What's best for transmission in stop/start traffic ?

[RickMM]

Don't know whether others have seen this thread?
It largely relates to cars with a conventional torque converter, and gets a bit wayward in the middle regarding brake lights, but was curious what people with the automatic clutch type transmission (e.g. MCT on later C63s, etc) do in this situation?

P on Traffic Lights?

 

[Headhurts]

Personally I have never wondered about this but now you have given me something to be concerned about.

Seriously though my practice is to use the hold function and if traffic is exceptionally busy and queuing then I switch on start stop.

My car rarely is used in busy environments as I’m retired so tend not to be stuck in traffic these days.

My car is an E350 with 9 speed auto by the way.

Robin


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[cawkyuk]

I use the Hold feature on my C63.

 

[Gazwould]

Hold , park or neutral is not recommended .

 

[cawkyuk]

What would be the recommendation?

 

[Gazwould]

Staying on the brake or a 'hold' function if fitted .

 

[cawkyuk]

Sorry I was getting confused as you said the hold function was not recommended.

 

[Steve84N]

Still better to be in neutral with brake HOLD applied if you're stationary for a while. That way if you get bumped you won't fly forwards if you hit the accelerator by mistake and it uses marginally less fuel.

 

[cawkyuk]

Hold , park or neutral is not recommended .

Sorry I just reread this and now I see the comma my mistake

 

[John]

Depends how long you are going to be stationary.

Most transmissions incur more wear when changing from P to D and vice versa so manufacturers usually advice remaining in D unless for a long duration (on traditional CVTs too).

MCT is a regular MB transmission with a wet clutch instead of a torque converter so the same applies as their regular torque converter auto.

 

[RickMM]

This is what I was wondering about. With the wet clutch transmissions do you run the risk of wearing the clutches? (as you would if riding the clutch in a manual car) Bear in mind that the car wants to creep forward if sitting in D, so there must be some (minimal ?) contact between the clutch components. The traditional fluid coupling torque converter creeps but doesn't have the direct mechanical linkage.

 

[John]

There will be minimal wear.

The clutch pack is a number of discs with areas of friction material on them next to a metal-toothed plate, then another friction disc and so on. These sit in an oil bath (hence wet).

When pressure is applied to the pack, it is forced together and grips. When not forced together, the metal-toothed plates can rotate without creating wear.

This is nothing like a typical clutch setup in a manual car, which uses friction to gradually engage.

 

[RickMM]

Essentially just like most motorbike clutches then, but the plates are pushed together by hydraulic pressure rather than springs?

 

[grober]

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[Atavus]

The pictures of the MCT start clutch show multiple friction plates but without the intermediate metal plates found in a motorcycle clutch.

 

[grober]

The pictures aren't clear but rather than having alternate double sided friction plates interspersed with all metal plates if you make each plate metal on one side and friction material on the other you get essentially the same effect of metal to friction material interaction?

 

[Deleted member 6183]

Isn't this the second thread on the same subject in the last few days?

 

[John]

When I first saw it in a video yonks ago, it looked to me like individual metal plates and friction plates but this picture shows it's as Grober states:

 

[grober]

What the picture also shows is that each alternate plate is driven from the outside circumference splines or from the inside splines - thus all the "outer spline plates " are coupled together and all the inner spined plates are coupled together correponding to the input and outputs. Explained here with alternate friction and metal plates but the principle is the same.

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[Steve84N]

Isn't this the second thread on the same subject in the last few days?

Another invaluable piece of wisdom from the resident Dr...

If you're not going to add something useful to the thread then don't bother!