Technical Damaged Transmission - Inside

[fixfiat]

Went to replace the clutch (due to scraping sound when pressing, and clanking noise when in gear).
Turns out the clutch is fine. Tried draining the transmission fluid before taking everything apart, but there was no fluid in it! Turns out the transmission has a large hole between the interior of the bell housing and the gear box.
Is there any way to fix this, or do I have to buy a whole new transmission assembly?
Vehicle is a 2012 Fiat 500 Sport - Manual. What years and models are compatible?

 

[jrkitching]

It looks like something has come adrift inside, got wedged between the crownwheel and the case, and fractured the case. You've been most unlucky; this is the first time I've seen this happen on a 500.

Given that whatever has come loose has been grinding about inside, and that it's been running without oil for an indeterminable period, that transmission is scrap.

As you'll pay a hefty surcharge on a rebuilt transmission due to the casing damage, and a new factory unit will likely cost more than the value of the car, I'd say your best option is to look for a suitable used tranny. I can't be exactly certain about compatibility for the North American models, but a cursory search would suggest that one from any manual 1.4NA donor car up to 2015 will fit - Pop, Lounge & Sport are just trim variations and use the same tranny.

Have a look at this ad. I'm not suggesting you buy it, but it does contain information about compatibility.

 

[Pugglt Auld Jock]

Reminds me of the problems VAG had some years ago. They were riveting the crown wheel to the diff spider gear casing and the rivets would sometimes, at random I think, come loose which then allowed the crown wheel to mill it's way through the casing, eject most of the oil and ruin the gearbox! I haven't heard anything lately about this being a problem for them any more so presumably they overcame it.

Anyone know if the 500 gearbox has a bolted or riveted crown wheel?

 

[jrkitching]

Reminds me of the problems VAG had some years ago

This also happened with reasonable frequency on the early BL transverse engined cars, where the gearbox was in the engine sump and shared the same oil. One of these failures was my first major car repair, on an ADO16 (the OP, if old enough, will know this as the Austin America). The damage was surprisingly similar to the OP's excellent pictures, and the resulting mechanical carnage totally trashed both engine and gearbox. I bought two complete scrap powerplants for £5 each - and somehow managed to create one good unit out of the parts, though it took me the best part of a week. I've still got a couple of small parts from that rebuild in the back of a drawer somewhere as a memento.

First time I've heard of this on a 500, though.

 

[Pugglt Auld Jock]

Although I don't remember the diffs being a particular problem on those JR, I do remember, from time to time, sorting out worn idlers (the gear between the crankshaft/flywheel and input shaft. They used to wear both the needle roller bearings and their thrust washers and if not sorted out would end up destroying the end plate. I also remember the "fun" of properly shimming the primary gear, the big one on the end of the crankshaft. If it had too much axial movement the primary seal would wear rapidly and then oil could leak all over the clutch. We used to do a primary seal every time we did a clutch and I still have the home made pullers for both flywheel and primary gear:

I also remember the "ever leaking" gear change seal. We used to put 2 seals in one on top of the other with HMP grease packed between them. Stopped the leak for a while but it always came back. You could walk down any street and tell which houses owned BMC/BL vehicles from the position and size of oil stain on the driveway!

 

[Ralf S.]

Impressive that the beast was still running, albeit with some noise.


Ralf S.

 

[fixfiat]

Impressive that the beast was still running, albeit with some noise.


Ralf S.

Ya, it drove like a champ. If I hadn't decided to replace the clutch, I would have never even guessed something this bad was happening in there.
Ended up sourcing a used transmission with 20,000 miles less than what the car has. Installation was a pain! Might as well have removed the entire engine first. Took me about a week working around 2 hours a day. Most of that was time driving back and forth from the store to buy another tool I needed. Installed a new clutch while I had it apart and this thing shifts like butter. It has over 140,000 miles, yet drives better than the other one I have with 98,000 miles.
Cost me $650 USD for the transmission. But seeing as how I got the car for $1,800, I'm laughing.