SWB Rear Rotors - 944 vs. Stock

[Neunelfer]

Hi Gang,

Some have been interested in the 944 rear rotor process. These are $149.00 each or you can have your local machine shop perform these mods for you.

The "red" circles are the new mounting holes. The 911 mounting holes are slightly further out than the 944 holes. We like to reindex the entire set of holes vs. milling over the top of the 944 holes. The "blue" circles are the 944 mounts. One of them is drilled out to make the new hand-brake star access hole:



Here's a look at the backside of the older 911 rotor. This one has developed cracks in the handbrake drum:



Here's the backside of the 944 rotor:



Only a very slight amount needs to be milled off the edge to make the outer diameter the same. On the last examples we received it actually made me wonder if it was needed. It seemed to be under 1mm. Here's a pair of the finished products:

[bob tilton]

Link saved to "technical reference" folder. Thanks Eric!

[super9064]

Is it really worth the trouble to drill and chamfer the disk, the wheel and lugs hold it in place. My understanding is that they are only there to keep it from falling on your foot while changing a tire. Am I missing something? I plan on doing this on my 68. The outer diameter needs to be reduced, as well, correct? Or is it just the inner portion that is used as the parking brake drum?

[Neunelfer]

They really aren't "all that" necessary. They are to hold the disc in place while setting the rear handbrake. You can accomplish the same with a couple open lugs.

Yes, as mentioned, the outer diameter needs to be slightly reduced. I'd almost like to bolt a set up and see how close it comes. It seemed to be under 1mm. Nothing on the inside.

[911quest]

Eric does material have to be machined off the e-brake drum or the rotor face itself?

[Neunelfer]

Eric does material have to be machined off the e-brake drum or the rotor face itself?

Nada... pretty straight forward that way.

[Bobs 67S]

Tony, that 944 rotor edge diameter is larger and looks like it will touch/hang up on the caliper when everything is bolted in place. If you turn the rotor to 285mm diameter the clearance will match the 1967 part. We used a brake drum lathe (with the cutting head facing in rather than out) to trim that outside edge. It left just enough of the wear indicators for them to be useful.

Eric, thanks for making these available. It sure is nice to have a alternate to the factory big buck item.

[Neunelfer]

My pleasure Bob... I like researching stuff like this.

The 944 rotor I got could have passsed for 285mm (almost). I'm sure someone has the details but, it was less than 1mm that needed to be shaved.

Has anyone tried it w/o shaving the edge? We shave them to 285mm but, it's hard to believe the caliper has that little clearance. I guess I was surprised at how little needed to be taken off the edge.

[Mudi]

I put my replacement 944 rotors on the S without the shave to the outer diameter. Works fine.. Certainly cheaper than the oem part number.