Overdrive?

  • Thread starter Thread starter Richard Setford
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Richard Setford

Hi all,

Just got my first ever Volvo. It's a 1990 740 SE Estate Auto and it
drives like a dream.

One question (from a Volvo Newbie). What is 'overdrive' and how do I use
it properly when driving. The button for the overdrive works as a
yellow/orange arrow appears on the dashboard but I don't want to engage
it and use it incorrectly.

Many thanks,

Richard
 
Hi all,

Just got my first ever Volvo. It's a 1990 740 SE Estate Auto and it
drives like a dream.

One question (from a Volvo Newbie). What is 'overdrive' and how do I use
it properly when driving. The button for the overdrive works as a
yellow/orange arrow appears on the dashboard but I don't want to engage
it and use it incorrectly.
Click to expand...

From my 740 Owner's Manual (a couple of years older than yours):

"The overdrive can be engaged in 4th gear only. To engage, depress the
push button in the top of the lever. To disengage, depress the button
once again. The clutch pedal should be depressed slightly when
operating the switch to facilitate smooth changeover.

"The overdrive is automatically disengaged when downshifting.

"We do however recommend disengaging the overdrive before changing
down.

"Use the overdrive as much as possible at speeds in excess of 45 mph
(75 km/h) for good fuel economy."


Specifically, an overdrive unit is an extra bit added on the end of
the gearbox, usually engaged electrically. When engaged, the output
shaft will rotate faster than the input shaft. In practical terms, it
adds an extra gear ratio, though this is usually restricted to top
gear (some cars enable it for 3rd gear too), and in effect makes a 4
speed box into a five speed.

Although the overdrive unit has its own internal type of clutch, and
is designed so that you can't crash the gears, it is a good idea to
relieve stress on this by dipping the clutch pedal as advised.

The light on the dash is simply a reminder that overdrive is engaged.
Remember that if you change from 4th + overdrive to 3rd, you are
effectively changing down two gears at once.

I've never really understood why an overdrive unit is fitted to a car
which has a perfectly good 5 speed option.
--

Stewart Hargrave


For email, replace 'SpamOnlyToHere' with my name
 
Stewart said:
From my 740 Owner's Manual (a couple of years older than yours):

"The overdrive can be engaged in 4th gear only. To engage, depress the
push button in the top of the lever. To disengage, depress the button
once again. The clutch pedal should be depressed slightly when
operating the switch to facilitate smooth changeover.

"The overdrive is automatically disengaged when downshifting.

"We do however recommend disengaging the overdrive before changing
down.

"Use the overdrive as much as possible at speeds in excess of 45 mph
(75 km/h) for good fuel economy."


Specifically, an overdrive unit is an extra bit added on the end of
the gearbox, usually engaged electrically. When engaged, the output
shaft will rotate faster than the input shaft. In practical terms, it
adds an extra gear ratio, though this is usually restricted to top
gear (some cars enable it for 3rd gear too), and in effect makes a 4
speed box into a five speed.

Although the overdrive unit has its own internal type of clutch, and
is designed so that you can't crash the gears, it is a good idea to
relieve stress on this by dipping the clutch pedal as advised.

The light on the dash is simply a reminder that overdrive is engaged.
Remember that if you change from 4th + overdrive to 3rd, you are
effectively changing down two gears at once.

I've never really understood why an overdrive unit is fitted to a car
which has a perfectly good 5 speed option.
Click to expand...

Thanks for that. I guess it's the same logic for an automatic is it?
 
Richard said:
Hi all,

Just got my first ever Volvo. It's a 1990 740 SE Estate Auto and it
drives like a dream.

One question (from a Volvo Newbie). What is 'overdrive' and how do I use
it properly when driving. The button for the overdrive works as a
yellow/orange arrow appears on the dashboard but I don't want to engage
it and use it incorrectly.

Many thanks,

Richard
Click to expand...

On the automatic, that's just a way to lock the transmission's top gear
out. The transmission was just a 3 speed unit when designed, they added
on 4th gear, aka overdrive. It was cheaper (I presume) to add the
electric control circuit rather than redesign the valve body. Normally
you just leave the button alone, so the transmission shifts through all
4 gears. When the arrow is on, then the transmission functions as a 3
speed, this is useful if you don't want the transmission to shift into
top gear for whatever reason.

--
Mike F.
Thornhill (near Toronto), Ont.

Replace tt with t (twice!) and remove parentheses to email me directly.
(But I check the newsgroup more often than this email address.)
 
Mike said:
On the automatic, that's just a way to lock the transmission's top gear
out. The transmission was just a 3 speed unit when designed, they added
on 4th gear, aka overdrive. It was cheaper (I presume) to add the
electric control circuit rather than redesign the valve body. Normally
you just leave the button alone, so the transmission shifts through all
4 gears. When the arrow is on, then the transmission functions as a 3
speed, this is useful if you don't want the transmission to shift into
top gear for whatever reason.
Click to expand...
Thanks for that Mike.

I really can't think of a reason why I wouldn't want to go into 4th gear
(unless it's to do with towing large caravans/boats etc).

Regards,

Richard
 
Thanks for that Mike.

I really can't think of a reason why I wouldn't want to go into 4th gear
(unless it's to do with towing large caravans/boats etc).

Regards,

Richard
Click to expand...

I sometimes find the overdrive button useful when overtaking/passing
at high speeds. When on a two-lane highway at 80-90km/h and you have
to pull out into the oncoming lane to pass you can hit the button and
get more direct power to the wheels to get more responsive
accelleration at that speed.

Just remember to switch it back once you finish passing. Also, even
with an automatic, it's not a bad idea to give it some gas and raise
the engine RPM before dropping the top gear because at higher speeds
the the transition from 4th to 3rd adds a couple thousand RPM all at
once.

Also, if you're in a particularly hilly area you might find that with
the OD off (arrow lit up on the dash) the engine remains more engaged
when coasting and will help when attacking steep climbs and also
improve control on the descent. In my 4-cylinder 240 Turbo this keeps
the car at a fairly constant 70km/hr (downhill) and supplies power to
the wheels for better control. Haven't tried it out on the V6 760 yet.

blurp
1983 240Turbo 320,000km and counting!
1988 760 GLE 320,000km and counting!
DISCLAIMER: I am likely less experienced than many
of the users on this newsgroup and can only provide
suggestions based on my own experience with my car.
Many of my problems have been solved by the more
knowledgeable members of this community.

In the absence of facts I will speculate wildly.
 
Thanks for that. I guess it's the same logic for an automatic is it?
Click to expand...

Ah. Auto! I must read the post before replying.

I didn't know there was an auto + overdrive option on a 740; I thought
that was only on the 240s. It seems strange that I've got a 4 speed
auto, but they were still offering 3 speed + o/d on later models.

--

Stewart Hargrave


For email, replace 'SpamOnlyToHere' with my name
 
Richard Setford said:
Thanks for that Mike.

I really can't think of a reason why I wouldn't want to go into 4th gear
(unless it's to do with towing large caravans/boats etc).
Click to expand...


When I've driven automatic Volvos I've occasionally used it on a hill where
the transmission kept shifting in and out of 4th, easier to lock it down to
3rd when it can't make up it's mind.
 
James said:
When I've driven automatic Volvos I've occasionally used it on a hill where
the transmission kept shifting in and out of 4th, easier to lock it down to
3rd when it can't make up it's mind.
Click to expand...
Thanks a good idea. Thanks for that one.

Maybe we should set up a competition, 'Find the best use for overdrive
in an automatic'. The prize is a weeks holiday in Iraq!
 
Richard Setford said:
Thanks a good idea. Thanks for that one.

Maybe we should set up a competition, 'Find the best use for overdrive in
an automatic'. The prize is a weeks holiday in Iraq!
Click to expand...

I also use it for extra drag on the same sort of hills going down. Maybe
I'll get the second prize: two weeks holiday in Iraq.

Mike
 
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