OVERDRIVE - SELECTION

[heralddolly]

Hi.

There are different thoughts on how overdrive should be engaged (E) and disengaged (DE).

Some say it's fine to just flick the switch and that's it, job done.

However, I've also heard that a slight "blip" of the gas pedal should be done  - certainly before DE.

In addition, there are some who press the cluthch pedal before doing either E or DE.

I'd be interested in any observations. I'm currently running a D-type O/D on the Vitesse.

Thanks.

Richard.

[nang]

Personally, I always use the clutch and treat o/d as another gear change.
I do this because some years ago I had a Sunbeam Rapier 'box apart to fix oil leaks and found the mainshaft and its splines badly twisted with what I assume was caused by some rough changes putting shock loads on the shaft.

[Deleted User]

I also use the clutch when both engaging and disengaging overdrive. Mots of the time I also blip the throttle when disengaging. A bit like fifth gear I suppose - and far easier on the metalwork in my opinion.

[G8HSV]

Hmm....   I have never heard of this using the clutch/throttle to change from and to OD.   There is no mention of it in any handbooks etc....not that I have.

I just let the OD switch do the work and dont even think about it.

[ferny]

I prefer to use the clutch. Not using it feels too harsh on the system.

[Freebird]

I always use the clutch to "E", but usually just a blip and no clutch to "DE". This usually produces nice smooth changes. Get the blip too early and "smooth" is not the word I would use though. :-/

If is feels smooth, it must be kind to the hardware in my book.

[GT6 M]

if your OD is old, and /or you got a bit moer power than normal,   then dipping of the clutch is a good idea,
reasoning, if the clutch is wearing, then less pressure will be on the cones, thus leading to a little extra slipping if engageing in power on mode
this especially when you in the lower gears, as it takes longer to engage.

As for coming down, I my self always dip the clutch, as I got alot moer pressure on OD cicuit, so it makes down changes very hard,jerky if no clutch used.

note, small D types are not as robust as the J,s so a little sympathy should be given to em.

Marcus

[bxbodger]

I just flick the switch and that's it...great fun dropping out of o/d on the motorway. It is after all an epicyclic box, similar in operation to an old-style auto box, and with a slushbox you just drive, no blipping throttles, no clutch dipping, etc, yet they seem to last forever.

There's no reason to treat an overdrive box any differently.

[Andy Flexney]

Engaging the overdrive the car is  usually under acceleration therefore no need to dip the clutch, disengaging you are usually under deceleration therefore dip the clutch.
The reasoning:
There is a small “one way” roller bearing at the back of the overdrive (well on my A type anyway) and you should always ensure that it is spinning in the right direction and not against the stops i.e. don’t engage overdrive in reverse.  During engagement and disengagement the input shaft of the overdrive should always be faster than the output shaft therefore engaging overdrive during acceleration without dipping the clutch is okay, also disengaging when accelerating e.g. round a hair pin bend on a pass. It goes something like this ... ... straight bit in second overdrive, in the apex hit the throttle and disengage the overdrive to pull round, with foot hard to the floor engage overdrive second and repeat until at the top, up the Stelvio you do this about 43 times and you are there . Disengaging when decelerating, just dip the clutch so it takes the main force instead of the one way bearing which is not really up to the job.

AndyF

[Stu 1986]

This is convenient that this thread has begun! It saves me asking how to use the OD when I finally get my Herald on the road. :)

[Doug Paterson]

The fun factor when engaging OD in 3rd with foot to the floor is worth a rebuild OD unit every 10 years or so  ;D

[G8HSV]

1953 wrote:

This is convenient that this thread has begun! It saves me asking how to use the OD when I finally get my Herald on the road. :)

Not a definitive answer though!   This is the first I have ever heard about using the clutch.  I just use the column switch and let the OD do its job.  Is this some sort of urban myth?

[Pete Lewis]

its simple  there are two modes of operation
have fun jerk all the passengers with a change under power ,
or for the more reserved
smooth changes all the way up and down by a quick  half dip of the clutch or synchronise the throttle requirement
as with any other gear change its down to preference
its obvious the smother the change there is  less machical stress.
Triumph handbooks are not utopia ,, they dont tell you how to blow a tye up but you mange , would you change gear without the clutch ...not unless you had too ,  so why subject the OD to a hard life .
Pete

[heralddolly]

Folks.

That has been very useful (especially for Stu 1986 !!) and much appreciated.

Thanks.

Richard

[Stu 1986]

3 wrote:

That has been very useful (especially for Stu 1986 !!) and much appreciated.

This is true! Thanks to this thread I won't be taking my O/D home in a Tesco bag! :P

S.  8)