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The following write-up is a review of the new All-Pro spindle arm gussets.

After I contacted Jon Bundrant out at All-Pro to express my interest in this product, he volunteered to send me one of the prototype sets that was made in their shop, prior to sending the design out to the laser cutter for production. Production is apparently underway, and these will be coming out shortly.

I received these yesterday, and I installed them this morning.

Before I show the installation, however, I'd like to mention a few things about why I think this is a good part to upgrade and why this is the way to do it.

Why reinforce the upper spindle arm?

At first, it may seem odd that the upper spindle arm can get damaged. It certainly seemed odd to me, at any rate, when I first heard about people bending them.

The steering knuckle on the independent front suspension (IFS) FJ Cruiser is attached to the upper control arm (UCA) and also to the lower control arm (LCA) with ball joints. One of the interesting things about a spherical ball joint is that it's impossible to "lever" across it in any direction. It can only transmit push and pull along the axis of whatever links to it.

How, then, can you bend a part that has a spherical ball joint at each end? That configuration *should* create a situation in which the part in between the joints only gets pushed and pulled. Lateral forces *should* be neutralized and therefore there should be no bending. It should therefore be IMPOSSIBLE to bend the spindle arm, because the knuckle is captured between ball joints... right?


There are a couple of additional factors.

First off, the spindle arm is NOT STRAIGHT. It's a complicated curved shape. Direct in-line tension and compression, therefore, CAUSES bending due to the curvature.

Second, the wheel is attached in the middle, between the ball joints! The wheel potentially takes LARGE FORCES pushing inward and outward (like when driving sidehill or putting a wheel up onto an obstacle or when coming down hard on one wheel). These forces are opposed by the fixation of the knuckle at each end... at the ball joints. The knuckle can therefore be loaded with a substantial bending force across the upper spindle arm.

Granted, most of the weight of the vehicle is transferred through the springs to the lower control arm and then to the wheel and hub, "bypassing" the knuckle. As the front suspension cycles, the main job of the joints which contain the knuckle is to orient the wheel correctly, relative to the rest of the car. However, when we drive offroad, we put that part TO WORK! Keeping the wheel oriented becomes much more of a structural challenge.

The fact is, people BEND spindle arms. The stock design is ok for 90% of uses, but for those of us who explore the 10% that exceeds it's capabilities, we need to start looking at that part and developing a plan.

How do we reinforce the upper spindle arm?

For solid front axles, there are widely utilized design standards which allow for upgrade parts to be marketable to a large number of end users with similar systems. The "Dana 60 king pin style" axle, for example is a design standard that many companies build off of, and the steering knuckle options are numerous. The stock knuckle is cast iron. Upgraded heavy duty cast iron versions are available as well as cast steel alloys and even welded parts... and that's just the knuckle.

The D60 king pin design has been around for decades, and many companies make parts that are interchangeable with the Dana axles or make axles with identical configurations. For this reason, aftermarket knuckles are widely used. However, nobody is making an upgrade knuckle for our FJ Cruiser IFS system at present. As popular as our vehicles currently are, upgrades for this system are not likely to be useful on other rigs. FJ Cruisers upgrades, at this time, represent a small niche market. For this reason, with respect to our steering knuckles, the existing part has to be the basis of any upgrades. This generally means that to get a stronger spindle arm requires constructing a spindle arm gusset.

Gusseting the spindle arm on IFS knuckles is not a new concept. Homebrew solutions abound. Typically, this involves shaping a piece of angle iron and welding it in place. However, for some well established popular IFS rigs, companies have developed spindle arm gusset kits. These require welding.

Why not design a bolt-on part?

The problem with the concept of a bolt-on reinforcement is that bolts are likely to concentrate force. In order to make a part that reinforces the existing knuckle with bolt-on methodology, the bolts would all have to be in existing holes (unless you think you can drill holes into the part and end up with a stronger part!). The reinforcing part would then have to be designed in a way for it to not interfere with existing components, carry a portion of the load, and NOT TRANSFER THE LOAD TO LOCATIONS UNABLE TO HANDLE IT!

That's a lot of engineering and manufacturing. That's basically the equivalent of manufacturing an upgraded knuckle.

What I'm saying is that it ain't gonna happen.

On the other hand, welding is an IDEAL method for reinforcing the knuckle. Welding allows us to add metal in a way that distributes the attachment along a broad zone, transferring load evenly instead of concentrating it at bolts. Welding allows an inexpensive upgrade part to be made which can be designed to so that it affixes to all and only those places that require reinforcement. Through welding, the existing knuckle can be upgraded in a way that makes it adequate for a heavier level of abuse, and if a failure is avoided, then we've saved money. Maybe a lot!

Remember... when parts break, they often destroy OTHER parts in the process.

The All-Pro spindle arm gusset:

I received the parts by way of the usual UPS delivery, with the following oddity:

My forum identity is on the package! How cool is THAT!? :D

Inside, there were the two spindle arm gussets:

Here's a closeup:

The construction is made from 1/8" plate steel. They're apparently cut to shape, drilled with the various holes, and then bent into final position on a sheet metal break. The upper corners are bent together but not yet welded. This needs to be incorporated into the final weld plan.

Mine are obviously prototypes. The edges show tool marks. They're not yet the laser cut versions, but the design has been worked out. There were still Sharpie marker measurements and the note, "good" on them. I presume that this means they were destined for "Goodman" ... me. ;)

I toyed with the idea of trying to weld them on "in situ", meaning that I'd try to leave the knuckles on the vehicle during installation, but then I quickly abandoned this idea since I wanted to get a good amount of metal prep done before the weld. I needed the knuckles off of the vehicle.

Here is the disassembly down to the knuckle. The wheel is off, as are the brake caliper and rotor, the spindle nut has been removed as well as the hub. In this picture, the wire that connects to the front hub sender still needs to be detatched:

Here are some parts to consider:

The red arrows point to the ball joints at the top and bottom of the knuckle assembly. The yellow bracket shows the upper spindle arm. The green arrow shows the steering arm with the steering drag link still attached. In the center, without any arrow, you can see the end of the front CV axle sticking out, now totally free of attachments. Along the upper spindle arm, you can see where the sway bar link is attached, too.

When the wheel levers on the hub and axle, you can see here how that would tend to put a bending force on the spindle arm.

As I disassembled the system, I came across this failure-in-progress in my sway bar link:

This is a failure that I believed myself to be immune to, because I don't do high speed desert driving. I'm glad I found out about it *THIS* way instead of through complete failure. It suggests to me that I ride these parts harder than I may have originally anticipated. The upgrade parts are already ordered. ;)

Here is the knuckle, taken down to where nothing else is attached other than the grease seal that the axle rides in:

I learned about ANOTHER failure in progress at this point. The seal had eroded. One of the garter springs had eaten through it's own lip:

I have not serviced this side, although the opposite side has seen a disassembly for the purpose of replacing a broken CV axle. I presumed (it turns out correctly) failure on the other side as well, and got two of these, the appropriate seals. These need to be acquirred at a Toyota parts department because they are not yet released to places like Napa or Autozone:

Of note, I left the seals IN for the time of welding. I checked them out during and after the welds. The heat transfer was minimal. Had I not needed to replace these seals, then the welding operation would NOT have damaged them further and the knuckles could have gone back in with the previous seals intact.

I tested the fit-up of the parts and it was pretty darn good. There was some gapping along the complex curve shape where the gusset meets up against the spindle arm, but it was well within the zone that would be incorporated into the weld. When I fit-up parts, I gap them on purpose to facilitate weld penetration. These were within my specifications.

The bend at the top, however, did not align the plate steel adequately with the top of the spindle arm. There was a small angular mismatch. The gusset has been bent to a right angle, but it sits slightly off of this. I was easily able to customize the shape by clamping it with a large C-clamp. Once shaped, it fit quite well:

I prepped the metal with an 80 grit flapwheel sanding disk in an angle grinder:

Then I inspected the fit up one last time before tacking it together:

My welding machine allows for some very useful control variations.

There is an integrated welding guide for optimizing the settings relative to the thickness of the metal, the welding wire size, and the shielding gas:

Additionally, I like to set some post flow on the shielding gas in a number of situations. In this case, I wanted to be able to flow shielding gas until the cherry red spot dissipated, and I also wanted to be able to have continuous shielding gas going, even if there were breif breaks in the weld due to the complex curvature of the shape causing me to geek and lose my arc.

I set for 0.5 seconds of post flow. That means that for a half a second after the trigger is released, the gas continues to flow. This is ample time for me to get the weld restarted in a still-molten weld pool, if I lose my arc. It's also about the duration of the cherry red spot in 1/8" metal, in my experience.

Here is the finalized weld on the passenger side gusset:

Here is the finalized weld on the driver's side gusset:

I gave them a couple of coats of Krylon:

Here is the passenger side and driver's side knuckles going back in after the seals were replaced (I popped the old ones out with a few taps using a brass punch and then tapped the new ones in directly:

Various notes for potential installers:

Other than the welder and associated stuff, I used an air impact wrench with 17, 19, 21 and 22 mm sockets, a couple of 1/2" drive ratchet wrenches, a 12 mm box end wrench, a 17 mm box end wrench, and a needle nose pliers for the cotter pins in the spindle nut retainer and the steering arm castle nut. I pulled the steering drag link using a 3 jaw puller, and I found use for a ball peen hammer a couple of times. I used a 5 mm allen wrench to unscrew the socket head cap screw holding the wheel sender into the knuckle, and I used a standard screwdriver to unsnap the electrical wire.

When you get down to the knuckle, the major attachments are the taper-fit connector at the upper ball joint, the taper fit connector at the steering drag link and the two bolts in the bottom of the knuckle that take a 19mm socket. The bolts on the bottom are easy. The UCA balljoint taper connector is pretty tight, but the spring in the coilover is working FOR you. The trick to opening this up is to loosen the nut on the bottom PART WAY, and then tap on the flat in the front of the end of the spindle arm with a hammer. This will shock-free the taper and the mechanism will fall open onto the nut, which you've wisely left in place. However... DETATCH THE STEERING LINK FIRST!! The reason is that the knuckle is still stabilized by its other connections. I used a 3 jaw puller since I didn't want to muck up the rubber boot with a fork-type separator. Break the steering link free, but leave it attached. Then break the upper spindle arm balljoint taper free, and leave it attached. THEN take the bottom bolts and unscrew all the rest.

I tend to clean parts with brake cleaner as I go, along with prior to welds. I also like to use a wire wheel in an angle grinder on metal after I weld it.

It's important to have a good floor jack and jack stands. The floor jack needs to be used to move the LCA up and down when you're taking apart or putting together the front suspension.

It's helpful to be able to activate my front air locker when it comes time to tighten the front spindle nut. If you can't get the axle to stop turning by putting the vehicle into 4 low with an open diff, then you'll need to grab a lever and put it betwen some of the wheel studs and get someone to oppose your tightening torque.

This is a more advanced modification than just installing front coilovers or doing a body mount chop. Nevertheless, if you can do both of those, then you can do this one too. This should probably NOT be the first structural weld that you do with a new welding machine. If you get surprised by the behavior of your welder, you'll be really bummed out. This is not a weld that would be easy to re-do! I would advocate to be stance-ready before starting the weld. Make sure that you're comfortable and that you can follow the whole course of the intended weld with the tip of the gun before you strike arc. The curvatures in the weld mean that the angulation of the tip needs to be constantly changing in order to keep the angle relative to the weld pool constant. This is a little tough. If you can't do it in one continuous push, do it in sections. Whatever you do, DON'T settle for a marginal weld.


This is a well made part that looks like it will susbtantially reduce the risk of an upper spindle arm deformation.

I consider it to be a good insurance policy!

I'm going to go test these in the morning. More to follow. :)
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