Omega Owners Forum

Omega Help Area => Omega General Help => Topic started by: gsizoli on 18 November 2009, 19:28:33

Title: Auto diff in a manual car
Post by: gsizoli 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

Title: Re: Auto diff in a manual car
Post by: Andy B 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.

Title: Re: Auto diff in a manual car
Post by: Mr Skrunts 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.

Title: Re: Auto diff in a manual car
Post by: Andy B 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

Title: Re: Auto diff in a manual car
Post by: gsizoli 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

Title: Re: Auto diff in a manual car
Post by: Ghost 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.

Title: Re: Auto diff in a manual car
Post by: Marks DTM Calib on 19 November 2009, 12:03:17

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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

Title: Re: Auto diff in a manual car
Post by: Seth on 20 November 2009, 09:04:32

You'll probably notice slightly better acceleration and hill-climbing. Better for towing caravans too!

Title: Re: Auto diff in a manual car
Post by: Andy B on 20 November 2009, 20:33:57

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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!   ::)  ::) ;)

Title: Re: Auto diff in a manual car
Post by: Marks DTM Calib 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

Title: Re: Auto diff in a manual car
Post by: Andy B 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