Rear Vented Rotors, Big Tires, Clearance Issues, Options for installing as much tire as you can with vented rotors... Options

[Eric_Shea]

This should be an important thread for those looking to get as much tire under the rear using vented rotors.

If you want to install vented rotors on a 914 you have a couple of options:

1. Pony up about $600.00 to have a pair of 914-6/GT rotors imported from Porsche DE. They're still available.

2. Put a 5mm rotor spacer under the hat of a 911 rotor. Our vented rear caliper kits come with a set of these spacers. If you want to cram as much meat under your rear fender (and a lot of us do) this will eat into 5mm of your tire space.

3. Put 5mm spacers underneath the caliper mounting ears. This will now have your calipers rubbing right up against the handbrake adjustment tube on most cars (some there is no issue).

4. Try a 944 rear rotor but, you would have to mill 2.5mm off the caliper and the mounting ears (spread the 5mm distance between the two) because the offset is too far out.

I finally dug into this today as I tried a set of 944 rotors for fit. No go. I wasn't about to mill my factory 914-6/GT calipers either. Next...

I could buy the 914-6/GT rotors. While $600.00 is a tad much for a pair of rotors, it's not that much in the grand scheme of things.

While I was under the car trying the 944 rotors I decided to see if my arms would work with the calipers spaced back. It fit but, it was rubbing on the arm where the handbrake adjustment tube is welded through the arm. I was only a few short steps away from solving this problem and then I could use a more affordable 911 rear rotor. I ended up getting out a bur grinder and finishing the edges of the handbrake arm tube. There was easily 5mm there to grind off and the bur grinder made short work of it.

(IMG:http://www.914world.com/bbs2/uploads_offsite/hphotos-snc3.fbcdn.net-1110-1269819442.1.jpg)

Here's the area that needed to be ground down:

(IMG:http://www.914world.com/bbs2/uploads_offsite/hphotos-snc3.fbcdn.net-1110-1269819442.2.jpg)

Here's the bur at work. If you do this on freshly powdercoated arms, make sure you put layers and layers of duct tape down first. I didn't have any and the bur "will" jump and nick the arms. Better yet, hopefully you'll see this thread "before" you powdercoat your arms and do this then:

(IMG:http://www.914world.com/bbs2/uploads_offsite/photos-a.ak.fbcdn.net-1110-1269819442.3.jpg)

Basically 1/2 way there on this side:

(IMG:http://www.914world.com/bbs2/uploads_offsite/photos-f.ak.fbcdn.net-1110-1269819442.4.jpg)

With the grinding work done, I needed to protect the metal:

(IMG:http://www.914world.com/bbs2/uploads_offsite/photos-f.ak.fbcdn.net-1110-1269819443.5.jpg)

I used a Testors paint marker and laid it on thick:

(IMG:http://www.914world.com/bbs2/uploads_offsite/hphotos-snc3.fbcdn.net-1110-1269819443.6.jpg)

Done:

(IMG:http://www.914world.com/bbs2/uploads_offsite/hphotos-snc3.fbcdn.net-1110-1269819443.7.jpg)

The calipers mounted up perfectly. I actually had two different spacer combinations on the car. about 4.8mm on the drivers side and a full 5mm on the passengers side:

(IMG:http://www.914world.com/bbs2/uploads_offsite/hphotos-snc3.fbcdn.net-1110-1269819443.8.jpg)

Here you see the spacers under the mounting ear. Basically "washers" in various thicknesses. The Ferrari factory did the same thing to make up for manufacturing differences on their mounts... not a problem:

(IMG:http://www.914world.com/bbs2/uploads_offsite/photos-d.ak.fbcdn.net-1110-1269819443.9.jpg)

Wheels are mounted back on:

(IMG:http://www.914world.com/bbs2/uploads_offsite/hphotos-snc3.fbcdn.net-1110-1269819444.10.jpg)

And I'm keeping my fingers crossed that this much meat will actually fit under the car now! LOL

(IMG:http://www.914world.com/bbs2/uploads_offsite/photos-c.ak.fbcdn.net-1110-1269819444.11.jpg)