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Technical Transmission slip 80SX bravo

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Technical Transmission slip 80SX bravo

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symonh2000

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Hi All..

I have a problem with my Bravo.

When pulling away, rapidly there appears to be a slip in the transmission.
When this first happened, I thought the clutch was slipping, so I have fitted a brand new clutch, but the slipping is still there :confused:

There is a slightly rough noise from the transmission when the sliiping is taking place, and it only happens when pulling away quickly. Not when changing gear, going uphill etc..

Has anyone any idea as to what the problem may be?

Also when I drained the oil from the gearbox before changing the clutch the oil was silver due to having lots of metal in it.
 
Last edited:
Just posted this like 5 minutes ago in the Punto section:

Differential. The 1242cc puntos (I'm assuming this is yours) use a shrink-fit crown gear on the differential like the Bravo 1.4 and I'm guessing this is what's gone. Assuming you're clutch was fine before, but either way you're going to have to take the gearbox off and it would make sense to change the clutch anyway.

Do you know the gearbox number? I have a Fiat gearbox overhaul manual so if you know the number I can look to see what type it is and if this is a possibility. I think it would be a C.514.5.10

Best bet is to take the gearbox out and take the diff cover off. If it's knackered get a scrapper gearbox + diff for say £120, that's what I did.

Be careful because if the diff is slipping and then locks with the clutch out in gear you will wreck the engine as the timing belt won't hold that force.

Et voila:



DSC01272_2.JPG
Click to expand...

My thread here might be of interest:

https://www.fiatforum.com/bravo-brava/203294-death-misadventure.html
 
Last edited:
Thanks mate.

That doesn't look good.

If I had known that the diff was failing, then I would have swapped the clutch at the same time as a gearbox. :cry:

Never mind. At least I know how it all goes together now. :(
 
The thing is the car is only a runabout for the girlfriend to learn to drive in, and for us to use for work.

I have plenty of things to do on the Alfa GTV, without having to work on the Bravo as well. :(

Never mind.
 
Do any other gearboxes fit other than the Punto sporting?

The 1.2 8V box looks the same, but is it?

Cheers.
 
Punto 1108, 1242 spi and 1242 mpi use C.514.5.10

Uno 999, 1108, 1372 (hence bravo 1.4), and 1498 use C.514.5.13

I assume the final drive or gears or both on the two boxes are different and I'm trying to determine how exactly.

My guess is even a C.514.6.10 from a Punto 1108 6-speed would fit but the extended casing for the 5th and 6th gears would probably foul the body. I can't remember how close it is under there and you might need a different linkage etc. Would be nice though.





 
C.514.5.13 gear ratios:

1st - 3.909
2nd - 2.158
3rd - 1.480
4th - 1.121
5th - 0.902
Final - 3.886

...

Just stopped myself, the 1.2 16v Bravo uses C.514.5.13 same as 1.4 so you could get one from a Bravo 1.4 or any of those Unos.

You'd have to find someone with a Punto service manual to find out if the ratios are different on the 510 box, I'd assume so.
 
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Cheers mate.

That opens up my options for a secondhand box anyway.

Like I say, the Bravo is purely a runabout so I don't need to go for a 6 speed box or anything fancy. I just need to get it functioning again. :)

That is a very poor design though, if a car with as little torque as a 1.2 can make the ring gear slip.
 
No probs, and once it's working it's done (y)

Mine's done 6k on the replacement but it could always happen again I suppose. I'm afraid it's just a throwback from the old Unos, other Fiat boxes have 12 bolt construction so :confused:
 
Dan89 said:
C.514.5.13 gear ratios:

1st - 3.909
2nd - 2.158
3rd - 1.480
4th - 1.121
5th - 0.902
Final - 3.886

...

Just stopped myself, the 1.2 16v Bravo uses C.514.5.13 same as 1.4 so you could get one from a Bravo 1.4 or any of those Unos.

You'd have to find someone with a Punto service manual to find out if the ratios are different on the 510 box, I'd assume so.
Click to expand...


Dan, I don't suppose you have the ratios for the C.514.5.10 do you?

I am tempted to chuck one in the Bravo and see what happens as they are far easier to get than the C.514.5.13

Cheers.
 
symonh2000 said:
Dan, I don't suppose you have the ratios for the C.514.5.10 do you?

I am tempted to chuck one in the Bravo and see what happens as they are far easier to get than the C.514.5.13

Cheers.
Click to expand...

I'm afraid I don't, if you ask one of the Punto guys with a Fiat service manual they should be able to help (y)

It's in the intro & tech data section near the end.

Dan
 
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Right quick update.

I managed to find a 1.4 box quite local to me for £50

I am going to pay cash on collection. The seller tells me the diff is ok and the box was tested before removal from the car but is there any easy way to tell?

I suppose I could take the diff cover off and check the screw isn't sheared couldn't I?

Cheers.
 
Yeah you can take off the plates (4 bolts each) and the cover (4 bolts I think) and have a look inside (y)

Otherwise there's no way to know until it's on the car
 
Cheers mate.

Thats what I will do.

I don't want to put it all together and find it has the same problem.


Out of interest is there any way of modifying the diff to stop it happening again? Maybe welding the ring gear to the diff with a tig welder?
 
It's a good idea but I think it would make it out of balance and the heat you would be putting into it wouldn't really help either. It would be possible to get a bolted crown wheel but they have a different number of teeth so you'd need a whole different box and then you've got the ratio problems.
 
Thats a shame. Still if the replacement Diff lasts a year or two I will be happy. The car will probably have rusted away by then anyway.

My GTV has a bolted crown wheel, but the Diffs still fail. Normally the small planet gears shear off and end up going through the casing.

I might get a Q2 fitted to stop it happening. :D
 
Righty ho. I have the replacement box and I have taken off the diff cover.

I found the roll pin that sick inside the diff and it appears not to have sheared off. Everything seems to line up here.

IMG_0996.jpg


There are a few marks on the planet gears, but I would expect that on any used box.

IMG_0997.jpg


I can't see any evidence of the ring gear having slipped. The edge of the ring gear also lines up perfectly with raised edge of the diff.

What do you guys reckon? Is it a good-un? :)
 
It does look like a good one (y)

There is no evidence of slippage, if you look at my pics on page 1 you can see my crown wheel had moved away from the raised edge and this had also caused scoring on the crownwheel when it slipped.
 
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