I'm refering to the clutch housing spacer piece that goes between the wok piece and the block and surrounds the clutch and flywheel.

If during my rebuild I come across one with either the breather holes or the mounting block undrilled will it simply swap for the current one without breather facility?

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David L


My greatest fear in life is that when I die my wife will sell my Mini and tools for the price I told her I paid for them!

If your refering to the transfer case - thats the bit that has the big orrange clutch oil seal and contains the ends of the transer gears (drop gears) well yes and no.

It certainly bolts up fine and is unchanged for all A series engines (believe an A+ one is different) and can be used from one engine to another.

The NO bit is that the casting was not an exact science and the thrust washers that support the drop gear come in different thicknesses to suit the varying clearances - if you change a transfer case you usually find the transfer gear thrust washer is either too tight or too loose and has to be changed.

Yes, as Mike says above though, the idler gear clearances etc will need to be reset, usually a good idea even with the same housing.

It is a good idea to have the breather on this housing though, you can have it drilled and tapped to suit, and the centre piece ground out for the breather. That's what I had done!!

Cheers
Matt

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68 Deluxe.... it's shiny..... I like shiny!!

So would the advantages of adding a breather on there outweigh the hassle of going through the excercise of measureing and installing the right thrust washer?

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David L


My greatest fear in life is that when I die my wife will sell my Mini and tools for the price I told her I paid for them!

I think you may find the outer diameter of the needle roller bearing is larger on the later type housing with the breather provision. The shaft diameter is the same but the needle roller bearing is different. This is not to be confused with the larger A+ idler gear which has a larger shaft diameter and an even larger outer diameter needle roller bearing.
The breather type housing used the idler gear with the unequal length shaft on each side of the gear.
Fitted to later 3 synchro boxes using the commonised gearbox housing 22A1288 and 4 synchro boxes.
Late MK1 S, MiniDeluxe and Morris 1100S.

Hope this helps.
RonR

Okay to specifically answer your question

The mini powerplant creates a lot of air movement and cyclic pulses and when an engine wears, there is compression by-pass directly down into the sump / gearbox. Now unless this air has adequate breathing then you are going pressurise the sump and blow oil out the current breather which are (depending on the motor) the oil dip stick hole and either the rocker cover breather or the tappet cover breather.

I personally believe that you cannot have enough breathers on a mini motor so tapping and drilling the transfer case is a good move. You can either use a PCV opening or closing valve type of system or simply use an open system that has an open type cone filter. But you must have a filter of some sort.

The reason for that is that while the motor is running and creating pressure it expels and then once the motor is shut down and cooling it sucks in air. The PCV type close and restrict s the air suck. The cone filter type allow free flow of air and that would (if unfiltered) also allow the ingress of dust, moisture, insects and probably wallabies and wombats.

The down side of an open filter system is that on cool nights and short runs the ingress of moisture gives creamy oil in the rocker covers that looks very much like the product of of a blown head gasket. However it usually evaporates off in a good run.

The PCV types allows the inlet manifold to to suck the pressure and oil fumes to be suck into the engine and burnt off

Bottom line - drill the transfer case and let the engine sump area to breathe more efficiently