coxsteve wrote:
Thought this Topic needs a bump,but rather than just do that I could offer some advice for people building or having a Differential center built,many years of building these for both circuit and rally use gives me some experience here,most mechanics do not build Differential Centres generally only specialists.
1:Generally use factory settings for setting up your crown wheel and pinion for road use .
2:If the crown wheel and Pinion are somewhat old have them inspected for wear on the hardening,if not too severe they may be lapped for a noise free road diff.
3: I do not recommend lapping for competition use,better to use new Gearsets.
4:When building a centre for a high horsepower use it may pay to set the Differential Pinion a little deeper into mesh with the Crown wheel this then results in the Gearset being in optimum mesh under maximum power such as in Drag Racing as when under power the Pinion tends to be driven out of mesh.Logic will tell you that you want optimum Gearset mesh under maximum power for best results regarding power loss and Crownwheel and pinion life.
Being a geared Torsion style LSD Centre these are the most maintenance free units you can have,there is no need to play with Ramp angles or Plate preload to adjust the LSD for optimum handling,the ramp angles are what the Japanese aftermarket suppliers refer to when they talk about 2 way 1 way and 1.5 way LSD centers.
* 2 way has ramps that will lock the LSD under both Acceleration and Decelleration.
* 1.5 will lock better under Acceleration but not as well under Decelleration.
* 1 way locks only under Acceleration
The reason for this is that if an LSD is set very tight on plate preload they will induce understeer going into corners hence why the various options are made,the Torsen style is rather unique in how they work and is Ideal for front wheel drive and very driveable in rear wheel drive cars in varying conditions.
Viscous type LSD units are very much influenced by temperature and can be quite erratic and are best limited to moderate road use only for those who may have considered one of the Subaru types for an IRS Datsun.

Oils are important when I was rallying a Stanza most people were replacing the crown wheel and Pinion due to the pinion turning blue with heat about 2 to 3 times a season,I was using a special Castrol oil known at the time as AH3976 thanks to a sponsership deal,this is now actually sold as Castrol Differential oil Number 1 and contains a lot of Moly and other specialised additives this oil rsulted in no wear on the gearset and a loss of only 2 pounds of LSD plate preload over a full season,others such as Redline also do good products do not cut corners here.
Hopefully this will enlighten some of you on why you would like an LSD,what it will do for you and how to specify or set it up for your application. Cheers coxy
Just had a look at the Tech Wikki maybe this could be added there as it is relevant in that area of the site