Let's talk limited slip differentials

[cvjoint]

I'm considering upgrading from the stock Torsen type differential that comes from the factory. It has survived 275 wheel torque for nearly 10 racing hours which is quite spectacular and does put the power down decently well. I'm going to raise the boost pressure and expect to see 325 to 375 wtq from 5000 rpm to 8000 rpm. Considering that is more than twice the factory torque amount I'm considering an upgrade and hopefully get better power delivery while I'm at it. Worst of all the factory diff breaks down on my tuner's dyno, I want to avoid the embarrassment.

I noticed the 3.5R and V8 Atoms state having an adjustable differential. To me this suggests it is a clutch type differential. Is it safe to say it's an OS Giken? Has anyone upgraded from the factory diff or have any experience with anything other than the factory Torsen on the Atom to share?

Would be lovely to have more torque capacity, less understeer on power, and more stability under breaking

[Peter255]

I don't believe the 3.5R has a different differential to the 3.5. No idea about the v8 though.

I can't remember a different diff ever having been discussed....

[autobackup]

Peter

That's true as far as the UK produced cars but I think that CV has an Atom built by TMI in the US who diverged from Ariel UK in terms of turbo cars several years ago and seem to offer many more options than Ariel UK - one of which might be a choice of diffs?

[Monza]

Atom V8 and real 3.5R with sequential gearbox have both Sadev gearbox (of 2 different models) with Discs LSD.

[speedmachine]

Brammo and gm engined atoms in general have different gearbox and thus diffs

[cvjoint]

Ah, of course. A lot of these diffs are a package deal with the engine or transmission.

A lot of the turn in behavior from model to model could be the differential and less to do with say suspension geometry changes. I'm really curious to know what the sequential models are using in terms of differential settings, since the clutch types are adjustable, and more likely to use ideal settings for the platform than the front wheel drive Torsen differentials we inherited from other cars.

[cvjoint]

The OS Giken website shows different starting settings for LSDs designed for FWD cars vs. RWD. See for example RSX Type S vs. S2000:


RSX-S:
Ramps - 3/50
Lock Timing - 336
Total Plates - 12
Preload - 6S

S2000:
Ramps - 25/35
Lock Timing - 336
Total Plates - 24
Preload - 10S

I wonder if I should go for the RSX-S LSD so it fits the trans but go with the S2000 settings for RWD application.

[thrlskr]

That logic makes sense to me, as a starting point. You are running much more torque than either.

[cvjoint]

Turns out OS Giken will do tune ups based on power, aero, etc to tailor the application. So I went with them and let them figure out the setup. Pretty excited to see how different they are from the OEM Torsen.