X5 E70 Transmission problem

[Fastrac10]

Hi,
Got a 2010 X5 E70 about 50K miles.
Seem to have a transmission problem with it.
Get a bump sound when changing forward to reverse and reverse to forward.
Also when you come to stop it also makes a bump sound.
When you turn tight, it bumps on the tyres and knocks as the diff is slipping and you can feel it on all four wheels as they turn. A constant diff slip noise as the wheels turn.
Thought the problem was just on the front to start with, so changed front diff oil.....but no change, and it's on all four wheels.
Someone suggested servo motor.
Mine has a rectangular shape motor not the wiper shape type that some have.
Does anyone know if you can also change the plastic gear in this type.....and if so where you might buy one from...
Thanking you in advance.......

[X5Sport]

What tyres have you got fitted? Are the tyre pressures right?

What is the difference between the tread depth front to rear axle sets and tyre to tyre?

Have your tyres got a ‘*’ mark on the sides? This indicates they are homologated for BMW. That unfortunately means premium brands like Dunlop, Continental, Michelin, Bridgestone and one of two others.

Tyres with a tread difference of more than 1.5mm front/rear and/or fitted with non-specific tyres run the risk of breaking either the diffs or transfer boxes. The symptoms you are describing are very similar to those others have experienced with the wrong tyres.

The xDrive system is very intolerant of wrong rubber or wide tread depth as these cause transmission wind up. It also shows up more often on cars with staggered wheel set-ups.

This isn’t always the case, but is a frequent cause of what you are describing. It can happen on ‘*’ marked tyres but is much rarer.

[Alan Gunn]

Tyres all wrong i bet.

[Fastrac10]

Thought i'd replied, but looks like I haven't.
When the car was new it had 20inch wheels
About 20 months ago I fitted 19inch 467m wheels......think that is the number.
Stagged set, 285 rear 255 front.
I wanted an all weather tyre I could keep on year round.
After speaking with BMW and Vredestein direct, Wintrac Extreme were fitted, the same as their Quadrac five but with a softer sidewall.
Again, taking advice direct, these are run at 5PSI higher than normal, front and rear, to reduce side wall wear.
Tyres are flat across the top, very even wear and less than 0.5mm wear between front and rear.
They do not have the '*' mark on them.

[X5Sport]

It will be worth measuring the actual circumference of the tyres with a bit of string. At least one member on here found that supposed correct size tyres (which yours are) but without the ‘*’ mark were 32mm different and this lead to issues with his transmission which went away after fitting ‘*’ marked tyres. The only approved All Season tyres are from Continental, Bridgestone and Michelin.

One tyre place I spoke to a while back made a comment about how tyres expand under rotational force and this can also cause an issue as the diameter increases at speed and stresses the components, I would not be surprised if the softer sidewall also stretches and two sizes would stretch different amounts.

Interesting the BMW indicated you would be OK considering anyone with a warranty who fits other than ‘*’ marked tyres loses any support if there are transmission issues.

Try dropping the pressures and see what happens. I ran a winter set at full pressure due to cargo load and my X6 was very unhappy until I reduced the pressure to 32psi again. That was on 19” ‘*’ marked Pirelli winter tyres.

[Fastrac10]

Ok, Sorry it's taken a while to check.
Tyre pressure was Ok on every wheel.
Measured circumference on each tyre.
Both fronts exactly the same, which is 2mm smaller than rear.
However one rear was 14mm more than the other.
Not sure that would be a problem?

So measured 20 inch ones which I still have, all within 2mm of each other.
* rated runflats
Fitted this set back on, and did an 80mile round trip.
Problem still there, bump when you stop, and jumping on the tyres on full lock from a standing start.

Any thoughts please?......

[X5Sport]

Needs the transmission looking at by a specialist. If one tyre was 14mm different then that’s one wheel out of three turning at a different rate every revolution. It builds up until eventually the damage is permanent.

Are there any error codes logged by the car? Even if a warning light isn’t showing the car may still have the issue recorded in memory, hence getting it checked - though you can do that yourself with a code reader (such as Carly that I use) or one of the OEM readers. Generic code readers often don’t give a usable code to narrow the problem down.

If BMW told you those tyres were OK then I would be talking to them about this.

[Fastrac10]

Having now got these wheels off the car, I've re measured them.
They are all within 5mm. So very happy with that. String must have got in a tread when on the car, hence the difference.
Yes BMW garage were happy for these to be fitted, and now looks like it's not the tyres fault.

No error codes or warning lights showing, so looks like it will need to get looked at.
Would rather take it to a good independent garage by choice, if they have a correct code reader.

[Alan Gunn]

What is your location ?.
Somebody might recommend a good indi close to you.

[Fastrac10]

My location is near Berwick upon Tweed, about half way between Newcastle and Edinburgh

Any recommendations, and help very much appreciated