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Old 11-19-2023, 12:36 AM
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Spartan Spartan is offline
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Originally Posted by andrewwynn View Post
I think this is an x-drive issue more than pre x-drive.

Original e53 had open diff planetary gear that should allow any speed front or back. The x-drive uses a variable clutch that can/will lock the front and back axles. I'm not sure what the limits are for differences in rolling circumference on the original.

You know me, the one of little knowledge, but I did get some info re the TFC to 2003 and the Xdrive 2004 onwards.
Pre-face lift X5s use a permanent 4wd system with 35% front and 65% rear split. All auto gearboxes are 5-spd and the TFC uses ordinary ATF oil as you would in the transmission.

Post face lift X5s use a completely new 4wd system based around a clutched transfer box. It can send all the power to either the front or rear based on various inputs. All cars use a ZF 6-spd box which is much more robust than the 5spd unit.

All X5s have proper traction control.

Based on this concept I am only making a generalized assumption that the Xdrive system should cope better if the rolling diameter of a pair of wheels was slightly different, due to the ability to transmit the power accordingly.

All E53's carry a 17" spare wheel, while they are fitted with rim sizes of 17", 18" and 19" from point of sale. This is not delving in to the dreams of wild custom builders, but everyday people. Shouldn't the Xdrive cope with the variation better?

I am always ready and willing to be corrected if this is incorrect information
I own a BMW E53...Always questions, unfortunately I can rarely supply solutions. I will try to give results to my problems if they are fixed and how it was done.

Last edited by Spartan; 11-19-2023 at 12:47 AM.
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