[Adam Skelding]

I don't know if they'll fit the B44 or BJ4.
If someone wants to try and fit a stock HB diff into a BJ4 or B44 and let me know they're welcome to.

The parts are really durable. I've had mine in since Batley Outdoor Regional last year.
Jimmeh failed to notice these parts until recently...

You do have to shim the diff slightly different to the standard diff and compounding tolerances never quite add up.
But shimming gearboxes is very rarely the same.

Here's how I normally shim them.
1. Use the same shim as you normally use on the input gear (since this has not altered).

2. Take the built diff and only place this in the bottom half of the gearbox. If the bearings are a push fit it in, make a small ~0.5mm chamfer on both sides of the bearing journal (as shown in the diag). This stops the bearing being pinched and frees up your drivetrain)

3. Now using the silver and brass shims, shim the diff only from the back of the gear side until the diff has no side to side movement but still spins freely.
(This gives you the right amount of shims to 'play' with)

4. Move 0.2mm (1 Silver or 2 brass) to the other side of the diff. This provides a good starting point normally. check for back-lash between the input and ring gear. You should be able to feel some but not much.
Another tip here is to get it so there is none then move 0.1mm to the front of the ring gear.

5. Write down where you put your shims on a piece of paper for your front and rear diff!!! Makes re-building so much easier