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C6 Aisin 6 Speed Automatic Transmission Servicing
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gmerry   
Thu Feb 17 2011, 11:46am
Joined: Dec 11 2009
Member No: #21
Location: Scotland
 OK, Citroen's take on the routine servicing for the Aisin TF-80 (SC) transmission is that it is sealed for life, no specified servicing requirements.

Talking to a reputable Automatic Transmission Specialist, these boxes are subject to significant wear problems for the internal solenoid valves, caused by wear debris. The spares importers down in Sussex are busy supplying these spares to the overhaul shops. These boxes are fitted to loads of Mazdas, Fords, Volvos, Peugeots, etc so the service and repair guys are starting to see the reality of the these boxes as they age. Wear in the solenoid valves manifests as worsening gear shifts, clunks in the transmission etc. A post has already been made on this forum re what could be causing transmission clonks.

The specialist has confirmed that the design does not allow for the internal filter to be changed without a complete dismantling of the transmission. However, a fluid change is a straightforward operation and for the specialist I spoke to, they carry the special Aisin fluid at £11/ litre. Assuming a double change (ie two partial changes of 3 litres each time), the fluid cost itself is reasonable at about £70. Advantages of changing the oil include reducing the debris particle count which will reduce the solenoid valve wear problems. Plus the crucial viscosity/friction characteristics of the fluid will be back to spec. If there are real problems in the box, this will be obvious from the fluid condition.

So overall, Changing the fluid every two years or so is probably a very good idea for anyone planning on keeping the car beyond a couple of years.

A link to anyone with a curiosity as to the internals - Click Here -

Regards
G
C6Dave   
Thu Feb 17 2011, 01:02pm

Joined: Oct 01 2009
Member No: #1
Location: Northumberland
 Changing the fluid has already been posted on by another member, though not in so much depth and seems like a good plan as you say G
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tonyrome   
Thu Feb 17 2011, 05:00pm
Joined: Nov 22 2009
Member No: #15
gmerry wrote ...
OK, Citroen's take on the routine servicing for the Aisin TF-80 (SC) transmission is that it is sealed for life, no specified servicing requirements.

gmerry wrote ...
Talking to a reputable Automatic Transmission Specialist, these boxes are subject to significant wear problems for the internal solenoid valves, caused by wear debris. So overall, Changing the fluid every two years or so is probably a very good idea for anyone planning on keeping the car beyond a couple of years.

So, Citroen reckon it's maintenance-free but I'm sure they won't be coughing up when it goes wrong, at huge expense, as seems likely from the experience of the specialists

I can't wait to get back to a manual gearbox car
gmerry   
Fri Feb 25 2011, 03:06pm
Joined: Dec 11 2009
Member No: #21
Location: Scotland
 Looking at the Mechanics Guide and alternatively talking to some of the transmission specialists, it appears there are two completely different methods for changing the fluid on the autobox.

A/ Mechanics Guide Method (Guessing Citroen Dealer Method)

This method is just to drain the 3 litres out of the 7 litres total capacity. Refill and change again?

Maths: change ratio r is 0.43 (ie 3/7): after one change % old fluid will be 1-0.43=57%, After n changes, old fluid is (1-r)^n

2 changes, 32% old fluid (6 litres used), 3 changes, 19% old fluid (9 litres used), 4 changes 11% old fluid (12 litres used), etc.

Bearing in mind that retail price of fluid likely to be about £13/litre. - Click Here -

B/ Diaphragm machine change

This method uses the internal ATF pump that pumps fluid through the transmission cooler. The machine intercepts the ATF coming out of the box where it goes into an internal chamber with two compartments separated by a bladder. The old fluid goes into the bottom chamber.

On top of the bladder but at the same pressure is a chamber full of new fluid. This is connected to the return line from the transmission cooler. Note that the actual change % achieved depends on the amount of internal leakage/diversion of fluid as not all fluid goes via the cooler circuit, amount of fluid in the upper chamber, time on machine etc.

There is a 3rd method, variant of method A, which invloves dropping the pan and changing the filter. Not applicable to the AM6 transmission as there is no pan to drop and filter cannot be accessed without a total stripdown.

Note well, have not yet presented the vehicle to a ATF specialist to confirm whether the machine hookup to the cooler is feasible or needs specialsit interface.
Regards
G
 

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