131mirafiori forum

I removed the half shafts on my Lime 131 Sport today as both wheel bearings seem noisy and had far to much play.

I found 2 brand new half shafts complete with the bearings fitted and several used ones. I decided to fit the new shafts only to find that the ones i removed were 10mm longer and a lot thicker in size. I always thought all the 131 diff fitment of internals were the same. I suspect the diff is from a late 131 Super series 3 or it has 132 internals.

Go's to show why my dads seies 3 B89 NLA did 120k on the original diff and still going with just a slight hum from the pinion bearing.

The series 3 has a wider track than the series 2. I guess the rear axle must be wider.

I'll measure the diff tomm. I also suspect that series 3 axles are a lot stronger.

The series 3 does have a wider axle and the half shafts are longer and slightly larger diameter on the spline end.
If your sport has the longer halfshafts someone must have fitted a series 3 axle at some point.
The weak point on these axles isn't the halfshafts its the pinions which break up.
I have never had any trouble with the halfshafts breaking or the splines shearing on them with either type.
As you mention noisy rear halfshaft (wheel) bearings are a quite common problem.

I suppose that's why the mid range and top end was so good. Pulls like a train.

It sounds like you had a 10/41 fitted ?  Take the backplate off and count the teeth on the crownwheel.
They do have it stamped on the front of the axle but it will probably be covered in old oil and may not be legible now anyway