. Is your inner or outer primary something other than stock? Sometimes if a jackshaft is over tightened, it will not move freely in it’s bushing. I know you said the ring gear was replaced. Was it installed correctly with the beveled edge facing in the correct direction? There are ring gears with less teeth that work really well. Try powering your starter with direct battery voltage. If engagement is better, you need to look at your wiring. Check your starter relay. You might be losing voltage somewhere. If the problem still exists, it is more likely to be a mechanical issue.

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15 Responses to “Harley Jackshaft”
  1. Geoff

    Having the privelegdge of owning a 1976 Shovel with a stock 4 speed this issue sometimes (read more often than not) when a “mechanic” replaces parts in the staring system they leave off that lovely little copper thrust washer because it is a pain in the ass to install. Missing this washer is many times the cause of the issue you are experiencing, the jack shaft is allowed to travel to far and is not only hammering the inside of your outer primary case it is damaging the teeth on the gear as it is forced into past and back through it.

    Geoff AKA Troll
    1976 Harley FLH Liberty Edition

  2. michael alzamora
    michael alzamora

    I sorta had a similar problem when replacing outer primary cove.when I removed original primary a ware washer fell out in my hand,i said ok remember to put back with new primary.so I did!!!well would not start only make a big banging noise rite there at side cover? well got to talking with machic friend and he said most after market covers don’t need washer,and solved my prob that was driving me crazy,,,sounds like you are just opposite,bare with my spelling!!1986 fxstc mike…

  3. Steve

    There are two couplings, one long and slim that connects the starter clutch to the jack shaft and the other is short and fat that connects the jack shaft and pinion gear to the ring gear. Both have retaining rings on them. The short and fat coupling that connects the jack shaft and pinion gear to the ring gear may be worn and on the verge of breaking. Replace it and see if it solves your problem

  4. Guillermo

    THANK YOU all very much for your responses (!), I didn’t log in from a few months ago and didn’t read your help comments! The primary parts are original. Have a busy week, but I’ll think about all your posts and get back to you on week-end. Thanks again!

  5. Ron

    I have a 95 FXDWG and the jackshaft will not engage it just spins ,do you have a video replacing this unit ?

  6. Richard

    I brought my fatboy in to have the ring gear and jack shaft replace I paid out a lot of money just to have it after 5or six times start doing the same thing so I pulled off the cover and the jack shaft is way to tight you can see where the clutch hub has been rubbing the case so I looked down inside the case that the jack shaft extends in to and not only is the bushing smoked you can see where the jack shaft hasn’t disingadged and ground a groove under the bushing also the thrust washer was not put back I paid 400 dollars for a knew ring gear and jack shaft and 400 more labor it needs another knew ring gear and jack shaft they keep trying to say its not there fault I know it is im disabled and broke and they want to charge me to fix it I can fix it myself and have decided if I cant fix my bikes I wont ride my bikes is there a way I can make them cover there screw up prove it?

  7. Daniel

    have a 2015 Softail Heritage Classic. Have had similar issues. I go to start it be it when cold or hot, its sporadic. I turn it on, click run, after the EFI stops fueling, I hit to start it and get the usual whining noise to start once then it clunks and the odometer changes to ‘Lo Rng’. It’s a metal to metal clunking noise. Its been in the shop alot for this issue work done so far, Replaced battery twice, cleaned and lubed electrical connections, Replace clutch basket, replaced starter. This is still occuring. Any help anyone can offer will be appreciated.

  8. Ltank

    What is the proper orientation of the two starter couplings? The larger diameter that the jackshaft fits inside on the clutch basket side? It has an internal C clip that has a shallow and a deep side due to the offset of the clip. The spring goes in the shallow side?
    The starter to jackshaft coupling also has an internal offset with a shallow and a deep side. One end has a tapper the other end is concave. Which side goes to the starter? The Service manual does not specify?

    • Customer Service
      Customer Service

      Hi Lynn. I emailed the response along with an attached photo.
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  9. Todd

    I have starter jack shaft problem 1 keeper tab broke got new one 2 jack shaft bolt keeps backing out ,,,why and how do i fix it ,,,,torque it and loctite maybe,,,third time im going to have to take primary off,,,HELP