Please vote - what differential ratio do you have in your 3.0 CSI

[Wladek]

Hello Guys, Happy New Year to All!

I have a question that has been bothering me for a long period of time - proper 3.0 CSI differential ratio?
Why i am asking & why i am asking you to vote?:

3.25 (39:12)
3.45 (38:11)
LSD = Limited Slip Differential
Open = Non-LSD

1. My 1972 3.0 CSI came to me with 3.45 LSD type
2. According to BMW parts catalogue - spare main gears for CSI where 3.25
3. According to BMW parts catalogue - open type differential for CSI was 3.25
4. According to BMW parts catalogue - LSD type differential for CSI where 3.45 & 3.25, depending on production years, earlier 3.45 later 3.25
5. According to BMW brochure (below) - differential for CSI was 3.45
6. Some time ago @sfdon wrote that couple CSI's that he had at that time in his shop had 3.45 ratio

So as you can see the thing is not so obvious
Or maybe both are right - let's find out
CSI owners please vote!

 

[Bejoe16]

Mine had a 3.25


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[Wladek]

Mine had a 3.25


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Please make a vote according to the car production year & differential type, so we could have some statistics to analyze

 

[Bejoe16]

Please make a vote according to the car production year & differential type, so we could have some statistics to analyze

Mine was a 73’ (January 73’ build) 3.0csi Italian delivery.


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[Wladek]

Mine was a 73’ (January 73’ build) 3.0csi Italian delivery.


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Thanks
On top of this thread (under thread title) you can vote, you also need to choose open or lsd - so we had objective statistics in the end.

 

[rsporsche]

i cannot vote as i don't have a 3.0csi. i have a '71 - 2800cs. i would like to have a 3.64 gear. the difference with the 5 speed at 3000 rpm is a difference of 4 mph (75 vs 79). the 3.25 would be 84 mph at 3000 rpm. the acceleration is much better with the higher gear. i loved the 4.11 in the e30 m3 - although 3000 rpm is 66 mph. potential top speed changes a bit

6250 rpm 4.11 / 138 - 3.64 / 156 - 3.45 / 165 - 3.25 / 175 ... of course the ability to get to that rpm in 5th gear is a big question.

 

[sfdon]

3.64 diffs are so common- you should have trouble finding one.

 

[adawil2002]

i cannot vote as i don't have a 3.0csi. i have a '71 - 2800cs. i would like to have a 3.64 gear. the difference with the 5 speed at 3000 rpm is a difference of 4 mph (75 vs 79). the 3.25 would be 84 mph at 3000 rpm. the acceleration is much better with the higher gear. i loved the 4.11 in the e30 m3 - although 3000 rpm is 66 mph. potential top speed changes a bit

6250 rpm 4.11 / 138 - 3.64 / 156 - 3.45 / 165 - 3.25 / 175 ... of course the ability to get to that rpm in 5th gear is a big question.

Athena at 3K Rpm is ~ 84-85mph

 

[Markos]

I voted. My CSI was built on 10/09/72. It had a 3.25 LSD. It is slated for my 2800 CS.

 

[Ohmess]

I have a 3:64 lsd in my 3.0 CS.

Steve - if you are seeking one, I have a 3:64 open dif in the basement. Let's talk.

 

[rsporsche]

I have a 3:64 lsd in my 3.0 CS.

Steve - if you are seeking one, I have a 3:64 open dif in the basement. Let's talk.

too many higher priorities at this time ... have to get the car out of the paint shop and put back together. i will then do the rear axle

 

[RJRuiz]

Voted. My CSi came with an open 3.25, switched to a 3.64 LSD.