Overdrive

martin.herwitson · #1 25-11-2007, 21:46

Hi all,
just bought another Silvia as a restoration project and was intending to swap it from auto to manual G/box but having driven it home I'm not so sure if that's the best idea. The auto box makes Silvia a much better motorway cruiser 2700-2800rpm @ 80mph with overdrive on! Makes me wonder why Nissan never fitted an overdrive option to the manual.....did they?

PukkaSilvia · #2 25-11-2007, 22:23

the motorway limit is 70 martin

martin.herwitson · #3 25-11-2007, 22:40

Did I mention that I picked it up from Berlin?......Obviously

zxocmars · #4 25-11-2007, 23:31

Quote:

Originally Posted by martin.herwitson

Makes me wonder why Nissan never fitted an overdrive option to the manual.....did they?

The overdrive option on a manual is called "5th"

O/D wouldn't work with a manual box, I'm not sure why, i think because it would then be a 6th gear.

30psi · #5 25-11-2007, 23:41

5th is over drive, purely because its over driven.

Worth checking your speedo against GPS but chances are your doing closer to 70mph even if the speedo is saying 80

sideways danny · #6 26-11-2007, 01:56

Quote:

Originally Posted by 30psi

5th is over drive, purely because its over driven.

yip, 1,2 and 3 are underdrive, 4th is 1:1 and 5th is overdrive.

the auto is fine and makes the s12 a nice car to drive, ideal daily driver infact. not overly exciting though and I wouldn't bother with tuning an auto at all

old-and-rusty · #7 26-11-2007, 12:26

Quote:

Originally Posted by sideways danny

the auto is fine and makes the s12 a nice car to drive, ideal daily driver infact. not overly exciting though and I wouldn't bother with tuning an auto at all

I would second that. My s12 (when she was running) had an auto box. I tuned her up to just over 200 bhp at the wheels, but the auto box couldn`t handle the extra power. Kick down and the car would red-line before the auto box had chance to catch up with engine speed.
I had to have the box reconditioned three times cos it kept blowing seals

.

Great motorway cruiser though and still very quick (when she was on the road

).

Regards,
Ian.

Ronin · #8 26-11-2007, 15:58

Quote:

Originally Posted by zxocmars

The overdrive option on a manual is called "5th"

O/D wouldn't work with a manual box, I'm not sure why, i think because it would then be a 6th gear.

You can get O/D on manual boxes I've drived old V6 Scimitars GTE with a 4 speed manual with O/D. I sure there were BL cars with the same sort of boxes.

30psi · #9 26-11-2007, 16:13

A 5 speed box is a 4 speed box with O/D, its just a different marketing method to describe them

Ronin · #10 26-11-2007, 17:03

The Scimitar box had a button on it you had to press to engage O/D so you would have 1st, 1 1/2 (O/D), 2nd, 2 1/2 (O/D) and so on up the box. If you've seen Mark Evans An MG is Born on Discovery he fitted a similar box to the MG B he built and he actually went to the place where the boxes are made/reconditioned.