Rascal's NB8A track rat

[greenMachine]

I never had a problem with wheelspin using a Torsen, though it did take some work. Essentially I softened the rear, allowing the inside to droop and keep the wheel in (light) contact with the road. I have a photo somewhere taken at T3 Eastern Creek showing the inside rear at full droop, the inside front just off the deck. That would have been on 205 AO50s, more/stickier rubber may have changed that, or maybe just growing a bigger pair ...

Having said that, a clutch pack is the better choice, certainly for a racecar that sees little or no road duty.

I haven't heard of those diffs, are they related to either of the better known ones (Kaaz and ?)?

[rascal]

You can definitely get them to work (better) by compromising your ideal suspension setup, as you found, but since I was getting a new diff anyway (orig was open) then it made sense to go for a clutch pack that wouldnt require any compromise to do its job as required.
This is also 12 years ago now, so I probably did have a bigger pair back then, as youthful exuberance was still around, and it was before kids. Common folklore might suggest I am two seconds a lap slower now (one sec per child apparently… )

I believe the Mazdaspeed clutch pack diffs were a Japanese market only thing, (and no relation to the diffs in the SEs which the yanks referred to as Mazdaspeeds, and which are torsens anyway)
Centreline had imported some of them at some point previously and had two left so I snagged one of them.
In fact they might be a rx7 diff as Centreline were (still are?) big in the rotary scene back then. And the rx7 internals are interchangeable with mx5 stuff.

[Zed]

the rx7 internals are interchangeable with mx5 stuff.

thought they had different driveshaft splines

Rich.

[rascal]

the rx7 internals are interchangeable with mx5 stuff.

thought they had different driveshaft splines

Rich.

Think that was just the SE with the thicker axles?

The big forum suggests they don't..
https://forum.miata.net/vb/showpost.php ... stcount=11
https://www.rx7club.com/1st-generation- ... post685600

Also my diff (assuming it came from an rx7 which is most likely) had the same spline count/size and fitted right in.

[Zed]

always good info & I'm more than happy to learn

Rich.

[rascal]

back to the story after a slight delay...

The day before the Winton event I loaded the car up for the journey.

The new diff had made its presence known even in the shed. Pushing the car around now became a straight line only affair, as any turning of the steering wheel made the inside wheel bind on the concrete floor and increased the manual pushing effort by 1000%. Acted just like a welded diff which I had experience with in the old car. (A CIG locker was much cheaper and easier to find than a proper LSD for a TG Gemini)
Starting the car and driving it to move it around became the new modus operandi.

Though, notably, once you took any load of the driveine, the diff unlocked. eg you could reverse around a corner with no throttle just letting the clutch out and it would shudder/skip the inside wheel but as soon as you dipped the clutch it would stop skipping and roll around the arc without issue. Nice..

Arrived at the track the next morning, unloaded, scrutineered and lined up (im)patiently waiting for the first session to begin.
After a warm of the tires on the out lap, my first flying visit to the cleavage (Turn 8 ) and I decided to just stand on the throttle on exit to see if or by how much wheelspin had reduced. To my delight the car absolutely launched off the corner with not a spec of wheelspin, and I nearly overshot the right hander onto the back straight.
Now that's more like it!! I continued around the track and was very happy to find my inside wheel spin had decreased from 7/12 corners to 0/12 corners...

The short twisty nature of the track, and low 1min lap times meant the 15min sessions were full on. Very little rest between corners and 11-12 laps per session. 120 corners at race pace in 15 mins is hard work.

By the last couple of laps of the session, the brake pedal started to get a little spongy. I had flushed the lines with hi temp fluid so knew it wasnt that, and was running Hawk Blues which should be (and have proved to be) perfectly capable of handling the heat, but the rigours of the short track, where you dont really get much of a break (pun intended) between brake applications was obviously overwhelming the standard rubber brake lines. Time for some stainless lines to fix that.