That's too bad. My understanding on these transmissions they are not adjustable as per the old days of "tightening bands". They are known for having the solenoids going bad. There are a series of solenoids at the very bottom, visible when drain pan is removed. When the solenoids get lazy, the slow shift can cause clunking. They are replaceable and available. A deeper analysis of course is necessary before investing in this direction. This is just a place to start a discussion.

 

Additionally the transmission can be readapted with a specific drive cycle. The basic cycle is fast acceleration and coasting. This would have to be confirmed by someone who has experience with this. Also the TCM can be reprogrammed at the dealer level. Again just things to think about.

 

So a couple of things on the fluid change and getting the level correct:

First, what NOT to do:

1. Forget all the nonsense you read about trying to capture and measure the amount of fluid you drain then try to replace that amount. What if the fluid level was already low? What if there was too much fluid put in with a DIY change? In both cases you'd be wrong with the new level.

What you should do (and the pros do):

First the theory - ZF determined the correct fluid level by the placement of the fill plug. BUT, since fluid expands and contracts at different temps, they needed to add another spec, namely, that the fluid level would be right at the fill plug edge at a certain temperature.

Second, some basics about automatic transmissions - When the transmission is running (at idle) fluid is circulating. When the engine is shut off and the trans is idle, then that same circulating fluid is NOT circulating and is back in the pan. THIS IS IMPORTANT to get the level correct.

ZF sets the standard (correct fluid level) with the engine running at an idle and fluid at a certain temperature. So two things we can deduce from this:

1. If we just pulled the fill plug with the engine stopped we would lose a lot of fluid (the fluid typically circulating during idle).
2. If we drained the entire pan filled it up QUICKLY with the engine running at an idle and at ambient air (fluid) temps until the fluid just spilled out we would have TOO MUCH fluid in the pan. Why? BC at ambient temps the fluid is contracted. However, as the fluid rises in temperature it expands spilling out more and more until the correct spec fluid temp is reached. It is at THAT point we want to cap off the fill plug and the correct fluid level is attained.

So quickly:

1. Drain off all the fluid
2. Remove the pan, change the filter, replace the pan.
3. With the ENGINE OFF, static fill the pan with fluid until it spills. Cap it
4. Start the engine, idle, shift from park to rev, neut, drive, and back to neut, rev, park.
5 Then QUICKLY with the engine still running, remove fill plug and fill until fluid spills (now you have too much new fluid at room temp)
6. Place a probe (digital temp) and monitor fluid temp. Fluid will begin to spill as its temp rises.
7. When the correct temp is reached, remove the fluid probe, cap, done. It takes about 12 to 16/17 minutes to reach correct fluid temp.

Now another mistake:
1. It is important to take FLUID temps to get the level correct. Some think they can use an infra red temp gun, zap the case and cap when the case reaches the spec. But the fluid will reach temp far more quickly than the case temp. This will make your fluid level REALLY low.

I use a digital thermometer and I fashioned a probe to look through the fill hole and actually sit IN the fluid. This is the only way to get accurate fluid temp, thus the accurate fluid level at idle while some of the oil is circulating through the trans.



Finally, this is a DANGEROUS job without a lift. I've done it with and without, there is nothing like a car on jacks with the engine running and you laying underneath trying to add fresh trans fluid at some ridiculous price per quart (don't care how good you are, you WILL spill good new fluid trying to get the cold fill complete).

 

Good points. Did the same for a temp probe. Works well and inexpensive.

 

As per attached original Bentley Service schedules at 10 Years | 100,000 miles | 160,000 kilometres, they actually included transmission oil change for 2004-2009 Continental cars.

For 2010 onwards cars transmission oil change is scheduled at 6 + 18 Years | 60 + 180,000 miles | 96 + 288,000 kilometres in original Bentley Service schedules.

Tadas

 

Yeah agree - The "fill for life" terminology that the car mfgrs were using at the introduction of the ZF6HPxxx was so nebulous that they ended up revising that language to spec a change at some point. Some instead, created a "severe use" exception with a mileage change usually around 60K miles. Even then, they kept severe use a little vague so it was difficult to pin down whether your driving need qualified. On Bentley, the service F group even specifies a change at 100K miles as you've IDed.

On the Bentley, those years (04-09) capture the 6HP used, after which it became the 8 speed ZF.

 

After reading this post and great info from Mr BWings I contacted the guy who looks after my car an independent Bentley specialist asked him to change the Transmission (gearbox) and Differential oil all in at £349. The cars covered 40,000 miles thought get it done ...

 

That's a pretty good price for gearbox and diff

 

Yah fantastic price, For that kind of money id change the oil every 3 years ...