While control arms might be considered the horizontal members of the front end, spindles would be the vertical member that ties the control arms together. Both upper and lower control arms attach themselves through ball joints to the spindle. This is a cast iron part where the machined “axle” is located. The wheel bearings and brake rotors are mounted to the axle, and the spindle also locates the brake caliper and tie rod end (steering). Steering knuckles are found on some late model trucks. They do exactly the same thing as a traditional spindle only there is no axle mounted in them. A hub center which has wheel bearings and wheel mounting hubs integrated together just bolts into the knuckle.
Steering Knuckles work on 4WD
This allows the OEMs to use the same casting (knuckle) for both 2WD and 4WD. Dropped spindles are simply spindle castings where the axle (or hub center) is moved up away from the lower ball joint. This lowers your truck by moving your wheel up in the fender well. There is a limit to how far you can move the axle up (you run out of casting), which is why you see most spindle applications drop about 2 inches. Precision is important when it comes to making spindles. DJM Spindles are machined on computer controlled mills and fit tested with wheel bearings and calipers before they get packaged for you. Drop spindles do a pretty good job of lowering especially the older axle type. If you just want a couple of inches drop for your 98 or older Chevy, spindles are hard to beat. You still need to watch out for wheel clearance and most drop spindles will not work on 4WD’s!
What about wheel clearance
In some cases you need to grind away material from the factory lower control arm to use drop spindles, in other cases you must buy at least 18” wheels or bigger just to mount the wheels and you
still will grind the exposed stud off the lower ball joint. Unfortunately this means you cannot use your factory spare on the front, which could be inconvenient. The spindles “sweet spot” is the amount of lowering you get when you using spindles alone. Often, to get more drop, a dropped coil spring is added to the mix. It accomplishes the purpose of additional lowering but you lose suspension travel (which reduces ride quality), lowered coils have a higher spring rate, (which reduces ride quality) and you usually need to replace your shock absorber with a shorter one (this could reduce ride quality) And all of this costs more. A spindle and spring combination will lower your truck, but pay attention to wheel clearance, alignment, and watch your ride quality. At some point the loss of suspension travel will get to you. The most popular and where spindles work best are S-10’s, C-10’s 88-98 Silverado’s and 92-99 C3500 OneTon’s and Dually’s.
See what others have done with drop spindles!