Accepted Answer

Hi,
On the rear of the Lincoln LS the calipers have twisting pistons in order to incorporate the parking brake system.
Because of this, to compress the piston during pad replacement, you need one of two special tools to twist the piston back into the caliper.

The first is a square block with nubs on it that engage the two indents on the face of the piston. Use it with a ratchet to twist the piston in. This tool is relatively easy to work with, but sometimes pops out and can be aggravating. This tool usually costs between $5 and $20 depending on manufacturer.
It is pictured here:

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The second option is a piston compressor, which mounts on the caliper and twists the piston in with the use of a wrench or a T handle as pictured. While much more expensive, this tool does not have the "falling off" problem of the less expensive tool, as it locks into the caliper during use. This tool usually costs between $40 and $100 depending on manufacturer.
It is pictured here:

	View Full Image

If you have further questions feel free to ask. Please be sure to click Accept when you are done to give credit for my response.
Thanks!

Expert:	Doug C
Pos. Feedback:	100.0 %
Accepts:
Answered:	10/24/2009

ASE Certified Technician

16 years automotive and OTR repair including specialized training from Toyota and Mitsubishi