Hi,
Thinking of installing new Solenoid Pack at next Service. Issue is Jolt on up-shift from 5th to 6th but worse issue is it gets 'stuck' in 4th gear when hard acceleration through the gears, resulting in very disconcerting huge jolt and engine revs screaming. Also, had on occasion all Gears show up on indicator in dash binnacle and the whole whole gearbox being stuck in the present gear and not being able to shift up or down until I pull over, stop and turn engine off and on again.
2005 with 61000 on clock. Had Gearbox oil changed and values reset. No fault codes showing when recently plugged in via a Bentley Specialist.
Next step i'm thinking just to swap the solenoids out at next service as this is a relatively quick cheap fix as part of the diagnosis/fix process. Any agreements or thoughts?
Thanks

 

Hello @bmw5series ,
I just wanted to ask, before you jump into the innards of the transmission itself, how is your shifter dust cover, as some of your descriptions of issues sounds like a faulty broken dust cover, whereas the magnets in said dust cover are not functioning as they should, therefore not shifting manually in triptronic mode as it should each time you move the shifter lever, and if the PRNDS is lit up, then iirc the paddles don't work, and possibly getting stuck until you move the shifter to park, and restart the engine, just a thought.

Do your symptoms change between auto drive mode, sport mode, or triptronic manual mode, and or using the paddles in any mode ?

When you had the "values reset", did anyone perform the proper driving procedure of gentle acceleration to speed, and coasting down to almost a stop, iirc, this is to be performed 6 times, at least according to other brand's tsb's.

I will add that the ZF 6HP-26 transmission does have it's issue in certain brands, "Hooting between 3-4" in some D3 Audi A8L/W12, "seal leaks" in the BMW, Jag, and Aston DB9, but I really can not recall anyone here ever having these issues with the Bentley, the Audi did a fluid upgrade, along with a software flash to the transmission control module for its 3-4 hoot issue, and I can say that my 2005 A8L W12 with the ZF 6HP-26A has never had issues, and that is now at 200K miles, my GT has the Supersports ZF 6HP-28, so I can not comment on the characteristics of the 26 in the B.

If you do replace the solenoids, be sure to replace the seals as well.

Johnny

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Hi Johnny,
Thanks for detailed response. It's much appreciated.
I don't think it's the dust cover tbh. It's fully intact and seems fine.
The problem is the same, regardless of auto ,
Paddles, manual etc.
I do get some hooting when it happens so perhaps that helps with the diagnosis?
The indie specialist reset the values electronically, not through road testing etc.
I did read somewhere another owner had similar issue and replaced the power lead to the valve body. Maybe I could try this too?
once again thanks for your comments.

 

Hello, ¿Did you ever fix tour issues with your transmission?

 

Hi
Yes. It was Solenoids in mechatronic. £1500 fix.

 

I am diagnosing some random jerks on my 2005 Bentley GT also when upshifting 2-3 and downshifting under braking 3-2-1. I checked the Solenoid (Pressure control valves) in the mechatronic via my scanner in P at idle, and the values I got are attached.
Valve 2, 4 and 5 have different readings than others. Could this be the problem?
Car otherwise drives great, idles great, starts every time, etc.

 

Im not sure, but in mine i had delayed reverse after 30 minutes driving, used to take 3 seconds to engage reverse and then you feel a bump like if someone rear end you, I replaced all solenoids, filter, bridge sleves and 8 liters of fluid and problem solved

 

Sorry to resurrect this, but needed your expert eyes kind sir. Do my Pressure Control values look okay? Symptoms are: slight shudders and jerks going from 1 to 2 to 3 on part throttle and back down from 3 to 2 to 1. There are no delays going into reverse and the shift is silky smooth there. Screenshot attached 2 posts above

 

That's what I'm trying to tell you, I don't know if those values are correct or not, I don't really have expertise in transmissions, actually the work performed to my car was the first time I ever worked on a transmission, but based on my research, I will try to readapt the transmission through driving cycles, you know driving in a empty straight road untill 6th speed then just let the car roll by itself with no brakes untill it stop allowing the transmission to make downshifts. If that doesn't work then I will proceed to replace the solenoids, and seals, that's easy if you have experience working on cars, if that doesn't fix your issue then the valve unit will need to be inspected thoughtfully, those odd shifts could be due a contaminated valve body or damaged valve body too, in that case should be rebuild, I've seen videos of how other ZF valve bodys are beign rebuild but probably I'll just pay an expert for that.

Just be aware that replacing the old fluid for new fluid in the transmission if your car is high mileage and the transmission never been serviced before, it may exacerbate the problems with the transmission.

 

Hi. Are you based in the UK?
I can recommend a gearbox specialist in the south of England if you are.
Solenoids

 

Thanks a mill! In my second post, I was aiming to reach Johnny Hotspur who helped correct a workshop induced problem with my car earlier.
I understand what you mean, and actually went the exact same route. Did the relearning method today, found an empty stretch of road at 6 am, observed the tranny fluid temp, let it warm up to 170 F which took about 20 mins of driving, then at 20-30% throttle let it accelerate and reach 6th, then coast and downshift on its own till 2nd gear (it doesn't downshift to 1st till I press brake). I thought this was the end of the official process but then I come back, read some more and apparently you have to do this 6 times. lol
However, in the above, I did not RESET the transmission values first, just cleared all faults from every module.
The results were: zilch. No change in the jerks.
THEN I dug in and observed the pressure control values of each solenoid. Interestingly, the valves 2,4 and 5 are at values 0.85, 0.63 and 0.68 A at idle in P. When I select D, car engages Valve 1 and its value rises from 0.05 A to 0.85 A, which is the same as Valve 2 at idle. This to me indicates a stuck Valve 2, hence, explaining the jerkyness now and then.
Tmrw morning I'll reset Tranny, and do the relearning drive 6 times, and see if the pressure control valves change. Excited!

 

I would be very interested in a trusted auto box. Especially if they are specialists. Perhaps they could offer upgrades to clutch packs etc?
Their address would be great please.
Thanks
Frank.

 

Most likely the valve body needs to be removed and separated. Than install the following Sonnax replacement and improved item : attached link. This will in most cases stop the hard shifts and down shifts. The old buffers are flattened and are not buffering shifts.

https://www.sonnax.com/parts/2678-ac...tor-piston-kit

At this point might consider a Sonnax rebuild kit for the valve body. Look up Sonnax to see more.

 

Yeah I was getting delayed shifts in 4, 5. It went from interesting to bad real fast. The transmission shop pulled it a couple days ago and pulled the box apart. Solenoids bad and now a few other things. I bought a lightly used (51k) gearbox instead of doing the full rebuild as the price was better. I'll probably get this rebuilt eventually. If anyone has any upgrade tips I'm all ears!