Differential overhaul

[Banned User]

Actually Phil mentions it in his post above.

[oliver90owner]

Nothing is moving in relation to each other. A shim is simply a very thin spacer.

[Banned User]

Nothing is moving in relation to each other. A shim is simply a very thin spacer.

Sorry, you’ve lost me there.

[oliver90owner]

[philthehill]

Looking through my various BMC/BL manuals the crush spacer does not appear to be mentioned in the Morris Minor wksp manual - not even AKD530 Edition 14.

The Morris Marina had basically the same diff assy as the Minor. The Morris Marina wksp manual gives much clearer instructions with good illustrations of how to set the diff pinion preload basically using the same special tools and procedures as when setting the Minor diff pinion preload.
The instructions in the Marina manual are for both solid spacer and crush spacer - it actually has a good illustration of the diff pinion with crush spacer.

The relative Marina manual is AKD7555 Issue 1. 51.15.07 Sheet 4. Rear axle and final drive 10cwt van.

Using both Minor and Marina workshop manuals would be of great help in setting the diff pinion preload.

For setting the crown wheel the Marina manual also has much better to understand instructions and illustrations on how to do the job.

Phil

[ndevans]

Reading back through the posts, I understand now that a pinion with a crush spacer does not need shims.

So in the next few days, I am going to tap out the pinion on my 4.22:1 diff, see what sort of spacer it has, and renew it if it's a crush spacer, or adjust the shims if it's a solid spacer. Hopefully I will then be able to set the pre-load properly!

Cheers N

[oliver90owner]

I don’t think you understand my post either. Do read it (or them) again and possibly save yourself some money.

[Banned User]

I don’t think you understand my post either. Do read it (or them) again and possibly save yourself some money.

How about explaining rather than posting unhelpful cryptic messages?

[paul 300358]

A shim does not rotate, it simply adds length to a component. The solid spacer that Declan put in measured 20.28mm, if he needed 20.5mm he would add a 0.22mm shim. The crush spacer won't need a shim as it collapses to the correct length.

Hope this helps
Paul

[ndevans]

It does, thanks Paul. I guess the clue is in the name!

[paul 300358]

The problem that you have Neil is that once the crush spacer has been crushed to length, it is impossible to re-crush it to the same length. You need to crush a new one or you will be still trying to get the correct tension next year. I would be tempted to purchase a few as you may over crush the first ones while you get a feel for it.

[ndevans]

Yes, I've worked that out. They are one shot. I'll just have to go carefully. However, the 4.22 diff may have a solid spacer. There's only one way to find out.

[Declan_Burns]

Neil,
You can always try adding a shim and re-using the crushed spacer. Try it as an experiment. Here is a rule of thumb:
Removing 0.001" / 0.025mm from the length of a spacer increases bearing preload by 3 in lbs / 0.338Nm and vice versa.
Add a 0.002 shim and see if the preload increases to within range. Then try adding a second shim and see what happens. Nothing to loose!
Regards
Declan

[ndevans]

Ah....I hadn't thought of that!
I'm a little confused though. As I understand it, you set the pinion height by adding/subtracting shims under the pinion head, but the preload on the pinion must be right before you measure the height. If the pinion height is not right, you have to dismantle again, then use a different size shim, then use a new crush washer to get to the right preload, then measure again?

[philthehill]

You are correct in that to set the pinion height you add or subtract thickness from the recessed washer that fits directly under the head of the pinion and against the rear pinion bearing inner race. The recess of the washer is towards the pinion head.
You can set the pinion height without the crush washer in place - just assemble without the crush washer and tighten the pinion nut to give 10 to 12 lbf ft preload. Check the pinion height and adjust as necessary by adding or subtracting shims. When the pinion height is correct disassemble the pinion - fit the crush washer and tighten the pinion nut progressively to a torque of 140 lbf ft whilst constantly checking the bearing preload. The bearing preload takes preference over the torque of the pinion nut but saying that the pinion nut has to be torqued sufficiently so as not to come undone.

[Declan_Burns]

Neil,
I think you are confusing two separate settings:
1) The pinion depth is set by the thickness of the thrust washer between pinion head and inner bearing-full stop. This is a setting determined by the factory and you do not have to change or set it if you are not changing the CWP to a different ratio. I do not have this setting for ATA or BTA differentials but it can be measured. The special tooling is shown in the WSM but there are more modern methods.
2) The bearing preload is set as Phil has mentioned without the spacers or seals.
These are two discrete operations.
There are actually another two which are easier to set but influence each other. I am sure we will get to that later. They are
3) Setting backlash
4) Setting carrier preload

Regards
Declan

[philthehill]

Declan is right in that item No 25 - recessed washer in the parts list is supplied in different thickness which are referred to in my post of the 31st Oct above.

I have amended my post of the 3rd Nov above as referring to the various thicknesses of recessed washers.

The recessed washers for the ATA diff carrier are:-

2.946MM,,,,,,,,,,,,,,,,,,,,,,,,,,,,.ATA7055.
2.997MM...……………………….ATA7054.
3.048mm...……………………...ATA7053.
3.099mm...……………………...ATA7052.
3.150mm...……………………...ATA7051.
3,200mm...……………………...ATA7050.
3,251mm...……………………...ATA7049.
3.202mm...……………………...ATA7048.

The different thickness recessed washers moves the pinion closer or father away from the crown wheel teeth and ultimately effects the meshing and backlash.

Phil

[ndevans]

Phil, Declan,

First of all, thanks for your time and patience in explaining (more than once!) to me.

As regards setting the pinion height-I've tried setting the preload, with the pinion fully assembled with crush or solid spacers, and I couldn't get it to more than about 3-4inlb without exceeding the 140lbft torque on the nut. So how do I get to the correct preload without the spacers?

For measuring the height of the pinion- I have a dial gauge, but without the correct slip gauge I guess that's not very helpful. I guess the more modern method is to use engineers blue to determine the contract pattern on the pinion/crown wheel?

Cheers Neil.

[philthehill]

The spacer is stopping you getting the preload. Without the spacer you should be able to lock the bearings but that is not what you require.
Do not use the spacer until final assy. Fit the pinion and tighten the pinion nut until you have the correct bearing preload. Then check the meshing using engineers blue or the yellow past (link above).
Unless you have the correct factory setting tools you can only do your best in getting the pinion height and the correct meshing of the pinion and crown wheel teeth.
I have used engineers blue in the past but the yellow paste (link above) is what I intend to use in future as it gives a much clearer indication of the meshing and the position of the teeth in relation to one another. The instructions contain examples of correct and incorrect meshing.

[Declan_Burns]

I would not worry about the pinion height as you are not changing the CWP. Your pinion height is (almost) at the factory setting. You have lost the preload due to wear in the bearings. If you were to replace the bearings with exactly the same new bearings (neglecting tolerances) you would probably be able to set the preload with what you have. That is why I suggested adding a shim to the pinion spacer as an experiment to what you have to see if it restores the preload.
The priority is:
1) Pinion height at factory setting (which you already have as it is determined by the pinion thrust washer thickness) and then….
2) Pinion spacer length adjusted to obtain the preload at this factory pinion height.
Regards
Declan