Belltech drop spindles

Drop spindles are the only way to lower the front without adding more bump steer.  But until very recently, no one offered them for the 97-03 F150.  In 2005, Belltech came to the rescue.

But not without great criticism and controversy.  First, despite Belltech's claim that the spindles do not alter stock geometry, they do.  Dropping the axle without moving anything else creates a larger scrub axis.  For reference, the steering axis inclination (SAI) is approximately 13º on both the stock and Belltech spindles.  Using my eyeballs, a straightedge, a level, and a measuring tape, none of the other measurements except axle height have changed.

At the tread surface of a 295/45-18, the distance between the face of the hub and where the SAI intersects with the road surface is approximately 3.5".   With a 5.8" backspace, I figure that's about a 5." offset.  So I approximate a 3" scrub radius with the stock spindles.  According to Tex Arcana, the SR increases to 3.5" with a 2" axle drop.  That's huge.  Most cars run less than 1" of SR.

But the bigger issue is that even if the minimum wheel diameter -- 18" -- is used, the lower ball joints must be trimmed and special thin nuts used, which makes the use of a cotter pin impossible.  The photo below shows the clearance when mocked up on a bench with 01-02 stock wheels.

For reference with other wheels, my (rough) measurements are that the 01-02 wheels are 17 5/8" ID at the inner edge, tapering down to 16 5/8" at the hub face.  Note also that the .59" gap is measured at the center and closes up at the edges of the nut due to the curvature of the wheel.

These thin nuts were the subject of much controversy on the Lightning boards.  The Belltech nuts do not have a provision for locking (the supplied internal star washer is a joke).  Additionally, some felt that the nuts are too small to handle the stress.  The Belltech nuts are jam nuts, which are intended to be used only in sheer -- not tension -- applications.

Those who do not like the thin nut solution recommend making a 0.100" to .125" countersink (radiused to prevent stress raisers) in the surface where the nut attaches.  This will allow for the use of the full-sized castellated nut, a washer, and cotter pin.

Those who feel that the Belltech nut is sufficient make the counterpoint that cutting the spindle may weaken it.  They also point out that the actual thread gripping surface (the part not cut with cotter pin grooves) of the stock nut was not much more than the Belltech thin nut.  Here is a comparison of the stock (silver) nut, the Belltech jam nut, and the nut supplied with Moog ball joints:

They are all hardened.  The rough measurements are as follows:

* .14" of the castellated portion of the Moog joint is also threaded, and there is about half in contact with the stud.  That area is threaded on the stock nut, but it does not actually contact the ball joint stud.

After much hand wringing, I decided that I am more comfortable milling the spindle than relying on a non-locking jam nut in a tension application.

The Moog nuts are .63" tall, which means that they are only .04" too big (at the center) to fit the .59" gap using the 01-02 wheels.  The stock nuts would just about fit, but leave almost no clearance.  I wanted to use the beefier nuts.

Note that Belltech supplies some spindles already machined on their face (the "t"-shaped cut in the image to the left).  They have removed .100" from the entire bottom of the spindle.  Those should be good to bolt on and go.  But what was Belltech thinking creating a massive stress raiser with that sharp inside edge?  I prefer just doing a circular countersink.

Note also that the circular .100" countersink shown in this photo was added by the purchaser.  And like the Belltech cut, a potentially dangerous stress raiser was left on the inside corner of the countersink.  While it's true that ductile iron is not as sensitive to stress raisers as a more brittle material, might as well do it right.  A more proper cut is .100" like shown, but with the inside corner radiused to prevent creating a failure point.

That being said, I could not find a machine shop that could do the chamfer.  The best that I could do was a .125" X 1.200 simple countersink.  That will accommodate the Moog nut just barely on its OD, with .085" room to spare on top of the nut for a washer, and a little room to spare so as to not scrape the wheel when changing.

For the stock nut, a .050-.075" deep and 1.1" diameter countersink should work fine (again, using measurements for 01-02 wheels).

If you use the Belltech nuts, Loctite is a must.  Safety wire would also be a good idea.  Madferraristi from NLOC came up with the design at the left.  Its a great idea, but seems like a hassle to get the washer right, and then have to re-cut it if the nut needs tightening after initial installation.

To cut the ball joint stud, torque the joint to the spindle.  Take a chisel and strike the threads at the end of the nut to make a guide mark for cutting.  I used a cut-off wheel, then dressed the cut on a fine grinder, then a belt sander.

I then reinstalled and marked the end of stud for the 1/8" cotter pin hole.  I then countersunk the cotter pin hole for ease of pin installation and chased the threads with a die.  Since I used Moog joints, I also masked off the boot, clean them with acetone, and shot them with black paint to ward off rust (the Moogs rust quickly if unprotected).

I took the opportunity to replace the wheel bearings while I was at it.  NAPA sells quality S&K bearing and race sets for a reasonable price:

Outer - NAPA part # BR12 (S&K JL69349 brg, JL69310 race)

Inner - NAPA part # BR11 (S&K LM12749 brg, LM12710 race)

The final insult is that Belltech apparently drilled the tie rods on the wrong side of the knuckle.  The first version (left) mounts the tie rod from above, while the revised version mounts the tie rod from below:

To minimize bump steer, the rule of thumb (and it's just a rule of thumb, not an accurate measurement) is that the tie rod should be parallel to the lower control arm.  Under is more parallel.

This photo comparing the stock to Belltech spindles is proof positive that the tie rod-over configuration was a manufacturing error.

But the tie rod ends have a taper -- approximately .55 to .70".  So I couldn't just flip the tie rods.  I had to bore out the hole for a straight bolt.  Because of the .70" large end of the taper, the bolt must be 3/4".  That's a huge heim, pretty much the largest available.  But given the questionable lifespan of heims, bigger is better.  The only downsides are weight (no big deal) and the thickness of the larger heim might interfere with minimizing bump steer.  No way to know for sure without measuring.

Bullet Proof Steering has very heavy duty tie rods with uber-high-quality spherical bearings (AKA "heim joints").  A BPS tie rod is shown below compared to stock.

More standard racer parts (QA1 rod ends, standard aluminum tubes) are available from Stock Car Products.  The conversion requires 4 heims, 4 center bolts, 4 jam nuts, 2 tie rods, and washers/spacers for the center bolts.  Note the trick upper washers from BPS.  They are designed to keep the tie rod from falling off if the joint fails.

I bought the BPS system based on 16.5" center-to-center.  The cost was just under $400.  The BPS tie rods weigh about 4 lbs. each versus 2.5 for the stockers.

The tie rods are pretty close to parallel.  I know that the bump steer is reduced greatly from my previous spring drop, but without measuring the BS, I can't say for sure that it's eliminated.  There is plenty of room left to shim the wheel end of the tie rod down to make it more parallel, but again, there's no way to know for sure whether that would increase or decrease BS without actually measuring it.

The Belltech spindles increased my turning radius substantially.  What used to be 3.5 turns lock-to-lock is now 2.5.  But other Belltech spindle users report the full steering travel.

I'm hitting the steering stops dead on the money, so I can't explain the difference.  It's great by me, though, as routing the brake ducts is now longer a problem.  With full travel, the inside edge of the tires used to hit the ducts.