M42club.com - Home of the BMW E30/E36 318i/iS
DISCUSSION => Engine + Driveline => Topic started by: wadhip on June 09, 2008, 06:53:32 AM
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Is that the differential can fitted on my E30 318is ?? :)
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Yes but you will be slower.
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Why would he be slower? The ratio is the same (assuming he has the stock diff now).
The extra weight from the slightly larger diff wouldn't be enough to be noticable.
And do you mean slower acceleration or slower top speed?
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Internal friction and another 35lb on you rear axle. Not worth it to me.
Page 5
http://www.metricmechanic.com/pdfs/metric-mechanic-differential-booklet.pdf
Look for a 3.91 or 3.64 small case LSD instead.
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I've removed too many noisey used-up small case diffs to worry about the extra weight and internal friction of a medium case unit.
Plus I'm unconvinced it's as much as 35lbs lighter. Have you ever set the two next to each other?
When I did the weight difference seemed negligible, even the size difference didn't seem like much at all.
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To each his own. The numbers quoted by MM are accurate. I've weighed 3 differentials so far, 2 small case, one medium case. LSD also weighs an extra 5lb over open diff but thats less to the point. My small case 3.64 came out of a 1984 318i with 220k miles and I abuse it on a daily basis. No noise, no problems. If you want to give up another 3% in drive train loss at the wheels and add 1% weight to the car its a worthwhile swap for some people for the extra peace of mind. Personally I'll just swap another differential when I kill this one. 4.1 and 3.73 medium case LSDs are dime a dozen in the local JYs. The hard part is finding small case LSDs. If you are breaking small case differentials with a 1.8 liter engine, you need to re examine your driving style. Also the differential's maximum torque rating increases as the numeric ratio goes up. A 3.64 is stronger than a 4.1.
Not my picture but it gives you an idea of the size. Theres an easy 35lb hiding between them.
(http://farm4.static.flickr.com/3188/2564792603_3672e8243e_o.jpg)
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no kidding.
well huh. Just read the MM link, + trust your experience. Never would have guessed it was that much.
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Why would he be slower? The ratio is the same (assuming he has the stock diff now).
The extra weight from the slightly larger diff wouldn't be enough to be noticable.
And do you mean slower acceleration or slower top speed?
slower in the turns, it takes power to fight against the LSD action in a corner....you will notice a difference in the M42, but in low traction conditions the power lost is well made up for in the better acceleration out of the corners.
....not to mention 35lbs in the "ass" of the E30 M42 does give it better balance, sure your adding weight, but its in the right place.
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wtf is tj smoking. 4.10 is the stock gearing. LSD is better handling (more so when sliding) and putting more power to the ground. stop smoking lsd and get a lsd.
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(http://www.alteredstatez.com/images/Smoke%20Crack.jpg)
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Do it!!! I put a medium case 4.10lsd in my e30 m42 and yes you can feel the extra weight but like stated above it is in the right place. All the changes i experienced where for the good handleing was improved dramatically and the extra weight helps keep that happy e30 rearend in place.
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Well, you could just take out the spare tire to make up for the added weight(unless you have already done that:rolleyes:).
Another added benefit to the medium case M3 diff, is that you can add on the finned diff cover from the M coupe for added cooling on track days and because it looks really cool. M coupe finned diff cover is less than $200 with mounting hardware from the dealer from what I have gathered. part # 33 11 2 282 482 I think
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tjts1 please stop talking and filling up this thread with ridiculous reasons not to use a med case. You may be trying to make yourself sound smart, but your only hurting yourself.
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I'd say it's worth it just for the extra piece of mind in having a bigger case. Harder to break especially with an m42. And like everyone said, its in exactly the right area, low and in the back. Take out your AC if you want weight reduction, it doesn't help with drivetrain strength, atleast the diff is going to hold up under more pressure.
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In our 3 318is's I have changed 3 small case open diffs to medium case 4:10 LSDs. The weight difference is 20 pounds, 65 to 85. 20 pounds is 3- gallons of fuel, not enough to worry about unless its a race car. Still have 2 more to do in some 318i's.
David Beagle
E30s - M3, 318is, 318i, 325 race car
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tjts1 please stop talking and filling up this thread with ridiculous reasons not to use a med case. You may be trying to make yourself sound smart, but your only hurting yourself.
Well excuse me if I disagree with your dogma. All of a sudden adding weight is the greatest thing since sliced bread and the medium case 4.1 LSD out of an M3 is sooo much better than the medium case 4.1 LSD out of every run of the mill 89+ 325is slushomatic. You can pick up a 3.73 or a 4.1 medium case LSD in the Hayward JY for $75 right now. But I dont know what im talking about so nevermind.
There is nothing special about one of these heavy lumps and it certainly won't make a 318 faster or better handling. I'm sure metric mechanics advocates going to a small case diff because they have no idea what they're talking about either. Just keep piling on the pounds and rotational mass. Eventually your car is bound to get faster.
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anyone who says open diff is better than LSD is retarded. its not rocket science. everyone has an opinion and yours always seems to be negative. gg kthx tjt is a hater.
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anyone who says open diff is better than LSD is retarded. its not rocket science. everyone has an opinion and yours always seems to be negative. gg kthx tjt is a hater.
Listen bud disagreeing is one thing. You're just pulling shit out of your ass. When did anyone say an open diff is better than LSD? I have an open 3.64 in my car because that's what I was able to find at the time. I would switch to an LSD in a heart beat if I find one in a small case with the right ratio. In the mean time I suggest you lay off the bench racing crack pipe and try turning a wrench for a change.
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Well excuse me if I disagree with your dogma. All of a sudden adding weight is the greatest thing since sliced bread and the medium case 4.1 LSD out of an M3 is sooo much better than the medium case 4.1 LSD out of every run of the mill 89+ 325is slushomatic. You can pick up a 3.73 or a 4.1 medium case LSD in the Hayward JY for $75 right now. But I dont know what im talking about so nevermind.
There is nothing special about one of these heavy lumps and it certainly won't make a 318 faster or better handling. I'm sure metric mechanics advocates going to a small case diff because they have no idea what they're talking about either. Just keep piling on the pounds and rotational mass. Eventually your car is bound to get faster.
The m3 diff and the 4.10 diff out of 325i's are the same thing. So because one over priced tuner says go with a small case means you need to argue over it? Yes the small diff is lighter, but it is also weak, if it was so great you would think that BMW would have installed it in the M3 from the factory. All this info coming from a guy that has a 3.64 open diff and no obvious experience with a med case LSD, Mr. "try turning a wrench for a change". Like I said earlier, you trying to sound smart is only hurting yourself. Besides, how easy it to find a small case LSD in the US? Obviously not.
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Listen bud disagreeing is one thing. You're just pulling shit out of your ass. When did anyone say an open diff is better than LSD? I have an open 3.64 in my car because that's what I was able to find at the time. I would switch to an LSD in a heart beat if I find one in a small case with the right ratio. In the mean time I suggest you lay off the bench racing crack pipe and try turning a wrench for a change.
Nah man i've seen you openly admit that you like you prefer open diffs over LSD and thats your problem so stop trying to make it mine. I don't like you because you are a hater. WTF you telling me to wrench? i wrench when i feel like wrenching. i dont need people like you telling me what i need to do over the internet. get a life tjt. maybe you should work on your car more and talk smack here less? Every thread you get involved in with me you never quit. look you admire me so much you put me in your signature keep runnin that junk arco 87 octane hope your compression drops..... why dont you do like everyone else and take pride in your car and not me
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rawr
cat fight!
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Whats the point in adding weight to your car by putting in a larger case diff than you need? My car has almost 300,000 on it with the original 4.10 small case lsd, and a little motor work. the diff is still working. a small case 4.10 can obviously handle more power then the m42 can make in its original form. For this reason, I do not see any need to put a larger case diff in a an m42 unless your doing some serious work to it.