[s-cars] New clutch, and rear diff limits

[Jim Green]

On 10/25/05, djdawson2 at aol.com <djdawson2 at aol.com> wrote:
>
> OK,
> So I was all excited... 12.4 at 113, and it seemed very limited by the
> clutch's inability to deal with a competitive launch. So I called Javad
> (034efi) to discuss clutch options. He had a unit built by Spec that he said
> was good to 600ft/lbs. So I ordered away... intent on a more successful trip
> to the dragstrip before the season ended.
>
> I drove the car back from Boise to Denver on Friday night. Got up
> Saturday, and started in. About 6 hours later, I had my new Spec clutch in
> the car. Everything's going fine. Out for a test drive...
>
> I decided to see how this clutch would hook up under power. I tried a
> moderate launch first... one that the Centerforce wouldn't hold. Wow... this
> thing stuck like white on rice... impressive. So now I'm all excited about
> the potential. So I go for an aggressive launch... 6k rpm with a gentle
> engagement to build boost, and then let 'er go. KABOOM!! This was a sound I
> knew well from previous experience with other cars.
>
> The rear torsen diff had unloaded, to the extent that a hole was blown
> through the side of the case. Fortunately, I still had my original diff...
> so I was able to swap that back in.
>
> So now I'm wondering... and scared. Is this the limit of the drivetrain?
> Are future trips to the strip just another blown diff waiting to happen?
>
> Anybody with experience... please share. How do you launch? What kind of
> abuse have you been able to put the drivetrain through without failure?
>
> Keep in mind, I'm not dumping the clutch. I usually start at a higher rpm
> (6k'ish), let the clutch out enough to put a load on the engine so that it
> rapidly builds boost, and then gradually let it grab completely. When done
> right, you get the feeling like you are in a slingshot... and there's
> nothing really sudden or abrupt about it.
>
> And yes... Mr. Pederson has repeatedly used the term "fuse." Maybe my rear
> diff is now the fuse, instead of my clutch. Hey, at least it wasn't the
> tranny.

  I wonder if it has anything to do with the torsen center diff shuffling
around the power. Nate's been running an 016 locker and V8 diff in his V8tt
90q with only good results. I know he beats the snot out of it too. Of
course his car is lighter, but maybe with the center diff locked it is
applying the power smoother?
 I'd like to do this mod some day so I'd like to hear other peoples opinions
as well.
 You weren't running some kind of crazy fluid like shockproof were you?
 For the launches, what you're doing sounds fine to me. Now go put the car
in the garage till Sat morning! ;)

--
Jim Green
'89 90tq
'89 80q
http://www.mswanson.com/~jgreen/car_home.html