final drive questions

[almondgreen]

How can I see, if a pinion from the final drive is A or A plus ?

Is the crown wheel for a 3,65 final drive, different to the one for a 3,44 one ?
I know they have different casting numbers, but are there more differences, as they have the same number o teeth.

[rich@minispares.com]

a plus are machined flat on both sides, early ones have the slight lump on them

most a plus have the groove machined in them as well

[m1cH1]

I know they have different casting numbers, but are there more differences, as they have the same number o teeth.

Yes, there are more differences! There are crown wheels and pinions from different ratios with the same tooth count, but different part numbers. Always use them in known combinations and never mix them up, as they have different tooth angles and are not interchangeable because of this!

You can for example find the known ratios & part numbers on the following page:
http://www.dummett.net/ime/website/ime/ ... drive.html

Cheers, Mike

[ianh1968]

Is the crown wheel for a 3,65 final drive, different to the one for a 3,44 one ?
...., as they have the same number o teeth.

The 4.133 is 15:62 using the same 15 tooth pinion as the 4.267 and 4.333
The 3.765 is 17:64
The 3.647 is 17:62 using the same 17 tooth pinion as the 3.765
The 3.444 is 18:62 using a DIFFERENT crown wheel.

I am guessing that the 18 tooth pinion is a larger diameter
than the 17 tooth. Accordingly, this would require a smaller
diameter for the crown wheel as the shaft centres are fixed.

A 4.133 also has a 62 tooth crown wheel, but with a 15 tooth
pinion. Here, the c/w would probably be bigger as the
pinion would be smaller.

... Then there is the question of the tooth angles to get
the correct meshing...

None of the pinions that I have seen have part numbers
stamped on them, just count the teeth. The crown wheels,
however, should all be very clearly marked. If a diff is already
built up, the numbers may be covered up by the lock-tabs...

I am not sure what would happen if a mis-matched parts box
assembly was attempted. It either might not go together in
the first place, or otherwise, it may not last for long if it did...

When I "do" a diff, I normally get a set of number stamps and
mark the lock-tabs themselves with the tooth-count and/or
the ration. The tabs are soft and stamp OK, trying to re-stamp
the actual gears will just ruin your stamps as the gears are
all case-hardened.

TOP TIP:
If you end up with "way too much" shim in the side of the diff,
make up a 2" OD disk/washer of a slightly smaller thickness.

The last one I did was about 0.050"...

Assemble this BEHIND the bearing. You will then end up with a
sensible amount of shims between the bearing and the
side-cover. It would also have a very slight stability benefit
as the two supporting bearings will now be further apart.

Be sure to make the bore hole big enough to allow allow for
the chamfers on the c/w or diff cage.
[Mark F. - Why is the spell checker rejecting "Chamfers"?]

Ian