Tech Forum : e21 euro 323i diff power rating

Dorzas323i	Posted Sunday, Jul 6th 2:53pm [Edit] [Quote] [IMS] [View car]
Member Post nr. 17 Victoria, Australia euro 1982 323i	i have my diff off my 323i, and i was wondering what the HP rating on the diff is, i know that the hp on the engine stock is 143HP, but i odn't know what HP i run through it before i have to do anything, there's gonna be 300HP easy running through it, once i finish my engine transplant. and what kinda stuff can i do it to it to hold more. i know that korman has new diff casing with fins that help cool it, but i don't know if this will make it handle more. and onw more Q: is there a chance that this diff is a LSD? ie:did 323i's ever come with LSD's? well dope someone has some info, thanks in advance. -Doran ps: thanks Tricord for the great sight withh all the info, and thanks everyone else for all the info so far.

Greg323i	Posted Sunday, Jul 6th 4:05pm [Edit] [Quote] [IMS] [View car]
Member Post nr. 7 Melbourne, Australia 1982 Hennaröt 323i	Hey Doran, yah, 323i's came with LSD's, but good luck finding one here in Melbourne. I've been to several wreckers with no luck. The diff in my 323i was toasted when I bought it and I had to replace it, so I've been through a lot of wreckers. I've got my old diff and I'm going to rebuild that as an LSD, hopefully a Quaife. That would be sweet. I think the stock diff is good to about 200hp, but I'm not really sure on that one. Ray could probably give you a more definitive answer. Oh, in case you're interested, I got my diff from a place called BM Only in Mitcham for about $300. A place called BM Spares was selling it for about $260, but they're in Dandenong and too far for me to drive if I got a bum diff. Another place I get most of my parts from is Auto Deutsche in Bayswater really good people out there and I got my rear discs from them for about $80 the set. There's a place in Prahan called Hanvic South Yarra Auto Parts that have really great prices, but they don't sell to the public. If you work in the repair business it shouldn't be any problem for you. Sorry to ramble, hope some of this helps.

RDAvena	Posted Sunday, Jul 6th 6:54pm [Edit] [Quote] [IMS] [View car]
Staff Post nr. 80 SELECT * FROM users WHERE clue > 0 1981 323i, 1988 545is, 1997 528i	The e21 diff can safely handle 225 Hp(approx), anything past this you will burn the clutches and the pinion bearing in the case. Alpina had no problems using the e21 diff, albeit with better cooling, in the e21 B6 with the 218hp rated M30 motor. Many have said and proven that alpina was always on the conservative side with their hp/torque figures.

JDBeyer	Posted Monday, Jul 7th 4:28am [Edit] [Quote] [IMS] [View car]
Member Post nr. 30 N. Humboldt county Ca. 82 323i on steroids	My experience has been that the LSD diff.is more reliable in high H.P. applications in that the spider gears do not explode as easily from the wheels spining constantly. Another clutch can be added to further avoid this. As for the Alpina diff. cover the cooling and oil capacity is incresed, and the diff. mounts to the body differently with 2 bushings directly to the body requiring welding another bracket to the pass. side. The cover also has a temp. sender to moniter oil temp. Here is a pic.of the cover installed and what it looks like from the rear...Please excuse the mess from a Humboldt County winter under my car. Jeff

Dorzas323i	Posted Monday, Jul 7th 2:14pm [Edit] [Quote] [IMS] [View car]
Member Post nr. 18 Victoria, Australia euro 1982 323i	thanks guys, greg: so your saying that my car would most likely Not have a LSD? just wondering, cause i was wondering if there is any physicle difference in the look of the diff, from the outside? and if the diff can't handle 300HP, like most of you said, is there any options that i can go with, something that i'm not gonna pay a fortune for. i know that i could order one from korman, but i'm looking at 2 grand then (or somewhere there abouts). and greg, you said that your gonna rebuild the diff as a LSD, can you use the normal casing, and if so, where can you get a kit to do this, and off this question, if i rebuild it into a LSD, can i get a stronger spider gears? well thanks for all the help so far. and JD, are you saying that witth the addtions to the diff i can make it handle 300HP? or are you just saying that i can make it handle more, but not quite 300HP? by the way, jeff, awsome car, looks, and sits REAL nice. catch yaz laterz guys -Doran ps: greg: i'll try some of those places for some parts, i personally use Pennisula BM, in mornington, i know the owner personally, so i get stuff cheap from there, that's where i originally got my two cars from, (the one i'm restoring,and a parts car to wreck for misc stuff, plus endless amounts of other stuff.) thanks for the info

Greg323i	Posted Monday, Jul 7th 4:07pm [Edit] [Quote] [IMS] [View car]
Member Post nr. 8 Melbourne, Australia 1982 Hennaröt 323i	With all the information I've stolen from the brains here, the LSD should have a big S painted on the side of the case (I think it's the right side, but I'm not sure). The other way to tell is to jack up the rear and spin one of the wheels. The other wheel should spin the same direction. If it spins opposite it's a normal diff. When I spun the wheels of my old diff the other wheel would not turn much. I don't think it would've lasted much longer at all. As far as rebuilding the old diff, I haven't really looked into it. I think the case is the same for either diff (Ray, is that true?). It's a little way off though, too many other things need to be done first. Maybe at the end of the year.

RDAvena	Posted Monday, Jul 7th 6:50pm [Edit] [Quote] [IMS] [View car]
Staff Post nr. 81 SELECT * FROM users WHERE clue > 0 1981 323i, 1988 545is, 1997 528i	The cases are the same and again it would be the way that Greg323i commented on checking the diff if it is an ls or not. The big "S" is painted usually on the front snout of the diff on the drivers side. Since it is painted it may not be there due to climate conditions(rust) or a previous owner painted it. You can also check the "toe tag" bolted on the rear cover for an "S" before the ratio number. It is a small brass tag that denotes the S option and the ratio. You can not make the diff 300hp freindly by just adding stronger spider gears or adding more clutches to the clutch pack. By adding clutches (2 for 40% and 4 for 65% with a machined carrier) it will only increase the amount of break torque offered by the diff and not strengthen the case or the pinion any. It has been known that the Quaife Torque biasing differential will allow higher hp than the 225. But again the weak link will be the pinion and associated parts. Some have been known to change out diffs to either an e12 or an e28 diff. ut a lot of modification will have to go into the subframe and the driveshafts. This pic shows an e12 diff modified to work in an e21. So it is possible but the cost involved is an issue. Personal experience, I had to add the largest diff made by BMW to my 535i (e28) so that it could support the 450+hp that will be made by the m106 e23 745i motor. Compared to the regular e28 diff that was in there at 58lbs (wet). The new diff came in at 117 lbs with all of the trimmings. It is not related to weight but the side bearings and the pinion shaft itself was made for this higher output. Limited slip was a side benefit.

Dorzas323i	Posted Friday, Jul 11th 1:23pm [Edit] [Quote] [IMS] [View car]
Member Post nr. 30 Victoria, Australia euro 1982 323i	thanks for all the info. i looked on both the cars i have, and niether have any "s" markings, so i doubt that they are LSD's, but i can't be sure until i take them out of the car, and i can't find the brass tag that says the ratio, or 's' on it, so still not sure, but i'll deal with it when i get them out. so RD what would you suggest i do to be on the safe side. maybe if i said for now make it 250HP safe, and when i work the engine later, i can deal with the 300 then. i'm trying not to repeat myself, and i hope that i havn't, but if i have then just let me know, thanks again guys for all the info, and one question to you RD, if i keep my case to the diff, but change everyhting else out, new bearings pinnion, spiders, all that, is there a way to make this diff hold that much power, or is the case power restrictive, thanks again for all the info. -Doran

Tricord	Posted Friday, Jul 11th 3:03pm [Edit] [Quote] [IMS] [View car]
Administrator Post nr. 134 Belgium, Europe 323i Baur	Let me move this to the tech forum

Dorzas323i	Posted Saturday, Jul 12th 1:00pm [Edit] [Quote] [IMS] [View car]
Member Post nr. 34 Victoria, Australia euro 1982 323i	that's kool