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another E30 nut
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it wont change. just your Top speed. im not sure of the RPM change because i had a 4.10 LSD with an Autotragic
I have a 2.93 LSD which is for sale.
You dont have a LSD and this would make your car more fun
 

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Discussion Starter · #3 ·
mattdk318i said:
it wont change. just your Top speed. im not sure of the RPM change because i had a 4.10 LSD with an Autotragic
I have a 2.93 LSD which is for sale.
You dont have a LSD and this would make your car more fun
how can i check if i have it or not?
 

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another E30 nut
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If its an E you dont. If its an I you dont.
Only the IS and ES(except special orders)
Theres a tag on the back right of the diff.
Take a screwdriver to it and scrape off the crud If it has an S then its a LSD
 

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///M POWER
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366 Posts
Your rpms don't change in terms of not being able to rev as high.

What changes is the speed in each gear and the correspoding rpm.

Generally, the rpms are bumped up 500 rpms.
So if at 25 mphs you're at 5000 in first, then you'll be at 5500, but it really depends on other things like what gear etc.

Also, you lose about 5 mphs in each gear.
 

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another E30 nut
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I think you are better off with upgrading to a 2.93 LSD.
The reason you are probably asking is the swap right?
Are you planning on leaving the diff in the "I" when you put the "E" in? and vice versa?
 

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Not sure how accurate this is either but I think I lost on average between 2 and 3 mpg. X2theZ3 is just about right on the RPMs. If you want more punch, you definetly don't want to go 2.93 LSD. I put the 4.10 LSD in mine and it made a noticeable difference off the line and especially accerating out of corners. My $.02
 

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another E30 nut
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I though he was putting the E engine in his I. Hell im not sure what hes doing anymore.
then i revoke my suggestion a 2.93 wouldnt be a good choice. Only if you installed the E engine would you expect gains
 

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bratmeister
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mattdk318i said:
If its an E you dont. If its an I you dont.
Only the IS and ES(except special orders)
Theres a tag on the back right of the diff.
Take a screwdriver to it and scrape off the crud If it has an S then its a LSD
Actually, just about any 325 with an automatic transmission had the 4.10 diff.
The LSDs were found mostly on the IS and ES models.
 

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///M POWER
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mike b said:
Actually, just about any 325 with an automatic transmission had the 4.10 diff.
The LSDs were found mostly on the IS and ES models.
Actually,

You aren't completely correct. Only I's had the 4.10 and also only automatics ones from 9/88 and later. Yes, the LSDs are generally found on the S models but were options on all models.
 

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Discussion Starter · #12 ·
mattdk318i said:
I think you are better off with upgrading to a 2.93 LSD.
The reason you are probably asking is the swap right?
Are you planning on leaving the diff in the "I" when you put the "E" in? and vice versa?
i am putting the I engine into the e , but since the i had an automatic it has 4.10 so i was asking if i can swap them? and if i will have problems since the e is manual and manuak with 4.10 could be tooo high?
 

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Discussion Starter · #13 ·
mattdk318i said:
If its an E you dont. If its an I you dont.
Only the IS and ES(except special orders)
Theres a tag on the back right of the diff.
Take a screwdriver to it and scrape off the crud If it has an S then its a LSD
dude i check under the car and looked at the tag and its starts with an S (S4,10 405) i also had the car up when it had the engine and it was on and on D i try to stop the wheel but i couldnt cause both wheels spin and when i turn it off and spin one wheel both spin same direction???

since it starts with an S i will also swap the diff to the e

PS this car is a 325I 1987, the engine is goin to go into an E chassi as well as the diff since its a 4.10
 

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I have an autotragic 89 325i and have a 4.10 open diff and have toyed around with the idea of throwing in a 3.73 LSD to save a bit of petro and help the handling. I believe the eta's tranny is a lower gear ratio designed for the lower RPM'd torque of the eta. :dunno:
 

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///M POWER
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SWISS said:
I believe the eta's tranny is a lower gear ratio designed for the lower RPM'd torque of the eta. :dunno:
That is incorrect. The I and E trannys have identical gear ratios and therefore fuction the same.

Since we all know the E redlines much lower, a much lower ratio is required: 2.79 or 2.93.
 

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X2theZ3 said:
That is incorrect. The I and E trannys have identical gear ratios and therefore fuction the same.

Since we all know the E redlines much lower, a much lower ratio is required: 2.79 or 2.93.
Well i have a slushy....now, so the key term in my response was believe instead of know.Nice to know since I found an M50 local for $650 and the only 5spd's I can source are the eta's.
 
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