Aprilia differential output shaft

[John Larkin]

The attached photo shows a large castellated fastener on the output shaft of my 1949 Lancia Aprilia.  The guy working on my car has made a tool to fit but he has found the fastener to be very tight.  We are both concerned that the threads may be left-hand screw on one side and right-hand on the other, and we do not want to get really forceful unless we know that we are actually unscrewing it in the correct rotation.

Is there a helpful, kind person out there who knows what to do?

John Larkin.

[Sebastien]

I checked the parts book for the 2nd series Aprilia (available as a reprint, not expensive, from Gilena).
(It is also available on a CD or Memory Stick from Viva-Lancia)

On Tav. 19 this should be the part:
38-32645 Ghiera per cuscinetti albero propulsore.
This translates as Ring (or fastener) for bearings of the driveshaft.

The parts book quotes the number necessary for the complete rear axle housing as 2 - I assume one per side.
So it is the same part for left and right hand side!
Thus only one direction to unscrew! Now which one? The parts book does not say....

Hope this helps.

[John Larkin]

Thank you Sebastien!
I have the DVD parts catalogue, and I had looked up the item.  I failed to grasp that a single part number means that the fastener is the same left and right.  So they both probably unscrew anti-clockwise.
I appreciate your speedy reply.  Thanks again.
John Larkin. 
 

[Raahauge]

Lancias often used a wire clip to stop things undoing. The illustration in the parts book has a groove for such a clip though I cannot see the clip shown nor can I see the groove on your photo. It is worth looking carefully however.

[John Larkin]

Lancias often used a wire clip to stop things undoing. The illustration in the parts book has a groove for such a clip though I cannot see the clip shown nor can I see the groove on your photo. It is worth looking carefully however.

The locking tab is missing in the photo, but is present on the opposite side of the differential.  Im having a replacement tab made up.

[Hendrik]

To unsrew just turn left. There is nothing special.