[SpeedDemon]

How poorly does it actually affect gas mileage? I have the stock 17" sport wheels; I run 225/45/17's. I plan on possibly getting some 18" or 19" CSL replicas one of these days, but I'm fine for the time being with the stock wheels.

I feel like the gears are really tall coming from the M3, but maybe I'm just imagining things. What would it take to get an 328i geared like an E36 M3?

Also, wouldn't I actually only be doing about 3658RPM's at 80MPH vs. the stock 3100RPM's. That's an 18% increase, but it doesn't seem that ridiculous to be doing that at 80MPH. Is this bad for the motor?

 

[SD 328I]

For a daily driver you don't want anything really higher than 3.15 on your 5-speed. With the 3.15 ratio, you can achieve a speed of at least 60-mph without the need for a 2nd to 3rd gear shift.

 

[ASD123187]

How poorly does it actually affect gas mileage? I have the stock 17" sport wheels; I run 225/45/17's. I plan on possibly getting some 18" or 19" CSL replicas one of these days, but I'm fine for the time being with the stock wheels.

I feel like the gears are really tall coming from the M3, but maybe I'm just imagining things. What would it take to get an 328i geared like an E36 M3?

Also, wouldn't I actually only be doing about 3658RPM's at 80MPH vs. the stock 3100RPM's. That's an 18% increase, but it doesn't seem that ridiculous to be doing that at 80MPH. Is this bad for the motor?

I was looking into the 3.46 diff swap for my 328 also, but changed my mind due to the fact that a) high RPMs, worse gas mileage b) constant shifting c) loss of cruising ability and d) loss of really high end speed.

I was thinking about going 3.38, but they are hard to find and cost a bit more. Also, it isn't that much of a difference over the 3.38.

I recently read about someone installing a 3.23 diff in their car and am in the process of finding one. If that doesn't pan out, 3.15 here I come.

 

[KrzyBum420]

i'd like to go 3:15

 

[sycE46]

I lose probably 1-2 mpg by going to 3.46 diff. I can still get 27mpg on the freeway.. cruising probably 70ish.

 

[sycE46]

How poorly does it actually affect gas mileage? I have the stock 17" sport wheels; I run 225/45/17's. I plan on possibly getting some 18" or 19" CSL replicas one of these days, but I'm fine for the time being with the stock wheels.

I feel like the gears are really tall coming from the M3, but maybe I'm just imagining things. What would it take to get an 328i geared like an E36 M3?

Also, wouldn't I actually only be doing about 3658RPM's at 80MPH vs. the stock 3100RPM's. That's an 18% increase, but it doesn't seem that ridiculous to be doing that at 80MPH. Is this bad for the motor?

going to heavier wheels will probably kill your gas milage a little. My heavy breytons cause me to lose about 1mpg in city driving.

The slight increase in rpms shouldn't be bad for motor. it was really that bad... BMW wouldn't put 3.46 diffs on manual tranny 323/325CICs.

 

[sycE46]

Can anyone with a 3.46 in a 328i or 330i actually tell me that they regret doing it?

changing to a 3.46 in a 328/330 is no different then putting it into a 323/325. The transmission gear ratios are nearly identical. That said... my 3.46 in my 323 feels rather short. You'd need shark software to increase your red-line to offset the effect of the shorter gearing.

I'm happy with the 3.46 gearing. You do end up doing 1 extra shift in normal city driving, but I'm used to it. Some pple have regretted going to a 3.46 and switched back. its all personal preference.

 

[Alex323Ci]

How poorly does it actually affect gas mileage? I have the stock 17" sport wheels; I run 225/45/17's. I plan on possibly getting some 18" or 19" CSL replicas one of these days, but I'm fine for the time being with the stock wheels.

I feel like the gears are really tall coming from the M3, but maybe I'm just imagining things. What would it take to get an 328i geared like an E36 M3?

Well the E36 M3 had the 3.23 or 3.15 ratio diff if I remember correctly. But the tranny was different so it's not quite the same comparison.

The reason I asked about your wheels is that the larger tire combos have a greater 'moment of inertia', meaning it takes longer to get them moving from a dead stop. So if you had 18"/19" wheels 1st wouldn't be felt as bad. It's hard to explain. So something like the 3.38 or 3.46 wouldn't be so bad on those heavier combos. If you had 16s then you'd be breaking traction and spooling those wheels up fast.
If gas milage is a great concern, don't mod and stick with your current ratio.

 

[Transporter99]

For a daily driver you don't want anything really higher than 3.15 on your 5-speed. With the 3.15 ratio, you can achieve a speed of at least 60-mph without the need for a 2nd to 3rd gear shift.

I agree with this. I'm no longer convinced a 3.46 is for me given my tendancy to drive long distances at times, visiting my family in Oh. I sense a 3.46 will be way to un-nerving and a 3.15 will be a better comp.

What can a 3.15 be had for, and where's a good place to look for one (sorry, didn't mean to hijack the thread).

 

[SpeedDemon]

It's ok, I'm curious as well :dunno:

 

[SpeedDemon]

I think that I'm still going to go with a 3.46. If BMW did it in their 323/325 manual cars then that's good enough for me. I don't really do any long distance driving either in my car and if I do I'd just take my girlfriends stock 2002 325i. I like a sporty feel and don't think that the extra shift would annoy me that much. The car will never see any track days, but I would like an extra kick for driving around town.

 

[jmsanders78]

I have a 3.46 in my 328i, and I love it. I knew I would give up some gas mileage, but it's not any worse than an M car (I get a little over 28 mpg on long trips, at least I did over Christmas). I typically cruise around 80 on the interstate, and the revs don't bother me as much as I thought they might. I'd go for it!

 

[SpeedDemon]

I have a 3.46 in my 328i, and I love it. I knew I would give up some gas mileage, but it's not any worse than an M car (I get a little over 28 mpg on long trips, at least I did over Christmas). I typically cruise around 80 on the interstate, and the revs don't bother me as much as I thought they might. I'd go for it!

Thanks for the advice, I'm going to do it! You been enjoying the power increase?

 

[Alex323Ci]

I think that I'm still going to go with a 3.46. If BMW did it in their 323/325 manual cars then that's good enough for me. I like a sporty feel and don't think that the extra shift would annoy me that much. The car will never see any track days, but I would like an extra kick for driving around town.

Not trying to sway you either way or change your mind. But since you are new, you might not know that BMW put the 3.46 in the automatic 323/325s. But true the manual and automatic 323/325 convertibles did get the 3.46. You made it sound like you thought all E46 323/325 manuals had the 3.46.

 

[jmsanders78]

Thanks for the advice, I'm going to do it! You been enjoying the power increase?

For sure! I did the swap sometime last summer. I hate to say it, but like many things you get used to it somewhat quickly.

 

[dankbmw]

I think that I'm still going to go with a 3.46. If BMW did it in their 323/325 manual cars then that's good enough for me. I don't really do any long distance driving either in my car and if I do I'd just take my girlfriends stock 2002 325i. I like a sporty feel and don't think that the extra shift would annoy me that much. The car will never see any track days, but I would like an extra kick for driving around town.

BMW did NOT put a 3.46 in their 323/325 manual cars, they recieved a 3.15...3.46 came in STEPTRONIC only!!!

Gearing Ratio for e46's:
323/325 manual- 3.15
328/330 manual- 2.93
323/325 STEP- 3.46
328/330 STEP- 3.38??? (dont know this one)
330 zhp manual - 3.07
330 zhp- 3.38?????
m3- 3.46 LSD

other diff's for the e46: 4.10, 3.23 from an e36 m3(change flanges), 3.64

 

[Mteknic330ci]

OMG do it!!!!!!!!

 

[slow323ci]

BMW did NOT put a 3.46 in their 323/325 manual cars, they recieved a 3.15...3.46 came in STEPTRONIC only!!!

Umm, as far as I can tell 323 and 325 Tourings and Convertibles ALL came with 3.46's. Step or manual.

 

[Alex323Ci]

BMW did NOT put a 3.46 in their 323/325 manual cars, they recieved a 3.15...3.46 came in STEPTRONIC only!!!

Gearing Ratio for e46's:
323/325 manual- 3.15
328/330 manual- 2.93
323/325 STEP- 3.46
328/330 STEP- 3.38??? (dont know this one)
330 zhp manual - 3.07
330 zhp- 3.38?????
m3- 3.46 LSD

other diff's for the e46: 4.10, 3.23 from an e36 m3(change flanges), 3.64

As far as I can tell. I think you might want to change a few of these. No biggie, let me know if I'm off.
The 323 manual got the 3.07
323/325/328 automatics got the 3.46
323/325 Cic(convertible) manual/automatic 3.46
M3 3.64 LSD

 

[slow323ci]

As far as I can tell. I think you might want to change a few of these. No biggie, let me know if I'm off.
The 323 manual got the 3.07
323/325/328 automatics got the 3.46
323/325 Cic(convertible) manual/automatic 3.46
M3 3.64 LSD

Correct.

Also, dankbmw's post said the diffs form an E36 M3 fit the E46, that is absolutely not correct.

So basically they got more wrong than right! Aye carumba...