Performace Differential

[Vahan]

hi
I would like to change the differential on my 325i (89) an put an LSD.
I heard people suggest a 4:10 from m3, but I looked in some resources
(http://www.behindmatrix.com/e30/foto...023/f00023.htm)
So the 4:10 wasn't on m3 it was on 318i... anyway...
would like to hear somethig about diffs

tnx

[e30fanm3]

my '89 325is has a 4:10, and i about to change it. i dont like having no top end, im going with something a little lower like a 3:26. it should give me a little more top end but still good take-off

[jrhaile]

lots of people use a 3.73LSD.

[ILiveToRide]

Originally posted by Vahan@Apr 5 2005, 01:45 PM
hi
I would like to change the differential on my 325i (89) an put an LSD.
I heard people suggest a 4:10 from m3, but I looked in some resources
(http://www.behindmatrix.com/e30/foto...023/f00023.htm)
So the 4:10 wasn't on m3 it was on 318i... anyway...
would like to hear somethig about diffs

tnx

[snapback]325869[/snapback]

That list doesn't cover the US special cars.
Your M3 do have an 4.10:1 LSD differential, you got a different gearbox then the rest. Here the M3 had a dogleg gearbox with 1:1 final gear, that's why they had a taller gearing in the rear.

Your 325is was also a US only model, doesn't all 325isA's have 4.10:1?

[guywithblack88e30]

not to thread hijack but does anyone know the diff on a super eta????????
1988 325

[gotKRAUT]

Originally posted by guywithblack88e30@Apr 5 2005, 04:39 PM
not to thread hijack but does anyone know the diff on a super eta????????
1988 325

[snapback]326196[/snapback]

you have a 2.89 go to a 3.25LSD...mucho fun

[gotKRAUT]

Originally posted by ILiveToRide+Apr 5 2005, 04:33 PM--><div class='quotetop'>QUOTE(ILiveToRide @ Apr 5 2005, 04:33 PM)</div><div class='quotemain'><!--QuoteBegin-Vahan@Apr 5 2005, 01:45 PM
hi
I would like to change the differential on my 325i (89) an put an LSD.
I heard people suggest a 4:10 from m3, but I looked in some resources
(http://www.behindmatrix.com/e30/foto...023/f00023.htm)
So the 4:10 wasn't on m3 it was on 318i... anyway...
would like to hear somethig about diffs

tnx

[snapback]325869[/snapback]

That list doesn't cover the US special cars.
Your M3 do have an 4.10:1 LSD differential, you got a different gearbox then the rest. Here the M3 had a dogleg gearbox with 1:1 final gear, that's why they had a taller gearing in the rear.

Your 325is was also a US only model, doesn't all 325isA's have 4.10:1?

[snapback]326194[/snapback]

[/b][/quote]
not here in the states its a 3.73 on the I and iS

[egk2]

Originally posted by BMDubya+Apr 5 2005, 06:25 PM--><div class='quotetop'>QUOTE(BMDubya @ Apr 5 2005, 06:25 PM)</div><div class='quotemain'>

That list doesn't cover the US special cars.
Your M3 do have an 4.10:1 LSD differential, you got a different gearbox then the rest. Here the M3 had a dogleg gearbox with 1:1 final gear, that's why they had a taller gearing in the rear.

Your 325is was also a US only model, doesn't all 325isA's have 4.10:1?

[snapback]326194[/snapback]

not here in the states its a 3.73 on the I and iS

[snapback]326218[/snapback]

[/b][/quote]
325is"A" have 4:10's

I swapped in an e30 m3 4:10lsd with 40% lockup, I don't do much highway driving so I enjoy it, 1st gear is pretty useless though, way too short.

[Vahan]

So my car (325i) has 3:73. I would like to know is it worth to swap it with an 4:10 or higher from 318 ? (I dont think I can find a m3 one).
What will be the benefit and payback ?

[ILiveToRide]

Originally posted by Vahan@Apr 6 2005, 07:59 AM
So my car (325i) has 3:73. I would like to know is it worth to swap it with an 4:10 or higher from 318 ? (I dont think I can find a m3 one).
What will be the benefit and payback ?

[snapback]326466[/snapback]

If you take a differential from a 318 you will get a smaller diff. housing, that holds half as much oil as the standard 325 one. It will probably hold for the power, but is more prone to overheat. You will also loose a few pounds.

[e30fanm3]

i put a 5-speed in my 325isA, and it has a 4:10 but i dont know if they all do. I dont see why they would put a different diff. in each one made. I dont have much first gear either, its worthless. I dont do too much highway driving so my diff isnt a big priority, but when i am on the highway i would like to have a little more umph at high speeds. Plus i have a 3:27LSD sittin at the shop out of a 535 so i might as well use it.

I live to ride, do you even know what a dog-leg is? i dont think they put those in m3's, but i could be wrong

[ILiveToRide]

Originally posted by e30fanm3@Apr 6 2005, 10:29 PM
I live to ride, do you even know what a dog-leg is? i dont think they put those in m3's, but i could be wrong

[snapback]326880[/snapback]

They have the first gear towards the back, straight down from reverse.
In total they have a tall first gear and tighter between the rest.

And I don't mean a gearbox with dog-rings which is a totally different things.

[guywithblack88e30]

Originally posted by BMDubya+Apr 5 2005, 03:20 PM--><div class='quotetop'>QUOTE(BMDubya @ Apr 5 2005, 03:20 PM)</div><div class='quotemain'><!--QuoteBegin-guywithblack88e30@Apr 5 2005, 04:39 PM
not to thread hijack but does anyone know the diff on a super eta????????
1988 325

[snapback]326196[/snapback]

you have a 2.89 go to a 3.25LSD...mucho fun

[snapback]326212[/snapback]

[/b][/quote]

does changing diff change torque curve at what rpm?
cause i kinda like having a high torque at low rpm, its perfect for turbo

[ILiveToRide]

Originally posted by guywithblack88e30+Apr 7 2005, 12:09 AM--><div class='quotetop'>QUOTE(guywithblack88e30 @ Apr 7 2005, 12:09 AM)</div><div class='quotemain'>

you have a 2.89 go to a 3.25LSD...mucho fun

[snapback]326212[/snapback]

does changing diff change torque curve at what rpm?
cause i kinda like having a high torque at low rpm, its perfect for turbo

[snapback]326962[/snapback]

[/b][/quote]

The torque to the wheels is affected linearly(sp?). The torque to the wheels is engine torque multiplied through the gearing. So changing one multipel doesn't change the torque curve, only alter the magnitude.