3.73 LSD on 318is and my Sepang track outing

[fabianyee]

Put in a 3.73 LSD on Thursday and went to the Sepang F1 Circuit for the open session.

Tested top speed on the way to Sepang and noticed that top speed is lower at 200kmh@~5000rpm.
with the prev 4.10 open diff, top speed was 210kmh@6000rpm

And on the track, i only managed to hit ~150kmh on the start/finish straight before hitting the brakes to take the first corner.
The last time I drove there with the 4.10 open, I was able to hit ~170kmh.....

the tall gearing really takes a toll on the speed, however, at the corners I was able to hold on to the gears longer and the LSD gives a lot of traction (and confidence). I'm not afraid of oversteering now as I know I can catch it back more easily.

As for the car's setup, the front is a little on the soft side. I think it's about time to change absorbers or get thicker swaybars.
It was understeering at most of the corners, maybe my entry speed is a little too fast.

Managed to keep up with some modded japanese cars who came for the session. the Civic EF (with VTEC Engine conversion) were fast on the straight but then I was able to catch them at the corners.

on the side note: saw Brembo caliper on the track!!!! Must be from one of the Porsche GT3 or the Mitsubishi EVOs.... Don't know what's wrong but a Brembo caliper coming loose is worth mentioning...

[Stu]

Didn't notice too much difference between the 4.1 and 3.73 in my 318is. Little less responsive, and it held gears longer, but it didn't affect my cars performance against friends 318's (4.1 equipped).

Maybe you were braking early. :P

[MattM20]

i love the sepang circuit, i wish i could take my car on it

[fabianyee]

Didn't notice too much difference between the 4.1 and 3.73 in my 318is. Little less responsive, and it held gears longer, but it didn't affect my cars performance against friends 318's (4.1 equipped).

Maybe you were braking early. :P

braking point about the same between the 50m marker n the 100m marker... (te same when I was using the 4.10 open diff)
Can brake later but didn't want to torture the brakes and tires too much...

Also noticed top speed on flat road (on the expressway going to the circuit) is only at 200kmh.
I pulled all the way in 4th to 6500rpm, it was at 200kmh, then when I upshifted to 5th, it stayed at 200kmh... (@5000rpm) WTF...

With the 4.10 open diff,I can pull all the way to 180kmh in 4th, and then upshift and the engine will still pull to 210kmh(@6000rpm). But then the last 5 -10kmh will take a little longer but it has no problem going there. And with slight down hill, I managed to get up to 230kmh (@6300 rpm) and when got back on flat road again, it can maintain 220 kmh...

Now with the 3.73, theorectically I can gan higher top speed, but then not enuf torque after 5000rpm to push the car faster...

BTW, mine is an E36 M42 motor not the E30 M42 motor....

[pogiboy9]

Since you guys are talking about LSDs and swapping them, Any suggestions for my '84 325e.

Someone told me to wake up my car put the 3.73 in there... but someone also said it'd kill my gas mileage of course i know that. but how bad.... and any other diffs to put in there from what model etc

[fabianyee]

Since you guys are talking about LSDs and swapping them, Any suggestions for my '84 325e.

Someone told me to wake up my car put the 3.73 in there... but someone also said it'd kill my gas mileage of course i know that. but how bad.... and any other diffs to put in there from what model etc

What's your diff ratio now?
you can always go for ratios btween 3.73 and ur current ratio..

There's 3.64, 3.46, 3.15.. These are the ones I know exists...

I have come accross 3 3.15 LSD here but it'll kill my 318is' performance, for sure...

[pogiboy9]

2.79 or 2.91 How bad would my gas mileage be if i put 3.73, i'm really going to go for 3.46 since its between the 3.25 and 3.73, which sounds like its good performance + decent gas mileage if not i'm gonna go for 3.25 someone told me he got 25-28 mpg high and surface depending on driver :)

[decay]

dude, find yourself an m3 diff yesterday (or better yet, go shorter than that).

my m20b25 felt like a dog until i shortened the final drive, i can't imagine what an m42 must feel like with a 3.73...

[pogiboy9]

dude, find yourself an m3 diff yesterday (or better yet, go shorter than that).

my m20b25 felt like a dog until i shortened the final drive, i can't imagine what an m42 must feel like with a 3.73...

"find yourself and m3 diff yesterday"

Explain yourself....

3.93 LSD wow hows ur gas mileage, btw this car is still my everyday driver

[decay]

"find yourself and m3 diff yesterday"

Explain yourself....

3.93 LSD wow hows ur gas mileage, btw this car is still my everyday driver

ok- "yesterday" was for dramatic effect, read that as "as soon as possible".

but seeing as i mentioned m42 in my post, it should have been fairly obvious i was addressing the original poster and not talking about your eta-powered car...

i didn't notice a decrease in gas mileage going from 3.73 to 3.91- probably because i don't need to use my right foot as much in order to maintain what i consider "acceptable" acceleration.

and you'll notice my e30 is the only car in my sig at the moment :)

[fabianyee]

dude, find yourself an m3 diff yesterday (or better yet, go shorter than that).

my m20b25 felt like a dog until i shortened the final drive, i can't imagine what an m42 must feel like with a 3.73...

Like i mentioned, performance is acceptable on 1st, 2nd and 3rd but on 4th and 5th. Not enuf grunt from the M42....

Finding a LSD here is difficult, let alone one with desired ratio...

I have come accross 3 units of 3.15 LSD but hardly any 4.10 LSD...

Might be sufferring a bit with the 3.73 on straight line speed but am having fun at the corners..

Can't have best of everything ALL THE TIME..

Going for a drift event and time attack tomorrow organised by Proton Motorsport in Malaysia. With LSD, will be good, drifting without LSD is really suicidal...
Will be having fun there... :)

[e9nine]

Going for a drift event and time attack tomorrow organised by Proton Motorsport in Malaysia. With LSD, will be good, drifting without LSD is really suicidal...
Will be having fun there... :)

..if possible some pics and/or video footage will be greatly appreciated ;)

[Spoon e30]

i just put a 3.91 LSD in my 318is and i love it. It seems to be a very good balance between outright performance and good gas milage. The motor still has enough grunt to pull fairly hard with it as well. I had a 4.10 open before, btw.

[e9nine]

Spoon, how much did you pay for your 3.91 and what car did it come out of?

TIA

[DrMcDave]

3.91 came in the ix, i have one on my parts car...its kind of high miles but the rear end of ix's don't take much abuse.