XSeries-forum

Hi,

I have 06 3.0sd 110k miles on the clock. It just developed a jerky drive when accelerating and im not sure where to startvdiagnosing the fault, I thought id start with the plastic gear on the actuator for the transfer case but I haven't got any lights on the dash.

Thanks in advance.

Sorry to read of your troubles.

Have you had a diagnostics ‘dump’ done yet? There are a number of possible fault conditions that will not bring up any warning lights but will be recorded in the on board hardware. If possible get the diagnostics done with a system that will produce the proper BMW error codes rather than generic codes. That will make it easier to track down where to start looking and save you taking ‘shots in the dark’ with the fault finding. Some Indies and all main dealers have the correct kit. There are a number of systems you can get for yourself too - though the cost may be little different from an official diagnostic check.

You could be looking at tyres (as in type and tread depth), something loose in the system (prop-shaft/driveshaft joints), transmission fluid levels, the transfer box, gearbox itself, torque converter, suspension bushes, binding brakes and so on. This is why diagnostics is often the place to start and see what is logged.

Thanks, I will do a ecu dump and go from there. Just had a new set of Avon tyres on the front and it started with the drive problems, they are the correct size but not * rated. Rears are fine tread depth but again not * rated.

All xDrive cars are very sensitive to tyre choice. If the problem started when you changed the tyres then the chances are they are at the root of the issue. The tread depth front/rear must not exceed 1.5mm or the difference in circumference causes transmission wind-up (which you will feel as jerkiness or a rumble) and will break something (diff or transfer box) if ignored.

The recommended tyres (especially on staggered setups) are premium brands preferably with ‘*’ marking. Unfortunately that comes at a price (£880 the last time I changed the X6 tyres). Square setups are less of an issue but the tread depth limits must be adhered to. That often means replacing as a complete set at the same time

BMW are not alone with this, other premium brands with this type of transmission system and staggered wheel setups (or square with tread depth limits) have the same problems. You can also use MO/MOE marked tyres (Mercedes Original (Extended)) as BMW are OK with those too.

As above.
Change the rears for the same as you fitted to the front.
ASAP i would say and hope the damage isn't done already.
How long have you had the new front's on.

It would be interesting to know what the rear tread depth is ?

The fronts have been on for about 4 weeks

Supercooper04 wrote: ↑Sat Apr 17, 2021 7:26 pm The fronts have been on for about 4 weeks

And what tread depths are on the rear tyres?

We are interested in the difference front to rear as this seems to be when your issues started , front new will be approx 8mm , the thinking is now you replace all 4 together if possible to avoid big front to rear differences (yes I know if you have come from a 2wd car this seems a bit of a pain and a waste) small differences as said above are ok

Thank you all for helping out the rear is 4mm and the size is 255/40 19 100Y the front are 235/45 19 different brandvfront to rear and neither are *

I'm far from the most knowledgeable on this subject but 4mm on the rear and circa 8mm on the front is well outside of BMWs parameters. Non * rated tyres will probably exacerbate the issue.

I think your first step has to be replacing the rears with matching brand/type rear tyres. Crazy, yes, expensive, yes.

Welcome to the world of BMW X drive ownership

sapphireblack wrote: ↑Sun Apr 18, 2021 6:55 pmI'm far from the most knowledgeable on this subject

Me neither, but I completely agree.

sapphireblack wrote: ↑Sun Apr 18, 2021 6:55 pmWelcome to the world of BMW X drive ownership

Quite.

If you can get hold of kkx5 (member) via PM, he will tell you to change the set and fit ‘*’ marked rubber. His job is fixing broken BMW transmissions caused by exactly what you seem to be reporting. Unfortunately we’ve seen reports of shattered diffs and broken transfer boxes caused (usually) by incorrect tyres or tread depth. The E83 is amongst the most sensitive (closely followed by the E70/71).

I had one tyre go bad on my X6 and because of the tread difference (about 4mm) I had to cough up for a complete new set.

I feel your pain and frustration having been there too.

Are those the correct original tyre sizes ? as the front is 1% larger rolling already so fitting new front and worn rears makes things ever worse.

RealOEM shows those sizes as correct and with a 95W or 96W minimum rating (so 100Y is fine). ‘*’ marked may have been moulded so as to match the diameters correctly.