Simon's new Xantia V6 and Leaf blog

[white exec]

I think you can still search items on Mister Auto UK (I've done it a few times this week).
If stuck, you can also use one of their other sites (eg Mister Auto ES, or FR), which works in exactly the same way, and accepts the same search info (but not reg no, obviously). Would allow you to see choice and availability options, anyway.

[Mandrake]

More bad news - I had the front of the car jacked up today so I can investigate this problem further and the fault appears to be the gearbox not the driveshafts!

With both front wheels off the ground I tested it forwards and backwards.

Creeping forwards, no noise:



Creeping backwards, regular clunking:



Forward accelerating and decelerating: (quiet when accelerating, noisy when decelerating on the overrun)



Reverse at higher speed;



While testing it creeping in reverse I tried holding each front wheel still in turn to stop that driveshaft turning and the noise did not change, so definitely in the gearbox. So the gearbox is going to have to come out or be swapped to repair this fault so it's behind what I can do.

I've heard that it could potentially be the parking pawl making light contact when it shouldn't be (although why it would only clunk in one direction I'm not sure) otherwise I'm guessing it is a failed thrust bearing or a chewed gear. (Although I would have thought a chewed gear would be noisy in both directions?)

So for the foreseeable future the Leaf is off the road and I'm hoping the Xantia will stay reliable - it needs its MOT done in about a month and I haven't had a chance to fit its suspension arm yet. (probably good luck as it might have been off the road when this gearbox fault happened)

Rather than just running straight to Nissan to be gouged I'm making a couple of enquiries at independent EV specialists first. Could be a few weeks before it is back on the road as most of them are some distance away and the car would have to be transported.

[mickthemaverick]

Having watched this video Simon there seem to be two possible causes of "one way clonking". Maybe the earthing brushes shown at the first part of the strip down are damaged and/or out of seating, or maybe the loading spring on the parking brake mechanism has a problem? See what you make of it!!

[white exec]

I think Mick's suggestion about the parking brake mechanism is a good one.
The sound in the videos is very reminiscent of an 'interfering' park lock in a standard auto box, but with fewer and larger teeth.
The relative low frequency and bass note of the clonks seems to tally with the large 'teeth' of the Leaf p/brake.
My guess is that the mechanism (solenoid....toothed lever) has got sticky, sloppy or a return spring (there must be one, I'd guess) has given up.

[xantia_v6]

I think that it may be more serious than a loose parking lever, as the noise appears to be dependent on the direction of torque, rather than just the direction of travel.

One theory that seems plausible is failure of one of the bearings of the shaft with the park mechanism, which would allow the shaft to move closer to the parking mechanism. If I have correctly understood the direction of motion of the shaft, it would move towards the parking mechanism on the overrun and in reverse, and away from it in normal drive.

[RichardW]

Ouch that sounds nasty Simon!

Sure we could get the box out of that if you want to have a go.... got to be easier than an ICE car, surely??

[RichardW]

The parking brake actuator appears to be on top of the box and can be removed in situ. Might be worth getting it off, and seeing if a gentle pull on the operating level stops the noise. Perhaps the return spring on the brake pawl has broken. It looks in fact like you could pull the cover with the box in situ, but I think it would be much easier on the bench! Asking strong money for a 2nd hand box on e-bay, so worth opening it up to have a look!

[Mandrake]

I think that it may be more serious than a loose parking lever, as the noise appears to be dependent on the direction of torque, rather than just the direction of travel.

I agree. The parking brake mechanism is probably wishful thinking - as you note the noise happens depending on the direction of torque not the direction of rotation. Forward torque is quiet, reverse torque is noisy regardless of direction of rotation. (Which I tried to demonstrate in the videos)

My original thoughts when I narrowed it down to the gearbox based on direction of torque was a thrust bearing failure on one of the helical gears causing it to slide too far sideways under reverse torque until the gear is touching something like the inside of the casing. (The gears are a snug fit inside the housing with almost no room to spare)

One theory that seems plausible is failure of one of the bearings of the shaft with the park mechanism, which would allow the shaft to move closer to the parking mechanism. If I have correctly understood the direction of motion of the shaft, it would move towards the parking mechanism on the overrun and in reverse, and away from it in normal drive.

The parking brake mechanism with a broken return spring does look like it would "catch" more when the shaft is rotating towards the parking lever and less when it is rotating away, however on watching that teardown video I've realised the parking pawl is actually on the motor input shaft - which rotates 9x faster than the driveshaft outlets as the final drive ratio is 9 to 1.

With the wheels turning at about 5mph in the first two videos the clunking speed is about right for something turning at differential speed, but too slow for something turning 9 times faster than that, eg the parking pawl.

So sadly I think we can probably rule out the parking mechanism - it's more likely to be a bearing failure on one of the main gears allowing the gear to move in a way it shouldn't when the torque is in a certain direction.

[Mandrake]

Ouch that sounds nasty Simon!

Sure we could get the box out of that if you want to have a go.... got to be easier than an ICE car, surely??

The parking brake actuator appears to be on top of the box and can be removed in situ. Might be worth getting it off, and seeing if a gentle pull on the operating level stops the noise. Perhaps the return spring on the brake pawl has broken. It looks in fact like you could pull the cover with the box in situ, but I think it would be much easier on the bench!

The parking brake actuator that is mounted externally seems to just be a motor that rotates the shaft that controls the parking brake - so I don't think removing it would help much. But on reflection in my previous post the clunk rate is far too slow for the parking pawl which runs at 9x axle speed and has multiple detents per revolution as well. I think it must be a bearing on one of the helical gears gone.

Asking strong money for a 2nd hand box on e-bay, so worth opening it up to have a look!

The cheapest I can find from a low mileage car (my car needs a ZE0 box not ZE1) is around £1500

I've had a response from an inquiry to Electron Garage in Glenrothes - they were recommended to me and specialise in EV conversions of combustion cars/classics etc but also do servicing and repairs of regular EV's on the side. He said they would do a gearbox swap for £675 + the cost of the gearbox. He says they would need to source a low mileage second hand box but that he has seen them for £660 to £1000 in the past, so maybe has better sources/contacts than my quick google search. They're also only 55 miles from me so a fairly short trailer ride there and I could catch a bus to drive it home saving on return trailering unlike some of the EV specialists in England who are 300+ miles away. So at least I have one option option to me, still waiting for responses to a couple of other queries.

Part of me would love to tackle this myself but it's just come at such a bad time as I am up to my ears in other commitments and changes to our routines and working life. (Joshua starting school soon etc requiring changes in working hours and travel arrangements) Also my working conditions at home for a job of this size lifting out the entire drivetrain are diabolical. If I can't find a box anywhere near as cheaply as someone in the trade then it wouldn't save much money doing it myself anyway. I'm also lacking the service data and diagnostic tool I might need. So I don't think I'll be tackling this one myself like I did with the cell swap and charger repair on the Ion.

[NewcastleFalcon]

If you could come up with a solution to temporary transport difficulties, and create the space and time to personally investigate and find a solution to the gearbox problem, I am sure it would be a lot less expensive and ultimately more satisfying route. Not easy, but if the Xantia isn't the answer to that, maybe buying a temporary replacement of the functional but bargain basement variety, then selling when it has served its purpose may be something to consider. Believe me my bargain basement Micra is a very useful member of the stable.

Sure we could get the box out of that if you want to have a go.... got to be easier than an ICE car, surely??

Always better to share the misery and stress and work if you can, and who knows find the right place to do it, and one thing you will find out when you crack the gearbox case...exactly what the problem is.

Looking at what's in the box, as far as "gearboxes" go, could anything be simpler? The other thing about "whats in the box" is that it is parcelable, and sendoffable to a gearbox specialist.

With a gearbox in a box, and the right tools for pulling bearings off shafts etc, if indeed the problem is a bearing, how long would a gearbox specialist take to replace a bearing or two, and how different are Nissan leaf gearbox bearings from any other gearbox bearings. The answer to that question is I have no idea or indeed whether getting off the shelf bearings from the bearing makers, or Nissan to that spec is indeed a possibility.

I can offer little technical help, but lots of knowledgeable folk on here, and I've read your tale on Speak EV, so plenty of assistance on that score, and any pioneering work you do yourself can only help others.

Its an embryonic world the repair of EV's, and the net probably doesn't have a single incidence of your particular problem which isn't really EV Specific. The instant and partial failure with no warning, in a box that has been bathed in oil for 35,000 miles seems unlikely and despite your rejection on a very logical argument of the parking brake mechanism, that looks to me as the weakest link within that gearbox, and well capable of producing that ratcheting sound should it have failed for one reason or another. Looks like it gets pretty close to the transfer gear on the still from the video.

Good luck.

Regards Neil

[white exec]

This can't be the first one of those to have developed that fault.

[mickthemaverick]

This can't be the first one of those to have developed that fault.

Granted Chris, it seems unlikely, but someone has to be first!!

[Mandrake]

This can't be the first one of those to have developed that fault.

Not the first Leaf gearbox to fail, no. The guy from electron garage said he had seen gearbox failures on Leaf Taxi's before, but only rarely and only at quite high mileages, never at a low mileage like this.

However the problem seems to be very rare overall as I can find almost no complaints of gearbox failure/replacement on forums etc, and I've looked pretty hard when trying to find more info about what might have happened to mine.

[Mandrake]

For the inquisitive here is a complete strip down of the drivetrain of the Leaf. A lot of what is shown in the video probably isn’t required to get the motor and gearbox off the bottom though…

[NewcastleFalcon]

Sounds familiar I've started the vid at the section where he recorded the sound. In comments on the second vid one person said NISSAN had authorised replacement of the driveshafts and the reduction gear.



The second vid (just talking) where this comment was made. 2 years ago and "warranty work" I presume.
Jim Gassor responding

Just got a call from the dealer, apparently they have also replaced the reduction gear and 'both' drive shafts, which Nissan authorized. They state this has resolved the problem and that I can collect the car today. From my understanding, Nissan shipped them both the reduction gear and drive shafts at the same time and both items were replaced, which does not help to answer if the problem was in the reduction gear or the drive shafts. At least we know it was not in the traction motor. I will reply again after I pick the Leaf up this afternoon to confirm the problem is resolved for me.

Just picked up my Leaf from the dealer and drove home. Problem is definitely resolved. Replacement of 'reduction gear' and 'drive shafts' ultimately solved the problem. They had also been advised to comply with technical bulletin NTB-12-055F, which essentially instructs them to grease the axle hubs but they followed up with Nissan to state that this NTB did not resolve the problem.

Regards Neil