Matsu

Hello!

Im having an issue with my 06 cayenne s gearbox..
While driving in 5th or 6th gear with low rpm (1100-1200 sometimes little bit more) and trying to accelerate, well i mean flooring the gas pedal hard, the car downshifts to 2nd gear with a clunk. Sometimes i swear to god that it feels like im going to lose my tranny...
it only happens when the transmission has warmed up and is in working temperature.
if im not flooring the gas pedal and accelerating smoothly, the car downshifts to 3rd gear and it is smooth..
Otherwise all the other gear changes are super smooth.
if the psm is turned off then it seems to be smooth as well. Also no problems if i downshift manually.

I have changed the oil few times, relearned the transmission, went from 22" to 19" during the winter time and still the clunk appears. True, the clunk went little bit smaller, but it is still there and very noticable.

Has anyone had similar issue before? Valve body needs to be replaced?

ScootCherHienie

Unless somebody else had this same issue, we are going to need a lot more info about your problem before intelligent guesses about the source of the noise.

When you say you changed the oil a few times... what oil are you talking about? The transmission doesn't have "oil" per se, it's closer to hydraulic fluid. Did you mean you changed the ATF (automatic transmission fluid) a few times or the engine oil a few times?

If you changed the ATF, did you also change the filter inside the transmission (you have to remove the bottom cover I believe when replacing the filter)

Is the big clunk ONLY when downshifting to second gear at wide-open throttle? What about going up a hill and pressing hard enough on the gas pedal to make the transmission downshift without being on the floor? If you are going faster in 6th gear and floor the gas pedal so it downshifts to 3rd gear in stead of second gear, is there a clunk downshifting into third gear?
What happens if you are at higher RPMs, say 2500 in 6th gear and you floor the accelerator... is there a clunk then?

If you drive in reverse and slowly brake to a stop, then shift into drive, when the vehicle begins moving forward, is there any kind of clunk in the drive-train?

Are you selecting any of the 4-wheel-drive modes or is the Cayenne in "normal" mode with no locked differentials.
I thought somebody here fixed a clunk problem by cleaning a hole in the valve body that was plugged with debris, but I may not be remembering that right.

mtnrat

Valve body. Search it.

Matsu

Well atf has been changes with filter and the magnets were cleaned (they were suprisingly clean).
So basically what i did:
1) Changed atf + filter
2) After ~1500km changed atf again
3) Changed atf again in next service ~ 8-9k after first atf change.
The purpose of that was to get rid of all of the old fluids. At one point i even removed the valve body, to visually inspect and to get more fluids out of the tranny.

it does not matter, if i go downhill or uphill.
From reverse to drive there is no clunk.

So i just did some further testing to describe the situastion as clearly as i can.
first of all i read the rpms wrong.. the clunk/ jerky downshifts appear 1000-1600 rpm. Never over 2000 rpm.
Driving in 6th with 2500 it wont downshift to 2nd gear while accelerating. It goes into 3rd, what is normal, orherwise the rpms would be too high for 2nd gear.
No diff locks, it is always on normal mode.

So what i discovered during the last test drive that the car downshifts to 2nd gear, but for a millisecond it stops on the 3rd gear and then it goes into second.
So basically while driving in 5th or 6th gear at low speed/rpm and accelerating the car downshifts to 3rd and 2nd. The 3rd gear is only for a millisecond, i barely noticed it on the dash where it shows the selected gear.
the jerk or a clunk appears excactly in that moment where it goes from 3rd to 2nd.
Not 100%sure how automatic trannys work and its clutch system, but it feels like the clutch is not working properly and banging in the gear at acceleration at the moment it goes from 3rd to 2nd.
It feels like the clutch is not slipping at all at this moment and instead of smooth change it goes in hard and instantly.
Thats the best way to describe it.
If you sit in a car what has manual transmission and you put in first gear or any gear and release the clutch super fast without pressing throttle.. You kind of get the same jerky.


The only time it all happens is ONLY when accelerating hard at low rpm/speed while in 5th or 6th gear.





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Matsu

The valve body is one of the most possible scenarios indeed. But im having some doubts, because otherwise the change of gears is just very smooth.

hopsis

Valve body all the way. These gearboxes are extremely robust otherwise.

95_993

Downshifts being harsh signal sticking valve body to me. I went with Revmaxx and couldn't be happier.

jeff spahn

I second (or third) the valve body. It’s an easy job, just messy. If you have a lift it is much less messy(I’d still wear a Tyvek suit though). Figure a couple hours. Look at the pelican parts site for how to do it. Spend the money. Seriously. I am going to do it on my turbo S just as preventive maintenance.

Matsu

Thank you guys for all the responses.
Was kind of afraid that it is bad valve body. But in the other hand, it is a pretty simple fix but not the cheapest one.
Most likely will order a remanufacured one and replace it.

jeff spahn

yes. Revmax is the place to get it.

Brainz

If you are very handy and looking to save money, this is an alternative to a rebuilt valve body. Essentially its a kit that allows you to rebuild your own. Note that it's an advanced/fiddly project, but doable in a day or less. Search Touareg and Transgo for a DIY on the Touareg forum.

https://www.transgo.com/products.php...product_id=257

jeff spahn

I'll leave the part with drilling to the experts. $700 is a small price to pay.

hopsis

My day job is rebuilding transmissions. Even we don't rebuild valve bodies anymore on these Aisin boxes. Just scrap the old one and put a new one in. I can see the logic if You are indeed handy enough and can do it yourself. It will be better than the old worn one is but it will never be as good as new. If You had to pay someone to do it, forget about it.

The good news is, with a new valve body You pretty much reset the transmission shift quality to day 1. If the transmission isn't broken in any other way, it will shift like new after replacing the vb and will likely last as long as the original.