Join Date: Mar 2008
Location: West Coast, USA
What MFE said. The TA also holds the pinion angle constant, thereby preventing axle wrap (axle wind-up) under hard acceleration. Axle wrap destabilizes rear grip by causing bushing deflection, bind, wheel hop, etc.
When installing the TA you also remove the UCA's (along with adding a panhard bar or watts link). This lowers the roll center which further stabilizes the rear end.
Compared with the stock 4-link, the addition of a TA/PHB enhances rear grip somewhere between 25-50% according to my personal butt dyno. YMMV.
If you really want to improve rear grip, the TA/PHB is just a part of the equation. Tires, springs, ride height / LCA angle, swaybar (or lack thereof) also play big roles.
'87 Fox C-Prepared Mustang
2013, 2015 Pacific NW Regional Champ
Car has trophied at 2015, 2016, 2017, 2018 SCCA Nationals
Zero scrub SLA front end