M42club.com - Home of the BMW E30/E36 318i/iS
DISCUSSION => Engine + Driveline => Topic started by: FL318is on September 24, 2007, 02:28:25 PM
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Did a search but no luck.
Does anyone know what LSD came stock in the 318is? Or did it vary?
Also, which LSD is preferred, the 3.73 or the 4.10 and why?
Thanks.
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LSD was an option, 4.10 on the 318iS
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Thank you sir. Would you go with the 3.73 or the 4.10?
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i wouldnt change the 4.10 of course the 3.73 or 3.91 will give u better gas mileage but IMO i'd rather have flywheel, chip, and exhaust before changing the gear....thats just me!!!
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Here you can see what kind of diff that came stock:
http://wp1016621.wp027.webpack.hosteurope.de/fotost/f00023/f00023.htm
If you drive a lot of highways the 4.10 might be a bit high. But I think it is beautiful on small roads.
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Did a search but no luck.
Does anyone know what LSD came stock in the 318is? Or did it vary?
Also, which LSD is preferred, the 3.73 or the 4.10 and why?
Thanks.
Don't eat the brown acid! Oh God, I'm having a flashback!
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Don't eat the brown acid! Oh God, I'm having a flashback!
All I can say is WTF!
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Here you can see what kind of diff that came stock:
http://wp1016621.wp027.webpack.hosteurope.de/fotost/f00023/f00023.htm
If you drive a lot of highways the 4.10 might be a bit high. But I think it is beautiful on small roads.
what if you do both(freeway and country)? have you driven a 3.73lsd on a twisty? just curious because i do about 40% freeway driving and i like to cruise at 75mph and the 4.10 is very annoying, but i dont want to sacrifice any power.
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You will lose power. It is inevitable. Some seem to like the 3.91....I guess it can be a good compromise.
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You will lose power. It is inevitable. Some seem to like the 3.91....I guess it can be a good compromise.
Sorry guys,
I know this is pedantic but you won't loose power from changing a diff. What you will loose is the acceleration force (g for want of a better word). The engine still produces the same power it's just that youhave changed your gearing.
As stated above if you still want the peaky pirky acceleration stay with the 4.10. If you want better milage and do not mind accelerating a bit more leisurely then move to the 3.93 or 3.73.
Be aware that if you go to low (say 2.95 as example) your car will just feel like a slug and you will forever be changing the gears to overtake on the highway. YOu will also loose the fun factor of the M42 and is.
Just my 2cents.
Cristian
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LOL
No you won't lose power or torque. What you will gain is the ability to use 2nd gear all the way up to 60mph. Try doing an autoX with and without the 2-3 shift. In most real world situations where you actually care about gearing, you are using 1st, 2nd and maybe 3rd if you're brave. With the 4.1 you have to shift to 3rd no later than 54mph. So instead of constantly bouncing off the rev limiter or taking your eyes off the road to catch the shift point its easier and quicker in most real world driving situations (35-60mph) to use 3rd gear instead constantly shifting between the two gears at every corner. Now imagine your favorite windy mountain road or an autoX. with a 3.73 (or in my case 3.64) you put it in 2nd gear and forget about it. The only time you need to go to third is when you accelerate past 60mph at which point you are probably on a straight enough bit of road that you can afford to take you hand off the wheel.
Put another way
3rd gear with 4.10 has a combined gear ratio of 5.41
2nd gear with 3.73 has a combined gear ratio of 7.53
There is no doubt in my mind that if you were driving on a track lap after lap and you had your shift points committed to memory, the 4.1 would do faster laps. For the rest of us that live in the real world and have to contend with oncoming traffic, the odd bicycle or deer on our favorite mountain road, 3.73 or 3.64 is ideal.
So with a 3.73 you are giving up 9% of your peak torque in any given gear in exchange 3 more mph in 1st and 7 more mph in 2nd. Did I mention the M42/E30 is quicker to 60 with a 3.73 instead of 4.1? Its that damn 2-3 shift. 80mph at 3300rpm is the icing on the cake.
One of my favorite roads.
http://maps.google.com/maps?f=d&hl=en&geocode=&saddr=Fairfax,+CA&daddr=Bolinas,+CA&sll=37.0625,-95.677068&sspn=33.160552,59.765625&ie=UTF8&ll=37.959493,-122.644329&spn=0.064425,0.11673&z=13&om=1
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Thanks guys! Alotta good info.
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Don't eat the brown acid! Oh God, I'm having a flashback!
I think I am having one now!
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LOL
No you won't lose power or torque. What you will gain is the ability to use 2nd gear all the way up to 60mph. Try doing an autoX with and without the 2-3 shift. In most real world situations where you actually care about gearing, you are using 1st, 2nd and maybe 3rd if you're brave. With the 4.1 you have to shift to 3rd no later than 54mph. So instead of constantly bouncing off the rev limiter or taking your eyes off the road to catch the shift point its easier and quicker in most real world driving situations (35-60mph) to use 3rd gear instead constantly shifting between the two gears at every corner. Now imagine your favorite windy mountain road or an autoX. with a 3.73 (or in my case 3.64) you put it in 2nd gear and forget about it. The only time you need to go to third is when you accelerate past 60mph at which point you are probably on a straight enough bit of road that you can afford to take you hand off the wheel.
Put another way
3rd gear with 4.10 has a combined gear ratio of 5.41
2nd gear with 3.73 has a combined gear ratio of 7.53
There is no doubt in my mind that if you were driving on a track lap after lap and you had your shift points committed to memory, the 4.1 would do faster laps. For the rest of us that live in the real world and have to contend with oncoming traffic, the odd bicycle or deer on our favorite mountain road, 3.73 or 3.64 is ideal.
So with a 3.73 you are giving up 9% of your peak torque in any given gear in exchange 3 more mph in 1st and 7 more mph in 2nd. Did I mention the M42/E30 is quicker to 60 with a 3.73 instead of 4.1? Its that damn 2-3 shift. 80mph at 3300rpm is the icing on the cake.
One of my favorite roads.
http://maps.google.com/maps?f=d&hl=en&geocode=&saddr=Fairfax,+CA&daddr=Bolinas,+CA&sll=37.0625,-95.677068&sspn=33.160552,59.765625&ie=UTF8&ll=37.959493,-122.644329&spn=0.064425,0.11673&z=13&om=1
Well said Justin. It's just about what YOU as a driver want. I prefer the 4.10 ratio because I personally enjoy peaky 4-cyl. engines with short gearing. I love shifting and I don't mind it one bit.
If I wanted mileage, I would've bought a diesel or a SuperETA.
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I was puting it simply...I know the engine output doesnt change. By changing gearing your changing the ratio that affects the torque going to the wheels. It also depends on the gearing of the different gears in the transmission. I track the car on road circuits...I don't care about shifting but I care about going into the power band faster that is why I'd rather have a higher ratio. Nice explanation though.
By the way, theoreticly, you do lose power because the ratio multiplies the torque.
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Hey Justin,
You make a compelling argument. If I could find a 3.73 LSD I might just change it, but at the moment the gearing is just great for me around town out here in Oz.
My highway driving would be greatly assisted by the better ratio though.
Thanks for you words of enlightenment. I don't get to do enough auto X (call them motokhana out here though).
Cristian
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I think the trick is to keep both diffs around and swap them out quickly . I still have my 4.1 lsd in the back yard and I'll probably put it back in when the rainy/ski season rolls around. I was thinking about drilling 4 holes in the bottom of the trunk to make it easier for me to swap the diff. As much as i like my 3.64, its an open diff and i miss the LSD.
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LSD was an option, 4.10 on the 318iS
So I know I have a 4.10 diff because that's what the tag on the diff says. How can I tell if it is an LSD? Are you saying that the 4.10 diff is the LSD option?
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If the tag has S4.10 stamped on it, it is an LSD. It came with an open 4.10 diff as standard.
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Should be a S on the plate, or on the house if it is a LSD (Limited Slip Diffrential)
LSD was an option on E30 318is, and 4.10 was standard.
If the diff is on the car you can lift it up so one wheel is in the air, put it in free and try to turn the weel.
If you can turn it lightly it is an open diff.
If you can`t turn it, or it is hard to turn.. congrat.. you got a LSD!!
You can also put a torque wrench(or what it is called) on the wheel bolt, and it should make 50nm before turning.
It is several people who think they have a 25 % LSD because they get 2 stripes in the asfalt, but you can get that with a open diff as well.
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My 4.10 LSD started making all kinds of noise recently so i pulled it for a rebuild and put in a S3.73 that I had picked up from the junkyard for $35 with intentions of selling it on ebay. I have put 5 tanks of gas through the car since the swap and gas mileage has stayed EXACTLY THE SAME. I commute 100 miles round trip 3 days a week for school and I am simply amazed.
I can't really tell the difference in acceleration in 1st or 2nd but in 3rd on it feels a little sluggish. I even have to downshift to 4th to get up a grade on the freeway that was no problem in 5th with the 4.10
Moral of the story: stick with your 4.10
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This is an LSD.
(http://farm1.static.flickr.com/201/516801588_4472653c12_o.jpg)
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Link to a pretty basic gear program for fixed ratio transmissions:
http://members.dodo.com.au/~wawawa/ (http://members.dodo.com.au/%7Ewawawa/)
You can change the differential ratio and see MPH/RPM change. The problem with swapping differentials is that the old one could be perfect for the next track or AutoX layout.