Diff Lock / Axle Studs

Submitted: Thursday, May 06, 2010 at 15:03

ThreadID: 78257 Views:3203 Replies:5 FollowUps:5

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Member - Doug T (NT)

Since fitting a rear Auto locker in my 1994 75 series Troopy I had problems with the studs sheering, after the 1st time in Mt Isa I added some spot welds around the flange, that proved successful for 2 years until I decided to do the bearings, after that I also replaced the hub, but did not do the spot welds again, (Gunnado) and it has sheered twice since, so looks like adding the welds again, I had a Rocky with an auto in the rear and never had problems, so for any of you with other makes or later model troopies you shouldn't have any problems, I was toying with the idea of removing the locker but that would cost money so the cheaper option will be the welds, the first time I had replies on here about how dangerious it would be, to my thinking that's BS because the vehicle had been to the SD twice, towed the van to Perth, done many 1000's Ks working as a Pilot, then towed the van back across Australia to NSW and then NQ, then to the Top End NT, and never gave a problem....until the weld was removed.

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Reply By: Member - Andrew L (QLD) - Thursday, May 06, 2010 at 15:33

Thursday, May 06, 2010 at 15:33

This was covered just recently on another forum, can't find it though.

The cause can be attributed to loose wheel bearings in the full floating hub.

With the axle out, is there any play in the hub..?

Loose bearing adustment would give a different plane/axis for the hub compared to the axle due to the 2 different lengths of the hub, and axle.

A loose wheel bearing/adjustment wounld have the hub pivot on the inner bearing when loaded, .....

......and the axle would be pivoting in the axle/carrier of the diff centre.

This is what may cause the snapping of the axle end studs, and it may not be shearing as such, but stetching of the studs, weakening and then maybe shearing.

Sounds plausible if you think about it hard enough....

AnswerID: 415615

Reply By: Member - mazcan - Thursday, May 06, 2010 at 16:08

Thursday, May 06, 2010 at 16:08

hi doug t
the article that
andrew l
is refering to was on this forum thread 78243 only yesterday i think it will help your problem
cheers from another half blind man

AnswerID: 415619

Reply By: pop2jocem - Thursday, May 06, 2010 at 19:59

Thursday, May 06, 2010 at 19:59

Hi Doug,
Sorry to hear your venerable elderly (I wont say old) Troopy has had a minor disfunction.
I would be very interested to know if there was significant play in the wheel bearings when you removed the axle, that is if you checked them at the time.
A few of us had a brief discussion yesterday about whether loose wheel bearings contribute to broken/sheared studs such as you have experienced.
In my opinion the bearings would have to be extremely loose to cause such a failure. I feel that shock loadings are more likely to be the cause in the case of a fully floating setup such as the Cruiser (such as yours or mine which is a '91 model
Phil disagrees and I respect his right to do so as it appears he has had considerable experience with Cruisers.
Some time ago you and I had a discussion on this forum regarding the relative merits of air lockers v auto lockers (or more correctly unlockers) and agreed to disagree on there application in the rear diff. Not I would add from a reliability point of view but more from their affect on handling in certain on road conditions.
I would also like to add that having worked for the company here in WA that were the original importers of the Detroit Locker way back in the early 1970's and having installed them in various applications from Cruiser size to 5 tonne and larger trucks my opinion was that on lighter vehicles they could induce unpredictable characteristics cornering on wet roads. In heavier vehicles this was not the case.
I believe the later "soft lockers" did not have these problems to the same extent.

Just my two bobs worth

Cheers
Pop

AnswerID: 415650

Follow Up By: Member - Doug T (NT) - Thursday, May 06, 2010 at 20:23

Thursday, May 06, 2010 at 20:23

Pop
This is not the first time as I stated, it is caused when the locker must sit part open , when the clutch is engaged it snaps back into the lock position , in my opinion most other 4x4's would not have stud problem, (some owners might though.....tic..) but because of the small stud size when the kick happens it will sheer, as I said when I had the spot welds I had no problems, as for handling, wet or dry , never had any problems, 2 wheels driving the rear, not oneresults in more traction. reguardless of my small problem I still swear by the Detroit full NO-Spin locker.

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Follow Up By: pop2jocem - Thursday, May 06, 2010 at 20:36

Thursday, May 06, 2010 at 20:36

Doug, as far as their value as a traction aid I agree they certainly do their job. I guess the studs could certainly be broken if an air locker was engaged, only one rear wheel had grip and the driver got a bit exuberant with the accelerator and clutch. This is no reflection on the ability of either traction aid but rather the studs being a bit on the anaemic side to transmit power to the ground if one wheel is in mid air.
Have you considered fitting larger diameter dowels rather than welding your hubs
to assist the studs and make it a lot easier to get at your wheel bearings?
Maybe replacing the studs at earlier intervals as they may weaken over time. If I recall your vehicle has done very high miles.

Cheers
Pop

FollowupID: 685763

Follow Up By: Member - Doug T (NT) - Thursday, May 06, 2010 at 20:54

Thursday, May 06, 2010 at 20:54

Pop
The amount of Klms my 4x4 has done has no connection to this, the r/h hub was replaced with a new one along with all new studs around 6 months ago, also there is NO play in the bearings , this is caused by shock only , the weld will solve the problem as it did before,

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Follow Up By: pop2jocem - Thursday, May 06, 2010 at 21:02

Thursday, May 06, 2010 at 21:02

Doug
The fact that the stud failure was most probably due to shock loading and not bearing slack was what I was trying to get across.
If welding the hub works for you.....go for it end of discussion

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Follow Up By: Rockape - Thursday, May 06, 2010 at 22:12

Thursday, May 06, 2010 at 22:12

Doug,
I also run detroit lockers and have experienced one failure, I believe it was caused by shock loading when another person was test driving the vehicle, god bless his soul.

I also replaced the hub and have had no further problem since, will wait and see.

I had the old hub drilled out and tapped to take larger studs, from memory the studs are 80 series. I wasn't happy with the studs as they were sloppy when installing them in the hub, so it sits in a box in the shed. Maybe I will install them with devcon. Also have an axle to suit.

My bearings were fine, I believe the reason the studs broke was shock . I have been told it can be a problem when you have an auto locker in the back with the older cruisers.

I am also sure Phil has seen many with the bearing problem, as he knows them very, very well.

I also cannot fault the detriot lockers, they have been great.

Have a good one Doug.

FollowupID: 685782