Anyone using a 3.25:1 diff?

[liam012]

Just wondering if anyone uses this ratio diff and how do they find it? I have a 3.73 for the 2.7 prooject but ideally a 3.64 would have beeen best,
let me know what you think of it if you have one
thanks

[Demlotcrew]

Why would a 3.64 would be best?

Andrew

[maxfield]

Why would a 3.64 would be best?

Andrew

Maybe he does alot of motorway driving.

[Demlotcrew]

Why would a 3.64 would be best?

Andrew

Maybe he does alot of motorway driving.

So what?

Andrew

[maxfield]

Why would a 3.64 would be best?

Andrew

Maybe he does alot of motorway driving.

So what?

Andrew

Might want a higher top speed rather than accelaration

[Demlotcrew]

Ah yes but he would need to have loads of extra power to take advantage of the shorter diff! BMW dont just put in a shorter diff to give better high speeds. ITs all calculated to the engine power curve, the gearbox ratios and the air drag of the car.

What your left with is a car which can reach its maximum speed limit at its maximum power point in the rev range.

So putting a shorter diff on without alot of extra BHP wont result in a car which will have a very high top speed.

Just spend a little time on Google search for the different aspects of diff ratios and you will soon get a better understanding of how to use the different ratios available for the E30.

HTH

Andrew

[liam012]

Sorry - i figured for a well speced 2.7 that 3.64 would be the compromise diff? Maybe if i was still living in england on those peachy roads u have i'd go with the 3.73 for some fun seat of your pants driving at higher revs soaking up the power. However, every road is a b road here and not b roads like you folks know either - I am building a 2.7 with polished head hpoing to make use of the torque as i do a lot of comuting at what ye may consider careful speeds. I just dont go over 60mph, But i would be mostly driving at 55-60 for 300 miles a week. So i want a torquey low geared cruiser for me and my family. (But something that still able to smoke up the rears if i ever get the urge) - I just wonder does anyone have a 3.25 diff and does it take ALL the fun out of the car
sorry if i wasn't clearer to begin with.

[glenn]

mine has a 3.25:1 diff.
even at 70mph, in third, the torque is enough to spit rubber off the tyres in the dry without the use of the clutch.

[Widge]

Yeah but you do have a..... SPECIAL engine don't you?

[DieselMeister]

You really wouldn't notice the difference between the two diffs you're looking at.

If you want more "relaxed" cruising i.e. lower revs for any given speed, I'd go for the 3.25 or 3.15. However, as Andrew says, BMW give thought to all aspects of performance (accel, v-max, even economy) before gearing their cars. Seeing as their sixes are so smooth, I'd stick to a more responsive diff ratio. You'll enjoy it more of the time unless you're doing exclusively motorway miles.

In which case get thyself an E46 320d

[Widge]

Or one of those Saab things that does 55mpg

[jmc330i]

I would of thought a 3.25:1 diff will be useless with a 325i M20 gearbox (even with the extra torque of a 2.7), wouldnt it be way to long??