Tech Forum : 323i with dog leg 5 speed and 3.64LSD?

Al_Canuck

Posted Monday, Mar 7th 8:43am [Edit] [Quote] [IMS] [View car]

Member
Post nr. 209

Surrey, British Columbia
76 BMW 2002, 81 RHD 323i, 85 535i

Anyone else run that combo? I've got the dog leg in my 323i, along with the 3.25 diff. I have a couple of 3.90LSD's kicking around, but I also believe I recently acquired a 3.64LSD. I think the 3.64 is an ideal compromise for that gear box. Any input, or experience?

Speaking of the possible 3.64, here's the scoop. I recently went to one of my neighbour's, who has parted out a couple of E21's. I was looking through his stash of stuff, and came across a diff on a subframe. The subframe had a swaybar, so my first thought was 77 or 'is'. I spun it, and discovered it is an LSD. I asked him what car it came from, and he said the red one. The red doors he has are 04/77 production date, so that settles what year the diff came from. 77 is a 3.64, right?

Thanx,

Al

alpina1600-2

Posted Monday, Mar 7th 3:33pm [Edit] [Quote] [IMS] [View car]

Member
Post nr. 17

Massachusetts, USA
1982 323i, 1967 1600-2 Alpina

I have a 3.64 LSD kicking around that was off of my '78 320i. I bought that car new with the optional LSD so that is the standard LSD offered on the early models. I also plan on putting this on my '82 323i and replacing the standard 3.45 non LSD. The differemntial had 234,000 on it but seemed fine when that car came off the road with terminal body rot. I would also love to hear some feedback on this.

Wayne

Greg323i

Posted Monday, Mar 7th 4:14pm [Edit] [Quote] [IMS] [View car]

Member
Post nr. 115

Melbourne, Australia
1982 Hennaröt 323i

Hi Al, I'm assuming you haven't had the opportunity to drive your 323i yet, bought as a project, right?

The thing I find is with the standard 3.45, especially when it's wet, I lose traction like crazy! The LSD will definitely help you with that but in my opinion 3.65 is kind of overkill unless you're drag racing. Of course, my car's not choked with cats or any of the smog equipment mandatory in North America.

Greg

imaradiostar

Posted Monday, Mar 7th 5:07pm [Edit] [Quote] [IMS] [View car]

Member
Post nr. 287

Nashville, TN
81 323i, 82 525i, 85 524td, 90 535i

I am of the opinion the 3.64 is too low for anything other than track use. My last 323i had a stock engine and a four speed- I felt that highway revs became annoying after a while. I did however feel that with the 3.45 and a four speed that the gear spacing was too far apart which is why I looked for a dogleg CR box for my new 323i. Though the revs are still a little high on the highway, the 5 speed CR box and the 3.45 seem to be a good match.

Are you certain your 3.25 isn't a limited slip unit? I think it would be the ideal ratio for a 323i with a close ratio gearbox. I wish my diff were a 3.25 LSD!

jamie

Greg323i

Posted Monday, Mar 7th 5:33pm [Edit] [Quote] [IMS] [View car]

Member
Post nr. 117

Melbourne, Australia
1982 Hennaröt 323i

I'm probably wrong in this, and I'm sure Ray will correct me if I am, but can't you just change the ring and pinion from the 3.25 into one of the LSDs? Seems to me to be a relatively easy swap.

Greg

Al_Canuck

Posted Monday, Mar 7th 7:39pm [Edit] [Quote] [IMS] [View car]

Member
Post nr. 210

Surrey, British Columbia
76 BMW 2002, 81 RHD 323i, 85 535i

Good discussion, thanks guys. Greg is right, I've never driven my 323i, or any 323i for that matter. I was actually considering putting a 3.90 in it, but with that 1:1 5th gear, it would be awful. I can't help but think the 3.25 is too tall, and the 3.90 is too short. I fifured the 3.64 was about right. Hmmm, sounds like a 3.45 is the answer. What I will so is this. Install the 3.64, and run it as is for a while. If it's not right, I'll either swap the 3.25 ring gear into the LSD housing, or find a 3.45.

And Greg, no cats or emissions crud on mine either. They never sold the 323i over here, so unless someone did the whole proper, legit federalising procedure to their 323i, there won't be any of them with emissions crud anywhere.

Al

kpeters

Posted Monday, Mar 7th 8:12pm [Edit] [Quote] [IMS] [View car]

Member
Post nr. 335

San Jose, Costa Rica
1981 320/6 Kastanienrot-Metallic 5spd

Hey guys I'm a newbie on this diff matters, I have the 5 speed OD on my 320/6 but i don't know wich diff im running. The car seems to have a very long 5th gear. Is the ratio indicated on the diff itself? Where can I find which one I have? Thanks guys sorry bout the question, bet people ask it all the time :S

AL: I thought you got to drive your 323i before dismatling to do the paint job.

Konrad.

Al_Canuck

Posted Monday, Mar 7th 8:19pm [Edit] [Quote] [IMS] [View car]

Member
Post nr. 211

Surrey, British Columbia
76 BMW 2002, 81 RHD 323i, 85 535i

Konrad, someone will correct me if I'm wrong, but I think your 320/6 should have a 3.45 diff in it.

Nope, never drove mine. It had been sitting since 1988, so all the brakes are shot, suspension is hosed, engine was missing, tires were dry rotted all to hell, exhaust was toast, sunroof was leaking, and there was a steel bar across the engine bay, wired to the belhousing, to keep the gearbox off the ground. ALL of these things will be addressed, along with a bunch of other stuff. By a bunch of other stuff, I mean EVERYTHING is being done.

The car will go to the body shop with subframes in it, but I will pull them when it gets there, so he can clean up the underside of the car. I will bead blast and paint both subframes, and hang a bunch of new goodies on them, and then put it all together when it comes back. Every last nut and bolt is coming off of this car.

Al

DHoang

Posted Monday, Mar 7th 9:04pm [Edit] [Quote] [IMS] [View car]

Member
Post nr. 212

Texas USA
323i, e39 528i, Maserati Spider, Tundra LTD V8 p/up

Al_Canuck wrote:

Konrad, someone will correct me if I\'m wrong, but I think your 320/6 should have a 3.45 diff in it.

Al

Al, the blue book shows 3.64 gearset for the 320/6. It's the 323i that gets the 3,45 .

FOr flat out 1/4mile times, a 3.64 gearset used in a 323i would likely net you better trap times. But on a fast running roadcourse, the 3.64 would shorten the motor's revs between gears, and you'd likely wind up losing lap time having to shift up/down too often. OTOH, an autox course would see a HUGE advantage w/ 3.64, or even 3.90 gears. Dialing in the right gearset for the course is like a science.

DHoang

Posted Monday, Mar 7th 9:10pm [Edit] [Quote] [IMS] [View car]

Member
Post nr. 213

Texas USA
323i, e39 528i, Maserati Spider, Tundra LTD V8 p/up

kpeters wrote:

Hey guys I\'m a newbie on this diff matters, I have the 5 speed OD on my 320/6 but i don\'t know wich diff im running. The car seems to have a very long 5th gear.
Konrad.

The OD transmission being a wide ratio transmission, coupled w/ an overdrive gear, is ideally suited for grand touring. THe very long 5th gear will not fatigue/wear you out at the end of the day. You can eat up miles and miles and miles of long distance travel and still want to go out partying. I've done several 500 mile one-way trips, putting ~ 8hrs inside my 323i w/ the CR trans, and at the end of the day my ears and fingers would buzz. I never felt as fresh as when I started out.

And with all the buzz w/ gas prices soaring (they're talking $80 USD/barrel!!) this summer, I sure would love to have an OD tranny!

imaradiostar

Posted Monday, Mar 7th 9:14pm [Edit] [Quote] [IMS] [View car]

Member
Post nr. 289

Nashville, TN
81 323i, 82 525i, 85 524td, 90 535i

If you decided against the 3.25 ring and pinion I'm sure you could find someone to buy it from you! (hint hint)

For a higher-torque engine (m20 stroker or m30 or anything turbo) I think the 3.25 would be fine. I'm not positive but with a stock 323i engine the 3.45 might be a better idea.

jamie

RDAvena

Posted Tuesday, Mar 8th 1:33am [Edit] [Quote] [IMS] [View car]

Staff
Post nr. 1100

SELECT * FROM users WHERE clue > 0
1981 323i, 1988 545is, 1997 528i

Greg323i wrote:

I\'m probably wrong in this, and I\'m sure Ray will correct me if I am, but can\'t you just change the ring and pinion from the 3.25 into one of the LSDs? Seems to me to be a relatively easy swap.
Greg

Greg, you are not wrong but actually half right. You can switch the limited slip clutch unit to the open 3.25 diff. You will need to extract the limited slip clutch housing from the donor diff along with the side cover spacers. Remove whatever ratio ring is on this diff and replace the ring with the 3.25 ring. Make sure everything is cleaned out and that the bolt holes are tapped free of the loctite that was put in there. Make sure you do not mess up the ring retaining bolts when you remove the ring as these are NLA from BMW Mobile Traditions. Once you are ready to mate the ring to the clutchpack you will need to put the clutch pack in the freezer for a couple of hours prior to assembling it to the ring. Once you are almost ready to mate them together heat the ring with a torch`(not the electric type for you guys from Oz) until it is relatively hot. This will help expand the ring so that it slips over the clutchpack. After it is slipped on line up the bolt holes and let the parts cool/warm up. Thread the clean bolts in with Loctite and torque each of the bolts to 79 ft/lbs. After this is complete assemble the diff using the side cover spacers from the limited slip diff on to the diff that has the 3.25 pinion.

Greg323i

Posted Tuesday, Mar 8th 2:11am [Edit] [Quote] [IMS] [View car]

Member
Post nr. 118

Melbourne, Australia
1982 Hennaröt 323i

Cool!! There's another great nugget of information for me to squirrel away!! Thanks Ray!

imaradiostar

Posted Tuesday, Mar 8th 8:18am [Edit] [Quote] [IMS] [View car]

Member
Post nr. 291

Nashville, TN
81 323i, 82 525i, 85 524td, 90 535i

RDAvena wrote:

After this is complete assemble the diff using the side cover spacers from the limited slip diff on to the diff that has the 3.25 pinion.

...so the important thing here is you aren't just swapping the ring and pinion. You're actually swapping the limited slip housing so that it's the only change to your lower ratio differential.

jamie

imaradiostar

Posted Wednesday, Mar 9th 3:45am [Edit] [Quote] [IMS] [View car]

Member
Post nr. 295

Nashville, TN
81 323i, 82 525i, 85 524td, 90 535i

New reply for anyone that's interested- the more I drive my 323i/2.7, the more I'm convinced that a dogleg 5 speed would best be matched to a 3.25 differential. With the 3.45 it's very fast and great for keeping revs up but on the highway doing 70 the engine is revving a little to high to be comfortable.

Maybe it's time to revist the e28 differential swap since E28 3.25 LSD's are readily available.

jamie

RDAvena

Posted Wednesday, Mar 9th 10:46pm [Edit] [Quote] [IMS] [View car]

Staff
Post nr. 1111

SELECT * FROM users WHERE clue > 0
1981 323i, 1988 545is, 1997 528i

on the ETK it does not show a 3.25 gear ratio for the e21. This is the only list available:
CROWNGEAR SET I=38:11=3,45 1 3312120734 -EDIT-
CROWNGEAR SET I=37:9=4,11 1 3312120481
CROWNGEAR SET I=37:11=3,36 1 3312120908
CROWNGEAR SET I=38:9=4,22 1 3312120908
CROWNGEAR SET I=38:8=4,75 1 3312120908
CROWNGEAR SET I=35:7=5,00 1 3312120908
CROWNGEAR SET I=41:7=5,85 1 3312120908
CROWNGEAR SET I=37:7=5,29 1 3312120986
CROWNGEAR SET I=43:11=3,91 1 3121210742
CROWNGEAR SET I=40:11=3,64 1 3312121183
CROWNGEAR SET I=35:8=4,37 1 3312120900

Al_Canuck

Posted Thursday, Mar 10th 3:19am [Edit] [Quote] [IMS] [View car]

Member
Post nr. 216

Surrey, British Columbia
76 BMW 2002, 81 RHD 323i, 85 535i

So, what the hell came in a CR equipped 323i? I got that info from this site!

Al

Greg323i

Posted Thursday, Mar 10th 5:04am [Edit] [Quote] [IMS] [View car]

Member
Post nr. 119

Melbourne, Australia
1982 Hennaröt 323i

I'm pretty sure that all the 323i's came with 3.45.

Ray, that list doesn't even show the 3.45. That's a little strange.

Al_Canuck

Posted Thursday, Mar 10th 6:14am [Edit] [Quote] [IMS] [View car]

Member
Post nr. 217

Surrey, British Columbia
76 BMW 2002, 81 RHD 323i, 85 535i

Greg323i wrote:

I\'m pretty sure that all the 323i\'s came with 3.45.

Ray, that list doesn\'t even show the 3.45. That\'s a little strange.

Well, here's a quote taken from the "About" section of this very site.

"The 323i has a 3.45:1 ratio on the differential. If fitted with a sport gearbox, the ratio was 3.25:1."

That is where my info came from. I guess I'll have to crawl under there and take a look for myself.

Al

imaradiostar

Posted Thursday, Mar 10th 7:57am [Edit] [Quote] [IMS] [View car]

Member
Post nr. 299

Nashville, TN
81 323i, 82 525i, 85 524td, 90 535i

Well...we know for a fact that SOME cars had them because I've seen official literature listing specs of cars with 3.25 differentials. I think aardvark even has one listed on their parts catalog.

I'm pretty sure my car has the original differential and it's a 3.45.

jamie

Greg323i

Posted Thursday, Mar 10th 4:09pm [Edit] [Quote] [IMS] [View car]

Member
Post nr. 120

Melbourne, Australia
1982 Hennaröt 323i

Al_Canuck wrote:

Greg323i wrote:

I'm pretty sure that all the 323i's came with 3.45.

Ray, that list doesn't even show the 3.45. That's a little strange.

Well then, that's very different. Nevermind.

RDAvena

Posted Thursday, Mar 10th 5:32pm [Edit] [Quote] [IMS] [View car]

Staff
Post nr. 1112

SELECT * FROM users WHERE clue > 0
1981 323i, 1988 545is, 1997 528i

Greg323i wrote:

I\'m pretty sure that all the 323i\'s came with 3.45.

Ray, that list doesn\'t even show the 3.45. That\'s a little strange.

Must have left it off. The list has it included now.

Could be inconsistencies with this ETK. I only listed the black and white of what could be researched. Just found it odd there was not a 3.25 ratio listed. The best proof would be a dealer options list of the day.

Al_Canuck

Posted Thursday, Mar 10th 8:21pm [Edit] [Quote] [IMS] [View car]

Member
Post nr. 221

Surrey, British Columbia
76 BMW 2002, 81 RHD 323i, 85 535i

When I get the diff out of mine, I will calculate the ratio. My car is astonishingly original, having sat since 1988. I can guarantee the diff has never been changed.

Al

imaradiostar

Posted Friday, Mar 11th 2:46am [Edit] [Quote] [IMS] [View car]

Member
Post nr. 301

Nashville, TN
81 323i, 82 525i, 85 524td, 90 535i

so yeah...not that I didn't trust you guys but I just looked at ETK as well. No 3.25 but it lists all those other crazy ratios.

Perhaps this 3.25 is a myth!? I thought for sure the Schnitzer turbo had one (according to the German article that's around here somewhere).

jamie

Gabi_323i

Posted Sunday, Aug 14th 7:28pm [Edit] [Quote] [IMS] [View car]

Member
Post nr. 90

Bucharest, Romania
11/80 323i 2.7i Motronic 1.3

i have at home a diferential

on the top of it is a big 7
on the back alu case it says 33.1 - 1 204 898
on the bottom 33.11 - 1 207 219.0 GTS-G40
and a 2 or backed S 27.12.78

what ratio is this?

JJG323

Posted Sunday, Aug 14th 8:07pm [Edit] [Quote] [IMS] [View car]

Member
Post nr. 868

Reading MA USA
1979 BMW 323i

Gabi, I have no idea. Maybe the guys can tell you what ratio you have there.

Al_Canuck wrote:

Greg323i wrote:

I\'m pretty sure that all the 323i\'s came with 3.45.

Ray, that list doesn\'t even show the 3.45. That\'s a little strange.

Al_Canuck wrote:

When I get the diff out of mine, I will calculate the ratio. My car is astonishingly original, having sat since 1988. I can guarantee the diff has never been changed.

Al

myersport wrote:

J-
The ETK shows that all 323i's came from the factory with a 3.45 final drive, however I have heard rumors that those with the 'Sport' gearbox were supplied with a 3.25 final drive. With a purpose-built stroker I would reccomend the 3.45, 3.25 wouldn't be bad either, especially if you're hammering out high torque figures. Just be sure to upgrade to a LS if it isn't already!
--Dennis

Interesting discussion,

and this is similar to other thread going on. Al, I can tell you I have no idea what diff I have but its original as well.
My car has sat since 1993.

I had the car on the lift and looked under and could not discern any numbers, the case itself looks like the Titanic and once had letters and is a little rusty.

I have the dog sport gearbox, and I dont even remeber if its limited slip or not. I think I will try to convert to LS like Ray just talked about - assuming I have the 3.25.

Al let us know what you find out when you pull your diff, and along those lines are the numbers on the top part of the diff as well? Or is some secret trick- to discerning the diff ratio.

thanks
Joe

DHoang

Posted Sunday, Aug 14th 8:10pm [Edit] [Quote] [IMS] [View car]

Member
Post nr. 301

Texas USA
323i, e39 528i, Maserati Spider, Tundra LTD V8 p/up

Believe it or not, the last time I physically rotated the back wheel one revolution, I counted my driveshaft to have rotated closer to 3-1/4 revs than 3.5.

But, just a little driveline slop on my unit could have thrown this unofficial measurement off. The surest way is to count the teeth on the ring gear and on the pinion and make the calculations.

Gabi_323i

Posted Tuesday, Aug 16th 12:01pm [Edit] [Quote] [IMS] [View car]

Member
Post nr. 91

Bucharest, Romania
11/80 323i 2.7i Motronic 1.3

Gabi_323i wrote:

i have at home a diferential

on the top of it is a big 7
on the back alu case it says 33.1 - 1 204 898
on the bottom 33.11 - 1 207 219.0 GTS-G40
and a 2 or backed S 27.12.78

what ratio is this?

so?

DHoang

Posted Tuesday, Aug 16th 5:22pm [Edit] [Quote] [IMS] [View car]

Member
Post nr. 304

Texas USA
323i, e39 528i, Maserati Spider, Tundra LTD V8 p/up

Gabi:

Numbers casted on the differential housing only identifies that particular casing. It does not identify what gear ratio is inside. Casting is an expensive and tedious process. So maximizing this part to be used on as many product lines as possible makes more economic sense.

As RD pointed out above with the long list of part numbers for the Crowngear set options, there are numerous ratios available for that differential. And it is not likely for BMW to call out what the internal gearset will be by stamping it on the differential casing. It's just not a good way to organize product nomenclature that way.

So as best as I can tell, BMW creates a metal tag that has info on the gearset, and they externally bolt it onto the casing at the time of assembly.

Do you see a metal tag bolted onto the differential ? If so that should be where to look. When you find that tag, divide the two numbers and that should tell you the ratio.

Gabi_323i

Posted Tuesday, Aug 16th 11:49pm [Edit] [Quote] [IMS] [View car]

Member
Post nr. 92

Bucharest, Romania
11/80 323i 2.7i Motronic 1.3

unfortunally the diferential has no metal tag bolted on it

what can i do?

BruceH

Posted Wednesday, Aug 17th 1:04am [Edit] [Quote] [IMS] [View car]

Member
Post nr. 653

Atlanta, GA USA
81 323 Baur, 85 745

Get the car in the air and count the turns of the wheels vs the driveshaft.

Bruce

g323

Posted Friday, Jan 9th 12:01am [Edit] [Quote] [IMS] [View car]

Member
Post nr. 330

California
323i 1982

ORIGIONAL POST/THREAD - http://forums.bimmerforums.com/forum/showthread.php?t=1151632

ok, so I can turn the one side; count how many times the drive shaft rotates, and multiply that by 2?

Ok, I counted the amount of turns the driveshaft makes with one turn of one wheel off the ground and the other on the ground.

1 full turn plus ~260 degrees.

260/360 = .72

.72(turns) + 1(turn) = 1.72 turns for one rotation of one wheel off the ground.

1.72 x 2 = 3.44

Since I've gotten so many different numbers I'm reluctant to trust this one even though it seems completely correct - 3.45.....

Does this math atleast seem right to you all? what do you think Layne?

We'll, If layne's math is right then here is a chart I made to help myself. I'm pretty sure I have a 3.45 because I the driveshaft would have turned 34 degrees more if it were a 3.64.

Here goes:

To be completely honest, If this is the correct methodology, I think I might have the 3.25. But that is really weird:

The 323i dogleg is mentioned to have been packaged with a 3.25, but I've heard mixed things as to whether it's true.

Here are two links that say it is true:
http://e21.tricord.be/e21/about/m20/gearbox-info.php
http://www.e-z-ride.com/bmwe21/

I did the test again a few more times to be more accurate, and I feel that when I get to the second turn of the driveshaft, it stops at 225 degrees, which would put it at 3.25

Ratio /2 /2-1 /2-1 in degrees /2 - 1 on the clock /2 - 1 in sets of 45 degrees
3.25 1.625 0.625 225 7.5 5

Has anyone else heard of or confirmed this 3.25 Differential?

Using this calculator:
http://www.csgnetwork.com/rpmcalc.html

I would have a 200 RPM difference at 80mph between a 3.25(3933RPM) and a 3.45(4175RPM).

If I get a chance I will calibrate my tach to be correct at 4000 RPM's and will report back.

Horstl

Posted Wednesday, Jan 14th 8:54am [Edit] [Quote] [IMS] [View car]

Member
Post nr. 29

Austria
323i / 2.7, 323i, 315, M3

Folks,
just my 2c on this topic:
I've seen and disassembled lots of 323i here in Europe, so far I can say:
323i always came with a 3.45 (OD, dogleg, auto)
320/6 and 320i 4came with 3.64
318i and late 316 came with 3.91
315 and early 316 (both 1600ccm) came with 4.11

02 Turbo had the 3.37, but in the old style of
diff housing (4 screws on the output bearings)

I run my 327i with 5 speed OD and 3.64, have a dogleg on the shelf but this will not be the best joice with a 3.45 on high speed trips in europe.
Still looking for a 3.37

I've never heard of any 3.25 in a e21.
If someone is looking for a 3.45 ring and pinion -drop me a message.

rgds
Horst