Does anyone know what DIFFS will be a direct bolt up to my 99 M3 ? The stock 3.23 blows! I know about the 3.38 from the automatic but i dont wanna spend 500 bucks to make such a small change. Anyways advice would be greatly appreciated. thanks.
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good luck then.Originally posted by BMWTECH/E36 -
Lol way to go Roland.
Seriously, none. Nothing other than the 3.15 from a 95, or a 3.38 from a 97+ auto.
All other diffs are custom. There is a nice 3.46:1 40% lockup with polished ring and pinion on eBay for about $1000.Comment
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Roland is right, lol.
The 3.46 with those upgrades is a good deal for $1k, although I had my 3.91 custom built with a ton of goodies for less than that new with 3 year warranty from metrix.
Call metrix, they'll build you something good for cheap, link in my sig.Comment
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As others have said, Metrix has the cheapest prices for rebuilt nonstandard gear diffs. It also occasionally has questionable quality, but seems to repair under warranty.
Theoretically, you can build a diff yourself, but very, very few do it. Here is a link to get you started:
http://forums.bimmerforums.com/forum....php?t=1570362
The only direct fit, from the factory limited slips for the E36M3 are the 3.15 from 95 M3 manuals, 3.23 from 95 M3 autos or 96-99 M3 manuals, 3.38 (edit: 3.23) from 95 M3 Lightweights and 96-99 M3 autos, and 3.91 from early 90s auto 325s with winter package. Sometimes people find the 3.91s for $150 in junkyards. It is a lot of gear for a manual trans. While the car will be really fast within each gear, it may be slower over certain speed ranges because an extra shift will be required to cover that range. Would work best with a 7200 rpm redline and some top end breathing mods. You will be running much higher rpm on the highway. To get an idea, go to the diffsonline website and open up the gear/speed calculator in the technical section and plug in your tire and gear specs.
I have run 3.15, 3.23, 3.38 and 3.64 and would not go higher with a 5 speed on a street car.Comment
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The LTW got the 3.23... (and yea, it's LTW not CSL...lol Flame suit on...)Comment
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You say direct bolt up. On that note, the 3.38 is not "direct". You'll have to re-use your output shafts. The flange holes are not the same measurement. When putting a 3.91 in my auto, I had to swap outputs as did Todd to fit the 3.38 from my auto to his manual. With that said I would still sit the outputs next to each other on the bench and confirm sizing before going to put it in. Other than that they bolt up. The input may be a complete circular disk or may have a (what I call) hourglass shape, but the bolt patterns are the same. Easy swap. I've done it 4 times.
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I bolted a 3.38 LSD into my 99M3 with no changes to input or output. I am pretty sure it came from a 97 M3.
I was under the impression all M3 used the same axles and thus required the same output shaft ears on the diff. Non-M3 may use different output shafts and require different ears. Not a big deal to change.
Input shafts are either 4 bolt or 6 bolt, but I don't know which models had which except that it is not dictated by whether or not the diff is from an M3. These can be changed also, but the correct torque must be used to preserve the crush of the crush washer (which is inside the diff and not easily replaced).Comment
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The cheapest "custom" route would be to buy the gearset for ~$600?? and then have a local diff pro install them into your existing housing/internals. This procedure costs about $200.Comment
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When I put a 3.38 in my 95 I had to change the input yoke, and output shafts. The output shafts were easy, they literally snap in and out. The input yoke was a bit more challenging.Comment
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The OP has a 99 M3. The 95s had a bunch of parts that differed from the 96-99.
All 96-99 seem to have the same axles. I am not as sure about the input shaft, but the 95s seem to have 6 bolt input shafts and 96-99 M3s seem to have round 4 bolt input shafts. However the year does not absolutely determine whether the input is 4 or 6 bolt -- some older E36 had square 4 bolt input shafts and a round 4 bolt driveshaft will bolt right up. Some people have also reported that round 4 bolt driveshafts will line up with 4 of the 6 bolts on 6 bolt inputs, but I have not seen this and also do not know whether the contrary is true -- 6 bolt driveshaft to 4 bolt input. Driveshafts can be changed also if one decides that route is easier and a cheap good shaft is available.
Since all 3.38s were from 96-99 M3s, chances are pretty good it will bolt in without mods. Using early diffs in late cars or vice versa may require some swapping of parts. Here is a DIY for much of the work:
http://www.bimmerdiy.com/diy/e36diffswap/Comment
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