transfer box chain

[davey]

i know i,ll seem daft, but what does staggered mean, davey,

[jagr]

[quote="davey"]
i know i,ll seem daft, but what does staggered mean, davey,
[/quote]

Which wheels do you have? Are they like the ones I put on the last page?

If I remember correctly the staggered 18" wheels will be be 8.5" front and 9.5" rear (wide).

[davey]

ok, i,ll measure in the morning, thanks again, davey,

[X5Sport]

Depending upon which BMW wheels you have, a staggered set are 8" front and 9" rear.  Non staggered are 8" all round.

There have been issues on the forum with non'*' marked tyres, especially those with a widely different amount of wear as well causing broken transfer or diff boxes.  It is something to be mindful of as it seems some BMW running gear is a little fragile.  It's caused by the different circumferences of the worn/new tyres over stressing the transmission.

The '*' simply means they are made to the BMW spec.  Several manufacturers have tyres made to a specific requirement 'MO' marking means Merc

Richard

[jagr]

[quote="X5Sport"]
Depending upon which BMW wheels you have, a staggered set are 8" front and 9" rear.  Non staggered are 8" all round.[/quote]

E83 X3 wheel sizes:

17" are either 7J or 8J all-round
18" are either 8J all-round or 8J and 9J for a staggered setup
19" are 8.5J and 9J as staggered only

[davey]

ok, i,ve got staggered wheels, 9s on back, 8s on front, 255.45.18, back,  235.50.18 front, ??, davey

[X5Sport]

Those are the correct sized tyres for that setup.

[stevox5]

The X3 is very sensitive to tyres as I said earlier , it's not just the tyre size , if you measure the rolling radius of each tyre you will probably see that they are different from front to rear due to having different brands per axle. The non star rated ( BMW approved and tested ) tyres seem to cause the transfer box wind up you describe .

Best bet is a set of star rated tyres , or even better swap a set of wheels and tyres from a known good car with the correct tyres first for piece of mind before investing in a set of tyres.

I would be quite confident tyres are the issue.

[davey]

i,ll keep you all up to speed as i try the tyres, and check out the prop shaft u/j, davey

[535dboy]

This looks to technical for me !

[davey]

altho my tyres arnt star marked on the rear, i have measured the tread depth, 3 mm on one, 4.5 on the other,would that difference make the radious problem, ?seems to bear out the tyre thing, davey

[X5Sport]

Yes.  It means the circumference of the tyres is different and the difference might just be enough to cause what you are experiencing.  Although it doesn't sound a lot, it might be adding one or two inches to the overall circumference for each revolution of the wheel so the stresses start to build.

Star marked tyres have matched circumferences at new.  Yes the wear will gradually create a difference, but on my X5 and X6 the wear difference front/rear has always been less than 1mm.  I only use star marked tyres.

Richard

[davey]

getting new tomorow, will let you know the outcome, ........davey

[stevox5]

Make sure you get a set of star rated tyres or you will have same issue

[davey]

got tyres, a slight reduction in clunks but still there, had difs oil levels checked, all ok, and checked prop shafts for wear on u/js, front shaft has some wear, back seems ok, ho hum, !!!,  :(davey