V35 S2 At Coupe - Diff Ratio/lsd Question

[mattyray]

Hi all

Trying to confirm what diff ratio my car has. I believe that the auto's are fitted with a lower diff ratio (3.36?) than the manuals (3.54?) and that generally the autos are open wheelers and the manuals get a LSD standard.

However my V35 is an auto with a LSD fitted as a factory option. So i guess my question is 'will the diff ratio be directly linked to the fact i have a LSD?' It would seem to make sense my car will have the 'manual' diff ratio of 3.54 but i cant confirm this anywhere.

Tried searching on this topic here and the US forums, couldnt find much, so helping someone might be able to shed some light on this.

Cheers

[scathing]

What RPM are you doing at 110km/hr?

Compare it with someone that has an open diff, and it'll tell you approximately what your FD ratio is.

[mattyray]

Nice idea, cheers.

Will have a look at 110 then see if some friendly forum member will do the same for me.

[mattyray]

Righto....

100 km/h = approx 2300 rpm in 5th gear

110 km/h = approx 2500 rpm in 5th gear

Anyone with an auto (non lsd) able to do me a favour and test their car's rpms so i can compare?

[30Five]

Righto....

100 km/h = approx 2300 rpm in 5th gear

110 km/h = approx 2500 rpm in 5th gear

Anyone with an auto (non lsd) able to do me a favour and test their car's rpms so i can compare?

didnt really look at the 100km/h rev speed but 110km/h is at 2300rpm ( auto non LSD)

hope this helps.

[CeffyNSW]

Would say you have a 3.36 auto ratio, would not change to manual ratio just because it is a LSD. Different tyre sizes can make a difference also.

[mattyray]

Cheers for you efforts Beez35, but looking at you profile i see you have differing tyres sizes to me so its not 'apples and apples';

19" Intensive Hunk wheels.

19x9.5" +17 Fronts 245/35/19 Nexens

19x11" +10 Rears 275/30/19 Khumos

i run the OEM 19s on 40 series profile.

Thanks also Ceffy, though i am still not left 100% sure i have the auto ratio. Is there anyway to 100% confirm it?

[30Five]

totally forgot my speedo is just a little out from my tyre profiles lol.... my bad

[CeffyNSW]

If you want to be totally sure, you could jack up the rear of your car, make alignment marks on the diff input and outputs then turn the input until you have turned the outputs 1 turn, should be 3.3 turns (as opposed to 3.5 for manual). From my experience you would be doing nearly 3000 revs at 110 with a 3.5 ratio diff and an auto. Hope this helps.

[mattyray]

great info, thanks Ceffy, appreciate it mate.