I've been looking at the Tera BB Kit for some time but thought I was aced out because I have Spyntec hubs. Thanks to another Forum member I learned the BB Kit could be made to work by simply machining the center hole out to match the Spyntec hub. Nothing ventured, nothing gained, so I rolled the dice and ordered the kit, along with the larger bore master cylinder Tera is also offering.
First off, the Tera stuff is stout, 70 lbs of dual piston caliper & 13", slotted rotor. Regarding the latter, what really helps is that Tera has them made with both the 5x5 and 5x5.5" bolt pattern. The snag was that the rotors were made to work on the JKs unit bearing, held in pace by the wheel, not on a manual hub center, held in place by pressed in wheel studs. A call to Matt at Spyntec got the center hole size of their JK hub, 4.005".
Off to the machine shop, Pete's Paint & Body. Pete Lovett is a local car hero, hot rodder, Cobra body repair guru and just knows his stuff. I dropped them off, gave him the spec and left him to work his magic. He chucked them into his lathe using the center hat, indexed to center off the existing center hole. Couple hours later they were ready, slick as you please. He was a bit concerned about one, which he said had about .050 runout. He corrected it best he could. I checked the holes later and he was basically dead on spec.
Ok, so today was the day. I put the Jake on stands, pulled the front wheels and decided to work one complete side at a time. With the first side stripped out I put the assembly on my little shop press to pop out the studs:
Here's what the hub looks like without the rotor. If you do this you must be uber careful with the reluctor fins on the inner hub. I managed NOT to screw any of them up.
So, with the hub stripped of it's rotor I laid everything out so you can see the differences. I was surprised to see that the Spyntec rotor also had both bolt patterns. Spyntec says in the kit bill of materials that they use a Raybestos 3552, which I learned is the stock rotor for a late CJ7. But, I have a hunch that was not the case with my Spyntecs. More below. One point to mention, if you do this be sure to ask your machinist to put a slight chamfer on the inner edge of the hole to clear the Spyntec hub's radius. I didn't and had to do some work with a Dremel to get the rotors to seat flush:
Ok, now here was my leap of faith. The wheel stud holes in the standard Spyntec rotor are just drilled through leaving a square flat surface to seat the studs. (Note: Although Spyntec says they use a Raybestos 3552, when I looked up the specs fro that rotor it didn't come with a dual bolt pattern, and it only had a 3.75" center hole. Looking more closely at them today it appears Spyntec used a standard JK rotor and drilled it fro 5x5.5", plus opened the center hole to 4.005".)
I discovered that the back side of the bolt holes on the Teraflex rotors had been countersunk. This means the wheel studs would have to be pressed down into them, seating on a chamfer. This was almost a show stopper for me, but after measuring everything there appeared to be plenty of meat for the stud heads to seat on. The studs actually only protrude a bit more out the hub face side, maybe 1mm, due to tolerance stack-up:
Ok, so here we go, let's press the studs in. I drove them in part way with a brass hammer to align the knurls, then GENTLY pressed them into the assembly in a star, criss cross pattern to ensure the rotor seated perfectly flat to the hub face. Screw this up and you'll have vertical runout and rotor wobble. (Bear in mind, I was gambling the outer faces of the rotor hats were square to the machined surfaces of the rotors. THEY WERE!! Take me to the casino!) I also had to be sure the studs were pressed into the countersinks as flush as they could go, so I probably pressed them in in four total cycles.
Here's the assembled hub & rotor, ready to button up.
Here one of them is, installed, caliper & pads in and bled. I won't get into too much detail on this part, Teraflex's Dennis Wood had a great video on the installation that covers this all in detail.
BTW, this was the rotor Pete had been concerned about re: runout, and sure enough once it was installed in one spot the outer edge was rubbing a caliper casting bump. A small bit of Dremel work on the caliper and the issue was fixed.
Here's the same side with the wheel on.
A quick pressure bled and we were off for a test drive. One thing for sure, not only did everything line up and fit, they work GREAT, and no chatter, wobbles, pedal pulsation, etc. I had installed the Teraflex big bore master cylinder on Monday, so I got a feel for the standard brakes with the added fluid movement. The dual piston calipers ate up a bit of the reduced pedal travel I'd noticed, but not to worry, the thing stops like NOW!
Where I got really lucky was that as I mentioned above, the rotor hat outer faces are perfectly aligned with the machined surfaces of the rotors. If they hadn't been I'd have had to have the assemblies machined to the hub centers. Sometimes you do just get lucky.
Wrote this up just to show that it can be done relatively easily. This is not for the inexperienced to tackle, but you can pull your hub & rotor assemblies and have your machinist cut the holes and press in the studs for you. If your running Spyntecs with 35"+ this is really worth looking into. Hope Teraflex takes this into account and offers a special rotor just for the Spyntecs. That's all you'd need to make this a bolt-on.