Shimming Lockright

[cynic-al]

Ok, so after playing with the lockright for a while I wanted to find an easy way get the shimming correct without needing any special tools, this is what I did, let me know what you think.

The first problem was getting shim, suzuki only offer shim between 0.95mm and 1.2mm thickness and i won't repeat the prices per shim! I searched for a while and found a spring maker that sold shim washers the right size. I bought a selection of shims at 0.1mm, 0.2mm, 0.3mm, 0.5mm, 1.0mm and 1.5mm thicknesses. Saldy there was a minimum order value so I bought a LOT of shim! So if anyone does need to do this I can organise you a kit of shims with 2 off all the above if you want.

Back to the diff...

The aim of shimming the lock right is to get the correct distance between the driver and pinion shaft to allow the lock and unlock correctly. The manual states that this distance should be between 0.005 inch (0.127mm) and 0.020 inch (0.508mm) and within 0.008 inch (0.203mm) of each other. To find how much shim needed I first shimmed the diff to find out how thick the gap was.


1. Put the side gear in the diff with no shim under it


2. Drop the coupler on top and make sure the teeth are engaged


3. Slide the pinion shaft in


The gap we are trying to take up is the one between the pinion shaft and semicircular cut out in the driver. We can see that with no shim the gap is pretty big.

4. find out what this gap is I installed various combinations of shim under the side gear until the pinion shaft could just be installed. Too much shim and the shaft won't go through both holes, not enough and the drive can wobble up and down.

Shim under side gear


Here you can see too much shim stops the shaft going through


Basically it's trial and error and takes a while but is easy. My one main tip is don't get the shims mixed up, when they are not in teh diff keep them in marked bags so you know which shim is which diff and make sure you know whats on your side gear at any one time. If you get the shims mixed up you won't know how thick the gap is and so won't be able to correctly shim it.

5. Once you have achieved the correct shim count up what thickness you have and write it down. Mine turned out to be a 1.5mm and a 1.0mm shim, so 2.5mm of shim. Take all the bits out the diff and put them somewhere safe.

6. Shimming the other side is more difficult as it relies on the fit of the diff housing cover. You need to shim the side gear so that the cover just fits flat. Too much shim and the cover will not fit down, not enough and the side gear is loose. Do this in a well lit area and look for light between the diff housing and cover. You can also use feeler gauges or spare shim to check for gaps. Also make sure you use the other side gear and driver, the shimming stage is fine tuning, the parts are now handed incase of any slight variation between the two.

Assembling and checking gap


here you can see a small gap, too much shim!


Again take you time to get it right, mine needed 2.7mm shim at this side.

7. Now we know what the gap is and we know what the gap needs to be we can work out how much shim required. The gap should be between 0.005 inch (0.127mm) and 0.020 inch (0.508mm) and within 0.008 inch (0.203mm) of each other. Lets take the middle of the allowable range, (0.127 + 0.508)/2 = 0.3175mm. Our bottom gap was 2.5mm, therefore the amount of shim we need to pack the gear to leave us with the ideal gap is 2.5 - 0.3175 = 2.1825mm. My thinnest shim is 0.1mm so lets round this to 2.2mm of shim. Repeating for the other side gives 2.3825mm of shim, lets round to 2.4mm.

8. The gaps must be within 0.203mm of each other, to check this we must calculate what our gap will actually be with the shim in place. The bottom will be 2.5mm (the actual gap) - 2.2mm (the shim we are going to put in) = 0.3mm (the gap we are left with. Performing the same calculation on the top half gives a gap of 0.3mm. The difference is 0mm. Therefore the shim required is as follows;

Bottom 2.2mm
Top 2.4mm

[MrHawk]

Wouldn't this actually make the locker unable to unlock? there is supposed to be some slack between the coupler and side-gears according to my manual.

[Tim Pink]

Excellent write up, I will be doing mine sometime in the next month so will bookmark the thread.

Tim

[cynic-al]

yes, the gap should be between 0.005 inch (0.127mm) and 0.020 inch (0.508mm) and within 0.008 inch (0.203mm) of each other. I cannot set the gap to this as I don't know what the gap is to start with so I packed it so there was no gap to find out what the gap is, then did the maths to find out what shim i needed to create the gap stated in the manual.

[suzukishrek]

Nice one Al. One for the sticky methinketh, I suggest you PM Mr Ham.

Here's something else for you to test your brain on: How to reliably test the LockRight in the diff without having to put the whole 3rd member back in the axle?

[cynic-al]

more importantly, how can someone with home garage tools do that?

if they had a torque wrench you could put the assembled diff in a vice, each half shaft in in turn and turn one of the nuts at the end. Try work out a range or torques that it should unlock at?

[suzukishrek]

Well here's a little observation: When I fitted the LockRight to Peewees truck and drove it up a boulder I had laying around at the workshop (don't ask!) I managed to get one back wheel completely off the floor... of course it was locked so it just kept pushing the truck along as you woud expect. So, I help the truck on the clutch waving the rear wheel about 3' in the air, reached out the door, grabbed hold of the tyre in the air and span it freely by hand. It turned easily with no resistance and clicked away nicely.

This suggests to me that jaming the flange so it can't rotate and then applying a forward (or rearward) turning force on one side of the diff should effectively lock it. Now keeping that pressure on, the other side should be able to spin freely and start ratcheting away. Now remember, when I turn the wheel I was effectively using what equates to a 15.5" lever (half the diameter of the tyre) so that will make it nice and easy to turn the unlocked side. You have to forceably lock one side and keep it locked (I had the weight of the vehicle locking it and the flange locked to the engine via the slipping clutch don't forget). This needs to be repeated both sides and in both directions, so a total of 4 times.

Just got to make a method of jamming the flange (easy - angle iron bolted through two of the flange bolt holes) and then forceably locking the one side gear (an old half shaft with a lever welded on the end perhaps) whilst spinning the other end with a similar device.

[phil-zuki]

Just rebuilt mine today, fitted it this evening. working very well. hard to explain how i shimmed mine up but every time I do it It works spot on. clicking away free of friction.

[cynic-al]

someone like you who is fitting a lot could make a jig that bolts through a couple of the ring gear holes with a broken half shaft as you suggest fastened to it. Then it would hold one side locked to the diff so you could play with the other side with another broken half shaft with a lever on it.

Make it so the jig can be clamped in the vice for ease

Make the vertical section that comes up to the ring gear with a section that can be removed to account for the 2 height differences needed as that ring is nearer one side than the other.

But how do you make sure the side held by the jig is under load? Perhaps the half shaft would need some rotation with a screw for applying pressure?

Of course all this is an OTT amount of work for someone who is only fitting one!

[jwhswamp]

I never thought about shimming it that way when I did mine. I will be onto my third diff soon with the locker in. This way the job will be right.

Cheers John

[cynic-al]

finally got my repair kit for my locker so got to build it up properly today, however theres a mistake with the above, when working out how much shim you need you need to do it with that thick washer in place that goes between the side gear and spider.