transmission slippage
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transmission slippage
during normal driving at low rpms say before 2,000 rpm with very minor gas the rpms and transmisson shift good for the 1st and 2nd gears with no thumps or idle play,but switching from 2nd to 3rd it like clunks in and the rpms move up and down , u can feel and hear it happen , it also happens 4th and 5th gear,im doing the transmission service very soon, the fluid change and filter hopefully that helps,but what else could it be or does any1 else have or had that problem, thanks alot,
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From: Wilbur by the Sea
Welcome to the world of ZF transmissions
Since I got to drive in TozoA8's transmission when it would just pop into limp mode.....I think what is causing it is the wet clutches slipping too much.
He took his tranny apart and verified that one clutch was gone....and that's why it would work in reverse, because it would use a different clutch.
There are three wet clutches, just like a motorcycle wet clutch.
I think when you find the fluid is all dirty, it's actually clutch material that has worn away.....I'm not sure, but that's what I'm thinking.
By changing the fluid maybe there isn't foreign material between the clutch plates any longer and now the tranny can hook up?
He took his tranny apart and verified that one clutch was gone....and that's why it would work in reverse, because it would use a different clutch.
There are three wet clutches, just like a motorcycle wet clutch.
I think when you find the fluid is all dirty, it's actually clutch material that has worn away.....I'm not sure, but that's what I'm thinking.
By changing the fluid maybe there isn't foreign material between the clutch plates any longer and now the tranny can hook up?
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Re: transmission slippage
What is your year and mileage?
This is a common problem with the A8. The fluid & filter change may help - depending on mileage sometimes it needs to be done once, and then done again after 3000 miles or so.
Sooner the better. I am at 57k and will be doing my first fluid & filter change this month. My trans shifts like butter, but I'm starting to notice a very slight hunting in the 4-5 shift.
This is a common problem with the A8. The fluid & filter change may help - depending on mileage sometimes it needs to be done once, and then done again after 3000 miles or so.
Sooner the better. I am at 57k and will be doing my first fluid & filter change this month. My trans shifts like butter, but I'm starting to notice a very slight hunting in the 4-5 shift.
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Where are these clutches located?
In the tranny or the TC? If in the TC, can just it be replaced and fix the problem?
The reason I ask is because I am certain this is what is going on with mine. The fluid change made my slippage/hunting worse. When I did the fluid change, my magnets were packed w/ metal; I suspected it came from my clutches. I was quite certain it wasn't electrical. I'm happy someone has gone in and inspected it and seen what gave out.
Colby
The reason I ask is because I am certain this is what is going on with mine. The fluid change made my slippage/hunting worse. When I did the fluid change, my magnets were packed w/ metal; I suspected it came from my clutches. I was quite certain it wasn't electrical. I'm happy someone has gone in and inspected it and seen what gave out.
Colby
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From: Wilbur by the Sea
Clutches are after torque converter in ATF
<img src="http://www.audipages.com/Tech_Articles/auto_transmission/A8newtrans.jpg">
I would have to look at the PDF document on spare parts from ZF....but I believe they are aft of the torque converter (thing with vanes on it), right around that first gear you see in the picture above, just aft of the torque converter.
Colby, do you have an extra hinge that you used to mount your XM radio? I can't find one that works....if so, can you send it to me?
pw
I would have to look at the PDF document on spare parts from ZF....but I believe they are aft of the torque converter (thing with vanes on it), right around that first gear you see in the picture above, just aft of the torque converter.
Colby, do you have an extra hinge that you used to mount your XM radio? I can't find one that works....if so, can you send it to me?
pw
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This is clutch A and B.
I don't have a picture of the open torque converter, but here is A and B pulled from my tranny. If the fluid is black, that is the torque converter faulty. Mine was rebuild for a $ 100. The problen is that you have to take the tranny out to change the TC. I found a cheap place and it was $550.
<img src="http://pictureposter.audiworld.com/80919/dscn1351.jpg">
<img src="http://pictureposter.audiworld.com/80919/dscn1351.jpg">
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Can a torque converter "slip"?
Besides dropping in and out of lockout, my tranny also slips in most gears when accelerating. Obviously the clutches in the tranny can do this, but can a TC slip also? I would much rather spend $500 to replace a TC than $3k for a whole new tranny (but only if this would fix the problem).
Colby
Colby
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Yes, it can.
I think if the TC slip, it doesn't go into limp mode. If the transmission vehicle speed sensor G38 signal matches with the transmission input sensor G182 signal, then your tranny is ok. The TC can slip if N218 pressure regulator valve is faulty or if you don't have a fault code, it can be stuck mechanically.
Here is the N 218
<img src="http://pictureposter.audiworld.com/80919/dscn1029.jpg">
You can get to it from the bottom, after you remove the oil pan and the filter.
<img src="http://pictureposter.audiworld.com/80919/dscn1010.jpg">
If you remove this, you can pull out the solenoid valves and the pressure regulator valves. The last green valve is different, don't mix it up! You can test them with 12 v and blow some air into it, you will hear if it works.
<img src="http://pictureposter.audiworld.com/80919/dscn1030.jpg">
Here is the N 218
<img src="http://pictureposter.audiworld.com/80919/dscn1029.jpg">
You can get to it from the bottom, after you remove the oil pan and the filter.
<img src="http://pictureposter.audiworld.com/80919/dscn1010.jpg">
If you remove this, you can pull out the solenoid valves and the pressure regulator valves. The last green valve is different, don't mix it up! You can test them with 12 v and blow some air into it, you will hear if it works.
<img src="http://pictureposter.audiworld.com/80919/dscn1030.jpg">
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I have never gone into limp mode and never had any codes..
but it slips like mad. Most likely a mechanical failure inside the TC? What inside the TC slips? It doesn't have any clutches, does it? Isn't it just fluid w/ a lockout mechanism (can the lockout "slip")?
Colby
Colby