Took the end cap off a 6 speed gearbox and found that outermost synchronizer ring is broken to bits and pieces.

What gear is this? 6th?

What to do with it?
Would it be difficult to replace it myself? Where to get required parts?

https://photos.app.goo.gl/NvhHDTMsYK7GM8yj1

I was not aware that the Seicento used a 6-speed gearbox.

The gear inside the end cover will almost certainly be the highest gear in the box, so either 5th, or 6th if you have 6.

The teeth on the synchro ring are looking a little distressed too, but can't see what the ones on the gear are like. A failure like this is usually the result of lots of abuse, or a lack of oil. There is likely to be wear in the rest of the box too. If mine, I'd be taking the whole thing to bits and fully assessing it before deciding on any repair.

Fiat's parts listing does usually list all the internal bits in the gearbox, so anything should be orderable, we hope, but finding the extra diagrams can be more difficult, but any Fiat dealer should be able to do so. If the gearbox belongs to the car, finding part numbers should be easy. If it is a gearbox from another car, you'd need to know the source.

This could be helpful. I've assumed Seicento 1.1, so you may need to select your vehicle.
https://www.fiatdalys.lt/en/catalog/diagrams/212/1E/0/0/M2,M3/0/GS/gearbox

Or browse from here:
http://62.106.11.160:8000/navi?SBMK...VIOUS_KEY=PARTDRAWDATA&SB_CODE=-1&WINDOW_ID=1

In UK the brass / yellow coloured ring is called a baulk ring .
Were there any problems driving with the gearbox before you removed the end cover?

Or called synchro ring as previous post

Thanks for all the links, very helpful!

It's a six speed box (and 1.4 16V) off a Stilo that we are manhandling into a Cinquecento.

Bought Stilo couple of months ago and drove 300 km back home. Gearbox worked just fine except the 6th that tended to have a slight crunch when shifting but still engaged. No other noises.

Seller said that the gearbox has a leak. When we took the end cover off there barely was any oil in there so it was definitely oil starvation!
There didn't seem to be too many metal flakes in the bottom of gearbox - only some brass looking small flakes which must be from said synchro.

I agree that it would be good idea to take the gearbox apart and replace everything, but we lack the know-how and time is pressing on. There is a rally soon which we hope to partake and lots to do to get car back on the road.

The idea for now was just to fix the sixth if it is easy enough, fill up with oil again and see how it goes. When we have more time then we could replace all the bearings and other important bits and pieces.

If your rallying, the only option is to replace syncro's with dogs.:devil:

Dogs would be great! So far gearbox hasn't been holding us back a lot though. Driver is s.h.i.t and that is where the biggest losses come from.

http://62.106.11.160:8000/navi?SGRP...SUBGROUP_7&SB_CODE=-1&WINDOW_ID=1&DRW_NUM=2|0

Part 10 looks like 6th gear with 36/47 = 0.766 ratio. This would mean that the syncro I am looking for has part number 46772295. Am I correct?

If you've chosen the correct listing for the gearbox, that would be the correct part number for the synchro ring. They are the same for 5th and 6th gears, possibly for the others as well.

Replace the nut too, number 6. You don't want it coming loose. Usual way to loosen and tighten it is to engage two gears at once. This is usually with the gearbox partly dismantled, so no selector mechanism fitted. Might be able to release the selector forks from their rods to allow engagement of two at once.

That is valuable information!

Ordered a nut and a synchro ring.

Thanks :worship:

Stilo eLearn (Fiat workshop manual) says the nut is tightened to 118Nm. So very tight!

When removing the sliding sleeve,beware of the 3 small springs and rollers under the sleeve.these hold the gear in neutral whilst using other gears. The bolt is left hand thread (should have cuts on the edges) so turn it in the tightening direction to loosen it.!! Hope this helps.

Won't be a while before we have time to deal with it. Got to keep this remembered too or we will lose those little springs.

Done. Surprisingly easy job.
Didn't see any bolts with left hand thread. Just removed the nut, pulled gear off and put everything back together.