The stock center support bearing carrier holds the driveshaft in place with a layer of thin rubber. While that’s great for making sure no NVH makes it to the cabin, it doesn’t keep the bearing centered well under load, allows the bearing to sag and ruin driveshaft alignment over time, and creates slop in the driveline during shifts and throttle application. 

Over time the OEM bushing becomes brittle, eventually dry rotting and cracking. Even on the best-kept cars, the stock bushing can start to form cracks in as little as 5-10 years. 

When the bushing wears and sags, it changes the alignment of the driveshaft, putting more stress on the joints. During rapid loading of the driveshaft (launches, shifts, and quick application of the throttle), the bearing is allowed to travel off-center, introducing slack in the driveline, which results in laggy and unpredictable driveline response.

Our upgraded driveshaft carriers keep the driveshaft firmly in place at all times. The more solid bushings ensure the bearing cannot move from center, maintaining torque delivery and driveshaft alignment at all times, resulting in more direct driveline response under all conditions. 

Benefits as described by our customers include: 

    More direct throttle response 
    Firmer, more direct shifts 
    More instantaneous launches 
    Reduction in vibration due to driveshaft misalignment and/or rubber deterioration 
    Smoother low-speed on/off throttle behavior (1st gear in parking lots) 

Street and Track refer to the durometer (stiffness) of the bushings. Track are roughly twice the durometer of the street bushings. Both track and street are many times stiffer than stock and will hold up to whatever abuse are thrown at them, but the street bushings are better at soaking up drivetrain noise and vibration. Usually both street and track are completely silent and vibration-free, but in cases where there is an underlying drivetrain issue causing the driveshaft to vibrate badly, the track bushings may not be able to soak it all up, where the street bushings can. 

We generally recommend street bushings for any car that's not purpose-built for track or overland use, since the street bushings have a much lower chance of transmitting drivetrain NVH to the cabin at high speeds or under heavy throttle loads.