Overdrive in EVERY gear on a 240!
Travis Butchart
My friend grounded a part of the overdrive relay to bypass the
transmission overdrive switch on his '82 244. He now has the ability
to use the overdrive in EVERY gear. Ever experience a time when your
driving at say 55 Kmph behind some moron and you are in 3rd gear and
you want to switch badly into 4th gear but it would lug? Just switch
on the overdrive in 3rd gear. Perfect.
I'm going to have to see exactly what he did to the relay and what
pins. However, I have a question for the people who might have done
this in the past:
Would this cause any damage to the overdrive? I can't really see why
it would - it's just a bunch of gears in a separate box. It shouldn't
matter if it is being used or not. I just want to know if anyone has
tried this and what their experiences have been.
Travis
Bruce
that there is that inhibiting function in these cars. If you were to ever
inadvertently engage the OD in reverse and achieve the pressure in the OD to
engage internally, SERIOUS damage will result to the OD unit. Particularly
the one-way clutch and the output shaft of the transmission. Not a good
idea. I am aware that older P1800's had the availability of engaging the OD
in 3rd and 4th gear but this option is not available on later models. Hope
this helps.
Bruce
Travis Butchart <Travis.Butch...@home.com> wrote in message
news:37ae5356...@news.rdc1.on.home.com...
DAHoberg
>to use the overdrive in EVERY gear.
No he can not.
The OD function is a result of the sun gear of the planetary being pushed into
a brake ring by hydraulic pressure. this pressure is a function of
transmission output shaft RPM. Too low RPM and no OD.
The reason the relay and 4th gear switch are in the control circuit is to
prevent a partial engagement of the OD, where the carrier for the sun gear is
half way between its "OD" position and its "normal" frewheel postion (gears 1
to 4).
If in this position the drive force throught he OD from the transmission is
reversed, ie foot off the accelerator, a freewheeling of all paarts in the OD
occurs. When and how the parts stop determines if any damage occurs.
IF they stop while going forward no damage will occur. If they stop while one
part, the output shaft, ( if the car is slowing down via brake or otherwise )
the carrier tends to shear away from the sun gear.
When this occurs your friend will be looking for a used OD unless he has the $$
for a new unit.
It's his money. If he feels he is smarter than the engineers who designed the
unit and the controls for it so it will not get damaged then let him waste his
money.
Duane
83 245 LH 2.0 M46 181xxx
85 245 LH 2.2 AW70 130xxx
The OD Guru (Laycock only)
Address is SPAM blocked. ****Remove map.son from address.****
RCW
transmission and sees the full output torque. In lower gears, this
torque is MUCH higher than in the higher gears. Perhaps too high for
the OD.
"torque is cheap"
RCW
Daniel the Red
David Hueppchen of OJ Rallye Automotive in Wisconsin disagrees. He runs
*very* potent Volvo race cars with stock overdrive units, but with the O/D
selectable in every gear except Reverse (which would really ruin things).
He reports that 1st-OD is not an advisable combination, but 2nd-OD and
3rd-OD are just fine. If he can do this on his race cars without losing
OD boxes (and since he DOES do it, he obviously CAN do it), I don't see
any problem doing it with a daily-driver stocker. Just be SURE to wire it
such that O/D cannot be engaged with Reverse gear, or sooner or later you
WILL forget or accidentally have the O/D switch in the wrong position when
you hit reverse. Carnage. The Reverse-gear blockout is easy to do if you
think about it.
--Daniel
I present my posts without further .edu.
Can't figure it out? I won't hear from you.
--
NBCS b5f+wg+rp
--
DAHoberg
>OD boxes (and since he DOES do it, he obviously CAN do it), I don't see
>any problem doing it with a daily-driver stocker.
He is doing one thing that I do not think you will be doing. Turning high RPMS
all the time.
This puts his trans output shaft at or above the RPM's to generate sufficient
pressure to lock the OD "UP".
Trans output shaft must be at a minimum of 1800 RPM to generate sufficient
pressure.
In 4th gear that is about 25 MPH.
3rd gear about 40 mph with engine at about 3200 RPM.
2nd gear about 60 mph. with engine at or near 4600.
Your choice.
Duane
second gear about
Jon Purinton
and it being my first Volvo, I never even knew it wasn't supposed to. Did
the previous owner tamper with it? Should I have it fixed? I *have*
accidentally put it in reverse with OD on before and it sort of made a weird
sound and didn't move but it still works fine. Please help, I can't afford
to have it go out after all the money I've put into this car.
Mike Froebel
Yes you should fix it. One day you'll be tired and you'll destroy it.
There is a switch on the transmission that only allows the overdrive to
engage in 4th gear. Since you've done an engine swap, you may have a
newer transmission, but as far as I know all 4th gear switches have 2
terminals whereas the backup light switch has only one wire. They're
the 2 switches on the transmission, reverse is on the left side, 4th
gear on the right. Let us know if you have a push button or slide switch
on the gearshift lever (or something else somewhere else) to engage the
overdrive and we can advise you what to do.
--
Mike Froebel
Thornhill (near Toronto), Ont.
Change cant to ca and remove parentheses to email me directly.
Note my new email address Aug. 3, 1999.
Mike Froebel
Also, the engaged oil pressure can be raised by adding shims or changing
springs in the relief valve. The overdrive is at its most vulnerable
when it is in transition from direct to overdrive. There is an orifice
that controls the speed of engagement (for comfort during clutchless
upshifts as well as to reduce the banging on the brake drum) that can be
drilled out to increase the speed of engagement. Both of these mods
will improve torque capacity. I'm sure anyone racing with these
overdrives will have done this.
Also note that on the early 700 series turbos with the J type overdrive
(not J/P hybrid or P type), the fuel injection computer cut out the
injector to cylinder #2 to reduce torque as the overdrive shifted.
Jon Purinton
Mike Froebel <"metrixmf()"@netcom.cant> wrote in message
news:37B3288A...@netcom.cant...
>
>
> Jon Purinton wrote:
> >
> > Uh-oh. The 1977 264 I bought several months ago has overdrive in every
gear,
> > and it being my first Volvo, I never even knew it wasn't supposed to.
Did
> > the previous owner tamper with it? Should I have it fixed? I *have*
> > accidentally put it in reverse with OD on before and it sort of made a
weird
> > sound and didn't move but it still works fine. Please help, I can't
afford
> > to have it go out after all the money I've put into this car.
>
> Yes you should fix it. One day you'll be tired and you'll destroy it.
> There is a switch on the transmission that only allows the overdrive to
> engage in 4th gear. Since you've done an engine swap, you may have a
> newer transmission, but as far as I know all 4th gear switches have 2
> terminals whereas the backup light switch has only one wire. They're
> the 2 switches on the transmission, reverse is on the left side, 4th
> gear on the right. Let us know if you have a push button or slide switch
> on the gearshift lever (or something else somewhere else) to engage the
> overdrive and we can advise you what to do.
>
Mike Froebel
>
> Thanks Mike. The overdrive is a slide switch on the gearshift lever.
>
That makes it easy. The wire that now goes from the switch on the
gearshift lever to the overdrive soleniod should have a splice
somewhere. If it doesn't, cut it and connect the two ends to the two
wires that should be part of the 4th gear switch - assuming your
transmission is the original one in the car. A later transmission takes
a 4th gear switch that has no wires attached to it, however connection
is the same, two wires two terminals. Hopefully your overdrive is not
connected this way because the 4th gear switch is bad.
DAHoberg
The solenoid on the OD is stuck in the "on" position. It should click when you
put the switch on the lever into the ON position and the green light comes on.
If no click you will have to replace the solenoid on the OD.
The solenoid is always getting power wether the switch is on or off. There
should only be power at the yellow wire on the solenoid when the green light is
on. If there is power at that terminal with the green light off you have power
getting to the yellow wire due to loss of insulation somewhere.
You need to diagnose and get it fixed.
Duane
83 245 LH 2.0 M46 181xxx
85 245 LH 2.2 AW70 130xxx
The OD Guru (Laycock only)
Address is SPAM blocked. ****Remove map.son from address.****