Question about 7g

dannyfiveforty

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i have noticed that when my car is up to temperature and I stop at a traffic light for example as soon as the light turns green as I start to release the brake pedal the car momentarily jolts, as though it is engaging gear. What is this a symptom of on a 7g gearbox?

Thanks
 

SRE

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Can't say I have noticed mine do that.
 

L John

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Try holding with the parking brake, if you don't get the noise when you release the parking brake, the issue is more likely the main brakes releasing with a jolt. I always put my foot on the parking brake pedal when releasing the parking brake as the return is not damped.
Also try the other mode to what you're currently using (Comfort/Sport).
 

John Laidlaw

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Nope never had that on my last 3 x 7GS
 

Craiglxviii

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When you come to a halt do you press the brake pedal down to get the HOLD function? If so, when you set off the clunk you hear is the brakes disengaging.
 
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dannyfiveforty

dannyfiveforty

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Thanks guys, it feels like it’s the car engaging gear, what is the point of th hold function if my foot has to be on the brake pedal anyway?
 

L John

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Thanks guys, it feels like it’s the car engaging gear, what is the point of th hold function if my foot has to be on the brake pedal anyway?

The hold function (if yours has it) allows you to remove your foot from the brake and the brakes will remain applied until you give it some throttle. It's not like the few seconds you get with hill start assist.
 
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dannyfiveforty

dannyfiveforty

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Ah ok, mine is a 2011 s350 bluetec. There is no mention of this in the book and as soon as the brake is eased of the car tries to creep.

I have since tonight plugged my obd scanner in and went for a drive with live data for gearbox displayed, as soon as the car stops after a second or so the gear number disappears and it says ‘powerfree’ For however long the brake is pressed. As soon as I begin to lift the pedal it changes from ‘powerfree’ to ‘gear 1’ and that’s when I feel the slight jerk/jolt..
 

L John

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Mines a 7g 2008 350 but I've not heard of powerfree. I guess something disengages to give better efficiency/economy so it may be normal.
Mine doesn't have the hold function but many have found out they have it and never realised, it needs a second push of the brake pedal whilst stationary to activate the feature.

Hopefully someone with the powerfree function will know about your issue with the jolt.
 
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dannyfiveforty

dannyfiveforty

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A second push? So press the brake pedal to stop then when stopped release and press again?

Thanks
 

L John

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Have a look at this video...

 

John Laidlaw

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A second push? So press the brake pedal to stop then when stopped release and press again?

Thanks
Mine you just push it further down until HOLD appears, same in my last 212, the 230 was SBC HOLD but the same action
 
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dannyfiveforty

dannyfiveforty

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Ah yes well I never knew that mine does that also,

It’s not that releasing though that I am feeling..
 

John Laidlaw

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Do you get any similar ‘shunts’ when coming down gears? That can be a symptom of an electroplate issue which isn’t uncommon
 

Naraic

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Try in comfort...it wont go to 1st.
 


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