qualified transmission repair specialist. Any damage related to repairs caused entirely or in part from this DIY guide are the sole responsibility of the end user. Translation, if you botch the job and blow your transmission up don't come crying to me**
So in the spirit of crazy repairs, I've decided to take apart the valve bodies on my folks Boxster. It was slamming into gear while coasting on tiptronic 4-3 downshifts. I think it's an issue with the C clutch accumulator piston. I got the go ahead to pull it apart and see if anything's amiss.
So, here are some ground rules:
1) Cleanliness is ESSENTIAL when taking apart anything automatic transmission related. It's not quite as essential on the teardown. However it's critical on the rebuild. These transmissions run very small pistons relative to the parts that they actuate, so the bore tolerances are very tight. Grit and such can cause problems if they lodge in the bores during reassembly.
2) Order and attention to detail are key as well. Set aside a nice clear area to lay out the parts as you disassemble them. I used a large chunk of cardboard on the floor. Trace the valve bodies on the sheet and then lay out the pistons/springs relative to where they came out of the traced outline. Another hint is to make a divot in the cardboard to keep the parts from rolling around. I just dragged the butt end of a sharpie (not the marker part) to make an indent as I labeled the parts coming out.
3) Examine everything that comes out with a magnifying glass. The pistons are anodized, so if you see shiny parts on the edges that's a good indication that something's worn. Also, once you've cleaned the bores out, check them for signs of wear.
4) Document everything with a camera. I just kept my camera beside me as I pulled things apart. Audi made a lot of changes throughout the model years, so there may be slight differences on your particular model relative to the Boxster. This is especially true on the intermediate plate section (the part with the orifices).
5) It's best to order your parts in advance. I ran into problems getting the right parts and it ended up taking about 2 weeks. If you can't take that much down time it's best to have all the parts beforehand. Parts you'll need for sure are the intermediate plate gasket, piston dampers, check balls and check springs. The orifices under the intermediate plate should be changed as well, however I did put it back together with some of the old ones. Just make sure they stay in the same place and aren't clogged.
Here's the patient
Here's the operating room
Part 1) Removal from vehicle
Pull the pan and remove it. You'll have to pull the clips from the trans solenoids. Take care when removing them as they're quite brittle. After removing the six here, you'll need to pull another 2 once the valve body drops.
Here are the locations of the ones holding the valve body in
Here you see the two clips to the turbine speed sensor and the 7th soleniod
2) Disassembly
Once it's out, put it on the bench and pull the turbine speed sensor off the backside so you can lay it flat. Then start pulling the screws to start pulling each of the 4 valve body assemblies off. I suggest doing them one at time and completely disassembling them ***note, if you pull both the large, lower valve bodies (pictured here) off at once and flip the assembly to remove the smaller upper ones, the intermediate plate may fall off and drop all the orifices etc...*** What I did was pull a lower valve body, disassemble it and then put the valve body (sans pistons) back where it was and hold it in with a couple of screws. That will hold the intermediate plate on until you're ready to pull it.
Pic of the lower front valve body. See the pistons in their bores?
Underside of the upper front valve body
2.1 Disassembling the valve bodies
**I'm not going to show the entire disassembly process here, all the valve bodies follow a similar pattern. Just pull the pistons one at a time and lay them out as you do so**
Pay particular attention to the clips that you pull out. Keep the orientation relative to their slot in the valve body the same. If they're on a piston I placed them on the piston as I was pulling the assembly
Lower front valve body
There's a check ball assembly that should be replaced during the overhaul. It's circled in the lower left portion of this pic
Lower rear valve body
**Note that I labeled all the soleniods numerically**
Check that the solenoid screens and orifices are clear of debris. The ED (Black) type solenoids can get the screens clogged and malfunction. BTW these guys are responsible for line pressure modulation during shift overlap.
Upper front valve body
Upper rear valve body
Intermediate plate
This is the part under the two large (lower) valve bodies. You can see here, where the color coded orifices and damper plugs are.
Here's my problem child. A rubber damper plug that got deformed.
Here it is in it's spot on the intermediate plate
Originally Posted by FNK
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