Mondial 3.2 axle shaft thread size | FerrariChat

Mondial 3.2 axle shaft thread size

Discussion in 'Mondial' started by greatscott73, Jul 15, 2022.

This site may earn a commission from merchant affiliate links, including eBay, Amazon, Skimlinks, and others.

  1. greatscott73

    greatscott73 Formula Junior

    Sep 1, 2017
    446
    Eastern Tennessee
    Full Name:
    Howard Scott
    Anyone out there know the thread dimensions on the threaded end of the rear axle shaft on a 1987 Mondial? This is the stub end where the 44mm ring nut attaches. I have a brand new HE nut I bought as part of my bearing redo but it doesn't want to bite the threads on the stub. At $50 a pop, I would prefer not to chew up the nut, or the even more costly axle. I assume it won't be the easiest die in the world to find to try and chase the threads, but I'm a bit stuck as to what to do next.
     
  2. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
    26,831
    30°30'40" N 97°35'41" W (Texas)
    Full Name:
    Steve Magnusson
    If you mean the 102289 ring nut (that is also used on 308 and TR and a bunch of others), the 308GT4 WSM and the TR WSM show the thread size as M27 x 1.25P in the torque tables.

    Does your old ring nut still thread on OK? (Not 100% sure this is even doable, but) Have you tried threading the new nut on backwards just as a test?
     
  3. mike32

    mike32 F1 Veteran

    May 13, 2016
    5,962
    Isle of man- uk
    First off you need to get the thread pitch of the axle threads- a good way is to get a strip of white printer paper and press it on the threads- you should see the thread spacing impression in the paper. Using a rule or the internal tips on a vernier, measure up 10 mms and count how many thread peaks you have in 10 mms. This is the thread pitch.
    Next measure up the external thread diameter using a vernier set on mms.

    eg if you have 5 thread peaks in 10mms, then pitch is 2.
    Once you have the thread size and pitch you can look for a die.
    If this if a fine thread it is probably the initial thread on the axle needs a taper needle file to dress it up
     
  4. greatscott73

    greatscott73 Formula Junior

    Sep 1, 2017
    446
    Eastern Tennessee
    Full Name:
    Howard Scott
    Thanks guys. Yes Steve, thats the one. Putting it on upside down it does seem to bite better, though it only wants to go a couple of threads before it binds. The new nut wouldn't even approach the threads at first, probably due to someone hammering it out somewhere along the line and mushrooming it. I did lots of filing and trimming and got it to eventually drop into place, but it just doesn't want to grab. The old nut was pretty well distorted by the time it came off and probably was less than correctly applied when installed, so don't think its going to be much help. Its always something...lol.
     
  5. mike32

    mike32 F1 Veteran

    May 13, 2016
    5,962
    Isle of man- uk
    If the nut is binding, try some grinding paste on the threads, then screw it on and off several times . Clean it off and see if it helps matters
    Also try a junior hacksaw in the axle threads which will clean them out
     
    greatscott73 likes this.
  6. mike32

    mike32 F1 Veteran

    May 13, 2016
    5,962
    Isle of man- uk
    Take a thread impression off both nuts and compare the thread pitch spacing, let be sure you have like for like
     
    greatscott73 likes this.
  7. greatscott73

    greatscott73 Formula Junior

    Sep 1, 2017
    446
    Eastern Tennessee
    Full Name:
    Howard Scott
    I think the origin of the problem was some kind of debris on the new nut thread pattern. I don't know if these things are powdercoated, but that is almost what it looked like was falling out of the threads when I started attaching the fastener. I emailed HE and asked them about it, but so far have not received a reply. I ordered a new tap and die to renew everything, but like everything these days, it will probably be a month before I see it. Stay tuned....Since I may be waiting awhile anyway, I think I will look for a new source for the nut itself to see if that helps anything.
     
  8. mike32

    mike32 F1 Veteran

    May 13, 2016
    5,962
    Isle of man- uk
    Did you try the grinding paste trick as that would clean it out
    If you have to try a tap, then grip the tap in the vice and turn the nut onto a taper tap just a few threads. Grip in the vice and it will be oval as soon as you nip up the vice
     
    greatscott73 likes this.
  9. greatscott73

    greatscott73 Formula Junior

    Sep 1, 2017
    446
    Eastern Tennessee
    Full Name:
    Howard Scott
    Haven't tried it yet Mike. I don't have any grinding paste on my shelves so it is on the list of things to buy this week.
     
  10. mike32

    mike32 F1 Veteran

    May 13, 2016
    5,962
    Isle of man- uk
    Get the course type, you would think the fine but not much help.
    Its a trick that helped out over 40 years for me
     

Share This Page