New Polo problems - Register

[Lemonskin]

Anyone who freewheels down a long hill is looking for trouble Brakes heat up and fade and Bye Bye.

Have had it happen and its not a nice feeling

Ouch ok I guess I'll stop that then O_o

[Hillbilly]

I thought the 7-speed DSG on the Polo was a dry box, so there's never any oil going around it anyway.

The clutches are dry but the gears arent as in a normal gearbox or would get that funny blue look after a very short time

[alexaescht]

The clutches are dry but the gears arent as in a normal gearbox or would get that funny blue look after a very short time

Ah, ok then

[nomadx38]

Yeah I wouldn't put it in neutral, I used to but really I just found an easier way. When I cost down a hill I let it kick back a gear or too (so I get my engine brakeing and less brake fade) until its where I want it (usually between 2-3500 rpm) and then just hit the gear stick over to triptronic mode (manual) and hold the gear. As soon as I get to the bottom I just slide it back to D.

I also dislike the way it goes about automatically kicking down. I love the purpose of it and how quick it does it but if you are going down a big hill with the brakes on it will kick back to the lowest gear possible and will be at 5-6000 rpm which is not good for the motor at all.

There is nothing wrong with running the gearbox in neutral, won't overheat it or nothing but you will be more prone to brake fade. For city driving I doubt you will see a time when brake fade would cause an accident but if you go out "cruising" (really its never just a cruise) then you will get brake fade real quick.

[Hillbilly]

Just live in Queensland where there are no hills LOL

[LunchboxVRS]

In regards to lubrication the short answer is: if the engines running the the gears are oiled.

Long answer below:

The clutches are actuated hydraulically. Unlike standard manual transmissions, a DSG-transmission has its own oil pump. On picture 7, the pump and its driveshaft are visible. The shaft runs through both main shafts into the clutch housing. When the engine runs, the oil pump is running and oil pressure is present.
The oil that runs through the oil pump is being used for several purposes:
Lubrication of the gears, shafts, bearings and clutches
Cooling of the transmission
Actuation of the gearshift mechanism
Actuation of the clutches



But I will add that the pump is fixed displacement and will have more flow the faster the engine turns. So if you put it in neutral the gears being connected to the road via the diff will be spinning at a higher road speed compared to the pump spinning at the same rpm as the engine at idle. where as if the engine and gears are both matched to road speed the pump will be flowing at the desired road rate. So take that as you wish

[nomadx38]

Just like to point out the clutches and sliding sleeves for gear selection in the 7sp DSG (not 6sp) are operated solely by the mechatronics unit which has a dedicated multipole brushless DC electric motor and pump/oil pressure accumulator and is controled compleatly separately from any other component in the gearbox or engine.

The mechanical side of the gearbox (gears, syncros ad differential) operate as stated above. There are 2 different pumps / oil circuits inside the 7sp DSG

Source:

VW Self study program 390

"The 7-Speed Double-clutch Gearbox 0am"

Page 34 "Electrohydraulic control unit"

It's actually a really interesting read into the workings of this technological marvel.

[gavs]

Pity they still can't get it right though....

[nomadx38]

Yeah true that. Should have just stuck with the 6sp wet clutch DSG, appears to be much more reliable!

[Lemonskin]

All very techy. All I know is my car drives nicely and I dunno how it all works