drive shaft blocks...

[grubscrew]

... Changing the drive shafts to shorter ones in a 126 gearbox,(for my 500F, which in fact will be the 750), a straight forward job. Any way on original 500 crash boxes I have noticed that there are thin spring steel warped washers placed behind the metal machined square blocks, held on to the drive shaft by a metal pin cross ways to the shaft length, all within the confines of the crownwheel once split. These spread the blocks away from the shaft sides.
   So I find no warped washers on the original 126 shafts, so does that mean the people in Fiat thought it not required, or what? So I fitted the new 500 drive shafts without fitting these very thin warped pieces, seeing as there were not any in the first place. Incidently, it it quite clear the box had not been meddled with since factory. Any Ideas...? Rusty, can you shed a light? Mike

[Rusty's Uncle]

I know the bit you are talking about. Did I say on the forum that I have just stripped 5 gearboxes? Four 126 ones and one 500 one but as yet I have not split any of the diffs. However I did split a couple of diffs last year when I rebuilt a 126 syncro box with 500 bell housing and shafts. I found on two 126 diffs that there was only one of those spring washers which I thought was strange but went with it and it seems to work OK. So far I have re-assembled 3 syncro boxes but have not got to the diffs yet so should be interesting. 

[grubscrew]

.. Thanks for that. Be interesting to find out more.Mike

[Rusty's Uncle]

The sun came out about an hour or two ago so I went outside and split another 126 diff. Once again only one of those spring washers behind one drive shaft block.

[grubscrew]

I sent the rain North, but whilst it was raining, I had a look in a box which had an old 500 box, and that too had only one. It strikes me that the Polish bit had less stuff.     On that same subject, the rubber dome gaiters (against the gearbox) that conceal a spiggot with a seal in, some of these spiggots are metal, good ol` metal, and now Im coming across plastic ones, and yes this is a Polish box.

[Rusty's Uncle]

OK so the definitive answer is that there is no answer 
Split 3 more diffs , 1st no springs , 2nd 1 spring behind one block on 1 drive shaft and not on the other , 3rd no springs so none the wiser so it would be good to get an original parts book to see if they are mentioned. I also noticed on the last diff that the diff housing castings are marked for position on the flanges. No mention in the Haynes manal so not sure why it might be important and I have had no problems with prrevious rebuilds so just something else to look out for.

[grubscrew]

I am now resposible for all these split diffs in Chesham, look out in case you see one on the side of the road!  I will have another look in the various w/shop manuals, as I can say I did`nt see any printed, but then my eyes are not as sharp as they could be.Mike.