Technical Differential problems ?

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Technical Differential problems ?

^^^ I'd have to agree with Franko500.

The splines on your driveshaft are badly worn, if you look to the right you'll see the original spline size. Fitting new driveshaft flanges would probably get you mobile again but they'll quickly wear and fail again. Much of this spline wear is avoidable and due to lack of maintenance. They're supposed to be sparingly lubricated with grease and there's a small rubber boot which clips onto the groove in the driveshaft flange to keep out dirt and water. (Hint - order some new rubber boots!)

Unfortunately changing the driveshaft means opening up the gearbox but this has been covered several times on this forum (try doing a search, see search option in green line near top of page for previous relevant posts).

I had a driveshaft coupling fail once on a 600 (similar arrangement as the 500) while on a weekend away in a rural area- girlfriend not impressed! :mad:

I asked around locally, found someone into cars. He had an old Hardy-Spicer universal joint from a car driveshaft. I tapped some of the little needle rollers (hardened steel pins) into the gaps between the driveshaft and the flange splines, then fitted a hose clamp to hold them in place. Got going again and made it home - girlfriend impressed! :D

On the 600 the driveshafts can be removed from the gearbox simply by unbolting the large rubber boots. At the time, I was working in a truck repair workshop with it's own in-house machine shop. On Monday, I had the driveshaft splines built-up with weld and new splines machined, bought new flanges and fitted them that evening after work.

AL.
 
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Thanks for the advice, I think that I had come to the same conclusion myself...unfortunately. That series of photos is outstanding, I have yet to find a good write up and my manual lacks in this area, but I sure that the info is here and I will unearth it !!! I have read a lot about diff set up once you mess with it......more reading required before I launch into the job.
 
Thanks for the advice, I think that I had come to the same conclusion myself...unfortunately. That series of photos is outstanding, I have yet to find a good write up and my manual lacks in this area, but I sure that the info is here and I will unearth it !!! I have read a lot about diff set up once you mess with it......more reading required before I launch into the job.

To replace the drive shafts, which looking at the pics you need to do, you do need to dismantle the diff but you must mark and reassemble the main diff taper roller bearings exactly as they are to retain the most important crown wheel and pinion backlash (y)
 
Thanks for the advice, I think that I had come to the same conclusion myself...unfortunately. That series of photos is outstanding, I have yet to find a good write up and my manual lacks in this area, but I sure that the info is here and I will unearth it !!! I have read a lot about diff set up once you mess with it......more reading required before I launch into the job.

That link provided by gordinir8 is excellent and well done to Ricambi Fiat 500 for creating this guide. (y)


What Toshi 975 says is correct if you dismantle the gearbox piece by piece or start changing the diff bearings etc.

However, if you remove each diff side plate complete with bearing outer race and adjuster ring as one unit as shown in the above picture guide, you're unlikely to have any problem after reassembly as you won't have disturbed any of the adjustments. Just don't mix up the side plates!

Don't get into a panic over this job, it's not difficult as you're not setting up a diff.

AL.
 
Thanks for the tips and tricks. Not having to mess with the diff set-up is the secret to success in my mind. I can actually source axle kits locally (quite a saving on shipping) ....they are quoted as "large diameter" as an improvement over the standard 19mm ones. Am I correct in the assumption that assuming the boots provided are suited to the larger shaft diameter, this will not cause any problems within the diff during assembly.
 
Thanks for the tips and tricks. Not having to mess with the diff set-up is the secret to success in my mind. I can actually source axle kits locally (quite a saving on shipping) ....they are quoted as "large diameter" as an improvement over the standard 19mm ones. Am I correct in the assumption that assuming the boots provided are suited to the larger shaft diameter, this will not cause any problems within the diff during assembly.

Providing you get drive-shafts, rubber-couplings and oil-retaining boots with oil-seal diameters which are all matching, they will work well. The larger 24-25mm diameter shafts will fit the diff. without a problem. Double-check they are supplying the correct length for a 500.
 
I have purchased the necessary kit with all of the required parts and will launch into this within a couple of weeks when I return from a holiday. I will report back with anything that I learn from the exercise !!!
 
After quite a delay in this project, and hence discussion, my gearbox and diff has been completely rebuilt and is going back in. I decided not to do the rebuild myself but left it in the capable hands of a member of my local 500 club that does some work like this as a hobby (retired expert). My gearbox also has a new first gear that we thought worthwhile whilst it was apart. Can't wait to get it back on the road again, it has been far too long !!!
 
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