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///M3 Forum
The BMW E46 ///M3 is the M version E46 and puts out an amazing 333 HP and 262 lb-ft of torque at stock specs! There are an amazing amount of modifications for both the coupe and convertible models so read up and get started modifying your cars today!

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Old 03-28-2020, 06:34 PM   #1
Subbyrocks
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Diff replacement

As some of you know, my diff isnít doing so well and I need to replace it sadly.
My mechanic is on the look out for a solid rebuilt diff for my 03 M, and I also need diff and tranny bushings.

Given that this car is a bit of a mess, any other suggestions with respect to preventative work I should look out for during the diff work?

Whenever he sources the part, and gets mine down, Iíll snap a pile of pics and post em up.


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Old 03-28-2020, 07:57 PM   #2
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You could just upgrade it if the case is good. Change to a 3.91 or 4.10

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Old 03-28-2020, 08:02 PM   #3
Subbyrocks
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Forgive my ignorance, but I donít know much about the diff or any potential ďupgradeĒ benefits...

Whatís the difference between the ratios?


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Old 03-28-2020, 08:20 PM   #4
Nihilation
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The gear change was great and I only went to the 3.85 from the E92 M3.

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Old 03-28-2020, 08:40 PM   #5
Arith2
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Diff gears determine torque multiplication to the wheels. Basically your top speed in each gear will slightly be decreased but horsepower to the wheels increase. It's a very underrated mod.

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Old 03-28-2020, 08:46 PM   #6
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Diff gears determine torque multiplication to the wheels. Basically your top speed in each gear will slightly be decreased but horsepower to the wheels increase. It's a very underrated mod.

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*torque increase. Horsepower is unchanged.
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Old 03-28-2020, 09:03 PM   #7
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*torque increase. Horsepower is unchanged.
You're right. Basically performing the same work with slightly quicker rotation over shorter time. It makes your car quicker at the expense of needing more rpm to go the same speed.

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Old 03-29-2020, 12:29 PM   #8
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Ultimately, whatever I can find quicker is my choice. Iíve been stock piling bits to to get to work on this car and this diff situation has really taken the wind out of my sails.

Reliability is my number one for this car, as I plan on being buried in it!


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Old 03-29-2020, 01:01 PM   #9
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Turner or ECS probably have them in stock if you have the money. A new diff is going to be MUCH safer than getting a used one with an unknown history.

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Old 03-29-2020, 02:06 PM   #10
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Yeah, I know. My mechanic tells me he has a few shops that sell rebuilds with a warranty. In the area of $1000-1500. Where new is more like 3-4K.


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Old 03-29-2020, 02:29 PM   #11
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metric mechanic will exchange (yours is the core).

Quote:
Originally Posted by Subbyrocks View Post
Ultimately, whatever I can find quicker is my choice. Iíve been stock piling bits to to get to work on this car and this diff situation has really taken the wind out of my sails.

Reliability is my number one for this car, as I plan on being buried in it!


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Item Price Core Deposit
Sport Variable Limited Slip 3 Disc $2,695 $500
Additional Charge for Gear Change Ratio $450+
Replace Differential Bushings $200
HiTorque Flanges, Pair $800
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Old 03-29-2020, 04:20 PM   #12
Subbyrocks
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And thatís all in US dollars... My Canadian wooden dollars are 0.70 to US


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Old 03-29-2020, 05:43 PM   #13
Andrew 06M3Cab
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I would not go to 4.10 unless you want to essentially lose 1st gear. It becomes so short it is annoying. I have driven 3.85 and it is a nice improvement from the 3.62 stock but still has a reasonable length first gear.


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Old 03-29-2020, 05:47 PM   #14
Subbyrocks
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Nah, Iím thinkin stock is just what Iím after!


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Old 03-29-2020, 05:59 PM   #15
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Ummm...that's lunacy!

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and thatís all in us dollars... My canadian wooden dollars are 0.70 to us


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ok ok
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Old 03-29-2020, 06:04 PM   #16
Andrew 06M3Cab
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Mpartsworldwide often has used diffs some with low mileage. You can find them on Instagram.


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Old 03-29-2020, 06:17 PM   #17
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Yeah, I found a few of those but by go through the hassle of changing it out just to have another unknown.

With this one, I wanna do it right the first time... lotta lessons learnt prior.


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Old 03-29-2020, 07:48 PM   #18
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What exactly is wrong with your current diff?


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Old 03-30-2020, 09:10 AM   #19
Subbyrocks
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Diff replacement

Wish I could tell you. Loud, dirty rubbing sound from the diff in corners, but only when engaged.

Changed the fluid and it was better for a bit, but itís back with a vengeance and itís much louder.


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Old 03-30-2020, 05:57 PM   #20
Alex323Ci
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Quote:
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Wish I could tell you. Loud, dirty rubbing sound from the diff in corners, but only when engaged.

Changed the fluid and it was better for a bit, but itís back with a vengeance and itís much louder.
you try adding "friction modifier" to it to rule that out?
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OE CSL WHEELS - OE CSL BRAKES - OE AUTOFLD MIRRORS - CSL RACK - CSL TRUNK - CSL DIFFUSER - AA TUNE - AA PULLEYS - AS 40% SSK - BILSTEIN PSS9s
CF CSL LIP - NAV- BMWP CF STRUT BAR - BMW GROUP N MNTS - GRUPPE M CF INTAKE - SUPERSPRINT - UUC S/S LINES, RTABs - H&R SWAYS - 4.10 M-SPORT DIFF
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