I have a P reg Bravo 1.4 sx (seems to be where all the problems are), which I have had for a few months. there are various issues i have with it involving idling, small oil leak, bit of a misfire, but there is one huge proble, which is this:

A few times now, when driving for a reasonable period of time (about an hour) on motorway the car has all of a sudden disengaged itself. I have not touched the clutch nor the gears yet in an instant the revs go shooting upwards (as if revving when in neutral), and I lose all drive through the accelerator. The engine is running as usual, but all i can do is free whell to a stop. If I then try and put the car in gear, i can select the gear fine, the clutch feels fine, but there is no bite whatsoever, the clutch is engaged in any gear yet the car simply revs without moving.

The strange thing is that after about an hour the car works fine again (as if it has cooled down??). We assumed a clutch problem, and so the car has had a new clutch, but yesterday it happened to me again.

Please can someone shed some light on this as I'm at a loss, and clearly it makes the car hugely dangerous to drive.

Thanks

sounds like the differential on the gearbox.

Cheers for that. I'm afriad i'm not especially mechanical. How come it only happens when i assume its hot? I've driven this car around for 2 months, but because only doing 30 miles at a time every day there was never a problem??

sorry i think i read your first post too quickly

a clutch generates heat. slipping clutches usually gain heat faster than they can lose heat. temperatures rise to a level where friction materials lose their adhesive properties, metals lose their strength, wear rates become excessive etc. it sounds like thats your problem so its time to get a new clutch fitted.

thats the strange thing: we thought it was the clutch, so I just had a new clutch fitted. then the first big drive (over 20 miles) since then this break down happened again! I sat on the side of a motorway for 5 mins, tried to get the car moving again and it went!! Then crawled the rest of the journey on b roads to be sure! I thought after a new clutch this would go away, but apparentely not. Could something leaking onto the clutch be causing this, or would that not have such a sudden, drematic effect??

if something leaked onto the clutch (could only be engine oil or gerbox oil) it would never regain drive correctly, oil contamination kills a clutch.

i think i remember now why i originally suggested the diff. the problem happens suddenly, one second you're fine with no slipping, next second you lose all drive. if it can happen in any gear then it has to be due to the differential.

that sounds a lot like the problem! Only ever happened in fifth gear, but i suspect thats more to do with the fact i'm usually in fifth gear, especially when travelling any distance.

Is that likely to be a new gearbox job then? I suspect this is not going to be worth sorting!!

We had a similar problem on a bravo a few years ago. Lift the car in the air (ie no load on the wheels) and the gearbox would drive the wheels- put it back on the ground, no drive!

In the end it was a faulty diff- the teeth are fitted using heat, similar to flywheel ring-gear (this would explain your problem- as the gearbox heats up, the teeth are expanding greater than the rest of the diff until they loose grip).

A re-con (exchange) 'box isn't silly money- probably cheaper than getting the 'box stripped and rebuilt.

£50-75 for a scrapyard box, £100 fitting. could be worse.

Yeah, that is nowhere near as bad as I expected. Cheers for the advice!