BMW 3.46 Ratio differential review. E46, E39, E90
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TechTranscript
00:00Okay, so let's talk about this new differential that I've put in.
00:17So again, this is a 3.46 ratio on my 03 E46 325i, which originally had a 3.15 ratio rear
00:27differential.
00:29So that is, seems like a marginal increase, but I can tell you that I can feel a difference.
00:35Happy to report, because it was a lot of work, and it would be very unfortunate if I couldn't
00:42feel a difference.
00:44The first thing you're going to notice is that first and second gear run out a lot quicker.
00:49So first gear feels, I mean, it's not useless.
00:51I've heard some people say that first gear is useless.
00:54It's not useless.
00:55Third gear, though, wee, is fun.
00:58Sorry.
00:59Had to downshift for fun.
01:02So first gear runs out very quickly, but there is a very noticeable amount more torque going
01:07to the wheels, and there is a noticeable amount more torque going to the wheels in every gear.
01:12Third gear is where you'd think that you would feel it quite substantially, but you don't
01:18actually feel it as substantially as you think you would low down.
01:22I don't know why, what this has to do with, but you notice it more in first and second
01:26gear.
01:27You notice it more in fourth and fifth, which makes no sense because it's the same amount
01:30of difference in each gear.
01:32Someone wants to do the math for that.
01:34I have no idea why that feels different, but you can still notice a difference in third
01:37gear.
01:39So what I do like about this differential so far is that I'm in fourth gear going up
01:46a hill, and I put my foot down, and I can feel torque.
01:49I feel a wave of torque that I did not feel before.
01:53In fifth gear, you now have the ability to pass without downshifting if you're at highway
02:01speeds.
02:02Because I've gained about 500 RPM cruising, you're closer to the torque band of the car
02:09where the car has peak torque.
02:11So when you put your foot down in fifth gear on the highway, it actually does pull a lot
02:14more noticeably.
02:17I like the shorter ratios.
02:19It kind of reminds me of like I'm in a rally cross car or something, right?
02:22So you shift really quick, and it's kind of fun.
02:26I don't mind that at all, and I really do like the amount of extra kick.
02:30So the question is, is it worth it?
02:33Again, I'm going to say if you do this yourself and you don't mind getting your hands dirty
02:40and your shoulders sore, then it is worth it.
02:44For like the price that I paid, 200 bucks, this is a mod that I would do because you
02:48will notice a difference.
02:49It feels like a substantial amount more torque going to the wheels.
02:52But if the bill for this was going to run you closer to $500, I don't think that I would
02:58say, yeah, go do it because it's not that much of a difference.
03:02This was one of the biggest talked about mods when I started reading about E46 mods, and
03:07I was expecting a little bit more, if I'm honest.
03:09I was expecting it to be a lot more substantial.
03:12Everyone has said that, oh, you're going to lose so much in the top end.
03:16Cruising on the highway is worse.
03:17Your fuel mileage is going to be worse.
03:19I haven't noticed any fuel mileage difference.
03:20I've been driving it for a day.
03:22I'm sure it'll go down maybe a little bit, but I can't imagine it being a massive difference.
03:26Now, I'll show you what it looks like now cruising on the highway at highway speed so
03:32you can see where my RPMs are at because this is the big question everybody has.
03:37So that's what this looks like.
03:47So you'll see that it's not actually that different.
04:04I don't really find this to be a deal breaker at all, to be honest.
04:10Yeah, your fuel mileage might go down a little bit on the highway, but the trade-off is worth
04:15it.
04:16All right.
04:17Third gear.
04:18Yeah.
04:19All right.
04:20Straight away here.
04:21Whee!
04:22Fourth gear.
04:23Yeah, it pulls more than before without a question.
04:52Not a huge amount, but it's definitely more.
04:54I'd like to say that the DIY was fun.
04:59It wasn't.
05:01Working on an older BMW, I swear, something goes wrong every single time, and I showed
05:06you a little bit about it, but one of my CV bolts stripped because it was really, really
05:14stuck.
05:15So I had to Dremel it off, and it was just a whole thing, and I don't even want to think
05:20about it.
05:21It's a job on this car that didn't have some issue like that happen, but that's just kind
05:26of what I got myself into, I guess, so I'm not going to complain that much.
05:29But overall, I think that if you're really into modding, this is kind of a cool way of
05:35doing it.
05:36One more thing that I want to describe about how the torque feels going to the ground.
05:42It does not feel...
05:43It's hard to explain.
05:44It does not feel like you have gained more torque in the engine.
05:50It feels like it's noticeable that you've gained the torque by shortening the gears.
05:55So I can tell that my gears run out faster as I accelerate, and you have to shift sooner
06:00to get up to the same speed, and it's noticeable.
06:03It does still accelerate quicker overall, the car does, but you notice that the reason
06:07for that is because of the shorter gearing now.
06:10So that's what I mean.
06:13It's not like it feels like a power mod to the engine.
06:16It doesn't.
06:17It feels like a gearing change, okay?
06:20So don't expect something to do with, like, people call it the poor man's supercharger.
06:25No, not really, to be honest.
06:26First of all, it doesn't make anywhere near the power of a supercharger.
06:29And second of all, that is an engine modification.
06:32You're increasing crank horsepower.
06:36This is increasing wheel torque, and therefore horsepower.
06:40So you can tell that it's from shorter gearing and not from an engine mod.
06:44If you're okay with that, then do it.
06:46The shorter gears, you notice it every single time.
06:49I've been driving this car for, like, a year, and so I'm used to how the ratios feel, and
06:53now when I put my foot down in third or fourth, I watch the revs climb quicker than I remember
06:58them climbing before, partly because I'm probably accelerating quicker because it's fun.
07:02But that is definitely something to take into account, is that it's noticeable.
07:07Overall, I think that this is a worthwhile mod to do to an E46 BMW, but I would couple
07:14this with all the other mods that you're supposed to do, right?
07:17Because just this alone might just end up being annoying for you, to be honest, if you
07:22just lose a little bit of fuel mileage, a little bit of highway cruising, and the gears
07:25are shorter.
07:26Because now, first gear, you kind of have to shift almost definitely, unless you want
07:30to run it up to, like, 5,000 in the middle of a corner, pulling away from a stoplight.
07:35Okay?
07:36I kind of did that already, but now you really have to do that.
07:39So that's about all I have to say about this mod.
07:42I'm happy I did it.
07:43I'm excited to test it out on the track.
07:45Now, the reason I did this is because there's a section on the track that I always drive
07:48on where I get to the top end of my second gear, and I bounce off the rev limiter, and
07:54if I shift up into third, I just didn't have enough torque going to third to really pull
07:59me out of the corner.
08:00So my hope is that I'm going to be able to shift up as I'm exiting that corner, or just
08:05after I exit that corner, and then use the more torque available in third gear to really
08:09pull me out of the corner.
08:10So I'm excited to see what that works.
08:12I'll do a track review of this differential hopefully soon, because the shorter ratios
08:16are going to make it different how I'm getting my shift points and stuff, right?
08:18So I'm going to have to relearn that track driving this car.
08:22So like and subscribe again for more reviews like this coming.
08:26Hopefully in the future, very soon, I'm going to be doing some KONI yellow shocks.
08:30That's my plan.
08:31Lowering springs.
08:32I'll try and give you guys a DIY for that.
08:35I think I'm going to be doing a software tune, a custom software tune for this car, which
08:39will do things like raise the rev limiter, change the top speed, and just change the
08:46overall way that it deals with the intake and the exhaust modifications they've done
08:50to give me more power.
08:51So I'm excited to try that out and review that.
08:54I'll be hopefully doing another tire review coming up soon.
08:57Lots of stuff.
08:58Stay tuned.
08:59I hope to see you guys again.
09:00Leave your comments.
09:02I'd love to hear what you have to say about this.
09:04If you've done a different ratio differential, some people say the 3.38 is a little bit less
09:07intense.
09:09I don't find this one very intense overall.
09:11That's my final word on that.
09:12So I will talk to you guys next time.
09:15Thanks for watching.