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Diff lock 101

Locking a differential means that the differential action is lost totally by giving the same amount of drive to each wheel, this avoid the situation where one wheel has grip buit the diff unloads all the torque to the opposite wheel that has no grip at all. this does damage the turning circle a little, esepcially at speed but this is a scale forum.

also it is advisable to lock the rear diff first, and then the front if you need the extra traction, locking the rear will limt how much steering is lost but gain traction especially under acelleration where the rear wheel tend to grip better anyway, locking the front is good for climbing, but does hurt the turning circle more....(vehicles with locked rears can also powerslide nicely on loose surfaces Razz )

*those with Tamiya 3 speeds such as the brusier need not bother as your rigs dont have diffs*

first you need to ask a question? permanent locking or non permanent locking?.

Non permanent

method #1. XC chassis G parts - these fit all small Tamiya gears diffs such as those found in the pajero(not the one found in the juggernaut/TXT), the XC chassis came with locking plates on the gear sprue these replace the bevel gears and lock it solid but can be removed easily.

method #2. hot glue, stick this between the small bevel gears, re-assemble the diff and allow to dry, this is good because the hot glue conforms to the teeth but does not bond to them very well, mean you can pick out the glue in 3 lumps.

method #3. extra bevel gears, buy a set of diff gears from Tamiya and use at least one extra small bevel so that at least two of the bevels work againnst one another, ideally use 3 per diff for balance.

I have used 3 per diff before in the front of my XC, but they do need grinding front and back so that all 3 fit in place *pic to follow*

Permanent

Epoxy - JB weld, araldite or any slow setting epoxy. this stuff takes hours to set but is practically indestructible. this cannot be undone under any circumstances so I suggest you try a non permanent method first to make sure you want a locked diff.

the method is simple: clean out the diff making sure all grease is removed(or if building from scratch build it without grease), assemble it up to the point of have the spider gear and small bevel gears in place, but before putting the large bevel gear ontop you stuff in as much epoxy as you can and then finish assembling the diff.

make sure you avoid getting epoxy on the very centre of the spider gear, and make sure you dont glue in the diff outdrives as you will not be able to remove the diff from the vehicle....however whilst it is still wet you should test fit the outdrives to make sure the spider section is centred properly(otherwsie you just wrecked a diff).

I have it on good authority that this can be removed by boiling the parts, but cannot yet verify this... Confused

Bad methods/ideas

dont not attempt to use the following to lock a Tamiya style gear diff:

-5 minute epoxy - it isnt strong enough and may break loose with time
-diff lock lube(100,000wt oil) - it leaks out
-superglue - it wont hold and its a pain to pick off the gears later
-PVA wood glue - not enough strength.
-rubber bands - they get chewed and are stronger than u think for when it comes to wrecking gears

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