Factory finned differential cover

[KC ZHP]

Likely has been noted somewhere, but didn't find upon searching... I've noticed several otherwise stock in appearance ZHPs on the road with finned rear differential covers. Suspect that this is likely not a common upgrade as I never noted such an option on any of the ZHPs I looked at when searching. After mentioning this to a buddy, he reviewed the parts catalog - appears that cars equipped with automatics came with a different differential cover...has anyone noticed this difference?

[bullfrogs_M3]

Is it for cosmetic purposes? Otherwise, I don't really think our non-LSD diffs need any other additional cooling. As soon as you put on an LSD, then yes, a finned diff cover is a necessity.

*EDIT:
Tisher (getBMWParts.com) has this listed at about $120.

Product Details:

BMW OEM e46 finned rear differential cover. This will fit the e46 3 Series models and helps provide cooling to diff allowing limited slip clutch packages to remain cooler and more effect. Helps to prolong the life of the differential overall including expensive internal bearings. As a bonus, it is a nice dress-up part for the under side of your e46 3 Series!

Part number: 33 11 7 512 980
http://www.partsed.com/UserFiles/Image/originals/drivetrain_mz3_diff_cover_lg.jpg

Here is Turner motorsports:
http://www.turnermotorsport.com/p-1095-e46-high-performance-finned-differential-cover.aspx
http://www.turnermotorsport.com/image/drivetrain/drivetrain_e46_finnedcover_lg.jpg

Also here are some install notes about it. Looks to be a decent amount of work due to dropping the diff.....
http://www.e46fanatics.com/forum/showthread.php?t=674247

Image below is an e46fanatics image, so you'll need to have an account to see it.
http://www.e46fanatics.com/forum/attachment.php?attachmentid=314768&d=1242180730

[MasterC17]

I've noticed this. My dad's 2004 ZHP is an automatic and has a finned diff. cover, my 2005 manual does not. I presume it is because the automatic's generate more heat.

[bullfrogs_M3]

How does an auto generate more heat than a manual? That doesn't make sense? I mean, if I have a 3.06 manual diff and you have a 3.06 auto diff what exactly is the difference? We should be able to swap diffs all day long.

Is it because on an auto, you are constantly putting torsional stress on the diff? Like when you are at a stop or not moving but still in gear? Hmm this may be it, I mean, if I am on my brakes at a light then I am only really trying to keep the diff from spinning, right? That means the tranny and driveshaft are consistently trying to move the diff even though my brakes are saying NO

[Mike V]

KC ZHP... where is your intro thread? I think I know who you are. :)

[MasterC17]

How does an auto generate more heat than a manual? That doesn't make sense? I mean, if I have a 3.06 manual diff and you have a 3.06 auto diff what exactly is the difference? We should be able to swap diffs all day long.

Is it because on an auto, you are constantly putting torsional stress on the diff? Like when you are at a stop or not moving but still in gear? Hmm this may be it, I mean, if I am on my brakes at a light then I am only really trying to keep the diff from spinning, right? That means the tranny and driveshaft are consistently trying to move the diff even though my brakes are saying NO

Honestly, I have no idea, I was simply guessing :rofl. I figure there must be some logical reason; the one you mentioned would put more stress on the diff, but not enough in itself to require a finned diff cover I presume.

[danewilson77]

I like the way it looks. I think I may purchase that bad boy.

Droid + Tapatalk = FTW!

[Johnmadd]

I like the way it looks. I think I may purchase that bad boy.

Droid + Tapatalk = FTW!
M swap for you.

[danewilson77]

M swap for you.

Too much $$$.........and not enough go.......

[bullfrogs_M3]

M swap for you.

^^^^^ Needs more upvotes!! LOL M3 rear swap is the way to go! Components can be had for well under $1K. All parts drop out (330) and back in (M3) without issues. Although, if you have an Auto you have to get a new driveshaft. Otherwise, SMG and Manual driveshafts are fine.

[jvr826]

LOL at all of you who notice these things... I do too!

I have that cover on my open diff. When I swapped the 3.46 in I figured it was a good time to add some cooling. It's a half ounce lighter than the original... adding lightness helps. I think it reduced my lap times by .001s...

[Mtnman]

Finally the Autos have a leg up! I am not longer going to say I have an Auto, I'm going to say "I have a finned rear diff"

Sweet.

[danewilson77]

Finally the Autos have a leg up! I am not longer going to say I have an Auto, I'm going to say "I have a finned rear diff"

Sweet.

:rofl

[Marcus-SanDiego]

+1

[johnrando]

Yeah baby! FRD FTW!

[gr330zhp]

If I remember right, ECS Tuning had a killer deal on the finned diff cover!

Will find the link...

[danewilson77]

If I remember right, ECS Tuning had a killer deal on the finned diff cover!

Will find the link...

Please dhu...I haven't bought anything yet today.

Droid + Tapatalk = FTW!

[gr330zhp]

Guess it's not on sale anymore

If I remember around Christmas, the part itself was around $60, cuz I remembered thinking I will do it when I do fluids again! You know how awesome deals ECS puts on some stuff

Sighhhhh...guess not anymore for this :(
http://www.ecstuning.com/BMW-E46-330i-M54_3.0L/Drivetrain/Differential/ES2095895/

[danewilson77]

You know how I think about that $175.00 price tag.

If I took my car...to BMW to have diff fluid swapped out....what do you think they would charge.

I bet I'm saving money, still....even at that price, and I'm getting the cool cover...

Droid + Tapatalk = FTW!

[gr330zhp]

You know how I think about that $175.00 price tag.

If I took my car...to BMW to have diff fluid swapped out....what do you think they would charge.

I bet I'm saving money, still....even at that price, and I'm getting the cool cover...

Droid + Tapatalk = FTW!

That is very true!! I will prob do it when I do fluids again....

[danewilson77]

That is very true!! I will prob do it when I do fluids again....

Now we're talking....that's what I like to hear! Hehe...

Droid + Tapatalk = FTW!

[gr330zhp]

Now we're talking....that's what I like to hear! Hehe...

Droid + Tapatalk = FTW!

Hehe! It just looks beefy, loved how it looked on our old M3, though there was a bit more underneath the cover on that :foottap

[Terry]

Not sure if the ZHP auto diff cover has more fluid capacity, but I know a lot of the aftermarket ones tend to hold more oil.. Willing to bet this has more to do with the cooling than the bash fins ;-)

I'd say the only downside to this is clearance. Remember back when I used to drive on the track I could sometimes drag the cover on exit berms when running wide. I should clarify - not qualifying friendly ;-)

Not a clearance issue for normal driving though as it's located on the same axis as the rear axle.. Just when you're driving over an obstacle that your track completely clears. Cheesey diagram looking at your car from the front or rear. | = wheels, o = obstacle:
| o | Or if your car is lowered: / O \ ;-)

[gr330zhp]

Not sure if the ZHP auto diff cover has more fluid capacity, but I know a lot of the aftermarket ones tend to hold more oil.. Willing to bet this has more to do with the cooling than the bash fins ;-)

I'd say the only downside to this is clearance. Remember back when I used to drive on the track I could sometimes drag the cover on exit berms when running wide. I should clarify - not qualifying friendly ;-)

Not a clearance issue for normal driving though as it's located on the same axis as the rear axle.. Just when you're driving over an obstacle that your track completely clears. Cheesey diagram looking at your car from the front or rear. | = wheels, o = obstacle:
| o | Or if your car is lowered: / O \ ;-)

Hahah I like the diagram Terry! :biggrin