Hello,
I have quite a lot of experience with transmissions, I used to diagnose them and have put on rebuild kits on quite a lot - in general I consider my self to be quite knowledgeable on this subject. And yet this issue just left me completely clueless.
My car, a 2011 model year Volvo C30 equipped with a dual clutch MPS6 (Getrag 6DCT450) transmission with 82k miles.
The symptom is: jerking while in gear and slightly accelerating, this often can be triggered after I make a turn.
I have had the clutch, seals, damper, fluid, internal and external filters replaced - since then the car drove excellently for 2 and a half months (only the occasional stutter - that you'd expect from an early dual clutch).
I have found that the transmission seems to be slightly wet on the underside of the transmission but I can not understand if that is just left over dirt and smudge. From my experience with this type of gearbox, This leak doesn't seem severe enough at all (you'd have to loose about 2L-3L of fluid) to cause the gearbox to misbehave in such a terrible manner.
Recently, over the last 50km (or thereabouts) I began experiencing more and more intense stuttering and jerking from the transmission while driving in town.
Yesterday, was going on the highway, made a left turn with quite a lot of acceleration and after it and it just started jerking and the rpm started to go between 2,100 and 1,900 while driving at about 45 mph while the car was jerking back and forth.
but the clutch is new and does not slip, the oil pump and sensors return nominal readings, no relevant trouble codes, no relevant high-level information - I just don't understand why does it do what it does!
I have recalibrated the mechatronic unit, tested the transmission and electrical system repeatedly and could not make it act up during my testing. The only code visible to my TCM (from my experience) does not effect the transmission's ability to work properly ("Input Speed Sensor. Plausible Signal").
I have tried locking the car in gear, and I have tried scanning the car with even fancier scan tool - and yet... I have found nothing.
Could my differential gear inside of the transmission be going out at only 82k miles??? It'd be quite ridiculous but I really do not know another possible cause...
maybe this is a TCM or a Mechatronic / Solenoid issue that is somewhat slipping past diagnosis? maybe it's a brake switch or a rouge brake computer triggering random clutch disengagements?
Please help me.
I have never have encountered such an issue in years of working with transmissions.
I will take the car to another specialist tomorrow to see if he can find the source of the issue, the one that looked at it with me today was as dumbfounded as I am and could not point out a specific issue with the car.
I have as much experience as the specialists on this drivetrain so I'm not sure if that would be helpful.
I will keep this topic updated as best as I can,
@DayWalker , @Doc , @G-T , @Kaizen , @inthrustwetrust , @mountainmanjoe
Please help, If you know other people who may know what diagnostic steps should I take or what this issue could be caused by please add them to this topic.
Any help would be appreciated.
Thank you in advance 😃
Well the thing that gets me is after turns you say it acts up I would have the wiring system and the transmission computer module check closely it could be an electronic problem
Sorry, I've never worked on a DCT.
Since the problem is sensitive to making turns, then I would suspect the differential, as you said. Is it difficult to tear the unit down and inspect?
Yep… it would require me to drop it out of the car, and remove expensive seals that can’t be re-installed…
Isn’t this the infamous Ford DCT transmission which has a class action lawsuit against it?
I would suggest you not to dive into this rat’s nest, as I’ve seen friends left stranded (with clueless dealership mechanics) multiple times, with the Powershift transmission.
Take this as a sign from up above to get rid of it, while you still can.
https://drivelineap.com.au/2020/04/27/getrag-6dct450-470-dual-clutch-transmission/
Ford's infamous troublesome dual clutch transmission was the 6DCT250 (the "Dry Powershift", it has not much to do with the much older and better "Wet Powershift") - The weak points of the "Dry PowerShift" were issues with the electric shifting mechanism, and with insufficient clutch cooling causing premature wear.
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The 6DCT450 does not have those... it does not have an electric shift mechanism (it's a very clever hydraulic system with no mechanical clutch actuators, IMO the best control unit I have ever seen on any dual clutch transmission) and it has a clutch that is cooled by the transmission fluid making clutch wear much slower and the driving experience usually incredibly smooth
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As a matter of fact (if we exclude VW group built cars), since the 6DCT450 was launched in 2008 on Volvo models, transmission models related/based on it make up most of the dual clutch transmissions currently in production.
BMW StepTronic , BMW M-series Dual clutch (7DCI600), Mercedes 7G-DCT, Renualt EDC and Mitsubsihi SST and more are all wet dual clutch transmissions derived from the Volvo MPS.
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Basically this "Wet Powershift" has little to do with the "Dry Powershift" (that is known for breakdowns)... and from my experience these Volvo transmissions usually last 130,000-140,000 miles before having major breakdowns.
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But speaking of the "Dry powershift", as far as the infamous 6DCT250, the one that's known for jerking and very poor driving dynamics, I have repaired, owned cars and still own a car (a 2014 Focus) equipped with that transmission...
To be honest, reliability after the ~2013 model year was above average, The clutch assembly been improved, The weak TCM was improved, the software was re-written and with Ford's 7 year 100,000 mile warranty on this transmission have (in recent years) turned this transmission into a cheap and generally reliable although it still quite un-pleasant to drive.
(The only common repair on modern 6DCT250 is a clutch replacement at around the same millage as you'd do the timing belts, this is pretty much in the middle of the warranty period and my experience with using that warranty at my local dealer was very pleasant)
But I do agree that maybe I should get rid of it...
I am considering selling my old beloved C30 and buying a newer ~2016 era Volvo S60 equipped with an Aisin built automatic transmission (Although I know the ford built "GTDI" engine isn't very reliable and is hard to get parts for...)
I'm not sure what would be the correct path of action in this case as Lexus and Acura cost more then I would like to spend on a car...
What are your viable options? Realise no car is perfect. There’s always going to be downsides to a vehicle, even a Toyota/Honda product. I say - choose your poison, wisely.
I have no experience with automatic transmissions, I am not a mechanic either, but common sense tells me if transmission is ok, problem is somwhere else in powertrain. My thought was differential too. In some forums they suggest electronics, as Scotty mentioned, EGR valve, flywheel and transaxle. I suppose you don't drive with empty tank.
Good luck!
Any way to test the torque converter?
OP has a dual-clutch transmission.
Yep… there’s no converter, there’s a clutch with a damper and that part works great.
0 slippage and good take off…