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DirtyHarry88

ZF 6 speed transmission issues

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Car is a BMW e65 745i, 136k miles.

 

I've only noticed this in the first few minutes of driving from cold and it quickly disappears. When leaving for work it's not long before I hit an NSL section so always see it. When keeping a constant speed, say cruise set a 60, I noticed the revs would hunt from around 2000-2200rpm. Within 30 secs or so I'm turning on to dual carriageway, get up to speed again and the revs stay constant.

 

On my initial acceleration when hitting the first section of NSL, the car occasionally doesn't want to shift up into the last 2 gears and I do it manually. As above, I'm then shortly turning onto the dual carriageway and it shifts just fine.

I'd say the car can sound a bit whiney, most notable at lower speeds but as I don't have another to compare it to I'm not sure if this is just typical.

 

Torque converter issue? The gearbox itself had a decent amount of work done to it (it's a pistonhead user's old car) less than 30k miles ago and the gearbox itself was said to be in fine condition then.

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the gearbox has maps to control warm up where it'll allow the box to effectively 'slip' to warm the fluid up. If it's only doing it for the first couple of minutes when it's cold don't worry about it. Mine does this too and as soon as it's been driven for a few minutes, it'll start to lock the torque converter earlier as the heat gets into the fluid. In that 2 minutes when I first start mine the smallest input on the throttle will cause the revs to rise a touch.

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I don't think it's too serious, as Mashed Potatoes says the gearbox runs a different program when its oil temperature is below a threshold, 30C I think. That prevents the torque converter from locking up and holds lower gears.

 

The revs hunting is the torque converter failing to lock up fast enough. Probably due to some wear together with cold viscous oil. It might be the case that an alternative to Lifeguard 6 ZF oil has been used and isn't quite as good, or it might be needing an oil change.

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I'd read about the warm-up map the gearbox uses when cold but I didn't think this would stop shifting into the higher gears. It'll sit in 4th at about 3000rpm rather than change up.

 

Does needing the oil changed not sound a bit premature at less than 30k miles?

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In the various documents I have on the 6HP26 gearbox it says the gearbox basically stays in sport mode until the gearbox oil hits 60C. I think that also means it will never go into top gear. And until the gearbox oil is above 30C it will not lock up the torque converter clutch.

 

ZF say change the oil at 50k to 75k miles under heavy use (continuous towing, high temps, constant high speed, offensive driving). However when you change it you can only change about 70% of the oil without removing the gearbox. So 30k miles is a bit soon but perhaps excusable. 

 

 

 

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Just now, Grizzle_E60 said:

exactly what happens to mine in the morning seems as if your revving the nuts off it, but 5-10 mins and shes good as gold and the gearbox oil is up to temp. 

Good to know, I will keep an eye on it and see if anything gets noticeably worse. I think it's only obvious because I hit an NSL section of road so quickly when I leave for work.

 

Not sure what sort of issues with the transmission would actually throw some codes but I've just had the laptop and DIS on the car and there's nothing untoward showing regarding the transmission.

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29 minutes ago, DirtyHarry88 said:

Good to know, I will keep an eye on it and see if anything gets noticeably worse. I think it's only obvious because I hit an NSL section of road so quickly when I leave for work.

 

Not sure what sort of issues with the transmission would actually throw some codes but I've just had the laptop and DIS on the car and there's nothing untoward showing regarding the transmission.

 

You may be surprised at which gear it is in. If I leave work I'm straight out into a 50MPH area. Mine will sit in 5th gear but at 2500RPM still accelerating until the box oil has heated up. When the torque converter locks up when the box is up to temperature it'll plod along at 1300RPM, but still in 5th. My gearbox has the xHP remap on which allows me to see on the dash what gear it's in instead of just D. It shows D5 for example.

Edited by Mashed Potatoes

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The only way I've noticed is by changing to manual mode and it shows M4. Shifts up manually just fine when I tell it to.

 

A look at the previous invoice for the gearbox work a few years ago states 'Lube Guard 6 Trans Oil'. I can't find anything on that specific oil, I wonder if it's a typo and they meant Life Guard.

 

 

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There was a thread on a different forum about 545is doing something similar but at much lower rpms. Mine would do it both on a hot or cold engine but only occasionally. I thought it was a failure of the lock up clutch engaging. No one ever got to the bottom of it when I was looking, the TC was ruled out and the thought was the problem lay within the Mechatronic unit itself rather than anything mechanical giving issues. But it felt like the TC to me but this was then subsequently ruled out by a transmission specialist at a later date.

 

 A full service on the box with a new plug sleeve and mechatronic bridge seals replaced would help. The bridge seals get over looked at service time, crack and allow pressure to drop causing all sorts of weird intermittent faults that don't necessarily leave fault codes.

 

Had a look and I can't find the forum posts I saw, mostly USA based cars as so few E60s over here had a decent engine in them.

 

I could tell the TC was doing its job as I could hold the engine rpms constant and watch the speedo climb as the slip got less. I would imagine you could see that in yours and the bigger Diesels with more torque.

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I had a similar problem in my 2005 530d touring. I had an oil service and gearbox sump replacement (they are plastic things so the oil and the sump are sold as a kit). It took about a month ( I guess 170K miles of crap working their way out of the torque converter), but it cleared it up, so if that hasn't been done in the last 60K miles, probably worth doing.

 

The other fix that came up a lot was to add two tubes of Dr Tranny's (I kid you not) instant shudder fix (https://www.amazon.co.uk/Lubeguard-Automatic-Transmission-Instant-08313719610/dp/B00CJ83C5Q) - as the "hunting" is said to be caused by the clutch being continually engaged and disengaged. A bunch of threads I found had people swearing by this as a fix. Worth a punt for £30. 

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On 03/02/2018 at 5:28 PM, Mashed Potatoes said:

 

You may be surprised at which gear it is in. If I leave work I'm straight out into a 50MPH area. Mine will sit in 5th gear but at 2500RPM still accelerating until the box oil has heated up. When the torque converter locks up when the box is up to temperature it'll plod along at 1300RPM, but still in 5th. My gearbox has the xHP remap on which allows me to see on the dash what gear it's in instead of just D. It shows D5 for example.

I want that.. The next time you are visiting the opposite side of the country :D

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imo a gearbox service is the cheapest option, don't buy an ebay kit, most are fake!

Only use lifeguard 6, lots of issues using substitutes.

If you don't want to diy in Nottingham we have an indy who specialises in the ZF boxes but plenty of others come recommended, prices between 400-520, you should get the mechatronic sleeve replaced as well due to its age, you are basically double the mileage for a service as recommended by ZF (ignore BMW's lifes time BS)

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1 hour ago, GoNz0 said:

imo a gearbox service is the cheapest option, don't buy an ebay kit, most are fake!

Only use lifeguard 6, lots of issues using substitutes.

If you don't want to diy in Nottingham we have an indy who specialises in the ZF boxes but plenty of others come recommended, prices between 400-520, you should get the mechatronic sleeve replaced as well due to its age, you are basically double the mileage for a service as recommended by ZF (ignore BMW's lifes time BS)

As above, it's under 30k miles since the following work-

 

 

gearbox work.JPG

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No sign of the bridge seals being changed in that lot.  These are the O rings if you like between the mechatronic unit and the gearbox proper.  They age and leak loosing pressure and give all sorts of gearbox issues.

 

Part #2 in link below

 

http://www.realoem.com/bmw/enUS/showparts?id=NB32-EUR-05-2004-E60-BMW-545i&diagId=24_1027

 

 

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