The lower rear braces for the MR2 Spyder are member braces that triangulate the control arms on each side of the rear suspension. These braces connect the frame mounting points of the arms together, effectively reducing the flex under corning and acceleration. As a result, the rear end will feel more stable. However, by increasing the rigidity of the rear, the car will also tend to oversteer more so make sure to adjust your driving habits to suit.
The two braces are very basic pieces that will greatly increase the rigidity of the MR2 Spyder’s rear.
To access the mounting points, remove the engine diaper (not pictured) and then the second engine tray (pictured) The tray is held on by a combination of rivets and 10mm bolts. Just follow the perimeter of the piece and remove the connections until the tray falls down to the floor.
(Note: Place the car on ramps if you have trouble reaching under the car.)
Start on one side (passenger’s pictured) and locate the two mounting points for the control arms (labeled 1 and 2). Using two 17mm wrenches, remove the bolts at 1 and 2 and then install the brace (marked R for passenger’s side) between the mounts (1 and 2) securing everything back down by reinstalling the removed bolts. For reference, the bolt will now thread through the brace and then through the mount and control arm end before being tightened.
(Notes: It will take a lot of force to loosen these bolts so take your time and find the proper position to give yourself plenty of leverage. Also, the brace will appear to line up in multiple ways but in reality there is only one way. If the brace looks like it will contact the drive axle, flip it upside down for more clearance. Finally, if you have trouble aligning the control arm ends when reinserting the bolts, jack up the side of the car you are working on with a floor jack (not the spare jack) until the tire is off the ground. You can then slide the arm freely to help with the alignment.)
Once finished proceed to the other side and repeat the process. Finally ensure that all of the bolts are tightened back down and reinstall the plastic tray and diaper (optional).