Manual gearbox selection

[passatpout]

Anyone else had trouble with manually selecting gears at times?

A few times lately, the car just hasn't shifted when I've done a manual change either through the stick or through the paddles. First couple of times it wouldn't change to 6th at 60km/h, but needed to get to about 67-68, then today it wouldn't downchange to 3rd while slowing down at about 70km/h..

It only had the 30,000km service about 3 weeks ago, and they advised everything on the gearbox was fine... even though I still think it has its rough moments..

[Rocket36]

How warm was it? It won't do high torque / high rev shifts (which both of yours were) when it hasn't warmed up. Why were you changing down to third at 70kph though? Were you racing? Because slowing down should be done by the brakes and engine revs should match the drive required at the speed you're doing. The engine should not be used to brake the car unless you have a brake emergency.

[Pana]

The engine should not be used to brake the car unless you have a brake emergency.

but but but, the DSG programmed to downshift when you apply the brakes going down the hill so you can use engine braking to keep your speed down rather than riding the brakes

[Rocket36]

The DSG will NEVER shift down to 3rd at 70kph to slow the car down.

[Pana]

The DSG will NEVER shift down to 3rd at 70kph to slow the car down.

I was responding to your comment about how engine braking should only be used in an emergency - engine braking is quite a normal thing to do in any car down a hill - saves you from cooking your brakes

and now that I think about it - I have had the DSG shift down to 3rd at about 60 or so down a steep hill. I then took my foot off the brake and it stayed in 3rd until the bottom - when I put my foot on the accelerator again to keep going, it then started shifting up to 6th as normal.

[Rocket36]

60 is not 70.

[Pana]

Passatpout - as yours is a diesel, changing to 3rd at 70 may be above the limit of what the gearbox considers a safe downchange - on the R36's - it won't change down unless the revs in the lower gear is below about 4200 (or thereabouts). Wouldn't know what the diesel change point is

[Swallowtail]

The DSG will NEVER shift down to 3rd at 70kph to slow the car down.

Yes it will.

It will change down if you are descending a hill with your foot on the brakes in the R36 as long as the resultant engine speed is less than 4500rpm. 70 is 4000ish in 3rd. It does it, I tried it.

Having said that, as Pana said that may be too high a speed in the 2.0 diesel for 3rd. Don't know, haven't got one!

As to "The engine should not be used to brake the car unless you have a brake emergency"... it is a perfectly valid technique for reducing heat in the brakes particularly on long descents. Would you advocate descending a hill in 5th or 6th? If not then you are using engine braking to some extent, regardless of whether or not you are on the footbrake at the same time.

[Rocket36]

whatever... im done arguing and im done providing advice. there's no point when all that seems to happen is people want to argue. it's pointless.

good luck with the gear box passatpout.

[drbass]

Much speculation and opinion but so far no facts.

passatpout, since I have essentially the same car as yours (including a slightly clunky DSG) I thought I'd give it a try.

First let's go through some thought experiments. This is all based on using the DSG in manual mode (NOT D or S).

50 km/h in 3rd gear is just about 2,200 rpm, give or take. 75 km/h will be about 3,300 rpm, give or take. That is well below the electronically controlled rev limit of 4,500 rpm for the 125 TDI. The engine spins quite happily to that limit when accelerating, and the DSG then automatically shifts up a gear. Not the most efficient way to accelerate but possible.

This morning, doing 80 km/h (GPS, not speedo) in 4th gear with warm engine and gearbox (I would like to think) I pulled back the DSG lever, and 3rd gear was engaged very smoothly thanks to the ECU matching engine revs to the speed perfectly. Ended up doing about 3,500 rpm. No sweat.

I have, and I hate to admit this, inadvertently selected 1st gear instead of 3rd when accelerating, and have seen in excess of 4,000 rpms.

I would think that, as long as the selection does not result in rpms exceeding the rev limit the DSG should simply obey and shift down, for whatever reason the driver chooses to do this.

Anyway, hope this helps.

Regards,
Michael