Diff housing sizes [Archive]

L84THSKY

05-17-2005, 06:35 PM

I've asked alot of questions about diffs, but some things still seemed unanswered. We all agree that the 4 cylinder diff cases are smaller than the 6 cylinder cases. The stubs are different between 4 and 6 cylinders to keep the total width flange to flange the same size. Assuming this is true, then any 6 cylinder diff with the right bolt patter will fit our cars. The only issue would be getting the proper half shafts to go with the diff. That opens up the possibility of many 3/5/7 series cars to choose from.

My ratio of choice is 3.46 or 3.64. I have seen both those ratios offered in 7 series models. Here is a picture of a 3.46 out of a 1985 735i. Looks just fine for our applications. How many different half shafts are out there? Are there only 4cylinder, 6 cylinder and maybe M series half shafts?

cali-ti

05-18-2005, 01:29 AM

diff cover looks different. will a stock e30 6-cyl, ti or m-coupe finned cover fit that diff? if not, how are you going to bolt it up to the diff cover mount on the ti?

after looking at all this stuff, i think your best/cheapest option is the club sport 3.45 LSD. find one, but it, install it, be done.

L84THSKY

05-26-2005, 09:08 PM

m44ic

05-26-2005, 09:16 PM

L84THSKY

05-26-2005, 09:42 PM

I have found both 3.64 and 3.46 6 cylinder diffs that will fit. Unfortunately, I didn't win them on Ebay.

Here is one I didn't win. Change the rear cover and the flanges and you are all set. This is a 3.46 LSD from a 735i.

hey any luck finding a 3.64 diff that will fit yet?

cali-ti

05-27-2005, 05:21 PM

That would be the simple solution, if I never planned to add a DASC or any other power upgrade.

But, the 6 cylinder housing seems to be beefier, and more suitable to any upgrades. If I do the diff right, from the start, then any proceeding upgrades won't require replacment of the diff again.

the reason i had suggest the clubsport 3.45LSD was because the way you were talking before, you weren't going to DASC or engine swap in the future :) i guess someone is getting the buggaboo for more ponies now, eh? ;)

so ... WHEN you do the swap, i HIGHLY RECOMMEND using bmw reman'd halfshafts. my shop said he's almost NEVER seen a bmw diff fail, but as i've found the halfshafts are a potentially different story. from crevier bmw in CA, reman'd e30 halfshafts are $260/each and i'll probably get a pair in the future to swap out these used ones (which still have some play so you get a little occasional clunk on shifts, most noticeable on 1->2 and 2->3 under power). my guy said he wouldn't recommend reman'd halfshafts either, then i said, "even bmw ones?" to which he responded, "yeah, shouldn't be any problem there." :) i think reman'd ones from bavarian auto recycling were like $350 so why the hell would i go anywhere else but bmw when i can get them for $260/each? also, getting them reman'd from bmw, you should get a matched set unlike what i have now. you also won't have to worry about which side they were installed on the car they were pulled from. you ideally want them to stay on the same side as what they originally were when going used, but of course you have NO IDEA what side they were removed from when sourcing them used (unless you get to take them off or can get the place to make note of that for you). see all the stuff i'm learning for you L8!? lol

L84THSKY

05-27-2005, 10:02 PM

Hey Eric

You sure have been listening to what I've been saying. I did say I wasn't interested in a DASC or 6 cylinder motor. But on second thought, it seems smarter to just upgrade the diff to the large housing 3.46 or 3.64 LSD. That way I lose nothing in regards to any other future mods.

Turns out, finding a 3.45 LSD from a Club Sport is just as hard as finding a 6 cylinder 3.46 or 3.64 from any E30 style car.

So I might as well be a "Hldout" and find the diff of choice. My real motivation should be to finish work on the Vader seats.

cali-ti

05-27-2005, 11:01 PM

i tend to agree with your new view of things, that's one reason i went with the 3.73 LSD from the e30. i just wish i'd known some things i've figured out along the way to make it easier and quicker so that i didn't have all this damn down time i really couldn't afford (much like you since these are our daily drivers). can't stress the bmw reman'd halfshafts enough, especially for "doing the job right the first time" and for longevity. that does increase the cost a bit ($260/each vs like $74/each used), but i think the peace of mind and (theoretically) not having to worry about them being matched and working right is certainly worth it. i WISH i'd done that ... can't go back now, but i can sure encourage others to do it that way.

SportAuto

05-27-2005, 11:21 PM

I'm working with this dilemma right now- the M Roadser diff bolts right in, but puts the pinion flange approx. 1/2" forward of the stock location. The stock driveshaft has the proper bolt spacing however, and will bolt up, but in my case it must be shortened because the M3 engine also puts the trans back 1/2". The flanges on the M diff are 4.5", with a 94mm bolt spacing, whereas the 318ti flanges are around 4, with an 80mm bolt spacing. The splines are the same, but the 318 flanges will barely engage the internal diff splines so I'd rather not rely on them to transmit M3 power to the wheels. The ETK and my vendors show that there were two different axles installed in E36 M3s, both of which have a 4.5" flange. The smallest of the two has a 27mm diameter, which matches those in the Ti, so theoretically I'll be able to use the inner CVs from a 27mm/4.5 flange M3 axle on a 27mm Ti axle. I was shipped the wrong axles today (they sent the 38s) so I won't be able to confirm until Tuesday, but that's the idea. Using the M roadster rear subframe/trailing arms would probably alleviate this problem, but there are plenty of us looking to use 6 cylinder/M diffs in stock subframes so it'll be good to know. E30 flanges are the smaller 80mm spacing, with a 27mm axle -at least the 318 I measured for reference this morning was, don't know about the 6's offhand. I also measured an E34 525i this morning just for fun, and those are smaller as well. 540 maybe? I'll let ya know what I find when I have the new axles in my hands next week.

Tucker
SLO,CA

cali-ti

05-28-2005, 01:03 AM

ugh ... so either way (using the m coupe diff or not), you have to mod the driveshaft? sux

the e36 (non-ti) halfshafts i know nothing about. i KNOW the e30 halfshafts will work and fit w/o change into the ti hubs/trailing arms. i'd bet you could swap the e30 diff flanges into the m coupe diff w/o change since the opposite (swapping m coupe diff flanges into e30 diff) works. the advantage of m coupe subframe/trailing arms/brakes is that they're all improvements over stock ti. you'll need to reconfig the parking brakes and possible routing of other brake lines/sensors. when i swapped in the e30 halfshafts, i needed to shim the ABS sensors, but that was simple enough because i knew about it ahead of time. i used 6-cyl e30 diff/flanges/halfshafts so i'm not sure if they 318 are smaller, the ETK would confirm or deny those differences i would think. as i stated before, i would hate to see you cobble together halfshafts with different CVs and such because it would be a pain in the ass later when/if you need to swap one. from my perspective, it's much more preferable to use stock parts, even if they're from a different model rather than cobbling something together to make it work. i beg you, don't do it man! lol :)

SportAuto

05-28-2005, 04:33 AM

I'd rather not cobble it together, but it's all factory parts with fresh syn grease so I'm really not worried about reliability- the M subframe & arms just aren't in the cards right now. I don't think E30 flanges will work properly in the M diff for the same reason I'm hesitant to use the stock 318ti flanges, which fit too- they're just too short. I don't trust 250hp/tq and 1/4 inch of spline engagement :yikes:

Tucker
SLO,CA

cali-ti

05-28-2005, 01:20 PM

the 6-cyl e30 diff flanges are much longer than the stock 318ti flanges. i can take pics on tuesday when i get back in town if you want to see a visual difference between the two. i know constant also had a pic of those in his notes on the swap to e30 diff, let me find that (one moment) ... http://www.318ti.org/notebook/diff_conversion/index.html

scroll down about 2/3 of the way to the bottom and you'll get a shot of the comparison between 318ti and e30 (6-cyl) diff flanges.

i certainly agree with you, i wouldn't even trust my 4-cyl with the short spline length in the e30 diff.

L84THSKY

06-06-2005, 02:42 AM

Well, I won the diff I was looking for on Ebay, and at a very good price. The shipping was only $32.13, so the whole deal was under $200.00, can't beat that!!!!

No hurries about installing, I want to clean it up nice, and get the rebuilt half shafts too.

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&rd=1,1&item=7977675931&sspagename=STRK%3AMEWA%3AIT

m44ic

06-06-2005, 03:28 AM

cali-ti

06-06-2005, 01:23 PM

L8, can't tell from the pics ... is that a small or large case diff? see that it comes from a e30 318 so i'm thinking it could be a small case (not sure what they used in those).

L84THSKY

06-06-2005, 01:48 PM

I obviously overlooked the fact that it said it was from a 318. On the other hand, it saves me a whole lot of trouble. So this swap will end up similar to a standard 3.46 LSD from a 95 club sport. Oh well, I can't complain, it saves me hours of work, and over $500.00 in replacing the halfshafts.

L8, can't tell from the pics ... is that a small or large case diff? see that it comes from a e30 318 so i'm thinking it could be a small case (not sure what they used in those).

cali-ti

06-06-2005, 01:54 PM

sorry to be the one to point it out :( but YES, it will save you a whole lot of trouble. should be a nice swap. you won't have to source much new mounting hardware either (nuts for the drive shaft are one time use so get extras - i would even recommend using the old ones until you know it's the last time you'll mount it and then put the new ones on). don't have to remove the nuts on the end of the halfshafts which are at like 250 lb-ft or drive them out or worry about ABS sensor clearance ... yeah should be nice :)

L84THSKY

06-06-2005, 02:05 PM

One thing I wasn't sure of. Did you have to remove the wheels to get the halfshafts out on your diff? I use my brother's drive on lift, that would have been a pain in the ass to do. Now that it's only the diff, I simply drive on, drop the diff, and re-install. Should have this baby installed alot sooner than expected.

sorry to be the one to point it out :( but YES, it will save you a whole lot of trouble. should be a nice swap. you won't have to source much new mounting hardware either (nuts for the drive shaft are one time use so get extras - i would even recommend using the old ones until you know it's the last time you'll mount it and then put the new ones on). don't have to remove the nuts on the end of the halfshafts which are at like 250 lb-ft or drive them out or worry about ABS sensor clearance ... yeah should be nice :)

cali-ti

06-06-2005, 02:31 PM

i think if you didn't remove the wheels, it would be a real pain in the a$$. not sure you'd be able to even get an impact socket on the 30mm nut if you didn't. i suppose you could use an impact extension. we took the wheels off. would have been harder to drive the halfshafts out of the hub with the wheels on as well. the giant punch we used probably would have still been long enough, but the guy holding it while the other one hit it with a 10 lb sledge would have been more nervous with his hand closer to the end :p

yep, your swap should be pretty straight forward and easy to reverse if you had to for some reason.

L84THSKY

06-06-2005, 02:35 PM

Actually, you have a good point. Since my car only has 45K miles on it, re-installing the original diff when I sell the car is a bonus.

i think if you didn't remove the wheels, it would be a real pain in the a$$. not sure you'd be able to even get an impact socket on the 30mm nut if you didn't. i suppose you could use an impact extension. we took the wheels off. would have been harder to drive the halfshafts out of the hub with the wheels on as well. the giant punch we used probably would have still been long enough, but the guy holding it while the other one hit it with a 10 lb sledge would have been more nervous with his hand closer to the end :p

yep, your swap should be pretty straight forward and easy to reverse if you had to for some reason.

L84THSKY

06-07-2005, 03:44 PM

Wouldn't it seem logical to use the rear cover and flanges off of my current diff, considering the low mileage of my car?

Did they make a diff cover like the M-coupe finned one, for the 4 cylinder diff casing?

sorry to be the one to point it out :( but YES, it will save you a whole lot of trouble. should be a nice swap. you won't have to source much new mounting hardware either (nuts for the drive shaft are one time use so get extras - i would even recommend using the old ones until you know it's the last time you'll mount it and then put the new ones on). don't have to remove the nuts on the end of the halfshafts which are at like 250 lb-ft or drive them out or worry about ABS sensor clearance ... yeah should be nice :)

L84THSKY

06-07-2005, 03:52 PM

Hey Eric

Take a look at these links. They compare my cars flanges, with that of the car my new diff came from. The flange sizes and bolts are a different size.
I really don't car, so long as I can just put my flanges in, but how can I be sure my flanges will fit?

http://www.realoem.com/bmw/showparts.do?model=CG73&mospid=47506&btnr=33_0462&hg=33&fg=10
http://www.realoem.com/bmw/showparts.do?model=1074&mospid=47302&btnr=33_0144&hg=33&fg=10

sorry to be the one to point it out :( but YES, it will save you a whole lot of trouble. should be a nice swap. you won't have to source much new mounting hardware either (nuts for the drive shaft are one time use so get extras - i would even recommend using the old ones until you know it's the last time you'll mount it and then put the new ones on). don't have to remove the nuts on the end of the halfshafts which are at like 250 lb-ft or drive them out or worry about ABS sensor clearance ... yeah should be nice :)

cali-ti

06-08-2005, 12:04 AM

is there any way you can get the VIN of the 318 that your "new" diff came from? it appears they used two different size flanges and it may be a crapshoot as to which you're getting. looking at the size of the shaft seal, the 318ti is 44mm and the e30 318i is either 35mm or 44mm.

i still have my old 1996 318ti halfshaft and the diff. frankly, i don't know what i was planning to do with them before i move in a month anyway. the bearing on the right side of my diff is at least partially hosed. i could pull the flanges and ship them to you. you could then try 318ti flanges w/o removing your current diff so you'd know. just pay for the shipping and they're yours. if they don't work, i'd put that diff back on ebay (personally) and keep looking either for a club sport ti LSD or one of the large case diffs (again, then you're back to the $500+ for bmw reman'd halfshafts). send me an email or PM me and we can work details if you want the flanges. i should be able to box them up and ship them out by saturday morning at the latest.

L84THSKY

06-08-2005, 03:22 AM

I appreciate the offer. There really isn't any rush. I will pull the flanges from the diff when it arrives, and measure them. The question is, if the flanges are 35mm, can it be mated to our stock half shafts? I would rather not sell this, since I would hope to somehow use my current half shafts and save a bundle. Selling the diff is a last resort.

is there any way you can get the VIN of the 318 that your "new" diff came from? it appears they used two different size flanges and it may be a crapshoot as to which you're getting. looking at the size of the shaft seal, the 318ti is 44mm and the e30 318i is either 35mm or 44mm.

i still have my old 1996 318ti halfshaft and the diff. frankly, i don't know what i was planning to do with them before i move in a month anyway. the bearing on the right side of my diff is at least partially hosed. i could pull the flanges and ship them to you. you could then try 318ti flanges w/o removing your current diff so you'd know. just pay for the shipping and they're yours. if they don't work, i'd put that diff back on ebay (personally) and keep looking either for a club sport ti LSD or one of the large case diffs (again, then you're back to the $500+ for bmw reman'd halfshafts). send me an email or PM me and we can work details if you want the flanges. i should be able to box them up and ship them out by saturday morning at the latest.

cali-ti

06-08-2005, 03:31 AM

well, the rush would be mine, i don't really have much time. i'll pretty much be packing all my free time. if you want 'em just let me know so i can get 'em shipped. maybe check the ETK to see what it lists for the halfshafts between the ti and e30 318.

L84THSKY

06-11-2005, 01:48 AM

Eric

I measured the flanges, I have the 35mm one. Look at the picture below, I have part #1, the upper style flange.

well, the rush would be mine, i don't really have much time. i'll pretty much be packing all my free time. if you want 'em just let me know so i can get 'em shipped. maybe check the ETK to see what it lists for the halfshafts between the ti and e30 318.

cali-ti

06-11-2005, 04:56 PM

i was about to head to the post office ... i'm guessing this means you don't want/need the flanges i have, correct? i'll hold off on sending them then, i can always ship them next week if you still want them. i need to head to my parents house asap (already late because of work) so that's just the plan of action i'll take as i'm guessing you're not sitting there waiting for me to respond :p

L84THSKY

06-11-2005, 07:08 PM

You tell me? Does it seem like the 318ti flanges would not work? I would be willing to pay the postage to find out. Send them anyway.

Thanks
Eric

i was about to head to the post office ... i'm guessing this means you don't want/need the flanges i have, correct? i'll hold off on sending them then, i can always ship them next week if you still want them. i need to head to my parents house asap (already late because of work) so that's just the plan of action i'll take as i'm guessing you're not sitting there waiting for me to respond :p

cali-ti

06-12-2005, 03:21 PM

You tell me? Does it seem like the 318ti flanges would not work? I would be willing to pay the postage to find out. Send them anyway.my guess is they will not work (larger diameter on the flange than the housing on the diff). i'll do my best to get to the post office monday to get 'em shipped.

L84THSKY

06-12-2005, 04:30 PM

The real question is....do I even have to switch them at all? There is a very good chance that the flanges on the diff I bought will fit anyway. Why would they make two sizes, but use different mounting holes to the half shafts? Making two size diff flanges is one this, but why require two different halfshafts as well?
When I get your flanges, I will check the diameter of the out mounting and the bolt pattern.

my guess is they will not work (larger diameter on the flange than the housing on the diff). i'll do my best to get to the post office monday to get 'em shipped.

Constant

06-13-2005, 02:41 AM

I don't have any knowledge of the E30 4-cylinder diffs. This was, after all, supposed to be an upgrade not only via a shorter ratio, but beefier components. :biggrin:

Looking at the ETK, I would bet you cannot swap flanges from the 318ti -> E30 3.64 that you have. I would be concerned with the 35mm vs 44mm splined ends of the output flange, which engages the gears inside the diff. You know the inside of the diff will be clearanced for the 35mm shaft; it'd be like cramming a square peg in a round hole.

If you don't switch the flanges out, you have to be concerned about the output shaft diameter and bolt size/pattern.

Right off, I can tell you the 318ti axles won't bolt onto the E30 4-cyl output flange. The ti uses M8x40mm bolts, whereas the 3.64 uses M10x43/46mm ones...
Strike one.

Looks like the ti has a flange diameter of 80mm vs E30 diameter of 86 mm (unless this measurement refers to length), so either the bolt pattern is way off or the length is...
Strike two.

Obviously the inner CV joint diameter will match the diff output flanges, so they won't even mate up...
Strike three!

Of course for your sake I could be all wrong. Like I said, I don't know nuttin' about E30 4-cyl diffs... ;}

Constant

cali-ti

06-13-2005, 06:24 AM

i hadn't gotten around to scoping the ETK for the 4 cyl e30, thanks constant. i was hoping you were going to end up with the 44mm version eric, but if you have the 35mm, with what constant found regarding the e30 4 cyl halfshaft bolts ... it's sounding like that diff isn't going to be the one :(

i'll still plan on mailing you the flanges unless you tell me to forget it.

L84THSKY

06-13-2005, 02:13 PM

Eric

Read the private message I sent you in regard to the diff. DO NOT send the flanges till we talk.

Looking at the two pics, you will notice that from the taper roller bearing back, the parts are the same for all three flanges. If I swap my tapered roller bearing cover (parts# 4 ) in the 318i flange pic, with the one in my 318ti, then everything else should work...I think :?

Just curious....is the roller taper bearing cover, what hold the inner limited slip assembly in place? I don't want to pull off the covers( part# 4 ) and have the limited slip assembly inside fall out? The third picture is to demonstrate what I mean by this. Look at the three shiny bolts on the flange cover. If I remove that cover, will the inside come apart?

i hadn't gotten around to scoping the ETK for the 4 cyl e30, thanks constant. i was hoping you were going to end up with the 44mm version eric, but if you have the 35mm, with what constant found regarding the e30 4 cyl halfshaft bolts ... it's sounding like that diff isn't going to be the one :(

i'll still plan on mailing you the flanges unless you tell me to forget it.

cali-ti

06-21-2005, 11:29 AM

sorry, been away in denver finding a place to live and having a bunch of preventative work done on my car before the drive to colorado.

it's very possible/likely that they do hold the limited slip assembly. the other thing to keep in mind is when they put one of these together, they shim the bearings as needed for the unit, i don't know if these are movable between diffs or not. i asked about just replacing the BOLTS on the flange bearing covers and it was highly recommended NOT to touch them at all (so i didn't). that's why i mentioned to you before i would just keep the diff assembled and put it back on ebay and keep looking for exactly what you want. i saw your post regarding a 3.45LSD from a club sport and that's certainly the way i'd go. the diff cost may be more, but the total cost of the job and the ease of it compared with other swaps is way better. i should have my car back today so i can get the diff disassembled soon and boxed up if you still want.

cali-ti

06-28-2005, 06:14 AM

L8, ok .... i TRIED to get the flange bearing covers off and they didn't want to budge (not using sane/reasonable means anyway - i didn't want to destroy them getting them off). i still have the flanges themselves boxed up if you want 'em. otherwise, the dumpster gets 'em. let me know before the end of the week or they're garbagio.

Dredder

06-28-2005, 07:17 AM

If L8 Doesnt want them then can you send them to me......

L84THSKY

06-28-2005, 04:16 PM

Eric

I will take them. I didn't realize time was wasting. The LSD project has been on hold while I do other things. Send the flanges, if you still have them.

Thanks
Eric

L8, ok .... i TRIED to get the flange bearing covers off and they didn't want to budge (not using sane/reasonable means anyway - i didn't want to destroy them getting them off). i still have the flanges themselves boxed up if you want 'em. otherwise, the dumpster gets 'em. let me know before the end of the week or they're garbagio.