Nissan Micra CVT geerbox failure - advice, please ...

Hi Folks,

Last week the CVT gearbox on my mother's K11e Micra stopped working. By which I mean it just suddenly stopped transmitting drive to the wheels. No bangs, squeaks, rattles, thumps or clatters - just ... nothing.

According to the Arnold Clark garage where she bought it four years ago, and where it has always been serviced. it needs a gearbox repair costing £2000. They haven't taken it out yet but claim to have diagnosed this from tests.

I'd be very grateful if anyone could let me know if ...

1) If This is a known problem with the Micra CVT?

2) If two grand is reasonable to repair the box?

3) Of a good independent mechanic in Glasgow who would fit a second hand box if I sourced it for her

Many thanks in advance,

Ian

Reply to
Ian Johnston
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Just google for it !! There are problems, the electro mechanical clutch is often. the problem .

Reply to
MrCheerful

Yes, the iron filings clutch is a known weakspot. It may need replacement brushes, it may be totally shagged.

Tim. .

Reply to
Tim..

I'd be very surprised if this garage knows the first thing about any auto box. They will simply fit a re-con.

You need an auto gearbox specialist - and one who actually fix the things rather than just fitting someone else's re-con.

I can't help with one local to you, though. But 2000 quid sounds way over the top.

Reply to
Dave Plowman (News)

Ta. That would certainly match a complete and silent breakdown. Now, how can I be sure that Arnold Clark (100 miles away from me) have actually checked the fuse ...

Ian

Reply to
Ian Johnston

Thanks. Arnold Clark have apparently been in touch with a local auto box specialist who told them what tests to do. Unfortunately the only reported diagnosis was "two grand" so I am phoning them today to try to find out a bit more detail.

Is the clutch between the engine and box (like an honest, god-fearing Borg and Beck) or is it buried somewhere in the depths of the CVT unit? Sorry to ask such a basic question, but I don't have any experience of these things and I have to try to sound intelligent about them later today ...

Ian

Reply to
Ian Johnston

Frankly, if Arnold Clark told me the sky was blue, I'd be looking for a second opinion. Take it to the auto specialist directly and don't let Arnold's monkeys touch it.

Reply to
the.best.names.are.gone

If it was my car, that's what I'd already have done ...

Ian

Reply to
Ian Johnston

The clutch is in the regular place, and infact looks just like a manual boxed clutch- only there's wires to it, instead of a cable.

Chances are that the CVT box itself is okay, but obviously you cant tell without a working clutch.

Tim.

Tim.

Reply to
Tim..

Thanks. Sounds as if I need to get the car moved to somewhere who really knows about such things, as I suspect that Arnold Clark are suggesting an entire Nissan replacement gearbox to cure a broken clutch ...

Ian

Reply to
Ian Johnston

Hi Tim..

Purely out of interst, do you happen to know what the principle of these clutches is? Are they eddy current coupled, or a simple magnetic type? Do they fail in some way electrically, or mechanically?

I'm guessing from the OP's description of sudden failure with no noises that it's more likely to be electrical. In that case, I wonder if anyone repairs them. If it's a winding that's gone open circuit, that should be fixable.

I worked on eddy current speed control devices in industry years ago; they were crap! Pretty much all replaced with AC inverter drives now.

Chris

Reply to
Chris Whelan

In a nutshell, and largely simplified, a sealed drum betwix engine and box contains 4 plates (2 each side) and some iron filings. A electro magnet is formed in the plates, which when supplied with current causes the powder to stop being a powder and progressively 'stiffen' into a solid (depending on current ) which then transmits the drive between the 2 sets of plates.

Power is supplied by a brush / slip ring unit to the rotating assembly, via a power stage, via the ECU.

Tim..

Reply to
Tim..

Common enough with dealers. It would be different if it was a warranty repair where it's *their* money that's being spent.

Reply to
Dave Plowman (News)

Thanks Tim..

That's just about the simplest type of variable electrical clutch then.

The OP's problem could be caused by something as basic as a sticking brush;

2000 quid to fix that seems a touch excessive :-)

Chris

Reply to
Chris Whelan

Thanks Tim..

That's just about the simplest type of variable electrical clutch then.

The OP's problem could be caused by something as basic as a sticking brush;

2000 quid to fix that seems a touch excessive :-)

Chris

Reply to
Chris Whelan

Thanks Tim..

That's just about the simplest type of variable electrical clutch then.

The OP's problem could be caused by something as basic as a sticking brush;

2000 quid to fix that seems a touch excessive :-)

Chris

Reply to
Chris Whelan

Or a knackered power-stage.

Tim..

Reply to
Tim..

Indeed. I wonder if a small business might take on repair of these at some point in the future?

Chris

Reply to
Chris Whelan

I've been chatting both to Arnold Clark and an independent automatic transmission specialist. The fault code is apparently "O/P PULLEY SPD" which I think translates as "The wheels aren't going round" or in layman's terms "No shit, Sherlock".

Apparently this one doesn't have a powder clutch - it has a torque converter. The most likely cause of failure is thought to be a snapped belt, and that, I am told, normally means so much damage to the insides that a recon gearbox is necessary.

So that's what my mother's going for: a cool £1635 + VAT fitted, but she likes the car and it's in generally good nick. And she might get off with less if it does turn out to be repairable. She'd rather have the security of a proper warranty, hence not a second hand box.

Many thanks for all the help and advice. If any of the above looks insane, please let me know. Feedback on John Mackie Automatic Transmissions of Tollcross in Glasgow also welcome...

Ian

Reply to
Ian Johnston

No torque converters in these CVTs! The alternative to an electromagnetic clutch is the older style hydraulic clutch. These are usually reliable. But, the hydraulic pump may have given up. A snapped belt is also unlikely. Your specialist will probably check the line pressures first to see if the pump is at fault.

Or perhaps it's something sticking in the valve body. Not too expensive to remove and look over.

Reply to
Mark W

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