tassieporsche

I fear that my 04 955 Turbo may soon need a replacement transmission. The moment of truth will come when I drop the pan soon and find out if the whining it's making is due to a problem with the filter or o-ring, or if it's time to start searching for used gearboxes....

Anyway, if the latter is the outcome, is this a job that can be done without a total drivetrain drop as I see a lot of people do with these?
From reading on these forums, it seems like the main reason people drop the whole engine and front subframe when doing a gearbox is that access to the top bell housing bolts is difficult, and the torque converter bolts (where and how do you actually access these?).

Do you think dropping everything to get to the gearbox is reasonable, or do you think some mechanics just do this as they are lazy or want to net themselves a bigger labour bill?
One mechanic told me that it's a job which takes 5 days, so if you figure that means 60 hours at $150/hour that's $9k just in labour. Seems a little unreasonable for something which can supposedly be done without taking the engine and everything else out.

BamaScoot

A shop swapped out transmissions on my 05 turbo for around $500, so no, the engine doesn't come out. The junkyard guys were also able to remove the trans (that I ended up using) in about 2 hours.

theprf

The TC bolts are accessed through a little hole behind the driver's turbo.
I cannot imagine taking these out with the engine in the car, they are difficult enough with the engine out!
I suppose where there's a will there's a way.

tassieporsche

Sounds like it's possible as others have done it by the sounds of it, just a pain to access.

Fingers crossed I don't need a new gearbox but these Aisin units do seem very problematic. Ironic that the least reliable part of this German car is one that was made by the supposed kings of reliability - Toyota!

BobcatBrian

The transmissions are not problematic…where did you hear that? The early 955 models had some issues with sticking solenoids in the valve body, but other than that they are one of the most reliable parts on the cayenne.

tassieporsche

But they are. If you look at the 955's and the problems they have, the gearbox is one of the worst offenders. Valve body's are obviously the big one but people seem to experience a lot of other issues with them even after this has been addressed.
The torque converter clutches commonly wear out, as do the clutch packs, specifically for 4th, 5th and 6th. The wiring harness can wick fluid up to the TCM and ruin that, and there's wiring issues themselves due to corrosion and biodegradeable sheathing.

I'd be interested to know how much of the engineering oversight was from VW on these '09D' units, and how much was done by Toyota.

BobcatBrian

But how common are those issues? There are plenty of 955 CTT and CTTS with 150-200k+ on the original transmissions. I think a lot of the issues come from the age of the cars and that they're on their 3-5+ owners now. If the maintenance is kept up (fluid/filter changes), then I don't see how these are any more unreliable than any other 20 year old transmissions.

hopsis

I worked as a transmission tech a few years back. That Aisin box is very reliable if you compare it to, for example, anything from ZF from that era. Just google ZF6HP problems and you'll get my point. Of course there are going to be problems in 15 or 20 year old parts. The weakest links in 09D transmission are valve bodies and tc. A new valve body goes for something like 1500$ with fluids, gaskets, filter and labor and that will make the transmission behave like brand new. TC is wear item and when it goes, you just replace it like a clutch in a manual car, no biggie. It's not any more common than in any other transmission made to handle similar power.

I'd rather take that Aisin than anything else that was available when 955 Cayennes were built.