Audi A6 C5 5gear>6gear swap

[arnasa6]

Hey guys. I'm writing to inquire about a certain mod I am thinking of doing. I have a 2002 Facelift Audi A6 1.9 TDI (engine code AWX) 5 speed manual and I am thinking of swapping it with a 6 speed manual.

So does anybody know if it's plug'n'play from another 1.9 TDI engine(for example the one that comes from an Audi A4 B6 w/ engine code AVF or another Facelifted A6 w/ a 1.9 TDI engine just different engine code)?

Also, what's the difference between AWX and AVF, if they have the same power output, displacement?

Thank you!

 

[mrnice]

Avf has a touch more torque and came with six spd and larger diameter clutch plate I think

 

[desertstorm]

I swapped the 5 speed gearbox on my Passat which was an AWX engine for the 6 speed from an AVF. The only difference in performance between them comes from a slightly different map on the AVF to give it a bit more mid range torque. As the AVF has a 240mm clutch as opposed to the 228mm 5 speed clutch.
If you are swapping you need a 6 speed gearbox, get an early one made by Getrag, later 6 speed gearboxes were a copy of the Getrag box made by VAG and they suffered from diff bearing problems.
You will need the complete 6 speed change mechanism as it's completely different to the 5 speed, A 240MM clutch and DMF, A 6 speed starter motor as they are different to the 5 speed due to the larger DMF the starter ring is in a different place.
And lastly the engine subframes are different for 5 and 6 speed cars. One of the engine mounts on a 5 speed box is different to the 6 speed. I manufactured a custom engine mount so I didn't need to change the subframe.
I only changed mine as I got all the parts off a car that was being broken at a stupid price. It was a nearly new clutch and DMF as well.
There isn't much difference in the ratios, 1,2,3 are the same 4th on a 6 speed is like 3.5 on a 5 speed. 5th on a 6 speed like 4.5 on a 5 speed and 6th gear is pretty much the same at 5th on a five speed.
The 6 speed box is a close ratio box and not an overdrive box for economy. If you want higher gears then a 6 speed from a 2.5 V6 TDI has higher gearing. I think the DQS box is the one to go for.

 

[arnasa6]

@desertstorm , thank you for the indepth explanation! A couple questions though:

1. Is the 6 speed more economical than the 5 speed?(this is the only reason I'm thinking of doing it)

2. So for the swap I'll need:
1. 6 speed gearbox
2. A 240 mm clutch and DMF
3. A starter motor from a 6speed(will I need further modding to add this starter motor or is it just plug'n'play?)
4. A custom engine mount(or a subframe, if I can't make it?)
Is this list correct?

Also, excuse me from being quite a greenhorn, but what difference does higher gearing do(for example, a gearbox from a V6 2.5TDI A6? Thank you!

 

[desertstorm]

The 6 speed isn't really any more economical than the 5 speed if you use the gearbox from a 1.9 car. To get better economy you really need to reduce the RPM on the car so you need higher gear ratios. This is what you get with a 2.5 TDI gearbox. because it's designed to be used with a more powerful torquey engine the higher gears are longer so the engine revs less.
Even then the difference is marginal as regards fuel economy unless you drive thousands of miles every year on the motorway at 90mph.
This is from the build thread for my Passat when I changed the gearbox.
http://www.ukpassats.co.uk/phpbb/viewtopic.php?f=5&t=56110&start=50
The reason I changed it was to get a bigger240mm clutch as I was running 215bhp and about 340Lb/ft of torque. Also the 6 speed being a close ratio box is better for performance as the gap between 3rd and 4th is a lot less. And I got all the parts at the right price.
You would never make the money back in fuel savings swapping to a 6 speed box.
Fit the smallest wheels/tyres you can with low rolling resistance tyres. Get the car running 100% and maybe get an economy map on the engine.
Advance SOI timing and reduce boost request.

 

[arnasa6]

@desertstorm Thanks for the info!

 

[Jimmy TDI]

Do you not need the drive shafts too?

 

[desertstorm]

Driveshafts were the same on the Passat so assume they would be on the Audi.

 

[Jimmy TDI]

Fair do's. I know on the Mk4 platform the drive shafts were needed to do it.