Hellfire Knuckles for FJ80 Land Cruiser Axles

The Hellfire knuckles provide the missing link to add hi steer to the strong, wide FJ80 front axle.

FJ80 axles have had very few options if you wanted high steer. You could get some expensive right hand drive steering arms and...not too much else.

The FJ80 front is also an ideal axle for many swaps - it's wide, has big Birfields, and is still relatively easy to find.

So, we're going to take a look at the new Hellfire FJ80 knuckles and how they fit in with building one the the strongest Toy solid axles possible.

Table of Contents

  • Toyota Land Cruiser FJ80 and FZJ80 Chromoly Birfield Axle Guide and Comparison

  • Hellfire Knuckles for FJ80s - Driver Outer
    Put the Toyota shims away! These knuckles use a set screw for bearing preload adjustment. Yes, shimless adjustment!

    This knuckles has a lot going for it. It's had a couple of iterations now to make it great, and it's undoubtedly the strongest Toyota knuckle that you can buy.

    You need to buy a full hi steer kit that includes several parts that are designed to work together:

    • Two FJ80 Hellfire Knuckles
    • Two High Steer Arms
    • 25mm Upper and Lower Trunnion Bearings
    • Two 25mm Lower Bearing Caps
    • Eight 1/2" Dana 60 Chromoly Studs and Nuts
    • Twelve 1/2" Allen Head Bolts
    • Two Set Screws with Jam Nuts

    If you're wondering:

    No, it will not fit your FJ40, FJ60 axle, or any other Toyota axle besides an FJ80.


    Because the FJ80 uses the largest Birfield, and thus has the largest knuckle ball, of any Toyota. You can't fit a huge knuckle on a little knuckle ball.

    Of course, that's what makes the FJ80 axle so great - it has the largest knuckle balls of any Toyota because it needs to accommodate the largest birfields of all the Toyotas.

    If you're routinely breaking chromoly or 300M Birfs in a smaller-knuckle, smaller-Birfield Toyota, you should look at upgrading to the FJ80 axle.

    Hellfire Knuckles for FJ80s - Knuckles with Steering Arms
    The knuckles are cast and go through an intense machining process.

    About the Hellfire Knuckles

    So, these are undoubtedly the strongest Toyota knuckles available.

    Let's see how:

    First things first. Land Cruiser 80 Series knuckles are larger than any other Toyota knuckle since they need to encompass a larger Birfield. In theory, this makes them stronger than other factory knuckles. These knuckles then add:

    • Huge, heavy, thick knuckle casting: For everyone but the most extreme wheelers, cracked knuckles should be a thing of the past. Take a look just at the steering arm mounting surface!
    • Six steering arm studs that are larger than stock: There are now 6 studs per steering arm instead of the stock 4. 4 of them are chromoly Grade 10.9 Dana 60 studs and 2 are 1/2" Grade 14 Allen heads.
    • Steering arm studs have wider spacing: While other 6 stud Toyota knuckles use the factory stud spacing, these space the studs out to reduce the possibility of loosening.
    • Oversize trunnion bearings: It's been long recognized that a 25mm bearing with matching pins is much stronger than the stock setup. Stock Toyota knuckle bearings have a 20mm ID and this is matched by the steering arm and lower trunnion cap pins.

    The Hellfire knuckles are cast and machined in the USA.

    Hellfire High Steer FJ80 Steering Arms

    Hellfire Fabworks Six Stud FJ80 Knuckle and Installed Steering Arm
    These six-hole FJ80 knuckles have a larger bolt pattern, use 4 Dana 60 studs, and two allen head bolts to secure the steering arm.

    The steering arms that come in the Hellfire kit are also huge. The arms are 1.25" thick and come set up for FJ80 tie rod ends. There is plenty of material to ream them for GM 1 ton TREs or 3/4" heims.

    While it's not useful to most of us, it's pretty cool to see that both the right and left side arms are machined with drag link holes. This means that you can use these arms with a right-hand or left-hand drive vehicle.

    Here are a couple of additional measurements:

    • Trunnion center to tie rod hole center: 5 1/4"
    • Trunnion center to drag link hole center: 7 3/8"

    Other FJ80 Knuckle Improvements

    Hellfire Knuckles for FJ80s - Knuckle Components
    You also get an automatic upgrade to a 25mm trunnion pin. With the heavier, thicker casting, you can't get much stronger.

    These have shimless adjustment. Adjusting shims in a regular Toyota knuckle is kind of a pain and often requires that you need to install and remove the steering arms at least a couple of times to get the right preload.

    With these knuckles, preload is now set with a set screw - no more messing with shims! It should make installs a little less painless. You'll still need a fish scale, but you won't need to torque and retorque stud nuts a thousand times.

    The lower bearing cap is also counterbored to sink the bolt heads into the cap. This provides plenty of protection for guys that like to ram rocks up against the underside of the knuckle!

    Hellfire Knuckle Installation

    Hellfire Knuckles for FJ80s - Steering Arm
    The steering arms are specific to the knuckles and come in the kit. They're tapered for FJ80 tie rod ends. For more options, you can ream them yourself to fit the GM 1 ton tie rod ends or heims.

    The installation is pretty standard with standard Toy knuckle tools, with a couple of exceptions.

    The tool list looks like:

    • 10, 12, 14, 17, and 19mm sockets
    • 3/8 Allen wrench
    • Adjustable wrench
    • 54mm hub socket
    • Flat head screwdriver
    • Fish scale

    You need to install these knuckles via the "Camo" method. Because of the thickness of the casting, you likely won't be able to fit the Birfield bell through the new knuckle. RuffStuff has a video where they do an install with what looks like stock axleshafts with the knuckle installed, but we'd count on using the Camo method.

    Basically, you install the axleshaft into the axle housing, Birfield and all, then you install the knuckle on over it. This also saves a lot of time on the trail over conventional disassembly/reassembly.

    You might have a hard time finding these instructions. These are the full instructions from the Pirate 4x4 Toyota FAQ:

    Camo Method for Changing a Birfield Quickly

    • Pull locking hub cap and remove snap ring.
    • Unbolt seal/felts on back of knuckle.
    • Unbolt brake caliper and tie out of the way. (can be skipped if you have long brake lines)
    • Unbolt steering arm. (leave bottom knuckle cap alone)
    • Pull entire outer knuckle assembly off of axle.
    • Swap in your parts.
    • Put it back together.

    (It's a big-time shortcut since you don't need to mess with the 54mm socket or wheel bearings.)

    Why the FJ80 Axle Is Great

    You might not know that the FJ80 axle is a great axle for solid axle swaps. The lack of a high steer kit held it back, but the shackles are off!

    Let's run down a few of the specs and why the high steer kit makes it better:

    • 63.5" wide WMS-to-WMS: This is 8" wider than a stock solid axle Toyota and 5" wider than a solid axle with IFS hubs.
    • Chromoly/300M axle shafts are available. RCV even offers a 30 spline option where the star and the inner axle mate.
    • Some come with a factory electric locker.
    • It has a high pinion 8" diff. The diff is swappable with other Toyota 8" diffs in minis and 4Runners. The reverse cut gears are stronger than a standard gearset.
    • It comes from the factory with low steer. But now you can add high steer with the Hellfire Knuckle Kit.
    • It has full time 4WD. You can run drive slugs (factory), a part-time kit, or try to get other Toy hubs to fit. Lots of options.

    The 80 axle has always looked like an ideal axle for a Toyota axle swap. The pre-1986 mini and and 4Runner axles were always a little too narrow for people and it seemed like lots of us were very frustrated that we didn't have another option besides spacers and IFS hubs.

    The FJ80 front axle always looked like a good contender, but the tie rod was low and the drag link angle was high.

    Caveats and Gotchas

    Hellfire Knuckles for FJ80s - Knuckles Set
    These knuckles are the 2nd generation. The 1st Gen knuckles had a few bugs, but everything has been worked out in this version.

    First, these knuckles only work on 1991-1997 FJ80/FZJ80 axles. They don't fit smaller axles.

    Second, most normal people are going to be using this kit on a lifted 80 or a SAS swap into a Tacoma or other pickup/4Runner. But if you're using this on stock suspension on an 80, the kit won't fit without moving the track bar. This is almost not worth mentioning, but if you get excited and want to slap this kit on your 80 as the first part of your build, it won't work.

    That said, we'd expect that most people that are considering installing this kit have the means and the know-how to relocate suspension and steering parts to keep everything from interfering.

    Hellfire Knuckles for FJ80s - Passenger Outer
    You can see here the wide bolt pattern that uses 6 fasteners to secure the steering arm to the new knuckle.

    Third, you can kiss your ABS goodbye. Although some FJ80 chromoly axleshafts can take an ABS tone ring, they won't fit with these knuckles.

    This probably doesn't really matter anyway:

    Many wheelers will be installing chromoly axleshafts. For a street-driven rig, chromoly will wear faster than the stock axles because the fulltime four wheel drive always keeps the front axle shafts spinning. (And chromoly is softer than the stock axleshaft material.) To get around the wear issue, some people install a part time kit in an 80 or locking hubs in other rigs without the 80 transfer case.

    However, the ABS sensors require the axleshafts to spin for the ABS to work - you can't have part-time 4WD and ABS.

    So, the takeaway is:

    You can't use ABS with these knuckles, but you probably wouldn't use it anyway if you have front locking hubs.


Tyler Branham

Tyler came out of the womb with a Birfield in one hand and a stick of 6010 in the other, ready to weld any piece of trail-busted steel back together. He has wheeled, broken, and modified a variety of rigs, from Toyotas to Jeeps to Fords to Chevies. He likes doing long distance overland travel and would happily spend every night in the bed of a pickup under the stars.

Last updated: September 5, 2019