From: "M. T." <mmglass@ix.netcom.com>
Organization: M&M Stained Glass
To: lro@koan.team.net
Subject: Re: [lro] RR transmission issue (no Series content)
Reply-To: lro@land-rover.team.net
>I don't understand what difference it makes if you are turning out
>revolutions with the transmission in neutral, with or without the transfer
>case engaged. Isn't this is similar to being in park?
I guess what's needed is a better explanation of what the potential problem
with this ZF transmission is. People on the list said that if you shift
from Drive into Park after driving the vehicle and then rev the engine up
as in an emission test, you run the risk of damaging the clutch packs if
the fluid hasn't drained out of them, which is apparently what the
potential problem is with this transmission as used in the Range Rover
(and, I've been told, in BMW cars as well).
They said the only way to ensure that the fluid drains from the clutch
packs is to put the transmission in Park and switch off the engine for a
minute or so. I suppose the actual gear doesn't matter, but the emissions
testers always want you to shift into Park and put on the handbrake unless
you're a 2wd vehicle on the rolling road. Then after waiting a minute,
this procedure calls for restarting the engine, but it's critical that the
transmission not be shifted into any gear before revving it up, as doing so
puts fluid back into the clutch packs and you're back to where you started.
What I don't know is what gets locked when you shift into Park. But if
what happens is what the folks on the list said happens, the damage occurs
because the engine tries to spin up the clutch packs but they can't turn
because the transmission is in Park. So they fail or are damaged.
The solution would be to put the transmission in neutral, which would allow
the packs to turn with the engine IF nothing behind the transmission was
keeping them from turning as well. This is why I put the transfer case in
neutral, too.. Then I could apply the handbrake to lock the wheels to make
the emission testers happy, but all the components in the transmission were
free to turn if they were so inclined.
Putting the transmission in Drive and the transfer case in neutral would be
okay, too, I guess. The point is to not allow the engine to try to turn
clutch packs that are being prevented from turning by the transmission
being in Park or something else, like being connected to the transfer case
in High or Low which is prevented from turning by the handbrake.
Clear as mud, right?
________________________
C. Marin Faure
(original owner)
1973 Land Rover Series III-88
1991 Range Rover Vogue SE
Seattle, WA
marin.faure@boeing.com
faurecm@earthlink.net
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