Just curious as to why a lot of tracks have them in their rules as not allowed but they allow a full locker in most Hobby Stock classes. Wouldn't it be a down grade to run LSD instead of a locked rear? Or might there actually be some advantage in running a LSD like a TrueTrac? It's been a question I've always wondered about but could never get a straight answer.

The thing about LSD rears though is it opens in the corners supposedly helping it turn itself then locks again under power. A traditional "open" rear would transfer the power to the wheel with less resistance in the corner and it was always the left rear which was difficult to set up for. A unit like a TrueTrac advertises however that it will transfer the power as needed to each wheel always making the load on the wheels the same so one wheel never has too much load and one wheel never is freewheeling. So it always levels the power out.

The traditional open rear your open all the time. A LSD your open in the corner and locked while under power on straights. TrueTracs your locked on straight power and both are spinning in the corner  but just at different speeds to even themselves out. I know their popular on asphalt cars and in road racing.

triplexl46 wrote on 06/19/13 at 7:26am:

Hey triplex146   --  Is it possible you are confusing the LSD with a Detroit Locker?  The LSD has a clutch pack and springs in it and never completely opens or completely locks up. They are used a lot in pick- up trucks.  The Detroit Locker has springs and locking dogs in it, and does exactly what you are describing.  It completely unlocks under deceleration and completely locks up under acceleration.  We used to use them back in the old late model days when we had no tire stagger available to us.  It would unlock going into the turns allowing the car to rotate, and when the throttle was picked up, it locked.  Sometimes a little unpredictable, but they served the purpose.

Andrew, your funny. Lol. Old school, it's very possible. I just recently started learning about rears and what they do. I was mostly interested in finding out if anybody knew about the TrueTrac rears bc they claim to be a different type of limited slip working opposite of how a traditional LSD works. The other wheel turns and it never truly loses it's posi. It always spins both just compensating for the different amounts of spin needed for each wheel in the corners.

And the original question was as to why tracks that allow a fully locked rear often have it in their rules that LSD are illegal. Why make it illegal if it's a downgrade. My local track has always had it in their rules. Just another antiquated rule? Lol

So would a LSD or a TrueTrac make the car looser or tighter?