Hi, I recently bought a 645Ci and rhe SMG gear box seems fo have a lot of lag during changes.

Is this normal or can it be reduced with tuning.

Morning Adil

Welcome to the Forum

First thought is when (if ever) was the Transmission last serviced ? Back in 2003 many BMW Dealers were telling people transmissions were sealed for life ?? The gearbox in any car is often ignored/abused Engine oil and filters are often changed annually but gearboxes Manual. SMG or Automatic ignored until there is an issue?

Slow changes could be caused by dirty thick gearbox fluid or low fluid levels. My starting point would be, get the gearbox filters fluids and seals serviced correctly a ZF specialist will also be capable of updating software

Dave

8 hours ago, Greydog said:

Morning Adil

Welcome to the Forum

First thought is when (if ever) was the Transmission last serviced ? Back in 2003 many BMW Dealers were telling people transmissions were sealed for life ?? The gearbox in any car is often ignored/abused Engine oil and filters are often changed annually but gearboxes Manual. SMG or Automatic ignored until there is an issue?

Slow changes could be caused by dirty thick gearbox fluid or low fluid levels. My starting point would be, get the gearbox filters fluids and seals serviced correctly a ZF specialist will also be capable of updating software

Dave

Thanks. The gear fluids were changed 5000 kms ago when I bought the car.

Any other diagnosis?

Morning Adil

Did you have the fluids changed or did the supplying garage ? Is there a receipt that shows which fluids were used ? Was a software update done ?

A diagnostic scan is needed to confirm the fault it could be software related or the pump failing, fingers crossed its a simple fix

Dave