2001 Audi TT Quattro transmission/transfercase slippage?

[WheelerKB]

I recently acquired a TT with a broke timing belt. I just started the process of pulling the head. When I went to remove the front passenger side wheel, I put a lug wrench on the it to break the lugs loose and the wheel spun. Just the one wheel of the ground and it was in 6th gear. I tried 5th, same thing... then I put out in first and it didn't move. In second, sill didn't move. In 3rd, I could get it to spin with a lot of pressure.

Is this normal characteristics of the TT awd setup, and if so, can someone help me understand what is slipping?

 

[Jack@European_Parts]

How is this related to VCDS?
Please post an auto-scan..........

WTF are you doing trying to turn the wheel like this anyway in the air?

You better read the safety section of the repair manual, and start following the procedures in it before you hurt yourself.

If I am understanding you wrong..... please post a video of what it is you are doing.

 

[jyoung8607]

Just the one wheel of the ground and it was in 6th gear. I tried 5th, same thing... then I put out in first and it didn't move. In second, sill didn't move. In 3rd, I could get it to spin with a lot of pressure.

You're transferring torque from the wheel to the drive-train and engine, so the gearing effect is backwards. With the transmission in overdrive, it's easier to turn the crankshaft with the wheel.

Is this normal characteristics of the TT awd setup

Yes. This car uses the active Haldex AWD system rather than the mechanical Torsen AWD. Only the front wheels are engaged until slip is detected and the Haldex kicks in.

and if so, can someone help me understand what is slipping?

The inactive Haldex clutches, and the engine crankshaft, which will turn more easily when there's no compression due to a busted TB.

Unless you already have the heads off, you're contacting pistons with valves and possibly scrubbing down your cylinder walls with metal fragments every time you turn the crankshaft. So, if you care about re-using the bottom end of this engine, you may want to conclude this little science experiment.

Jason

 

[WheelerKB]

It's not really related to vcds, but I would imagine there are several people on here that would have extensive knowledge about the drivetrain of the TT.

I'm still pretty new to this forum, and didn't realize that it was only for problems directly related VCDS. (I now see the General one in the Misc section this should have been posted to.) Is there a way that I can move this thread to that location?

I'm not sure what you thinking that I am doing, but please tell me what you are thinking I am doing that would cause me to hurt myself...

 

[WheelerKB]

Yes. This car uses the active Haldex AWD system rather than the mechanical Torsen AWD. Only the front wheels are engaged until slip is detected and the Haldex kicks in.

The inactive Haldex clutches, and the engine crankshaft, which will turn more easily when there's no compression due to a busted TB.

Ok, so it sounds like there is a clutch pack that is slipping, by design, in the transfer case that is allowing the wheel to spin. I was worried that there was a direct mechanical gearing between the front and back wheels, but it sounds like it is just a clutch coupling the two.

 

[jyoung8607]

I'm still pretty new to this forum, and didn't realize that it was only for problems directly related VCDS. (I now see the General one in the Misc section this should have been posted to.) Is there a way that I can move this thread to that location?

This particular sub-forum is for troubleshooting with VCDS, but as you noticed, there's another one for purely mechanical stuff. No big deal though. One of the moderators will probably move the thread for us when they notice.

I'm not sure what you thinking that I am doing, but please tell me what you are thinking I am doing that would cause me to hurt myself...

I mean no disrespect at all, but I have to tell you, your post reads something like this:

"I'm pretty sure this torque on the front wheel should have turned my rear wheels as well. I just don't understand why my TT didn't start moving, fall off the jack, and start rolling down my driveway. It wouldn't fall off the jack no matter what gear I tried. In third gear, there was almost enough drive-train resistance to move the car with the front driver's side wheel through the differential instead of turning the engine through the transmission, but not quite. Is my AWD system broken?"
​

You wouldn't know it just reading his posts, but Jack is a great guy who really doesn't like to see DIY owners auto-Darwinate. We all start somewhere, and we all learn new stuff every day. This is something you really have to be careful with. Far too many people die every year, working on cars that fall on them or roll over them.

Jason

 

[Jack@European_Parts]

I mean no disrespect at all, but I have to tell you, your post reads something like this:


"I'm pretty sure this torque on the front wheel should have turned my rear wheels as well. I just don't understand why my TT didn't start moving, fall off the jack, and start rolling down my driveway. It wouldn't fall off the jack no matter what gear I tried. In third gear, there was almost enough drive-train resistance to move the car with the front driver's side wheel through the differential instead of turning the engine through the transmission, but not quite. Is my AWD system broken?"

You wouldn't know it just reading his posts, but Jack is a great guy who really doesn't like to see DIY owners auto-Darwinate. We all start somewhere, and we all learn new stuff every day. This is something you really have to be careful with. Far too many people die every year, working on cars that fall on them or roll over them.

Jason

That's exactly how I read it too.

Just don't want anyone hurt.
All to often I hear about something like this and it is not funny.

 

[Uwe]

Moved to General VW/Audi Repair.

-Uwe-

 

[Jack@European_Parts]

Not a total loss........ I learned a new term........

auto-Darwinate

Haldex must be active and you could observe its functions with VCDS in 0x22

The center differential is a mechanical operated only attached to front final drive....... output flange right.
Haldex is the rear dif using a viscous fluid directed by controller to operate after being sent via the propeller shaft.

 

[WheelerKB]

Ok, I see how that could be dangerous. There are a few basic details I left out... p brake was on, wheels were chocked, and it is on something a little more stable than a Jack stand. So, yeah, it is possible that it would roll, but I feel necessary safety precautions have been taken to mitigate that possibility.

 

[Jack@European_Parts]

Very good...........

Even on a lift or secured stand with chocks.......What is the purpose of what you are doing?

 

[WheelerKB]

I was just breaking the lug bolts loose to take the wheel off to gain access to the timing belt. It was just unexpected for it to act that way.

I now have the head off and I know 3/5 valve are bent, but I have a feeling that 5/5 valves are actually bent. Can anyone direct me to where I can educate myself about what heads I can easily use as a substitute for an AMU head?

 

[Jack@European_Parts]

The castings are all the same shit....... just different cams, adjuster, G40 reluctor or port sizes with SAI.

AMU should be small port like any 1.8T after 2000 except AEB in the states.

Easy enough........

 

[WheelerKB]

I looked at several 1.8t heads today, the AEB's do not have the port for SAI on them, but the ATW's do. How do I find out if it is a big or little port and what cams it should have in it?