I haven't driven both (just Quaife), but a friend of mine who used to race a showroom stock CRX professionally drove an SH. He said he actually preferred an LSD, but he said the difference is quite subtle. The main thing is that an LSD works in a straight line, where ATTS does not.

It also appears that ATTS is not variable, it's on or it's off.

 

Why do you say it is either on or off? It is a clutch based system that is variable depending on how much lockup is given to the clutch.

Personally I am divided on which is better, ATTS or LSD. The ATTS works beautifully in autocross and track driving. I enjoy the throttle oversteer I can get in tight corners in my TypeSH. On the other hand a LSD can do much of the same thing but weighs 40 pounds less. Also with a LSD you can change your ring and pinion for different gearing which is a huge advantage. I think if you are only autocrossing and doing the occasional track event the ATTS is just as good or better than LSD. If you are club racing and you are allowed to change your gearing, that combined with a LSD will give you better lap times than ATTS alone.

 

Thanks for the input. My car would see mostly club event/DE type stuff with the occasional autocross. I pretty much have decided to install a Quaife (if I don't buy an E30 M3). I am just nervous because there is nowhere here to have it installed and I don't have enough confidence in my abilities or the correct tools to do it on my own. SIGH.

 

Read my post about how ATTS works. It's either on or off. The clutches just engage/disengage either the planetary pinion gear assembly, or the left central gear. It appears that the clutches are on or off, and that's what biases the torque to one side or the other.

http://www.preludeonline.com/showthread.php?threadid=36298

I used to think that it was a slipper clutch type of mechanism that varied the torque, but it's actually gear driven. The gearing changes the speed of the right wheel relative to the left.

The differential allows for slip between the two wheels, so the output speed differences aren't directly driven to the wheels.

The amount of torque that is transferred is approx. 15%.

 

If you want to go to a lot of track events you better get a lot more confident in your mechanical abilities or run a very reliable car. I have two good friends that club race E30 M3 and they are in a constant state of disrepair. Neither of them are great mechanics so they pay out the ass for BMW mechanics to work on their cars. Since they both don't have gobs of cash they only get to run about 1/2 the events they would normally with a solid car. I drive my Prelude to track events and it has never stranded me. In fact I beat the living **** out of my Prelude and it has never broke. If you have not seen it there is a good video of me chasing my friend in his E30 M3 at http://24.4.32.210/racingnirvana.rm.

Billy, if you want to tear apart my ATTS to investigate it I am game. I would especially be interested if you think there is a way to change my final drive.

 

Personally I think ATTS is a nice trick to get the car to rotate faster than would normally for a FWD car. However, for a purpose built track car I believe a LSD will be a better option. With ATTS you can still vaporize the inner tire as you would with an open diff, plus it has a slight (very slight) reaction time which sometimes upsets the balance of the car during a turn. But for the time being (my car being a street car) ATTS is great!

~Doug

 

DR good video What type of camera are you using? What did you use to edit the videos with music and stuff. Like the Bboy one too.
I have read of the maintenance issues with an E30. Outside of valve adjustments what kinds of maintenance issues are your friends having?
I too have beat the snot out of my prelude and it merely cools off and goes back at it, which I like.
Its not my mechanical abilities I am just nervous about that large of an undertaking on my own, I am sure that I can pull it off. I guess that I should just jump in then huh.

 

There seam to be many weak points in the E30 M3. Several stem from the use of an aluminum head on an iron block. One over-heat and that head is gone. It is a damn nice car to look at and when it is running it is fast as ****, just too much of a maintenance headache for me.

To shoot videos I use a Sony TRV-120 digital 8mm camera. I capture and edit them with the Pinnacle Systems Studio DV, which includes a Firewire card and some really cool software.

I am a lousy mechanic but 71DSP and Marcucci help me out a lot. If you run in to any problems just ask them, they rock!!