Possible transmission problem

[AVI-8]

Hi folks,
My son came down today with his latest purchase, a 2012 X3 35D, I took it for a test drive (goes like stink!) however there is a possible problem with the transfer case ? I wouldn’t describe it as a judder like what you feel when the disks are warped or the control arm bushes knackered, it’s more of a very temporary loss of acceleration for a fraction of a second then it picks up and happens again, this happens a couple of times per second approximately so it is like a kind of juddering.

The tyres have all got good tread but I did notice that the rears have a couple maybe 3mm more tread and I know that this can cause issues with transmission, I will be changing all of the fluids in the near future as I don’t believe in sealed for life!

Have any of you guys had this problem with one of these cars? And if so what was the cause I will be phoning the supplying dealer tomorrow, independent garage not BMW to inform them of the problem, he only picked it up today, I know a BMW tech and he’s going to take it for a test drive tomorrow evening before it’ll get returned to the garage where he bought it on Friday
The car has 70000 miles and a full dealer service history but this is a definite fault which isn’t really acceptable on a car which he’s only just bought.

Thanks in advance

[Alan Gunn]

It could well be the tyres.

[X5Sport]

Tyres is the first place to start. Difference is out of tolerance and if they aren’t ‘*’ marked it could be more significant. One member on here found correctly sized, but not ‘*’ marked, tyres to have a 32mm difference in the circumference at new. Try full right and left lock at walking pace. Any juddering or jerkiness means transfer box or diff are unhappy and could have been damaged.

[AVI-8]

Hi, just to update the car is now fixed, Pirelli was on the rear and Dunlop on the front, the dealer fitted new Pirelli on the front and now it’s ok so it seems that these cars are indeed very susceptible to differences in rolling circumference. It’s going to get the transfer box and main gearbox fluid and pan changed next week as a precautionary measure.
Thanks for your replies guys.

[X5Sport]

Sensitive to both tyres and tread depth. 1.5mm is the permitted tolerance between axles. Unfortunately that means loss of a single tyre (puncture/wear etc) can mean the whole set has to be replaced in order to stay ‘in limit’. Keeping the tracking right is a good idea, making use of Hunter based all-wheel laser alignment being the preferred choice. These cars often came out of the factory poorly set.

I had a damaged sidewall last year and because the set were 2/3rds worn, a new tyre put the transmission out of limit. Almost £900 for a new set of 20” ‘*’ marked Contis fitted.

[AVI-8]

Luckily the tyres are all the same size unlike my X5, so I’ll rotate them front to rear every 5000 miles or so to keep them wearing evenly.
And yes our local alignment centre has a Hunter machine so it’ll be getting a full alignment, I got it done to my 1 series last year and it did make a good improvement to the way the car drove.