E30 325is question

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Grayson - 06 Oct 2005 23:12 GMT

Quick question about the E30 325is (can't find answer online, my
apologies if this is painfully obvious)--did both the automatic and
manual versions come with the 3.73:1 limited-slip differential, or does
the automatic have a different ratio like in some 5-series model (E28,
I think)?

PS On a related note, just bought my first BMW--an '88 325is,
zinnoberrot, 5spd. Looks like a fun journey up ahead!

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Ignasi Palou-Rivera - 07 Oct 2005 00:13 GMT

> Quick question about the E30 325is (can't find answer online, my
> apologies if this is painfully obvious)--did both the automatic and
> manual versions come with the 3.73:1 limited-slip differential, or does
> the automatic have a different ratio like in some 5-series model (E28,
> I think)?

4.10:1, I believe. Look at:

<http://bmwe30.net/cgi-bin/datacgi/database.cgi?file=articles&report=view&ID=0012
7&Section=14>
or <http://tinyurl.com/cs7jc>, if you prefer.

> PS On a related note, just bought my first BMW--an '88 325is,
> zinnoberrot, 5spd. Looks like a fun journey up ahead!

Obviously a man of taste!

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Ignasi.
'90 325is
(using SPAM trap e-mail address)

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C.R. Krieger - 07 Oct 2005 22:47 GMT

> > PS On a related note, just bought my first BMW--an '88 325is,
> > zinnoberrot, 5spd. Looks like a fun journey up ahead!
>
> Obviously a man of taste!

Especially in that color: http://www.cardomain.com/ride/578895
--
C.R. Krieger & Da Red Dog

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Randy W - 09 Oct 2005 02:47 GMT

>Quick question about the E30 325is (can't find answer online, my
>apologies if this is painfully obvious)--did both the automatic and
>manual versions come with the 3.73:1 limited-slip differential, or does
>the automatic have a different ratio like in some 5-series model (E28,
>I think)?

All 5-speed 325i/is/iC models came with a 3.73

The 87 & 88s Automatic cars came with a 3.73

The 89-91 (or 93ic) Automatics came with a 4.10

>PS On a related note, just bought my first BMW--an '88 325is,
>zinnoberrot, 5spd. Looks like a fun journey up ahead!

E30 Forum:
http://forums.bimmerforums.com/forum/forumdisplay.php?f=20

Randy
89 325is
http://tinyurl.com/exqqs

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Grayson - 12 Oct 2005 03:34 GMT

Thanks to all who replied! Yeah, a friend of mine curbed my car hard,
and took out the entire rear suspension,effectively :( Anyway, I found
an '87 325isa in a junkyard with an intact rear suspension, and hence
my question (which this answers quite well. Of course, I just pulled
the rear suspension anyway and confirmed that it's a 3.73 LSD by
reading the tag on the back of the diff...)

Can't wait to fix my car and start driving it again!

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Psycho - 23 Oct 2005 02:58 GMT

I am getting ready to do a 5 speed swap from an 87 325is to an 89
325i. How much difference will the 4.10 vs 3.73 rear gears make in top
end? I'm sure take off will be quicker and response to throttle
changes will be more pronounced.

>>Quick question about the E30 325is (can't find answer online, my
>>apologies if this is painfully obvious)--did both the automatic and
[quoted text clipped - 17 lines]
>89 325is
>http://tinyurl.com/exqqs

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Malt_Hound - 24 Oct 2005 13:23 GMT

> I am getting ready to do a 5 speed swap from an 87 325is to an 89
> 325i. How much difference will the 4.10 vs 3.73 rear gears make in top
> end? I'm sure take off will be quicker and response to throttle
> changes will be more pronounced.

You will lose 9.3% of your speed at any gear / rpm.

((4.10 - 3.73) / 3.73) * 100

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-Fred W

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John Burns - 24 Oct 2005 14:59 GMT

> > I am getting ready to do a 5 speed swap from an 87 325is to an 89
> > 325i. How much difference will the 4.10 vs 3.73 rear gears make in top
[quoted text clipped - 4 lines]
>
> ((4.10 - 3.73) / 3.73) * 100

4.1 is what I run in my 318iS E30, it's the stock ratio. But for a 325i
I feel it's the wrong choice. It'll be too buzzy at speed, drink petrol
and 1st gear will be gone in a flash. The 325i makes way more low down
torque than a 318iS and as a two valve engine isn't a suited to higher
rpms compared to the four valve 318iS. Stick to 3.73.

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Web : http://www.unixnerd.demon.co.uk - The Ultimate BMW Homepage!
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Malt_Hound - 24 Oct 2005 16:06 GMT

>>> I am getting ready to do a 5 speed swap from an 87 325is to an 89
>>>325i. How much difference will the 4.10 vs 3.73 rear gears make in top
[quoted text clipped - 10 lines]
> torque than a 318iS and as a two valve engine isn't a suited to higher
> rpms compared to the four valve 318iS. Stick to 3.73.

Really? I had an 87 325i and it loved to rev. Remember, this is not
the eta engine. I can't imagine a 4 pot that would rev more willingly
than the M20B25 engine.

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-Fred W

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John Burns - 24 Oct 2005 17:36 GMT

> Really? I had an 87 325i and it loved to rev. Remember, this is not
> the eta engine. I can't imagine a 4 pot that would rev more willingly
> than the M20B25 engine.

Try an M42 some day :-)

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Psycho - 24 Oct 2005 19:39 GMT

>> > I am getting ready to do a 5 speed swap from an 87 325is to an 89
>> > 325i. How much difference will the 4.10 vs 3.73 rear gears make in top
[quoted text clipped - 10 lines]
>torque than a 318iS and as a two valve engine isn't a suited to higher
>rpms compared to the four valve 318iS. Stick to 3.73.

The 4.10 rear appears to be the stock rear gearing for the car with
the autobox. I don't plan to change it and I understand that the 87
(also a 325i) has a stock rear ratio of 3.73. I could be wrong but
that's what I've seen posted.

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Malt_Hound - 24 Oct 2005 20:18 GMT

>>>> I am getting ready to do a 5 speed swap from an 87 325is to an 89
>>>>325i. How much difference will the 4.10 vs 3.73 rear gears make in top
[quoted text clipped - 15 lines]
> (also a 325i) has a stock rear ratio of 3.73. I could be wrong but
> that's what I've seen posted.

You should be fine. Unless you plan on running it out on the autobahn
in which case you will lose about 10mph to the car with the stock rear
gearing. So you'll only be able to go 110mph. But you'll get up to
that speed much faster. ;-)

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-Fred W

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