I am trying to convert my 1970 Dodge challenger front disc brakes to the larger 11.75 inch rotors. I changed my spindles out using a set from a 1973 challenger, but my problem is that when I mount the bearings and rotor The rotor will not slide on far enough to install the cotter pin in the outside opening of the spindle. I have checked several times and tried two different rotor manufacturers and can’t seem to figure out what I am doing wrong. The inner bearings are the 1 3/8” and slide all the way back on the spindle, they are Timken SET17s. It seems like the rotors don’t go back far enough because I mounted the caliper and it was pretty far to one side of the caliper brackets. Has anyone run into this situation before?

Those don't look like factory 11.75 rotors, they look more like a C body rotor with a longer nose. Could be junk Chinese rotors. When I was doing brake kits I used to keep an original factory 11.75 rotor on hand to use for checking dimensions. The rotors from China were garbage. The ones made in Mexico usually fit okay but were not high quality. The highest quality rotors came from Canada. Here is a picture of an 11.75 rotor that fits. Look at the shape and you'll see that it is very different than the rotor that you have.

I had similar issue, lip on the repo dust shield was too large.
Once I trimmed that down, it all fit.

BDW,

That was it, you hit the nail on the head, I was re-using the 1970 dust shield from the 10.87 rotors and the new 11.75 rotors were hitting the center lip and not letting them slide all the way back!! Thanks, I was about to buy another set of inner bearings thinking the Timkens were too large. Crazy, I could not tell from spinning the rotor that it was not set all the way back on the bearing and was riding on the flange. Thanks again!

Thanks Andy, I was thinking the same thing and bought another set of rotors hoping that would solve my issue, but they did the same thing.

As im doing the same to a 72 cuda and using dic-o -tec article. They call out dimensions of the spindle length. check article, and dimension and make sure yours are ok ?? My problem is (posted question in corning forum) I have a tall spindle and small caliper brackets. Check article for info. My help. Sure need help on mine Someone please read my question in other forum.

Glad you got it fixed. I never thought of the shield as being the problem, I haven't seen that before. The factory shield should clear the factory rotors but anything is possible with offshore rotors. I've learned that the hard way several times.

That happens when '70-'72 splash shields are paired with '73 and newer rotors.

Ah, that was the problem. I guess I just assumed that the OP changed over to the late model shields when he installed the late model knuckles and rotors but evidently he didn't do that. Bad assumption on my part. (and his)