Transmission knackered- Alleyniki confused and more confused

[AlleyNiki]

*SIGH*

Here we go again...

Guys I really feel like a leech asking for help all the time with this car...!

I've really got no option but to ask for your help/opinions AGAIN (sorry):

Basically, I was trying to pull away at the lights. I put it in first, let out the clutch and all I heard was GRIND GRIND GRIND GRIND. And the car went nowhere.

I tried all the other gears and got the same response.. including reverse.

All the gears seem to select.

Two causes come to mind:
1. Crown wheel / pinion shaft have worn or displaced (how does THAT even happen.. I haven't been dropping the clutch..?)
2. Clutch plate broken (which is unlikely as I have recently replaced it for new..)

Upon pushing the car (which I am getting good at nowadays) it made the same grinding noise when in gear and offered no resistance.

  (yes very confused.)

The only thing I can comment on at the moment is that once upon a time the gears locked up on me. I replaced the faulty worn pinion shaft bearing and everything seemed grand. Then some time later I seemed to hear a small 'klonk' on take up when letting out the clutch with  changing gear.

Alleyniki

[thepuddlejumper]

Havr you checked you drive shaft coupling. I had a similar experience and the rubber infill material had coma away resulting in a grinding noise when trying to drive.  Worth a check as easy fix replace drive couplings.

Ralph

[Rusty's Uncle]

Sorry to hear about your troubles . There are times when you feel there is no end to the problems when you get a bad run of luck.
I once had a similar experience when one of the drive shaft outer flanged couplings "exploded" at the splined section so it lost all drive. Easy to spot and easy to fix.

[AlleyNiki]

Puddlejumper & Rusty - now there's something I didn't think of.

Upon checking both sides I've found it indeed is the left flange that seems to be causing the problem! 

On jacking up the left side and turning the wheel it simply spins while the drive shaft stays stationary.

I've got to check properly to see whether it's the flange or the shaft that has worn, but at least I know the problem isn't terminal (yet!)

One other thing- when I jacked up the other side to check the flange it I turned the right wheel with the car in gear. This side was obviously working properly and I noticed a 'click' probably from the diff as I turned the wheel a few degrees. Would this have been bad for the diff?

Thanks guys, much appreciated

Alleyniki

[Rusty's Uncle]

Not sure about the diff but keep your fingers crossed. When my coupling went it was caused by a combination of the splines not being greased leading to excessive wear then the flexi coupling was breaking down so things were getting out of alignment.

[AlleyNiki]

Not sure about the diff but keep your fingers crossed. When my coupling went it was caused by a combination of the splines not being greased leading to excessive wear then the flexi coupling was breaking down so things were getting out of alignment.

I've done the not-noble thing and pinched one from another car! My ex was going to start driving a Fiat and has an old one sitting around that she is now giving to her brother. Fortunately there was not much wear in this one and plenty of grease inside it (unlike mine which was dry).

The car drives now..

But why would the car not drive if it is only the left coupling flange that has worn out? The right one on my car is fine.

[Rusty's Uncle]

Cos that is what a diff does as it will send the drive to the shaft of least resistance and why 4wd vehicles have things like diff locks & limited slip diffs etc 

[thepuddlejumper]

Hi glad to hear you are up and running again.

Ralph

[gsxr126]

Good to see you got it sorted. The advice on this forum is invaluable.

Here's a real coupling problem for you.

The bloody shaft on mine wore and not the coupling. Need to find out how this happenned so it doesnt happen again.

Any ideas anyone???

[Rusty's Uncle]

Not a lot of grease on there boy ! 
That is the worst one I have ever seen.
On the subject of grease I have seen loads of flexi couplings ruined because people have overgreased those splines then the excess grease attacks the rubber in the coupling and breaks it down. I use some really heavy graphite grease on the splines then push the coupling onto the spline , remove any excess at the flange end & put a little extra grease inside the seal at the opposite end 

[KAL SPL]

Good to see you got it sorted. The advice on this forum is invaluable.

Here's a real coupling problem for you.

The bloody shaft on mine wore and not the coupling. Need to find out how this happenned so it doesnt happen again.

Any ideas anyone???

Theres no easy fix on that , will require full strip down of box/diff to get the center apart.

[gsxr126]

Yep you're right Rusty, there's not a lot of grease on there "now" I did grease it but obviously not enough This is what happenned after 5000 klm. Will follow your greasy advice
Let this be a warning to all to "heavily" grease your splines.

KAL do you rekon I can get away with just swapping the whole diff shaft to shaft or am i being a trogdolite?

[KAL SPL]

You could swap the whole diff and 2 shafts yes , problem is the casing has to be split in half to get it out then all resealed and back lash set again.

I mean its not a difficult job , I know this because I did it all myself with no qualifications but the right tools and obviously considerable time is needed.
Personally I would be finding a second box/diff and build that 1 first then swap the lot over.

[gsxr126]

After doing some research, and looking at both sets of shafts I have (the knackered one above & the replacement I have for it), I found that these are different in spline length. I used couplings from splines that were about 38-40mm long on splines that were 45-47mm long. That's why I think the peculiar wear happened.

There are also couplings advertised that are "big hole" and "small hole" on the net - obviously suiting different types of driveshaft.

Anyone seen or heard of this before???

[Rusty's Uncle]

There are three different diameters of drive shaft that have been used on the Fiat 500 range. Ignoring the very early 500s that had a different coupling & off the top of my head the thinist were 17mms diameter (they look as if they would easily sheer) , next was 19mms up to 22mms on the L & R models which is the same diameter as the 126