I require some help in properly using the overdrive on my 1967 Mk2. I have a 4 speed Moss box (synchro) with overdrive. I frequently drive on country roads where there are straightaways then winding curves where downshifts are needed. So, I'm going along in fourth gear, move on to overdrive on the straightaways, and then come to curves where I need to downshift. Can I leave it in overdrive and shift to fourth, third, back up, etc. or should I take it out of overdrive each time to downshift? Seems like it would be less work on the unit if I left it in overdrive instead of clicking in and out of it each time. Anyhow, I have no idea which is best.

 

I'd like to know the answer to this as well.

I presumed overdrive is only for highway crusing and using it in lower gears under heavy load would be asking for trouble.

 

I don't have an over-drive on my car, but it is to my understanding that the over drive is electrically activated by a lever on the side od the steering column.
So with that said, to shift back into fourth you have to touch the lever to get back into fourth at which time the over drive is disengaged.
So when shifting into third from fourth, the over drive would be disengaged by that time anyway _ wouldn't it ?


The question here is it safe to activate the over drive while you're in third ?


The answer to that is, I think there is a switch somewhere on the trans that will only allow you to go into over-drive while it's in fourth.

 

Jeff, yes, I found you are absolutely correct. I was able to test the overdrive arrangement on a straight, flat road: From fourth I put it in overdrive, the rpms of course dropped about 500rpm. I went back to overdrive and down shifted to third and the overdrive was disengaged. So, overdrive is only available from fourth and if one downshifts directly to third when in overdrive, the overdrive is switched out.

 

The only stupid question is the one that is not asked:

Do you use the clutch to shift in and out of overdrive? My previous owner said yes, but I saw a MK2 book that said no.

 

No, you don't need to use the clutch with the overdrive because it uses an epicyclic gear train and a brake band to engage it under hydraulic pressure, so its a bit like an auto transmission in this respect.

There is a switch on the gearbox that detects top gear that allows the overdrive to engage when the driver switches it on. If the driver changes down the switch breaks the voltage supply to the overdrive. A solenoid is used to engage the overdrive, so when the solenoid has not volts the overdrive disengages.

 

I always use the clutch as it puts less stain on the o/d unit changing up or down, just use it like a fifth gear.