Omega Owners Forum

Please login or register.

Login with username, password and session length
Advanced search  

News:

Please check the Forum Guidelines at the top of the Newbie section

Pages: [1]   Go Down

Author Topic: Auto diff in a manual car  (Read 981 times)

0 Members and 1 Guest are viewing this topic.

gsizoli

  • Junior Member
  • **
  • Offline Offline
  • Hungary
  • Posts: 188
    • View Profile
Auto diff in a manual car
« on: 18 November 2009, 19:28:33 »
Hi!

What does it mean in practice if I use an auto diff (ratio 3.9) in a manual car (original diff ratio is 3.7).What about the speed, revs, 0-60, fuel economy.
Car is a 3.0 facelift.
Br
Zoli
Logged

Andy B

  • Get A Life!!
  • *****
  • Offline Offline
  • Gender: Male
  • Bury Lancs
  • Posts: 39768
    • ML350 TDM SmartRoadster
    • View Profile
Re: Auto diff in a manual car
« Reply #1 on: 18 November 2009, 21:17:13 »
slightly higher revs for a given speed = worse fuel consumption.

your prop will need to turn 3.9 times for the output (drive shafts) turn once instead of the 3.7 times at the moment.
Logged

Mr Skrunts

  • Get A Life!!
  • *****
  • Online Online
  • Gender: Male
  • Skruntie Land.
  • Posts: 25664
  • 3.O Elite Saloon with all the toys,
    • 2003 CD 2.2 Auto
    • View Profile
Re: Auto diff in a manual car
« Reply #2 on: 18 November 2009, 21:29:21 »
Quote
slightly higher revs for a given speed = worse fuel consumption.

your prop will need to turn 3.9 times for the output (drive shafts) turn once instead of the 3.7 times at the moment.

But slightly quicker getting there.
Logged
Ask yourself :  " WHY do I believe in what I believe?"

Remember that my opinions expressed here are not representative of the opinions of other members on the OOF Forum.

Andy B

  • Get A Life!!
  • *****
  • Offline Offline
  • Gender: Male
  • Bury Lancs
  • Posts: 39768
    • ML350 TDM SmartRoadster
    • View Profile
Re: Auto diff in a manual car
« Reply #3 on: 18 November 2009, 21:35:54 »
Quote
Quote
slightly higher revs for a given speed = worse fuel consumption.

your prop will need to turn 3.9 times for the output (drive shafts) turn once instead of the 3.7 times at the moment.

But slightly quicker getting there.

That too!  :y :y :y .....

I was letting someone else have a turn too!  ;D
Logged

gsizoli

  • Junior Member
  • **
  • Offline Offline
  • Hungary
  • Posts: 188
    • View Profile
Re: Auto diff in a manual car
« Reply #4 on: 18 November 2009, 22:17:50 »
Thanks guys, I understand now.I hope it will be okay for me, if not, I will look for a manaul diff with 3.7 ratio.But if the fuel consumption won't be much worse I don't care... :D
Logged

Ghost

  • Omega Baron
  • *****
  • Offline Offline
  • Gender: Male
  • Seaham, North East england
  • Posts: 2234
    • 2.6 V6 CDX Estate
    • View Profile
Re: Auto diff in a manual car
« Reply #5 on: 19 November 2009, 00:10:13 »
Also check your spedo. ( tacho ) it might be out showing roughly 10 kmh faster or slower than you are moving.
Logged
He who brakes Looses
To old to die young

Marks DTM Calib

  • Administrator
  • *****
  • Offline Offline
  • Gender: Male
  • West Bridgford
  • Posts: 34010
  • Git!
    • View Profile
Re: Auto diff in a manual car
« Reply #6 on: 19 November 2009, 12:03:17 »
Quote
Also check your spedo. ( tacho ) it might be out showing roughly 10 kmh faster or slower than you are moving.

Not a probelm as the speedo uses the ABS signals which are on the diff output shafts  :y
Logged

Seth

  • Omega Lord
  • *****
  • Offline Offline
  • Gender: Male
  • South Wales Valleys
  • Posts: 6646
  • If there's a 'system' - play it ... !
    • '99 2.5TD GLS Estate
    • View Profile
Re: Auto diff in a manual car
« Reply #7 on: 20 November 2009, 09:04:32 »
You'll probably notice slightly better acceleration and hill-climbing. Better for towing caravans too!
« Last Edit: 20 November 2009, 09:05:18 by Reliance505 »
Logged
Gettin' seriously hacked-off by those who ignore the wisdom of proven experience ... and Forum guidelines.

Andy B

  • Get A Life!!
  • *****
  • Offline Offline
  • Gender: Male
  • Bury Lancs
  • Posts: 39768
    • ML350 TDM SmartRoadster
    • View Profile
Re: Auto diff in a manual car
« Reply #8 on: 20 November 2009, 20:33:57 »
Quote
You'll probably notice slightly better acceleration and hill-climbing. Better for towing caravans too!

A 3.0 doesn't really need any help towing and I'd want any addition/modification to help fuel ecconomy not make it worse!   ::)  ::) ;)
Logged

Marks DTM Calib

  • Administrator
  • *****
  • Offline Offline
  • Gender: Male
  • West Bridgford
  • Posts: 34010
  • Git!
    • View Profile
Re: Auto diff in a manual car
« Reply #9 on: 20 November 2009, 20:39:12 »
Quote
Quote
You'll probably notice slightly better acceleration and hill-climbing. Better for towing caravans too!

A 3.0 doesn't really need any help towing and I'd want any addition/modification to help fuel ecconomy not make it worse!   ::)  ::) ;)

In theory it could (note theory) as the auto box would go into lock up a few mph lower and it should change down slightly less
Logged

Andy B

  • Get A Life!!
  • *****
  • Offline Offline
  • Gender: Male
  • Bury Lancs
  • Posts: 39768
    • ML350 TDM SmartRoadster
    • View Profile
Re: Auto diff in a manual car
« Reply #10 on: 20 November 2009, 20:41:00 »
Quote
Quote
Quote
You'll probably notice slightly better acceleration and hill-climbing. Better for towing caravans too!

A 3.0 doesn't really need any help towing and I'd want any addition/modification to help fuel ecconomy not make it worse!   ::)  ::) ;)

In theory it could (note theory) as the auto box would go into lock up a few mph lower and it should change down slightly less

Maybe .... but I generally get mine up to lock up speeds without problem.  :y  :y  :y
Logged
Pages: [1]   Go Up
« previous next »
 

Page created in 0.014 seconds with 17 queries.