I went to remove the brake calipers from my '91, expecting to find two 13mm bolts holding them on. Instead I find two small 12 point splined bolts. I pulled out my metric splined socket set, and it was smaller than my smallest 8 mm socket. I experimented around with 6 point sockets, and it looks to be 11/32". Does this sound right?

 

should be two 13mm 12 point bolts.... atleast that is what i have seen on a number of different xj's....

 

That is ok on my 87 it was a 7mm allen head to get the caliper pins out.

 

These are much smaller than 13 mm. The have rubber boots attached to them. Maybe these were some kind of aftermarket calipers. There are only three bolts per caliper, one where the brake line attaches, and these two with their rubber boots. It's just a real weird size with a small head. I have read every write up on them, and seen the youtube videos, and never saw this size bolt.

 

I can find something to fit it, I just want to make sure I am removing the right bolts.

 

If they're holding the calipers on, then they're the right bolts.

At least you had bolts. When I went to replace mine I found elmer's school glue and wrigley's spearmint gum fashioning it together.

 

most likely the bolts broke at some point ant the po replaced them with something else.