ZF Autobox, changes higher up rev range when cold

[SteveG]

Now it's colder, I've noticed that the auto in the RR is not changing up a gear until about 3000 rpm when it's cold. When it's warm all is ok.

Anyone had this before? I've looked at Ashcroft's FAQ's and it does have a bit about not changing out of 1st when cold, but nothing about the symptoms I have.

Cheers

Steve

[Turbocharger]

Mine does that and always has, so if they're both broken please let me know

My guess is that in colder weather the oils are all more viscous etc, so I need more throttle to get the same performance out of my piddly diesel engine. More throttle pulls the kickdown cable more, so it holds gears slightly longer (like it does when the engine's warm). I chose not to worry about it more than the more pressing issues, anyway...

[SteveG]

Mine does that and always has, so if they're both broken please let me know

Had two P38's from new and neither did it, so yes John, your's is fubar'd too ;)

[BogMonster]

Mine does something like that in the D2 if you start the engine and set off immediately from stone cold (sitting overnight, start, into drive and away within a few seconds) it will hold onto 1st gear till about 2500-3000rpm even on very light throttle, after that first change up it is fine. By the time I have shut the garage door and left it idling for that time, it is fine, so it doesn't bother me as its rarely left anywhere else. Not something I would spend money on unless some cogs come out through the side

[roguevogue]

And mine, and the P38 I heard this morning.

[will_warne]

My 90 always did the same - IIRC it is to do with the viscosity of the cold oil meaning the governor doesn't work as it should. Dave Aschroft rode passenger a few years ago when I was marshaling up at Muddy Truckers and I quizzed him about it on the Sunday morning when it was well below freezing and the truck was cold. He confirmed it was a characteristic of the gearbox and, IIRC, said there wasn't anything that could really be done about it.

[David Sparkes]

Well, as far as the 38A is concerned, there is a deliberate characteristic built into the complete assembly to delay the gear change. It helps the engine to warm up more quickly. It will be in the manual.

Without looking at this time of night, I think it's described in terms of not locking up in top gear until the engine is up to temperature, so that might not be exactly the same as you people are experiencing. How noticeable it is to the user may be influenced by the driving conditions they experience in the first few miles.

But as I say, it is described in the Manuals, somewhere.

Good Luck!

[JST]

My 90 always did the same - IIRC it is to do with the viscosity of the cold oil meaning the governor doesn't work as it should. Dave Aschroft rode passenger a few years ago when I was marshaling up at Muddy Truckers and I quizzed him about it on the Sunday morning when it was well below freezing and the truck was cold. He confirmed it was a characteristic of the gearbox and, IIRC, said there wasn't anything that could really be done about it.

and hence mine does it

[SteveG]

And mine, and the P38 I heard this morning.

OK, all is well then. It's been a few years since driving the other two, but I don't recall them doing it and it's that noticeable I thought I would remember. But, they were well looked after, so maybe that was it! ;)

Steve

[will_warne]

Well, as far as the 38A is concerned, there is a deliberate characteristic built into the complete assembly to delay the gear change. It helps the engine to warm up more quickly. It will be in the manual.

Without looking at this time of night, I think it's described in terms of not locking up in top gear until the engine is up to temperature, so that might not be exactly the same as you people are experiencing. How noticeable it is to the user may be influenced by the driving conditions they experience in the first few miles.

But as I say, it is described in the Manuals, somewhere.

Good Luck!

Dave, I'd say that LR put that in the manual to keep the buyers happy. The last thing you want to be doing is holding the vehicle in gear when the engine oil is cold - revving the nuts off it is bad news!

James, yes, I always just took it as easy as possible when cold.

[nas90]

Now it's colder, I've noticed that the auto in the RR is not changing up a gear until about 3000 rpm when it's cold. When it's warm all is ok.

Anyone had this before? I've looked at Ashcroft's FAQ's and it does have a bit about not changing out of 1st when cold, but nothing about the symptoms I have.

Cheers

Steve

When I put an auto in the nas it was a very secondhand ZF from a classic RR. After about 2 years it took about 2 miles to get out of 1st gear from cold gearbox with a trail of hooting cars behind me up our Lane

That nice Mr Ashcroft made me a new box and politely mentioned to keep the filters clean and change the oil to keep the cr*p out of all the little oilways. Maybe same problem?