Project Scion TC Part 4: Suspension and Brakes



Energy lower control arm bushings for scion tc
 The front lower control arm bushings are very complicated.  The rear bushings are very sloppy and allows a lot of flex and movement.  It cannot be simply replaced with solid urethane though.  It must be able to rotate on its axis without bind.
Front lower control arm bushing
 The steel piece is found in the middle of the stock bushing.  It is burned out of the stock bushing and reused.  It swivels inside of this three piece urethane ball and socket joint, probably the most complicated urethane bushing ever made!
bushing internal parts
 Here is how the parts are assembled.  You can see how the joint is free swiveling with no bind but still has little play and flex.
The lower control arm bushing in place!
 The bushing in the lower control arm, lubed up and ready to be installed.

The front suspension’s lower control arm had a huge rubber bushing in place at the forward pivot.  This bushing would allow for over 1/4th of an inch of deflection when loaded via a prybar as well.  Although this might be acceptable for grandpa’s Buick it was not good at all for fans of precise steering.  We had to get rid of all of this monkey motion to get turn in crispness and eliminate rear twitchiness when the car is pushed to its limits on the track.

Energy scion tc motor mount bushing
Some of the motor mount bushings take up the free space in the bushing to prevent movement but keep some of the stock rubbers cushion.

The TC’s engine was also mounted in a cradle of squishy rubber as well whose compliance added so much lash to the drivetrain that the engine would feel like it was attached to the throttle with a yoyo string at times.  This lurching contributed to a pounding case of wheelhop. Energy Suspension was our knight in shining armor, providing us with one of their bushing kits for Project TC.  The Energy bushings replaced all of the crossmember bushings with solid 80 durometer polyurethane.  The Energy bushings also replaced the large rear trailing arm bushing.  Since the TC’s rear suspension requires some bushing compliance to prevent bind, Energy only replaced select bushings, those that have the largest affect on keeping true wheel tracking  leaving some of them rubber to prevent bind.

energy scion tc motor mount bushing
The motor mount bushings that control fore and aft movement that have the biggest influence on wheel hop are solid urethane.

The large front lower control arm bushing was a work of art.  Energy created a multi piece ball and socket affair made of urethane to eliminate most of the gush while having less bind than the factory rubber part.  Revisiting the suspension with our semi scientific prybar test revealed that we had eliminated about 80% of the suspensions deflection. To address the engines windup and subsequent wheelhop we replaced two of the engines 4 mounts with Energy’s polyurethane parts. The mounts and the bushings effectively eliminated all of the wheel hop.

energy scion tc motor mount
The front motor mount bushing on the right allows for lots of movement and really contributes to wheel hop.  The solid urethane Energy piece really goes a long way towards controlling that.


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