CVT brushes - symptoms?

madmezza

Ex. Club Member
Has anyone actually changed the brushes on a CVT gearbox? If so, what was the car like before and after?

I've had a scary conversation with Nissan about them. Basically, they are an inspection item at 27k miles, not a replacement (my car's done 41k miles). And apparently, when you take the brushes out, you need to shine a torch into the hole and look at the contact point on the clutch assembly. If it's all black, then there's been lots of arcing and the clutch assembly needs replacing - £900+VAT for the part!!!

So, I'd love to know what it feels like when the brushes are low, to determine if I need new brushes or a new car! My car seems to need more revs to pull away from a standstill - and so takes a little longer to get moving as the CVT control unit doesn't apply high revs straight away. Also, going up hills at 70mph (ish) can be hard work...!

I do lots of motorway driving, so the car's usually doing 70mph - do you think this will wear the brushes quicker??

Cheers for any info/advice
 

NeX

You're after my robot bee
Club Member
no idea mate soz :) i wouldn't personally touch an automatic, they take the fun out of driving...

i would change the box for one in a scrappy... not easy but cheap :)

nissan will always over charge, they wanted £130 for a rear wiper and i got one from a scrappy for £5 :) so don't go to nissan if you can help it. if you can get a new box from a breaker then i'm sure someone can change it over for not too much... or you could put in a manual box instead ;)

but for £900 you could get an SR micra so it depends on what you want to do :)

i hope this helps,
 
S

squigbobble

Guest
madmezza said:
Also, going up hills at 70mph (ish) can be hard work...!

I do lots of motorway driving, so the car's usually doing 70mph - do you think this will wear the brushes quicker??

Cheers for any info/advice
It's a strain in my 1.0, it has no performance whatsoever past 70mph on the level and motorway hills are a real bugger.

Anyway, the clutch is driven off the engine so high engine speeds'll make the brushes wear faster so lots of hills an motorways could be doing that. I think the main sympton for overworn brushes are jerky clutch engagement i.e. it drops the clutch instead of gradually engaging it. I dunno if the brushes on my car had been replaced before my dad got it but I've done 25k miles in it and they've never been touched.
I'm not sure about the black deposit; I've changed the brushes on an old washing machine motor and that had a black deposit all over the contact surfaces on the commutator, I just assumed it was carbon deposits and the new brushes seemed to wear it off a bit with no trouble at all. Whether this is applicable to a powder clutch is another matter. One thing to remember is that copper oxide is also black so arcing could also cause it.

Another thing u could try is topping up the transmission fluid, on the off chance that it has an effect.
 
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madmezza

madmezza

Ex. Club Member
Thanks for the info.

I've put some pics of my brushes up on another thread - things look alright, so I'm quite pleased!

I just noticed that the interval for changing the gearbox oil is 12000 miles - I've done just under 30k since getting the car, and I don't know when it was changed before that!! I know the oil is critical for the operation of the gearbox (pressurised oil drives part of the gearbox), so maybe a change will do some good... (I wonder if it's a bit hygroscopic - maybe water in the oil reduces the effectiveness (like brake fluid) or something like that??)
 

NeX

You're after my robot bee
Club Member
yep keeping the oil new and free of particals and water is very important. if you haven't done it yet then do it now!!!
 
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madmezza

madmezza

Ex. Club Member
NeX said:
no idea mate soz :) i wouldn't personally touch an automatic, they take the fun out of driving...
i hope this helps,

I've got a Lotus Esprit turbo for fun driving! I thought auto's would be a bit crap, but I've been suprised - you can do loads of other things while steering with your knees!!!! (OK, don't take that too seriously - I don't want to be responsible for anyone killing themselves!).

The box is OK though - think it might need a fluid change, but she still accelerates OK on kickdown.
 
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