overdrive

hi guys and gals
just wondering does anyone know at what speed the overdrive should kick in please.
i have a 3ltr 2wd any advise welcomed thanks.
dave

For the 2.8 its dead on 40mph....believe its higher for the 3 ltr....

Working on memory now-

Under acceleration not until I eased off the loud pedal.
Cold about 40, warm could be as low as 35 but would stay in there if I eased off to 30.

thanks guys looks like i have a problem mine kicks in at 80 kph looks like it needs work

Hi, I'm just wondering how you resolved this problem and what was the cause? My '93 2.8 started to have o/d probs.. The o/d would kick in at a higher speed than felt right, then that speed increased more and more, and now it doesn't kick in at all. It has worked at random, but very rarely now. Have already tried changing the trans fluid and cleaning the filter - no joy. Same with the temp sensor. I'm guessing it could be the wiring to the soleniod, the solenoid itself, or hopefully not - channel blockages. Any advice welcomed, thanks.

I'd start with the overdrive gear lever mounted switch itself...then work back.
The solenoid is visible with the sump pan off as I've seen it...can't remember if that was before or after the filter removed....
Judicious use of multimeter spiked probes before the wires go into the gearbox may save some time and expense

now to sound thick !!! what does the overdrive do ??

Hi,
Edit after further research!

If I understand correctly, the overdrive is arguably misnamed- the button really just controls whether or not the highest gear is selected, much as the lower gear options on the transmission selector lock out third or second. It is done with an extra component in the transmission, though, and does drive the gearbox output faster than the input, so maybe it's correct...

The main unit in the auto-box is only a three speed, leading to higher revs than ideal for cruising. Adding the overdrive offsets this by effectively adding an extra top gear. It's a unit inside the gearbox, after the "normal" 3-speed arrangement, that makes the output spin faster than the input (this is where the name comes from) and it's integrated into the autobox control system. In a more recent system the control lever would probably be set up as D-3-2-1 instead of D-2-1 and having a seperate "O/D off" switch. I guess a combination of engineering and marketing made it seem like a good idea to seperate them.

In practice I would normally only disable it when anticipating a need for more torque at lower speed (approaching a hill, don't want to wait for a downshift? Preparing to overtake? yeah.. right!) or to force engine-braking, much as with the lower-gear options on the autobox lever.

Cheers,
W.

So I got my overdrive working again! Here's how:
http://taigenetsudo.blog.com/2012/08/28/overdrive-solenoid-bypass-mod/
I'll post in the repairs section too.