Technical Axle Sleeve Replacement

[pepl4776]

Hi

My 1973 was originally an F, sometime along the way a 650 cc (stock) was dropped in along with a synchro gearbox. Quizzing the previous owner didn't yield much on exactly what parts from the original or transplant are in the car.

Saturday while setting off from my driveway I heard a bang! rattle rattle and no drive. I immediately suspected a rear drive shaft. I suspect I either over-tightened or under-tightened the bolts holding it while working on rear brakes (don't ask)

After a push back to my garage, I found a broken axle shaft sleeve (at the hub end). At a minimum looks like I need a a 19 mm sleeve, spring, clip and 4 bolts to attach the flange to the flex joint.

Question: Should I proactively replace the flex joint and bearing, basically rebuilding the hub? Any issues with only repairing one side?

 

[Paolo66]

Your driveshafts should have been replaced with 25mm diameter ones. When you put a 126 gearbox in a 500 they come with 126 driveshafts which are too long for the 500. It looks like someone has replaced yours with standard 500 19mm diameter ones. The preferred option is to go with 25mm diameter at the correct length. It also looks like you have got 126 rear hubs. The 32mm nut is staked to the hub on yours whereas on a 500 they are split pinned. There should also be a spring plate fitted behind the nut against the flexible joint

Damian

 

[pepl4776]

Thanks for the reponse

Turns out the hub nut is 30 mm. And it will not budge despite a long powerbar and penetrating oil.

Is there some trick to taking off the staked nut? Do I have to grind it off and replace the axle as well?

 

[MOD500]

I've not seen a drive shaft flange split like that before!


If you over tighten the 4 nuts you will strip the aluminium threads of the flexi joint.
Under - tightened, the bolts tend to fall out.


there may have been a weakness in the drive shaft flange.


The flexi joint looks ok, I would leave it. Swapping the drive shafts for 25mm is a good idea in the long run, although the splines look good on your drive shafts so you could avoid that for a while.

 

[fiat500]

Thanks for the reponse

Turns out the hub nut is 30 mm. And it will not budge despite a long powerbar and penetrating oil.

Is there some trick to taking off the staked nut? Do I have to grind it off and replace the axle as well?

I only have experience of the staked nuts in the front hubs. But as they are much smaller it's relatively easy to force them to turn using the correct tools. I suspect that you might need to to attempt to punch out the deformed section of the nut before removing it. I haven't heard of anyone having to cut the nut off as a standard procedure.

 

[Franko500]

It looks to me that you have 25mm drive shafts.
You don't measure them across the diameter of the shaft but across the splined section.
There are various 25mm shafts, some of the early ones were 19mm shafts and the later ones went up to 25mm but they all had 25mm flanges that bolt to the flexi drive.
I would also say leave the flexi drive if the rubber hasn't broken away from the aluminium. If the threads are ok it should be ok.
For that flange to break there must have been a flaw in it as they don't usually break.