Date: Sat, 7 Nov 2009 02:12:49 -0500
Reply-To: Dennis Haynes <d23haynes57@HOTMAIL.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Dennis Haynes <d23haynes57@HOTMAIL.COM>
Subject: Re: Standard to automatic?
In-Reply-To: <6da579340911062131w7aa3f46t6ddbf459d22f4413@mail.gmail.com>
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The automatic in third gear (direct) and final drive ratio gives the same
overall ratio as the manual in 4th gear. At speed the slip should be less
than 3%. Off the line automatics should accelerate quit well. Yes, they lose
some efficiency due to the power needed to operate the hydraulics and the
non-locking torque converter. Towing and long hills are a bit of a concern
due to some of the torque converter heat but the converter has ample cooling
air over it from the air cooled days. For performance or towing needs I
would use a separate oil cooler for it.
Most auto tranny performance issues are due to bad torque converters. Yes,
they do fail. The one way clutch in them fails and then they no longer
multiply torque. Poor acceleration is the result.
Dennis
-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of
John Bange
Sent: Saturday, November 07, 2009 12:32 AM
To: vanagon@GERRY.VANAGON.COM
Subject: Re: Standard to automatic?
> Is this swap possible?
Sure. If anything, it's easier than going from auto to manual. Just make
sure you get all the parts.
> Surely someone has done this? One of the biggest differences I noticed was
> the automatic was connected to the cooling system. Why is that?
>
>
ATF cooler. Actually, it's technically a cooler/heater, intended to bring
the transmission up to operating temps quickly and then keep it there. Not
really necessary though. Some even consider it a liability, as the exchanger
is made of aluminum and can corrode. More than one transmission has been
ruined by an unexpected pressurized injection of piping hot water based
coolant into the transmission.
I think the real problem with the auto trannies are the design itself. I
have one van of each, manual and auto, and the manual has so much more power
where the wheels hit the road and gets better gas mileage to boot. The auto
transmission is limited by the fact that 1) it's a 3 speed geared low for
wimpy engines, and 2) non-lockup torque converter that steals engine power
and turns it into friction heat in the ATF. My auto van is great for
toodling around town in heavy traffic for work, but on the open highway, I
wouldn't trade the manual in my "fun van" for anything.
--
John Bange
