Hub Lock Bolts constantly coming undone




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  1. #1
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    Default Hub Lock Bolts constantly coming undone

    I have a 1980 C200 diff in the front of the Sani, and have now three times found one of my Hub Locks bolts coming undone. One bolt already gone AWOL the last time it did this about 3 months ago. I estimate about 200km of gravel where the Hubs were not even engaged, and a maximum of about 40-50km 4wd in soft sand in low range. I just got back from a little trip to town with about 25km gravel and 25km tar, and as I was unpacking the car, I see grease all over the left front wheel again. All the bolts are loose again and the Hub is flopping about, and has probably gobbled up a bunch of sand and dust off the sand/gravel road.

    I don't really like using Locktite, but this seems to be my next option in search of a solution. I want to know why it's doing this in the first place. Can one of the engineers maybe help with an explanation?

    While I am on the subject, does anybody know where I can get a replacement bolt for the one that is lost?
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    Default Re: Hub Lock Bolts constantly coming undone

    I'm by no means an engineer yet, but I can offer my opinion and theories till the big boys roll in here.

    Bolts work loose mainly from vibration so they probably worked themselves loose on the gravel roads. How bolts work, is that they stretch themselves by incredibly small amounts (almost immesurable on small bolts) till they are in tension which provides the necessary friction to keep them from loosening.

    I think the bolts on your hub are not tightened to spec for them to loosen, but even if they were I still think there is a small chance they'd loosen anyway.

    Do you have any horror stories regarding Loctite? Because if you use the blue one you will still be able to get the bolts off for maintenance, etc, as long as you clean the threads and reapply when refitting. It's just the red Loctite you should avoid for serviceable components.
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    Default Re: Hub Lock Bolts constantly coming undone

    I think these things tighten up with 6mm allen bolts, and they are already a mission to tighten, let alone torque. All my hubs to date get tightened up with the same allen key, and helped an extra half-turn or so with a persuasion tool. I have checked the right side every time the left has come loose, which was done in an identical fashion, and so far it is only the left side that keeps coming loose.

    I have just gone through our workshop, and only come up with red Loctite. I will have to go with that for now. Strangely, I do have a clicking sound on the right side, which I am still trying to figure if it's Hub or CV, as it does seem to change slightly when at full lock.

    Right now I just need to keep it sealed up enough to continue using it. We expect some decent rain in the next day or two, and then this road of ours changes into a nearly 14km water crossing.
    David/Hillbilly - 1997 SFA Nissan Sani 2,7 TD - 5" lift on 33" tires - Dual Transfer with 4.1 gears

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    Default Re: Hub Lock Bolts constantly coming undone

    Make sure you have no dirt or rust on the bolts thread or in the hub thread
    Last edited by Dungbeetle; 2021/12/04 at 01:16 PM.
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    Default Re: Hub Lock Bolts constantly coming undone

    Use Nord-Lock washers. They stay tight till you take them off.
    Bernhard Whitehead
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    Default Re: Hub Lock Bolts constantly coming undone

    Another option is to do a wire locking on the bolts like is done in the aircraft world.
    The head of the bolts need to be cross drilled with a 1mm to a 1.5mm drill bit. Once the bolts are torqued locking wire is threaded through the holes in a way that keeps the bolts tightened and then secured.
    When using Locktight make sure the bolt holes are clean and don't have any oily residue in them. Some grades are made to work in an oily environment and others not so make sure you use the correct grade.
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    Default Re: Hub Lock Bolts constantly coming undone

    Check te play on your wheel bearings.
    Also make sure that the seal between the free wheel hub and hub assy is OEM.

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    Default Re: Hub Lock Bolts constantly coming undone

    Quote Originally Posted by grips View Post
    Check te play on your wheel bearings.
    Also make sure that the seal between the free wheel hub and hub assy is OEM.
    I suspect you say this from experience...why is it important?
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    Default Re: Hub Lock Bolts constantly coming undone

    First prize would be to replace the hex cap bolts with studs and then use a nuts to tighten down the hub, but looks like there is definitely not enough space for a nut and socket to fit.

    Second best would be to get as close to a stud and nut setup as possible. Do this by using the longest hex cap bolt you can that will fit before bottoming out. Measure the total hole depth, with hub cap and washers fitted and cut a new long hex cap bolt a mm or two shorter than this measurement. Round (finish) the cut off end a bit with a file or bench grinder.
    The problem may well be that the hex cap bolts are to short and are allowing to much lateral play and movement when under load, thereby working themselves loose.

    Also if the bolt is to short, the few holding threads will quickly deform under load and the initial torque will be greatly reduced to a point where the bolt will be quite loose.

    Don't use spring washers.

    Use a bit of medium grade Loctite is also a good idea.
    Last edited by Searcher; 2021/12/04 at 02:18 PM.

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    Default Re: Hub Lock Bolts constantly coming undone

    Quote Originally Posted by Prof View Post
    I suspect you say this from experience...why is it important?
    Bolts mostly come loose when they are tightened onto an “air gap”. A seal that is too thick would provide an excellent “air gap”. Allowing it to work loose with vibration.

    Nordloc washers are the bizness if all else fails. They are rated as secondary retention.

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    Default Re: Hub Lock Bolts constantly coming undone

    Quote Originally Posted by Prof View Post
    I suspect you say this from experience...why is it important?
    Home made paper gaskets don`t work. Many guys go for a cheap solution.

    My money is on wheel bearings or king pin play. The reason why the come loose without 4x4 engaged.

    Best is to strip clean and inspect

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    Default Re: Hub Lock Bolts constantly coming undone

    This is an aftermarket hub might also be a fitment problem. The type of hub in the pic normally make use of studs and taper sleeves to secure them.


    Last edited by grips; 2021/12/04 at 02:13 PM.

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    Default Re: Hub Lock Bolts constantly coming undone

    Thanks Grips, will do some inspection a bit later, but you know my rig is very sensitive to things like kingpin bearings and wheel bearings. I get DW for the slightest problem. I must admit that the original Sani Hubs, and these C200 Safari Hubs never had any gasket by the time I got to take them apart for the first time. With my slipjoint that has so much play, I am also not keeping the Hubs locked all the time now, and only engage when I have run out of traction in 2wd to try and save myself the annoyance of the slipjoint rattle.

    Thanks for all the input guys. Those hex bolts can only be reached with an Allen key, and only just. Hex socket does not get into that gap, and you will not fit a spanner or socket in there to swing a nut on a stud.
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    Default Re: Hub Lock Bolts constantly coming undone

    Quote Originally Posted by grips View Post
    This is an aftermarket hub might also be a fitment problem. The type of hub in the pic normally make use of studs and taper sleeves to secure them.
    Mmm, interesting, I thought it was the standard hub that came on the 1980 Safari. I'll get it jacked up and check for play. I did have a problem a few months back on the right wheel with a wheel bearing that had worked loose. the bearing still looked ok, and I just tightened it all up and have been watching it to see if it has shown any play. So far nothing.

    Depending on what I find (or not), I may swop the two hubs between left and right, with their studs and washers, and see if the problem follows the Hub and studs, or if the problem stays on the left wheel. Also will check if those mounting holes are tapered, because that would be a problem.
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    Default Re: Hub Lock Bolts constantly coming undone

    Quote Originally Posted by bfreesani View Post
    Mmm, interesting, I thought it was the standard hub that came on the 1980 Safari. I'll get it jacked up and check for play. I did have a problem a few months back on the right wheel with a wheel bearing that had worked loose. the bearing still looked ok, and I just tightened it all up and have been watching it to see if it has shown any play. So far nothing.

    Depending on what I find (or not), I may swop the two hubs between left and right, with their studs and washers, and see if the problem follows the Hub and studs, or if the problem stays on the left wheel. Also will check if those mounting holes are tapered, because that would be a problem.
    Just to make sure that you understand what we mean by studs.
    Those are not studs, they are hex cap bolts.

    Studs work better than bolts do in high vibration applications combined with lateral loads, like on hubs.
    Bolts and studs woke equally well in tensile loads application.

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    Default Re: Hub Lock Bolts constantly coming undone

    Quote Originally Posted by bfreesani View Post
    I have a 1980 C200 diff in the front of the Sani, and have now three times found one of my Hub Locks bolts coming undone. One bolt already gone AWOL the last time it did this about 3 months ago. I estimate about 200km of gravel where the Hubs were not even engaged, and a maximum of about 40-50km 4wd in soft sand in low range. I just got back from a little trip to town with about 25km gravel and 25km tar, and as I was unpacking the car, I see grease all over the left front wheel again. All the bolts are loose again and the Hub is flopping about, and has probably gobbled up a bunch of sand and dust off the sand/gravel road.

    I don't really like using Locktite, but this seems to be my next option in search of a solution. I want to know why it's doing this in the first place. Can one of the engineers maybe help with an explanation?

    While I am on the subject, does anybody know where I can get a replacement bolt for the one that is lost?
    In high tensile load applications, its very important to use the correct length bolts and to torque them correctly in order to remain tight. If they have been not torqued evenly then they will continually come loose. it is also recommended that one does not reuse bolts in high tensile load apps as these stretch and can fdail when reused -

    The use of nord lock washers and or Locktite are reccommended in high vibration apps.

    In this instance , there maybe an underlying reason, so strip and inspect gaskets, seals etc and ensure that all the bolts are the same length. In your application it would be important to tighten the bolts evenly and I would use Nord lock washers with red locktite.


    Be sure to use the correct locktite for your app.

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    Default Re: Hub Lock Bolts constantly coming undone

    Quote Originally Posted by Searcher View Post
    Just to make sure that you understand what we mean by studs.
    Those are not studs, they are hex cap bolts.

    Studs work better than bolts do in high vibration applications combined with lateral loads, like on hubs.
    Bolts and studs woke equally well in tensile loads application.
    I modified the hubs on the Yank Ranger.
    Upgraded the Dana 44 front to heavy duty.

    Were a mission to tighten the free wheel hubs with a socket. Removed the studs. Drill and tap the holes on size larger.

    Then I stalled caps crews with locking washers. Sending 600nm though them with no ill effects. Has been like that since 2012.

    Still think BFree have bearing play ore a fitment problem on that hub
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    Last edited by grips; 2021/12/04 at 09:30 PM.

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    Default Re: Hub Lock Bolts constantly coming undone

    A common cause of bolts or nuts working loose during service is related to “thread stretch” where the mating threads no longer meet correctly to provide sufficient friction surface area.

    Thread stretch is caused by over use and or over torquing of threaded components, this is a common reason why wheel lug nuts or bolts come loose after changing tyres etc. a few times. Wheel studs or bolts should be replaced at intervals to avoid the related stretching of the threads.

    Stretching does not have to be any more than a minute amount for sufficient loss of friction to occur. Think of cylinder head bolts. How many times would you reuse them when doing a top gasket. (I’m not referring to the “stretch” type bolts either)

    The stipulated correct torque is critical in providing sufficient lateral force on the thread surfaces to bind them together without over stressing the area upon “first use”.

    in the case of these hub bolts it maybe pertinent to check the threads in the hub as well, and then use fresh “cap screws”. For interest check the threads with a thread gauge on the current “cap screws”.

    This is all based on experience gained.

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    Default Re: Hub Lock Bolts constantly coming undone

    This all getting a bit too technical for our bush "workshop". I'll have to see what we have here. It's been raining here since yesterday afternoon, so I will see where I can find a patch of earth to park out of the mud, and out of the sand, which is the only two terrains we have here.
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    Default Re: Hub Lock Bolts constantly coming undone

    Quote Originally Posted by putta View Post
    In high tensile load applications, its very important to use the correct length bolts and to torque them correctly in order to remain tight. If they have been not torqued evenly then they will continually come loose. it is also recommended that one does not reuse bolts in high tensile load apps as these stretch and can fdail when reused -

    The use of nord lock washers and or Locktite are reccommended in high vibration apps.

    In this instance , there maybe an underlying reason, so strip and inspect gaskets, seals etc and ensure that all the bolts are the same length. In your application it would be important to tighten the bolts evenly and I would use Nord lock washers with red locktite.


    Be sure to use the correct locktite for your app.

    https://www.henkel-adhesives.com/us/...eadlocker.html
    I would use Loctite 243 here - used that on wheel spacers.

    Agree on changing the lock washers - the old ones probably have rounded gripping edges by now
    Mike Lauterbach

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