[ajsalida]

Maybe a stupid question but is the e9x M3 diff not a drop-in? What about earlier 3-series models? e46 e36, or even 00-03 M5? etc.

[vasillalov]

Originally Posted by ajsalida

Maybe a stupid question but is the e9x M3 diff not a drop-in? What about earlier 3-series models? e46 e36, or even 00-03 M5? etc.

Nope. Driveshaft does not fit.

[vzehler]

Originally Posted by vasillalov

Nope. Driveshaft does not fit.

Not drop in, but it can be and has been retrofitted. Basically you end up with a shortened, hybrid (335i front, M3 rear) driveshaft.

[ajsalida]

Originally Posted by vzehler

Not drop in, but it can be and has been retrofitted. Basically you end up with a shortened, hybrid (335i front, M3 rear) driveshaft.

Good to know thanks. For american hot rods at least, driveshaft mods are relatively cheap. BTW there is a guy who stuck a corvette diff into an e30 + turbo s52, so maybe some similar creative thinking here is in order. $5k for an LSD is just stupid.

BTW he is selling the car, note diff piccs & esp. HP numbers on the turbo:

http://forums.bimmerforums.com/forum....php?t=1713683

[fl335i]

Bimmerworld has a few differential offerings. I can get the OS Geiken installed in my diff for a total of about $2,500. That's about my price limit for this project. I have a few local shops I am going to talk to also... to either buy and install it or just install the OSG.

[Aridk]

I've had my wavetrac for allmost 2 years and 15000 miles and it just runs flawlesly absolute love it by far the best mod I did ón the car especialy In the winter with snow, it's just so much more injoyable with the lsd :-)

[turugara]

I ran into an issue with a wavetrac unit a month back. The install + backlash was checked before install and checked again after I ran into a clunking issue and they were all to spec. The wavetrac unit itself had a problem.

Look at some of the other wavetrac clunking threads.

http://www.e90post.com/forums/showth...etrac+clunking

http://www.e90post.com/forums/showth...wavetrac+issue

Originally Posted by HP Autowerks

How often do you really go one wheel off the ground, really?

The truth is(we have tried both) Wavetrac doesn't work much better when one wheel is off of the ground, the inside tires still spins. At the end Wavetrac may need a rebuild where the Quaife will continue to work as designed.

This is a link to my experience with a wavetrac unit
http://www.e90post.com/forums/showth...etrac+clunking

In the end I went from a wavetrac to a quaife. The quaife has not had a single issue. No clunking, nothing. Performs perfectly on and off the track.

[fl335i]

Quafie or OSG. Leaning toward OSG... more than likely going that route.

[Bakeme521]

All I know is it was a noticeable difference when I switched to my wavetrac, in no way shape or form does it act like an open diff. I don't track the car but it sure made spirited driving more fun.

[805beemer]

So since I have an AT would the wavetrack be fine? Its seems as though most with the clunking issue are MT.

[Bakeme521]

Originally Posted by 805beemer

So since I have an AT would the wavetrack be fine? Its seems as though most with the clunking issue are MT.

I had the clunking issue but it went away after about 2k miles, works perfectly now.

[tunachris]

No clunking from my Quaife. Did change the diff. oil after about 1,0000 miles. 2010 with 6 MT. Not cheap, but makes way too much sense in conjunction with perf. mods.

BMW didn't do us any favors by only putting LSD into M cars. I'm sure they could sell them as an option if offered!

[flip4335]

Originally Posted by fl335i

What about the Drexler? I can't find any info on it on the net. Who is selling them and what price range are they going for vs the OSG?

Read this:

http://www.e90post.com/forums/showthread.php?t=591635

http://www.e90post.com/forums/showth...=383378&page=2

As for Quaife, lots of manufacturers use it, including 2004 Dodge SRT-4, 2008-10 Chevy Cobalt SS turbocharged, Ford Focus RS, to name a few.

What's the diff between the clutch and torque biasing diff?

"Limited Slip Differentials

In an effort to solve the problem of the open differential gear train designers have come up with a number of solutions over the decades. One of these uses several clutch plates coupling the axles to the bevel gears. It was made famous by General Motors during the muscle car era as the "Posi-Trac,' but the proper name for this type is the 'Salisbury Differential.' In the early Salisbury units like the Posi-Trac, the amount of wheel spin allowed is controlled by the preload on the clutches. The theory was great, but in practice the preload was difficult to get right and changed as the plates wore. Many refinements to the Salisbury differential have been added by other manufacturers over the years, including one by Xtrac, the Hewland Powerflow and a new diff called the Variloc introduced by Taylor Race Engineering. Although there are differences among them, all use ramps splined to the inside of the housing which load the clutch discs through the end gears when power is applied. The loading of the discs is therefore controlled by the ramp angle employed.

Since we want differential action entering a turn and need to reduce wheel spin when the throttle is applied, the ramp angles are different between the coast and power sides. The coast ramps are usually 80, 83 or 90 degrees to load the clutch plates little, if at all, allowing speed differentiation under braking. The drive ramps can be anywhere between 30 and 60 degrees depending on how much lock-up is needed out of the corners. Additional adjustments can be made by the type and stacking order of clutch plates used and by preload on the plates. These units can be set up anywhere between an open differential to something approaching fully locked, both entering and exiting turns. Although they are very effective when properly set up, some power is lost as heat when the plates are slipping.

In the '60s. Hewland began shipping many of their larger gearboxes with a differential they called the “Cam and Pawl" It uses inner and outer concentric fluted cam with pawls that wedge between them when power is applied. These fully lock the differential and they are non-adjustable. Since all of the parts that limit slip are made of hardened steel, the wear rate is relatively high and it takes constant maintenance to keep them working correctly. When slightly worn, they lock both wheels together, but then slip a tooth or two, causing a series of jerks. When severely worn, they act like open diffs. Many vintage cars that use Hewland gearboxes have extensively worn Cam and Pawl differentials. In other words, open diffs.

Another type of limited slip differential that Ford popularized is the "Detroit Locker." It uses a ratcheting mechanism that fully locks the differential when power is applied and unlocks it when the throttle is lifted. Although that action may be a bit abrupt, the real disadvantage appears when part throttle is used. In these situations, it cannot decide whether to lock or unlock and jerks until full power is applied. This can greatly affect traction in the mid-part of a turn. The Detroit Locker supplies torque to the wheel that is rotating the most slowly. In normal cornering, this is the inside wheel. Consequently, that inner tire drives the front of the car toward the outside of the turn, causing comer exit under-steer. Compared to other types of limited slips, the Detroit Locker has few recommendations except by a few diehard road racers who continue to use them- and by NASCAR.
Limited slips require a reference wheel speed. If the inner rear is lifted off the track due to rear droop limiters, shocks too short, etc., no speed limiting will occur until it touches down again with a chirp.

Torque Biasing Differentials

Limited slips are reactive. They limit over-speeding of the inner wheel by coupling it to the outer, more heavily loaded wheel. In contrast, "torque biasing" differentials are proactive. They send increased torque to the tire that is more heavily loaded prior to wheel spin. Two makes are in use in race cars, the Gleason-Torsen and the Quaife. Gleason made a few diffs for race cars in the '80s but are no longer producing them except for some Japanese street car manufacturers. The Quaife is virtually identical in operation and is still being produced.

Torque biasing operation is based on the fact that worm gears transmit torque efficiently only in one direction. In practice, side gears are coupled to each axle and mate with several pair of overlapping planetary worm gears. These worm gears float in the housing and when power is applied, the gears are pushed outward, causing friction between their tips and the recesses inside the case, thus resisting rotation. This allows more torque to be biased toward the wheel with more traction.

We have two means of adjusting torque biasing differentials. The first is by the helix angle and pressure angle of the gears; the second is by varying the number of beveled washers exerting outward pressure between the end gears. However, most racers who use them have no extra gears, so the only practical adjustment is the preload or the end gears.

While they have the advantage of being proactive. torque biasing differentials are not without faults. First, they are quite heavy and have a lot of mass concentrated just inside the case, giving them quite a bit of rotational inertia. Second, a fair amount of power is turned into treat due to the friction of all the gears inside the case, and they never fully lock. Finally, they send more torque to the more heavily laden outside wheel which, opposite to the effect of the Detroit Locker, gives the car a power-on over-steering tendency."

source: http://www.teamhealeytexas.com/Techn...erentials2.htm

Lots of choices!

[fl335i]

OSG.