In order to fit 18 inch wheels on your p400 defender, the rear calipers must be either replaced with smaller calipers or the ribs must be shaven off. This quick write up shows you what was involved with shaving the rear calipers on our own defender. It’s a cheap mod that can be done fairly quickly. Please view each picture for a more detailed description of that step.Be sure to use safety stands anytime the vehicle is lifted. Safety glasses AND face shield are a must as the debri from grinding is coarse and can cause a serious eye injury. Basic tools are required for the job. I won’t go over the basics of removing the wheels and proper jacking of the vehicle as it is assumed you should know this before tackling a project of this type.
DISCLAIMER: MODIFICATIONS OF ANY KIND WILL VOID YOUR FACTORY WARRANTY IN REGARDS TO THE COMPONENTS AND SYSTEM THAT IS BEING MODIFIED. MODIFICATIONS TO YOUR VEHICLE MAY OR MAY NOT BE LEGAL IN YOUR COUNTRY OR STATE. WE ARE NOT LIABLE FOR ANY DAMAGES DONE TO YOUR VEHICLE, PERSONAL INJURIES, OR ANY LAWS VIOLATED. THIS IS SIMPLY A WRITE UP OF HOW WE DID OUR VEHICLE. IF YOU WISH TO PURSUE THIS MODIFICATION, YOU ASSUME ALL RISKS.
The sanding disk used was a 40 grit for the initial grinding. It will remove material quite quickly with a grinder but will leave deep sanding marks. Once enough material is removed, an 80 grit sanding disk was used to give it a better finish.
Here I used a venier caliper to mark 1/4 of an inch.
Here’s a rough outline up to where the sanding will be. Notice the slight curve towards the bottom of the rib (marked by the red line). You’ll want the rib to merge flush towards the red line.
Begin at the front of the caliper towards the bottom of the rib (marked by the red arrows). Work your way inwards smoothing out the area and flattening out as much as you can up to the 1/4″ line (marked with black sharpie).
Once done, it should look something like this. Be sure to blow out all shavings from the pads, caliper and around the hub with compressed air. Any debri left in between the pad and rotor can cause a squealing while braking and potentially cause damage to the rotor.
Test fit your wheel to check caliper to wheel clearance. You should have at least a 2mm gap. If not, keep grinding. Put the transmission in neutral with the parking brake disengaged and spin the wheel. Make sure there is no rubbing. Due to different wheel designs and offsets, you may need to grind more. This will be dependent on your wheel. Also, be aware of the clearance needed to install the wheel weights. More than likely they will have to be installed towards the outside of the wheel. In some extreme cases you may need to use beads instead of wheel weights. Consult with your tire shop for this.
Before With OEM
Here is how it looked before with the oem 20 inch wheels.
After With Shavings:
Here’s how they look after shaving down.
Here’s our defender p400 test fitting 18 inch wheels and 34.5″ tires. No more fear of sharp rocks.