Bimmer-Bob's 128i Belated Build Thread

[E91WAG3N]

Originally Posted by Bimmer-Bob

So this happened...

Oh hello fins!

[Suprgnat]

Originally Posted by Bimmer-Bob

Nope, it's a Performance Gearing clutch-type LSD. The cover is a BMW OE part for an E60.

Is it the one for the Type 188k diff, and if so any mods required?

[Fume]

Originally Posted by Bimmer-Bob

Nope, it's a Performance Gearing clutch-type LSD. The cover is a BMW OE part for an E60.

Very nice! So many questions.

What made you choose a clutch-type LSD over some sort of torsen/helical based LSD?

The fins are part of the cover? Looks nice but how's the ground clearance to it?

Most importantly, is the handling characteristic noticeably improved (both in normal driving and in more spirited driving)?

You're doing all the mods that I want to eventually do to my car but either don't have the money to spend on car parts at the moment or am a little scared to completely void the 2 extra years of warranty I have on my car. Not gonna lie, I'm pretty envious.

Edit: Oh another question: Did you get the coding stuff done to disable the e-diff that the X1 owner mentioned in the track/autocross subforum?

[dailowill]

Originally Posted by Bimmer-Bob

Nope, it's a Performance Gearing clutch-type LSD. The cover is a BMW OE part for an E60.

Nice! What final drive ratio did you decide to go with?

[squidge]

Originally Posted by dailowill

Nice! What final drive ratio did you decide to go with?

Also curious.

Did you order this through Turner?

[Bimmer-Bob]

Originally Posted by ubersteuer

Oh hello fins!

Super sexy, aren't they?

You know, I'm a function-over-form guy, but any chance to get a little form with your function seems like a win-win. I found out that the E60 finned cover fit our diffs a while ago, and I decided I would upgrade as long as I was doing an LSD anyway. It's such a pricey mod, that it's nice to have a little bling to show for it, even if I'm the only one who will ever notice.

Another plus (in the function column) is the finned diff has drain and fill plugs incorporated, which will make the break-in and annual gear oil changes a lot simpler.

Originally Posted by Suprgnat

Is it the one for the Type 188k diff, and if so any mods required?

It's actually for the Typ 188L diff. It required a 15mm spacer and a longer bolt to work, but otherwise it's the same bolt pattern and a direct fit.

Originally Posted by Fume

Very nice! So many questions.

What made you choose a clutch-type LSD over some sort of torsen/helical based LSD?

A helical diff is good from a set-it-and-forget perspective, but from everything I've read it's not really the best choice from a performance standpoint. Primarily, if you lift a drive wheel (as might occur with aggressive cornering) with a helical diff, it basically reverts to an open diff. Plus, with a clutch-type diff from a custom builder, you can have things built to your specifications. In my case, I just went with the builder's (Jim Blanton at Performance Gearing, by the way) recommendations. Jim's pretty well regarded in the BMW world, has built diffs going back at least 15 years, is on his 6th generation "version," and has been featured in Roundel, the BMW CCA magazine. Seemed good enough for me.

In the end, I wanted a fully-built pumpkin, so I could just take the whole thing to a shop and have it installed without worrying too much about their diff-building expertise. Jim quoted a price to build his diff that was cheaper than getting a Quiafe or Wavetrac DiffsOnline unit, plus he didn't charge extra for the finned cover, or require a core deposit (or even require my original diff in exchange). It really seemed like I was getting a better quality diff custom-built for less money.

Originally Posted by Fume

The fins are part of the cover? Looks nice but how's the ground clearance to it?

The fins are part of the cover. The intent is that they catch air flow underneath the car and cool the gear oil inside the diff. They necessarily hang kinda low, but not enough to really affect clearance. I mean, I wouldn't take it off-road or anything, but that sort of goes without saying.

Originally Posted by Fume

Most importantly, is the handling characteristic noticeably improved (both in normal driving and in more spirited driving)

In addition to the LSD, I also had the following installed:

1. M3 differential bushings (replaced OE diff bushings)
2. H&R 27mm front sway bar (replaced M3 26.5mm bar)
3. H&R 20mm rear sway bar (replaced OE Sport Package 12mm bar)
4. Whiteline rear subframe bushings (replaced Whiteline rear subframe bushing inserts)

Needless to say, it's a bit hard to completely isolate how much each mod contributed, but suffice it to say, the entire rear end feels really super buttoned down now. Obviously I can only push the car so hard on public roads, but it feels like the rear end is much more willing to come around and rotate on turn in. The LSD has 35/60 ramp angles, so is active on both acel & decel (but acel>decel), and the car feels more stable in both scenarios, and in turns it really feels like it's digging in and putting power down efficiently. I don't feel like I'll fully appreciate it until my next autocross in March, particularly because I live on a military base (i.e., low speed limit & strict enforcement), but I did get to drive the car pretty hard from the shop in Raleigh back to Camp Lejeune (maybe 150 miles).

Originally Posted by Fume

You're doing all the mods that I want to eventually do to my car but either don't have the money to spend on car parts at the moment or am a little scared to completely void the 2 extra years of warranty I have on my car. Not gonna lie, I'm pretty envious.

I wouldn't worry too much about the warranty. I mean, they can't void your entire warranty based on any single mod - but they can deny any claim that they might attribute to that mod. But most reputable aftermarket parts come with warranties of their own, so it's kind of a wash. But certainly don't do more than your budget allows.

By the way, if we run into each other at an event in WA after I move there this summer, you're more than welcome to have a closer look at my car and take it for a drive.

Originally Posted by Fume

Edit: Oh another question: Did you get the coding stuff done to disable the e-diff that the X1 owner mentioned in the track/autocross subforum?

No, that's sort of next on my list. I'm going to be away from home all next week for work, so it'll probably be sometime after that. My understanding talking to Jim is that, on the street, the LSD should keep the electronic nannies at bay a little bit, but pushing it hard and the nannies may interfere with the LSD. So my plan is to have it sorted at least before the start of the autocross season in March, but probably by early February.

Originally Posted by dailowill

Nice! What final drive ratio did you decide to go with?

I ended up with a 3.73, which delivers about 15.5% more torque to the wheels than the OE 3.23 unit. You know, listening to the nay-sayers, I would've thunk that our already short 1st gear would be completely useless, and the cruising RPMS's on the highway would be unacceptably high. I haven't found either to be the case. In fact, the change is almost a bit underwhelming! 1st gear is still completely usable (thankfully) and cruising RPM's are about 3300 at 80 MPH, if I recall correctly. Acceleration does feel quicker, particularly when you're really getting on it. Regular cruising around isn't really noticeably quicker, because you're either giving it less throttle or shifting to a higher gear sooner to compensate for the extra torque. In fact, that is one of the most noticeable things - shift points are changed. It's a bit annoying, because I've gotten quite used to the stock gearing after nearly 6 years, but I suspect in a couple of weeks I won't even notice the change.

It remains to be seen how the new gearing will perform on the autocross course. I think I will enjoy the extra thrust on corner exit, but I'm a little worried about the shortened 2nd gear requiring an extra shift to 3rd. To be honest, I think it will be more fun even if it ends up being less competitive (and it may not be) so I don't really have any regrets. So far it's certainly been more fun in day-to-day driving. The car just feels lighter and more eager and responsive. Sportier, I guess. But it's not as dramatic as you might think, judging from what you read on forums.

Originally Posted by squidge

Also curious.

Did you order this through Turner?

No, I ordered directly from Jim at Performance Gearing. I've heard that Turner's diffs are actually built by someone else - either Jim Blanton (again, from Performance Gearing) or Dan Fitzgerald (from DiffsOnline). It may be neither of those, for all I know. Either way, I'd recommend cutting out the middle man and just dealing directly with a diff builder. Either Jim or Dan are said to be very good and have stellar reputations, although I'm obviously partial to Jim at this point.

[Suprgnat]

Originally Posted by Bimmer-Bob

It's actually for the Typ 188L diff. It required a 15mm spacer and a longer bolt to work, but otherwise it's the same bolt pattern and a direct fit.

So it's not 33117516280, which is for the Type 188K? E82 has the 188L.

[Bimmer-Bob]

Originally Posted by Suprgnat

So it's not 33117516280, which is for the Type 188K? E82 has the 188L.

I'm a little confused by your comment: you say "E82 has the 188L" but seem to think the finned cover should be from the 188K? You're right, the E82 N52 has the 188L, and that's the size cover our diff requires (at least the manual transmission version, I haven't looked into the auto).

[Suprgnat]

Originally Posted by Bimmer-Bob

I'm a little confused by your comment: you say "E82 has the 188L" but seem to think the finned cover should be from the 188K? You're right, the E82 N52 has the 188L, and that's the size cover our diff requires (at least the manual transmission version, I haven't looked into the auto).

To end both of our confusion, what's the P/N of the cover you installed?

[Dafttt]

I missed a lot of updates on this car. So impressive... really, everything.

Loving the extensive feedback and reviews on all accounts!

[Bimmer-Bob]

Originally Posted by Suprgnat

To end both of our confusion, what's the P/N of the cover you installed?

I don't know, because the diff came built from Performance Gearing. But Jim told me the cover was the 188L size, and not the 188K. RealOEM supports this, and I suspect the part number is 33117528319, but I've sent an email to Jim to make sure and will update the thread when I hear back.

But what is your confusion? Our cars undoubtedly use the 188L size diff...at least the manual cars. Is the auto diff sized differently?

[Suprgnat]

Originally Posted by Bimmer-Bob

I don't know, because the diff came built from Performance Gearing. But Jim told me the cover was the 188L size, and not the 188K. RealOEM supports this, and I suspect the part number is 33117528319, but I've sent an email to Jim to make sure and will update the thread when I hear back.

But what is your confusion? Our cars undoubtedly use the 188L size diff...at least the manual cars. Is the auto diff sized differently?

My only confusion is what the is the correct P/N for the finned diff cover that fits a 188L. This is my first time running across this particular P/N, and I can't find an image of the P/N 33117528319 with fins. Sounds like I should just get a PG diff and not sweat it.

[Bimmer-Bob]

Originally Posted by Suprgnat

My only confusion is what the is the correct P/N for the finned diff cover that fits a 188L. This is my first time running across this particular P/N, and I can't find an image of the P/N 33117528319 with fins. Sounds like I should just get a PG diff and not sweat it.

Yeah, I can't find an image of the part anywhere, either. Usually ECS Tuning is pretty good about posting several images of each part, but not so for the part number I gave earlier (which I got off of RealOEM, btw). In any case, I'll let you know when I hear back from Jim with the exact part number, as I was only speculating.

[swagon]

Bob, how visible are the PIAA's in daylight/sun? You haven't coded the AE's to be brighter, right?

Thanks

[Bimmer-Bob]

Originally Posted by swagon

Bob, how visible are the PIAA's in daylight/sun? You haven't coded the AE's to be brighter, right?

Thanks

I have not adjusted the angel eye voltage, at least not yet. Sometimes I think they could stand to be a little brighter, like if I'm looking at them from an angle in bright sunlight. But it hasn't bothered me enough to do the coding so far.

[Bimmer-Bob]

Just saw that Bimmer Performance Center featured their recent work on my car in their Facebook feed. Sharing them here. Pretty cool to see the rear subframe dropped completely out of the car!

For some reason the mobile app isn't letting upload multiple images. Will have to wait until I get back home in a few days...

[E91WAG3N]

Always great to have some in action work shots. Car looks great on the lift!

[swagon]

Originally Posted by ubersteuer

Always great to have some in action work shots. Car looks great on the lift!

But only when it's there to get some upgrades and not repairs.

[Suprgnat]

Originally Posted by Bimmer-Bob

Yeah, I can't find an image of the part anywhere, either. Usually ECS Tuning is pretty good about posting several images of each part, but not so for the part number I gave earlier (which I got off of RealOEM, btw). In any case, I'll let you know when I hear back from Jim with the exact part number, as I was only speculating.

Have you had a chance to verify this? The P/N should be embossed on the right hand flange of the cover.

[Bimmer-Bob]

Here are the rest of the photos from the install last week:

Having spent a little more time driving the car around, it's amazing how much better the car feels now. The back end just feels so super solid and planted, really digs in when you put power down, and the rear end tucks around. I can't wait to get it on an autocross course to really feel it out.

This is not an inexpensive upgrade path, but to anyone considering an LSD for spirited driving, I'd strongly recommend simultaneously doing the RSFB's, diff bushings, and rear bar as well. They just seem so complementary, and as you can probably tell from the pictures, there is a lot of overlapping labor involved.

[Bimmer-Bob]

Originally Posted by Suprgnat

Have you had a chance to verify this? The P/N should be embossed on the right hand flange of the cover.

Haven't heard back with a specific p/n, although judging by RealOEM I strongly suspect it is 33117528319.

Anyway, are you saying that the highlighted portion below is the part number?

There is definitely something alphanumeric embossed there. It would be much easier to see with the car on a lift, but I can try to see if I can make it out another way...

[Suprgnat]

Originally Posted by Bimmer-Bob

Haven't heard back with a specific p/n, although judging by RealOEM I strongly suspect it is 33117528319.

Anyway, are you saying that the highlighted portion below is the part number?

It is on the other covers I've been looking at, for instance:
one can see "7 516 281" on this P/N 33117516280, so there's some correlation. Incidentally, this part is for an 01-05 E60 525i/530i Type 188K diff.