StangerSite © 2008
All pictures, diagrams, text and illustrations are the property of StangersSite and may not be copied or reproduced without the express written permission of the Webmaster
The Power Cylinder pivots on the centerlink and is anchored to the drivers-side frame rail by a cast metal bracket. The cylinder pushes and pulls on this bracket, effectively moving the centerlink back and forth, turning the wheels. The original bracket is a short cast-iron piece that is mounted to the frame rail by 1 bolt horizontally through the frame and 2 bolts vertically into threaded inserts collapsed inside the rail.
POWER CYLINDER DROP BRACKET
When installing most long-tube headers into a Mustang with power steering, the header tubes tend to run very close to the cylinder rod, specifically the stretch boot covering it. If not actually physically hitting the rod and boot, the headers are so close as to melt the rubber boot. Most header suppliers recommend and sell a "drop bracket" to replace the stock piece that lowers the mounting point of the cylinder and moves the rod and boot away from the header for clearance.
Although the idea behind the Drop Bracket sounds good, it often causes problems which can cause damage to the frame, the power cylinder and cause loss of steering control.
You can see from these photos the difference in the power cylinder mounting point between the original factory bracket and the Drop Bracket. This relocation of the mounting point, and the basic design of the bracket itself, can cause the following problems:
1 ) Lowering the mounting point of the power cylinder increases the leverage on the bracket, which puts much more stress on the bracket and the mounting bolts. This causes the bracket to move and flex more than the original which may cause the welds to break, the bolts to tear out of the frame or the frame to actually tear out of the rail.
2 ) Lowering the mounting point of the cylinder rod on the bracket causes the rod end and the bushings it is mounted in to set on the bracket at a greater angle than the original bracket. This can cause the rod end to get chewed up by the hole in the bracket and the bushings to wear faster and fail. While the cylinder moves around a bit during turning and suspension compression, the rod end sits fairly perpendicular to the frame bracket. On the Drop Bracekt, it is constantly at an angle and normal operation will cause it to be at a greater angle than it was designed for. This is why occasionally the rod end will bend due to the increased stress and angle.
3 ) Although while driving, the power cylinder angle changes where it is mounted to the frame and the centerlink, these changes are not great with the original frame bracket and the cylinder stays fairly well level with the centerlink and frame. With the Drop Bracket, the cylinder is always pushing up on the centerlink during a left-hand turn and pulling down on the centerlink during a right-hand turn. This puts more stress on the cylinder swivel stud, the centerlink and the idler arm.
4 ) The mounting hole for the cylinder rod in the drop bracket does not have any cup or indentation to center and support the rubber bushings that insulate the rod from the frame bracket. This, along with the increased angle, causes the rod end to rub against the inside of the mounting hole, which will cut into and damage the rod.
All the header companies and suppliers seem to sell the same bracket. Though they vary in color and plating, they basically all seem to be constructed exactly the same. The extra holes and slots allow the bracket to be used on several car models, although early Mustangs are the most common recipient. In actual use, it has shown to be a poor design and has caused damage to countless cars. It is not the bracket that fails, it is the bracket being torn out of the frame rail or actually breaking the rail apart where the failure occurs. Until someone comes out with a better design, there is only one way to avoid the problems inherent in using a Drop Bracket - don't. Install "shortie" headers if at all possible and retain the original factory bracket.
Go HERE for information on the stock factory frame mount bracket and mounting parts
HERE is a good video clip of frame rail flexing when using a header drop bracket