Consistent with my other experiences with the FJ40, there is always something new to learn. After researching the brake cylinder rebuild process a bit more I decided to give it a go. I thought my worst case would be that I over hone the bore rendering the cylinder unusable and have to buy a new one. At $5 per cylinder rebuild kit, it seemed like a reasonable enough first step. A quick call to Napa and the next day I picked up a couple of rebuild kits so I could do both cylinders on the affected wheel. My plan was to do the other front wheel next weekend. So, this morning I cleaned up a bit of the gunga off the backing plate.
While cleaning out the old grime it was clear that the soft brake hose had seen its better days and was over due for replacement.
With the leaking cylinder out, it was time to lay out the parts and take a picture for help out in the reassembly later on. It was about this time that I noticed that the cylinder from my truck had more replaceable rubber parts than where in my rebuild kit.
Some researching on the net and reading of the brakes section of the Body and Chassis manual and I learn that this cylinder is not for the front brakes, but for the rear. Front brakes have a single piston and a cylinder bore of 1 1/4" and the rear brakes have dual pistons and a cylinder bore of 7/8". My FJ40 is running rear brake cylinders up front.
A quick check of the cylinders on the rear brakes confirms that their bore size is appropriate for an axle from an FJ55, they are stamped with 15/16.
Not knowing if my "wrong size cylinder" problem was limited to just the one leaking cylinder I removed all four from the front and sure enough the are all sized to be on the rear brakes.
Despite the comfort I got from knowing the cylinders were all the same size and knowing that consistency is generally a good thing - I'm not sure it is a good idea to run the rear cylinders up front even though it appears it can be done.
Another quick call to Napa and they have all four front cylinders at their warehouse. They are on the way to my local store and I'll pick up on Monday if I get out of the office early enough. With a bit of luck, I'll find the time to get them installed, bleed the system and drive the 40 to the meeting on Wednesday.