4.10 or 3.64 diff

[crazyenglishman]

sorry if this is a dim question but whats the difference. ive got a 325i 89. what change would the 4.1 diff make 2 my car?
cheers

[SGP]

I believe it will improve accelleration,reduce fuel economy, lower your top speed and probably make you wish you had a six speed gearbox! But I'm probably wrong...

[crazyenglishman]

so it should be better 4 me as i want the car 4 drifting n poss track days? is 1 a simple fit?
what car are they off e30?

[SGP]

My 89 320i has a 4.1 diff, its on its second one now! The diff is matched to the gearbox for the best all round performance on the street,the swap over was straightforward enough simply disconnect the two half shafts with the allen key bolts, support them on wires to avoid damage to the cv joints,remove the speedo sender,get the prop shaft bolts off,raise the diff slightly on a trolley jack,disconnect the rear diff bushing to floor mount and there are four 19mm bolts on top of the diff which mount it to the axle carrier.lower the jack enough to get at these(or cut a hole in the boot floor if she's a slag!)Always have a trolley jack under the diff to support the weight.And remember to replace everything you disconnect in the right order.You need good tools for the job.And plenty of penetrating oil..goodluck.

[Pal318is]

My 89 320i has a 4.1 diff, its on its second one now! The diff is matched to the gearbox for the best all round performance on the street,the swap over was straightforward enough simply disconnect the two half shafts with the allen key bolts, support them on wires to avoid damage to the cv joints,remove the speedo sender,get the prop shaft bolts off,raise the diff slightly on a trolley jack,disconnect the rear diff bushing to floor mount and there are four 19mm bolts on top of the diff which mount it to the axle carrier.lower the jack enough to get at these(or cut a hole in the boot floor if she's a slag!)Always have a trolley jack under the diff to support the weight.And remember to replace everything you disconnect in the right order.You need good tools for the job.And plenty of penetrating oil..goodluck.

Is that a 4.10 lsd bud?

Pal

[SGP]

No,standard.

[StephenWust]

Greetings all...

I'm new to this forum and while browsing around stumbled across this post... as it would happen, I too have an '89 325i which I have swapped in a 4.11:1 LSD for the original 3.64:1 open unit...

My car has the original Getrag 260 'box and I'm finding that the 4.11 is annoyingly short on the top end... the acceleration has improved but it is painfully revvy on the open road and in addition the 1st gear is almost unusable..

I cooked up an elaborate excel spreadsheet which calculates the effect of diff ratios on road speed and have come to the conclusion that the best setup for my application would be either a 3.9:1 or 3.7:1... so i'm currently hunting for that ratio..

If anyone is interested, PM me and I can email the spreadsheet to you..

[liquid079]

I have a 91 320i, would this have a 4.1 diff?

[SGP]

Erm, the diff is on the rear axle.They left the factory with a steel tag embossed with the ratio on,not always ledgible nowadays though.

[liquid079]

yea sorry i put that slightly wrong I meant would the diff on my 320i be a 4.1 cos like you said i can't read a thing on mine

[SGP]

Most likely a 4.1 yes.