5-spd Swap

[Axxe]

Just pulled out my automatic tranny, but I forgot to measure the driveshaft length. Now, do both trannys take the same driveshaft or does the manual take a longer shaft?

Also, will I have to change my rear end? I really hope I don't have to, since the 325is' rear end is pretty rusty (5-spd donor) and has 410,00 km on it. How can I tell which ratio the diff is and whether or not it is an LSD?

[mspiegle]

AT and MT driveshafts are different. I think I have an AT laying around somewhere in my garage.

The differential should be the same for both trannies.

[Jon325i]

As for the driveshaft, you will have to change it out to the proper one. While you're at it, replace the guibo (flex disc) while you have everything apart.

In regards to your differential, you say the car is a 325is? If this is true, the car came equipped with a 4.10 limited slip ratio which is highly desirable for improved acceleration. If you're more concerned about mileage and having a quieter cabin at highway cruising speeds, install a 3.73 ratio differential.

So how do you tell what ratio diff you have? That's an easy one. Simply get the rear of your car safely supported on some jackstands and slide under there so you're looking at the back cover of the diff. One of the bolts that holds the rear diff cover in place should have a metal tag afixed to it with engraved numbers on it (its located on the right side of the diff). A 4.10 diff should read "4.10LS" or something like that.

Here's a pic to simplify things. You'll find the tag in a horizontal position pointing towards the center of the diff. Its located at the top bolt on the right side.



Jon

[Rigmaster]

Jon's close- but not quite 100% correct. The E30 325is with Auto tranny had a 4.10 LSD from '89-91 only (were there any '91 325is'?). '87-88 325is with Auto tranny had 3.73 LSD's.


Also, the tag will say something like "S 373" (plus some other numbers indicating manufacture date codes), and the tag is NOT normally horizontal- all of those that I've seen are vertical. You cannot rely 100% on the tag either, but it's a pretty good start.

Bret.

As for the driveshaft, you will have to change it out to the proper one. While you're at it, replace the guibo (flex disc) while you have everything apart.

In regards to your differential, you say the car is a 325is? If this is true, the car came equipped with a 4.10 limited slip ratio which is highly desirable for improved acceleration. If you're more concerned about mileage and having a quieter cabin at highway cruising speeds, install a 3.73 ratio differential.

So how do you tell what ratio diff you have? That's an easy one. Simply get the rear of your car safely supported on some jackstands and slide under there so you're looking at the back cover of the diff. One of the bolts that holds the rear diff cover in place should have a metal tag afixed to it with engraved numbers on it (its located on the right side of the diff). A 4.10 diff should read "4.10LS" or something like that.

Here's a pic to simplify things. You'll find the tag in a horizontal position pointing towards the center of the diff. Its located at the top bolt on the right side.



Jon

[Erick]

(were there any '91 325is'?).

No, there were 325i's with the sport package. Same thing as the iS though.

[Jon325i]

(were there any '91 325is'?).

No, there were 325i's with the sport package. Same thing as the iS though.

It depends on the market it was sold in when new. In the US, they were known as the 325is. In markets such as the UK, they got the 325i Sport. Virtually identical cars mechanically, but the UK cars got the very sexy M-Tech II body styling enhancements as standard equipment.

I sure wish we got more of those here in the states :x

Jon

[BS87]

He meant that in 91 there were no "Official" iS's, but the regular i with the "Sport package" was bassically an iS without the badge.

[Axxe]

I think you guys misunderstood me: the 325is is 5-spd (with a shot motor and chassis) while the 325i is auto (with a rebuild head and clean body). They are both '87. So what I'm asking is whether or not the "is" comes with a LSD and what the ratios are.

Basically I'm swapping trannies between the two (except that the automatic is dead).

[Digitalwave]

Not all iS's came with LSD's, it was always an option unless you are talking about an M3.

The manual drive shaft is longer. Replace the guibo and center support bearing while down there. I also replaced all the seals, bearing, bushings, shift linkage, and clutch parts while I was at it :)

[Jon325i]

I think you guys misunderstood me: the 325is is 5-spd (with a shot motor and chassis) while the 325i is auto (with a rebuild head and clean body). They are both '87. So what I'm asking is whether or not the "is" comes with a LSD and what the ratios are.

Basically I'm swapping trannies between the two (except that the automatic is dead).

Man I feel like such a tool now :oops:

Jon

[Erick]

Not all iS's came with LSD's, it was always an option unless you are talking about an M3.

You sure about that? I've always read that all 325iS's have LSD, and that it was an option on 325i's and 318iS's.

From all 325iS's I've seen in person ( about 4-5 ), all of them had LSDs, regardless of transmission.

[Rigmaster]

Not all iS's came with LSD's, it was always an option unless you are talking about an M3.

:)

To clarify what Digitalwave is saying. In my experience, ALL E30 325is' came with LSD (see my post above for explanation of which year/tranny had which ratio).

His statement is correct about the "other" E30's 325i/318i/is (both the M10 '84-85's and the M42 '90-91's), these cars do NOT have LSD as standard equipment- it was always an option though.

So, to answer the latest question posed by AXXE, both of the cars you have ('87 325i auto and '87 325is 5 speed) have 3.73:1 diff ratios, but the 325is should have a LSD, while the 325i will likely NOT have LSD. Hope this is clear.

Bret.

[Digitalwave]

I apologize, I do believe Rig is right, that all 325iS's had LSDs.

[Rigmaster]

I apologize, I do believe Rig is right, that all 325iS's had LSDs.

Gotta give full credit to Digitalwave here for stepping forward with this comment- too many people on the (mostly BMW-related) boards I frequent like to post half-assed info and other completely wrong crap and then disappear, or start insulting those who try to correct/clarify the wrong info they are spreading. While the wrong info in his original post was pretty harmless- it could add to the loads of misinformation that is out there without his follow-up.

Thanks Digitalwave!!

Bret.

[Axxe]

Thanks guys. From some recent driving, reading and drifting) I have come to the conclusion that I do have an LSD. Thanks for the help.

Digitwave: I was planning on changing all that anyway, but thanks for reminding me.