| Rogue Engineering Performance Differentials
A look at the parts replaced in a Rogue
Engineering E46 M3 Performance Differential.
How many parts does your builder replace?
Racecar speed secrets
for the Street!
What's the Secret?
One of the benefits of being associated
with professional race teams is being privy to their "speed
secrets" that they use on the track. One of these secrets
include the allowable rear differential gear changes.
For the Grand-Am GS E46 M3s, they were
allowed to change their gearing from stock 3.62 to 3.91. Of course,
most "street" guys know that the 4.10 ratio is really the most desirable
gear (but again, not allowed in Grand-Am racing rules). After many
seasons of racing, we were told that these race-prepped vehicles had their
rear differentials torn down to be rebuilt for the upcoming season.
What they found out inside the differential, told an interesting story.
Start From Scratch
One of the mandatory keys to the rebuilds
is replacing EVERYTHING in the differential possible. Although the
M-Variable unit is left intact, every single bolt, seal, bearing, o-ring,
crush washer and circlip are replaced. Even though the existing one
may have been ok, it's not worth a potential failure for a small
part. Typical racecar mentality is to replace everything with new
parts. However, most all differential "builders" will not
spend the extra $500+ in parts (shown above, not including the BMW
Motorsport ring/pinion) when building a differential. Most will
replace the absolute necessary parts (like a bearing or a crush
washer). The other problem is that the above parts are not available
"easily" from the local BMW dealer as the E46 M3 differential is
not available as individual parts. The BMW Motorsport gearset is the
most costly item, at close to $900 from BMW Motorsport approved
dealers. These are usually only available as special order through
One of the other obsessive details is the
REM polishing of the BMW Motorsport ring and pinion parts. By having
this additional finishing process done, it lowers the frictional
resistance between the teeth and lowers differential temperatures, if only
a little. After a full season of racing, REM polished gears show
virtually NO wear and can be used again! Gearsets that do not have
this finishing process done do show additional wear after a full season of
use. This kind of service typically adds approximately $195 to the
gearset. All our differentials get this finishing.
REM Polished 4.10 Ring and Pinion
Break-In? Drive it!
Using factory fluid, the there is no
"wrong way" to drive the newly installed differential.
These differentials are built by the same company building for Pro
Grand-Am teams and expect the differentials to be used hard and put away
wet. Their only requirement is to drain and refill using factory BMW
differential fluid after 1200 miles. That's it.
For The Select Few
have a few number of E46 M3 differential cores available, but at most
times, these are supplied on a wait-list basis and require a $1000
deposit. 4.10s are the common differentials we have built.
3.91s gears are special order, and require a $1000 deposit.
the differentials are priced at $2550 plus core, plus
shipping. They are shipped WITHOUT the factory rear cover, as yours
will be reused.
To reserve a differential, contact us at firstname.lastname@example.org.