The Savvy/Vanco Brake Install: Making Room for The New Hotness
Let's start this out with a quick recap: after getting rid of the stock front brakes we're ready to start getting the Vanco system bolted on. Well, maybe not entirely
ready...but almost. First, we have to bolt in the new knuckles and replace the axle shafts, and then we need to make some room for the not-quite-bolt-on rotors.
It's easy to tell from the photos of the knuckle in the first installment that there's a LOT of machining and fitting that's already taken place...but the machining and fitting isn't quite
over with, yet: Vanco and Savvy have done a lot but we've still got a bit to do on our
end with our
specific Jeep. This is where the confusing picture that I showed at the end of the last installment comes into play. However, some of you might not have realized that it could be a confusing picture, and the slower members of the class are probably wondering if there's a chicken hidden in it somewhere (there isn't). Let's show it again and then explain what's easily missed by telling you The Question That You Should Be Asking.
The Question That You Should Be Asking: "Why - if you're only doing a front brake job - do you have the Jeep on four jack stands?"
Answer: "Because we're going to reduce the diameter of the unit bearings while they're rotating. Duh."
Translation: "We're going to have Greta suspended on jack stands, running, in-gear, and spinning her front axles in four-wheel drive while we're blithely taking a grinder to them...and we're probably going to get seriously injured while doing it. Duh."
Read that last sentence again, because I'm not kidding about it: most of what follows is exceptionally dangerous even after taking the proper precautions, so if you try this and accidentally die it's totally
your own stupid fault. However, if you want to do some metal surgery and get it exact
without access to a full-bore machine shop, this is a good way to go about it. More on that in a minute, though...first, the new knuckles. They seat easily but it's a good idea to use a deadblow hammer to settle them before you torque down their castle nuts.
After the new knuckle gets installed the stock axle shafts and still-attached unit bearings can slide back into place over the factory debris shields. The shields themselves looked horrid when they came off but they cleaned up pretty well. We shot them with some black paint anyway, just to make them a bit prettier. A lot of people ditch their debris shields when they do these conversions, but you have to be careful when doing something like this due to tolerance stacking.
Valuable Information: Rotor, caliper and saddle castings may vary slightly in thickness even after final machining. Additionally, the Vanco kit only has about 1/8" of clearance on either side between the saddle and the rotor faces, but this 1/8" is normally more than enough to prevent any interference. If the rotor and saddle are slightly thick, however, the elimination of the debris shield may shift your caliper saddle too close to the outside edge of the rotor and cause one to drag against the other. Either leave the debris shield in place or add spacers of the proper thickness in place of the shield.
It's good to be careful when re-installing the shafts: we gave the splines a once over and then Annabelle directed the shaft itself back into place. Andrew provided the motive power while safely off-camera because he thankfully had the foresight to not intercede into what has to be The Best Picture of Axle-Shaft Installation in The Entire History of The World, and because of this each and every one of you needs to send him a thank-you card. I bought mine earlier at Hallmark.
Once the shafts were in place we torqued in the 12-point flange bolts...and right about that time is when life got downright dangerous. Before we started seriously
trying to injure ourselves, though, we had to have some manner of reference line scribed into place to help us know when we'd reduced the unit bearing diameter by the correct amount . To do that, I borrowed a trick from the painter's studio:
Notice the blurred wheel studs: the unit bearing is in motion...as in, "rotating." It's moving because we started the engine, slipped the t-case into four-high and let the clutch out slowly to see how we were looking. When there were no problems, I braced a torque wrench across my knee and the front arm of the knuckle and touched a Sharpie to the rotating surface in order to make a reference line. If you ever do this, here's a tip: it doesn't matter where the line is, exactly, because you're just using it as a visual guide to determine how much material has been removed. Speaking of material removal, let's address another concern, quickly:
Why We're Grinding The Unit Bearings:
The hats of the new rotors do not allow a direct fitment onto the stock unit bearings because the interior of the rotor hat is just incrementally
smaller than the exterior of the unit bearing diameter. In scientific jargon this condition is called "so d*** close that we shouldn't have to f*** around with it." However, "close" still didn't fit so the unit bearings would have to go under the knife. In the end we had to reduce the diameter of the unit bearings by close to 1/16". Now, several of you have probably already deduced that this particular cat can be skinned in more than one fashion. Thus, it's worth asking ourselves another
Why are we doing such an incredibly f****** stupid thing? Can't this be done in a safe manner?!?!
Yes, it can be done in a much
safer manner, but I'm overly obsessed with perfection at all the wrong times. You can perform the entirety of the surgery on the unit bearings without the axles turning under the engine's power: from either side, all you need to do is have someone manually turn the opposite hub, which thereby allows an equal and reasonably-accurate scribe/grind around the length of the unit-bearing's perimeter.
Basically, you're creating a slow, manual lathe. However: I wanted mine as close to perfect as possible so we used Greta's axles like a built-in powered lathe and applied the marker to the rotating metal exactly as you would in a machine shop. Later, we applied the grinder in the same manner. Here's a close-up view of the scribing process...
And here's the completed reference line.
Remember that quip I threw in about people becoming the reason for warning labels? Right about this time the warning label on tractor driveshafts that says "Danger - Rotating Driveline - Avoid Entanglement" was going through my head. But the rotors weren't going to fit themselves, so...time to f*** up some metal.
Valuable Information: I've found that when I'm working with rotating stock it's often easier to look away from the area in which the tool is working because my eyes can get distracted by all the movement. Thus, I kept the grinder lower than the apparent horizon of the unit bearing edge, which consequently let me keep everything flat and perpendicular to the faces...and that can be a serious challenge when working with a flexible flap wheel. However, using a softer surface slows down the metal removal process - you're basically sanding it off rather than grinding it - and this helps you to not remove too much. Again, Savvy's suggestions prove to be exactingly accurate.
Here's a good view of the tool placement.
You'll also have to grind a bevel on the edge of the unit bearing face in order to clear a chamfer on the interior of the rotor hat. The grinder can get VERY close to the rotating wheel studs at this point.
We kind of overdid it here, but it's better take a bit more off at the bevel than risk an out-of-alignment rotor when we're working so hard to prevent one by grinding the unit bearings in such manner in the first place. This next view shows rotation and the proper angle of the grinder against the edge. 45 degrees is optimal...anything close will work. Also, shiny metal...
Removing the metal with a flap wheel - even a 40-grit one - is about a ten minute process...and the entirety of it is done in an uncomfortable position. You can tire rapidly, and working in this kind of situation is NOT something you do when you're tired. Annabelle took over when I stepped back for a quick break, and the result is about sixteen different kinds of sexiness all wrapped up in one picture...
I think she deserves a thank-you card, too.
That's all for tonight...but stay tuned. There's a lot more shiny metal where this came from.