Possible diff fault

[davidmpye]

Hi,

I've noticed a problem with my 2014 Leaf (54k miles) and I wonder if it might be the diff.

Driving along 'straight' is fine - no noises etc. The problem comes with low-speed cornering, where you get a very clear feeling that one of the front wheels (usually the one that has the longest 'arc' to transcribe when going round corners) slips - particularly in the wet, it feels like the car just doesn't want to go round the corner and would prefer to carry on straight!

Looking at the tyres, the outer part of the front tyres are noticeably more worn than the inner parts.

I've had the tracking etc checked and all is spot on.

I've tried jacking the car up and putting it into drive with the wheels in the air - interestingly the passenger front wheel spins and the driver side does not. If you manually jam the passenger side wheel, the drivers' one does then turn. If you put the vehicle in park, and turn one wheel forward, the other does turn fairly freely backwards so that part of things does seem to work as expected.

I don't think the problem is driveshafts, because I can't see how that would make the skidding happen - though I can see how it might make clacking noises.

Any thoughts or suggestions would be very welcome!

David

 

[cornbinder89]

I think you tests have rules out the diff. Ackerman (sp?) angles or geometry when the wheels are turned can effect how well the track.
I know you said you had the alignment checked, but I would talk to the alignment shop or choose another and tell them of your concerns.
Because of how the weight is distributed on the Leaf, I have noticed a tendency to "plow" straight on slippery ground when turning and applying power, but letting off the power and slowing a bit solves that issue.

 

[Cameron]

I think you'll find that with tyres, once an undesirable wear pattern has started (like through misalignment or caster/camber issue), they will continue to wear in same/similar pattern. Bear in mind that the minimum tread is around 2-3 mm (1/8"), so when a low spot/area develops on your tyres, they're likely toasted. It's a near impossible scenario to correct an issue with noticeable wear on the shoulder and hope that the wear won't get worse. Prevention is better than cure - tread wear indicator tool is your friend.

 

[aqn]

If you put the vehicle in park, and turn one wheel forward...

This doesn't sound right. If the vehicle is in park, the parking pawl would engage the transmission and it won't turn, therefore the wheels won't turn either. Did you mean "put the vehicle in neutral"?

 

[cornbinder89]

Differential is after the gear reduction, the reduction gear is held stationary but the spider gears inside are free to rotate. This is just as it is on a conventional car with a transmission, when the ring gear is stationary the axle shafts will move at the same speed in opposite direction

 

[Chad E. Mo]

Sounds like classic misalignment, toe-in, camber, or both.

I'd take it to a shop that has the full 4-wheel alignment rack and provides a printout of before/after with specs.

 

[davidmpye]

Hi,

Thanks for all your replies - the vehicle's off to Nissan tomorrow to see what they think.

I still think it's a diff fault, because it isn't slipping as easily as it should.

Simply put: If you jack up the front of the vehicle and put it in drive, both wheels should turn. The fact that only one does so (despite both being free to turn) suggests that the diff is not distributing power correctly to the front wheels. In addition, you have to jam the turning wheel completely before the other turns at all.

We'll see what they say though!

 

[cornbinder89]

More likely a brake hanging up. any fault in the diff would cause either no power to the wheels or both wheels to spin with no differential action at all.
Less likely would be a wheel bearing issue

 

[davidmpye]

I thought that too, but I can spin the wheels by hand with it in N without noticeable difference each side....

 

[cornbinder89]

Without being there and seeing/feeling for myself, everything is a guess, but diff problems will make noise, either grinding or bearing noises.
There will be more friction when spinning with it in park, as the spider gears have to spin.
A final drive that didn't make noise but failed would be very unlikely.
It is hard to explain without visual models, but any failure in a diff is very unlikely to cause what you are describing.
Report back once Nissan has had their say, I'd be interested to know what they found.

 

[Learjet]

do you have the e-pedal on?

Isn't there some small torque automatically applied to the motor when the car is in drive?

 

[Drew21]

Assuming the Leaf has an open differential, the behaviors described by the OP are completely normal.

With an open differential, torque moves to the wheel with the least resistance/traction. That's how you get the classic "one tire fire" when you try to do a burnout in either a front or rear wheel drive vehicle with an open differential.

In the situation described by the OP, one side has slightly more resistance than the other (perhaps because of the different drive shaft lengths or maybe one brake has slightly more drag) and 100% of the torque is transferred to the other side, causing only that wheel to spin. It happens on every cheap front wheel drive hatchback I've driven from the 1980s through today, including my 2010 Honda Fit Sport and 2014 Nissan Leaf SV.

Conversely, if you had a locking differential, both driven tires would spin with the axle in the air and the vehicle in Drive. That's why a locking differential (or at least a limited slip differential) is a critical tool for sports cars, proper four wheel drive vehicles, etc.

As far as the other scenario described, where the front wheels turn in opposite directions when the car is jacked up in Park, cornbinder explained that perfectly. I will add that this scenario illustrates why it's so important to use both the parking brake and wheel chocks when jacking up a car - once you jack up one front tire the other side can turn, even in Park.