Park Brake

[bobgolden]

I've noticed that my car seems to lurch forward slightly whenever the engine is switched off.

Sequence is as follows:

Reverse up drive which is a 2-3% slope nosewards
Press P
Set handbrake
Press Stop --> car lurches forward an inch or so as if handbrake has been released and car is sitting on P only.
Park brake light remains on.

Have noticed similar on level ground but not with a nose up pitch - doesn't lurch backwards.

Any other F15 owners had similar ?

[535dboy]

Is it not best to put handbrake on before putting it in park.............

[X5Sport]

Not according to BMW.  I think the manual may actually tell you the sequence is:

Select 'P', switch off, (release foot brake), apply parking brake.

That is the sequence in my X6 with the same gearbox etc.  If I do it the way you do, mine lurches as well due to the transmission releasing its tensions.

Putting the handbrake on before selecting Park can also leave the systems under 'tension' - and can lead to a lurch.

Try it yourself and see it it's any better....

Richard

[535dboy]

But surely you are locking the car on the transmission components then instead of the brakes in that order?

[Dr C]

I get the lurch too, regardless of which sequence I use.

[X5Sport]

[quote="535dboy"]
But surely you are locking the car on the transmission components then instead of the brakes in that order?
[/quote]

I'm only going on what BMW state, and on a level road the system should 'relax' and then the brakes are on.  Mine always moves a little bit fore/aft but once settled then I put the brake on. 

On a hill I do put the park brake on before releasing the root brake though.

Richard

[bobgolden]

Thanks for the constructive input (but why is it some reply to a question with a rephrased version of the scenario) and agree that it seems to happen regardless of sequence having tried it again. Ordinarily, you would only expect a lurch on the transmission park due to it settling on the gearbox locking pin. You shouldn't get any movement on the park brake.

[X5Sport]

Park brake is on the rear wheels so it might be the front end unloading?  I know mine does it and I think it's just everything settling.  TBH until now I've never really given it much thought.....now I'm intrigued.  (Sorry - Engineers can be like that - Ed)

Richard

[bobgolden]

Never experienced it on the XF or Discovery, which both had the ZF auto box and electric park brakes acting on the rear wheels.

The curiosity is that it only does the lurch when the engine is turned off rather than when the footbridge is released - almost as if the hand brake is released again and it's defaulted back to the gearbox. I'll just factor it in tight parking situations - wouldn't want to nudge up to something only for the car to deliver an extra bump.