What Diff would be best?

[Daz318is]

Hi
I've got a standard 318is and use it for work, thing is it seems to rev a bit high in 5th, like it could do with a 6th gear, anybody any idea what Diff i could swap it to, to lower the revs?, dont need fast acelaration just relaxed cruising

Cheers
Darren

[leeparkes]

3.64

[andrews]

According to specs 4.10 ratio diff is installed on your car(if stock condition). So if you want to lower the revs you should try a diff with lower ratio value(3.91 or 3.64 as leeparkes offered for instance)

[daimlerman]

You should have a 4.1,about 65mph at 3000rpm. A 3.64,as suggested above will be about 75mph at 3000rpm. Diff ratios are marked on a tag attached to one of the rear cover bolts,BTW. Two sizes of diff were fitted to E30's,small one has 6 bolts to the rear cover,other has 8 bolts. They are interchangable with a small ajustment to the length of the propshaft.

[Daz318is]

Thank you all!!!!!!!!!!!!!!!!!!!!
will roll under the car to check whats under there, and see if i can find a 3.64

Cheers
Darren

[E30BeemerLad]

a 3.64 would make an iS VERY sluggish with accelerating.

If it was me i'd go 3.91

Got to remember you've got a revvy 16V engine there.

The wife's 16V golf is doiung 5k at 100mph

[StuBeeDoo]

a 3.64 would make an iS VERY sluggish with accelerating.

Got to disagree Lee. I've had a 3.64 in my 320i for 3 years now. I've been happy with the performance, and I doubt if more than a handful of really good drivers could notice a difference in it.

iS has slightly more power than the 320i, so results should be similar.

[Jon_Bmw]

That sounds familar Lee. A proper 100mph with a gearing calculater works out at 5236rpm

On the plus side full throttle changes from 2nd to 3rd see the revs drop to a mear 5136rpm, 3rd-4th 5586rpm 4th-5th 5773rpm.

Always in the mi16's sweet spot. A poor 12v unit would be dead in the water at those rpms

Agreed about the 3,64 that would be seriously lame.

[E30BeemerLad]

a 3.64 would make an iS VERY sluggish with accelerating.

Got to disagree Lee. I've had a 3.64 in my 320i for 3 years now. I've been happy with the performance, and I doubt if more than a handful of really good drivers could notice a difference in it.

iS has slightly more power than the 320i, so results should be similar.

Ah but does the 320 have the same closer first couple of ratios like a sport box, compared to the 240 box in the iS homodominatrix?

[Brianmoooore]

A 320 uses a 240 box, the same as the 316 and 318.

[E30BeemerLad]

now where did I put that spade

[StuBeeDoo]

Ah but does the 320 have the same closer first couple of ratios like a sport box, compared to the 240 box in the iS homodominatrix?

Nope! All ratios identical.

[Daz318is]

Thanks for all the help!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Cheers
darren

[dannyboy759]

If it was me i'd go 3.91