Rocky Road Outfitters' Spidertrax Birfield Rings

Nov. 01, 2005 By Adam Leach
Why a Birfield Ring?

"When did you bust your first Birfield?" It's a saying that marks a right-of-passage for all Samurai people. It's akin to a first kiss. Well maybe not. Those days might be over if newbies install this new ring. Spidertrax Birfield Rings from Rocky Road Outfitters (formerly known as Summit Off-Road) are a sure way to prevent those Suzuki Birfield joints from breaking.

These new Birfield Rings are a great stocking stuffer or last minute birthday gift that can't go wrong. They add necessary meat to your Birfield joints to help overcome this weak point. The product is a clean and good-looking, made from high quality chromoly steel and machined to optimize the strength of the Birfield joints. I was quite impressed when mine first arrived.

As many know, it does not take 33 inch tires to bust a Birfield joint on a Samurai. Even a stock 205/70 tire stuffed between the body and boulders can cause these weak links to crack, quickly ending a day of four-wheeling. As a long-time Samurai guy, I thought I would have to live with the Birfield busting and just replace them as needed.

It has become common knowledge to Suzuki four-wheelers that adding bigger tires causes more strain and stress to develop in the front Birfield joints. The worst situation -- for the Birfield joint -- is when a majority of the weight load is on the front tires and the wheels are turned hard to the left or right. This opens up the weakest part of the Birfield joint and almost always causes the joint to split open or "grenade". But this it not the only way to break a Birfield.

"When did you break your first Birfield," you ask? I was on the beach, of all places. I was totally flexed out and my front left tire was stuffed hard in the wheel well. I wanted to back up to get a better angle for a drop off of a sand dune. With the wheel straight, I applied a little gas, and POPOPOP! There went my first Birfield because of a stuffed tire, and the wheels were not even turned!

Some History and Theory

(As told by the guys from Spidertrax)

Before Spidertrax designed this product, Eddie Casanueva (one of the founders of Spidertrax) had broken six front axles -- always at the Birfield joint. Eddie is not alone. The Birfield is the weakest link of the front drive train and can make four-wheeling a Samurai rather expensive.

The problem of a broken Birfield is common among all Suzuki four-wheelers, especially those running front lockers and oversized tires. After studying many broken Birfield joints, it became apparent that it was always the outer race that would split open causing the Birfield joint to fail. The split always occurred at the thinnest point on the outer shell where the grooves for the ball bearings are machined.

The idea of the Birfield ring is simple; to add more material to the outer wall of the Birfield joint to prevent the joint from splitting. Design of the Birfield ring took time -- mainly due to the limited space available inside the front knuckles. With the space limited, Spidertrax chose to use a high grade of heat-treated alloy steel to ensure enough strength was achieved.

One of the tricks to the Birfield ring is the minimal grinding in the axle knuckle, allowing a significant increase in the size and thickness of the Birfield ring. The finished Birfield ring, when installed on the joint, increases the wall thickness of the thinnest point on the outer shell by 100%.

Before introducing this into the market, extensive testing was performed that produced more than normal stress to the front Birfield joints. The Birfield rings were tested on several vehicles (all with front lockers, low gearing, and 33" tires) over a course of two years. In that period of testing, not one Birfield ring or joint failed.

One extreme example was that of Eddie driving up a steep incline, backwards, with the rear drive shaft removed. In addition to being abrupt with the gas, Eddie was essentially trying to get something in the front end to fail. To the astonishment of a large group of four wheelers present that day, nothing broke.


Rocky Road Outfitters had them mailed to me lickety-split and Spidertrax assured me that they have done everything possible to make the assembly of the rings easy. When I was reading the directions for the first time, I was very scared that this project would be too hard. But not so.

Pressing the Birfield Ring into placeThe most difficult thing for most buyers will be where the assembly requires press-fitting the Birfield ring onto the Birfield joint. Maybe in the future it will be possible to buy new Birfields with the ring already pressed on; who knows? Luckily for me there is a machine shop nearby in my home town with some great guys who pressed both rings on for a total of only eight bucks.

Note: When pressing on the ring, use a lubricant and make sure that the ring comes all the way flush with the flat side of the Birfield.

The ring in place on the BirfieldNow that the hard part was done, it was time to complete the setup. I went home feeling happy because I knew that in a couple of minutes I would have the new joints in and everything assembled. I was hoping I would be able to race out to our local BLM recreation area and test the rings that day. Well, here is where you can learn from my mistake: When you pull your axles, take the wheel bearings and king pin bearings out, clean them and take a close look at the condition of all the bearings.

The Birfield Ring in place on the BirfieldHalf of my bearings were shot, so I had to wait about a week to get them replaced and installed. This is also a good time to change the rubber and felt seals that go around the outside of the knuckle, and clean up the rest of the disassembled parts from the grime of years of four-wheeling, giving them a good coat of Rustoleum.

After all that was taken care of, it was time to get cracking.

Grinding the inside of the knuckleThe next step took some thinking. To maximize the strength of the ring, minor (which does mean minor) grinding will be required inside the existing knuckle. Reading the provided instructions about which area to grind is sort of confusing, but once you've pulled the Birfield out, you will quite quickly realize what needs to be ground.

The areas that are to be ground are supposedly extra material formed from the casting process. To me, they look more like two pairs of parallel ridges that have been left over from the manufacturer machining the axle shaft hole and axle seal seat.

Inside the knuckle after grindingI used a simple stone grinding bit on the end of my household drill. A Dremel would have been the best tool for the job. Spidertrax assured me that "the grinding required will not weaken the strength of the knuckle," so I ground away. Grinding is necessary to provide clearance to allow for the most meat for the Birfield joint. I assume that not removing material from this area will cause the Birfield joint and ring to grind along the axle housing and possibly fail prematurely.

This is also a good time to replace your inner axle seals so they do not have to be done in the near future. Reassembly of the axle and steering knuckle is going to be a little different from now on. With a stock Samurai, it is possible to remove the axle and Birfield without removing the knuckle assembly. With the ring in place, the joint is physically bigger, so the Birfield and axle must be installed and or removed with the knuckle assembly disassembled. This is no big deal because nine times out of ten when a stock Birfield grenades, the whole assembly must be taken apart anyway. Thankfully, removing the knuckle adds only a couple of extra steps.

The assembled Birfield Ring and axleIt was finally time to hit the beach. I was very excited about these new rings and while spinning my front wheels down the soft sands of the beach I was imagining that the rings were making my 33's spin faster and handle better. Of course this was just my imagination and the rings would not have any effect here, but it was fun to imagine that anyway.

I got over to our "Mini-Rubicon" and had a go. I tried stuffing my tires and carefully backed out. Not a sound. I listened for grinding of the ring on the axle housing while turning hard and not a sound was made there either. If I had heard something, it would have meant that I would need to pull the axles apart again and re-grind the knuckle housing.


I have had these rings for almost three months of wheeling and daily driving. No problems, not that I expected any, anyway. They are a really nice piece of insurance and peace of mind while wheeling in the back-country. While a blown stock Birfield does not mean you are stranded and it is possible to drive out, it is a real big pain to keep changing them and its nice to know that under normal hardcore wheeling I am not going to bust a Birfield.

Inserting the axle in the knuckleThat said, it is also important to realize that it is probably not impossible to break a reinforced Birfield, or that something further down the driveline won't break. To avoid this it is very important to realize that one must avoid stuffing a front wheel into the wheel well. This is one way to make things in the driveline quickly break. A stuffed wheel in the wheel well has tons more grip that a wheel sitting on a flat rock, and the wheel well is not going to move in relation to the axle, wheel or truck. Something must give, and without a new Birfield ring, it's usually the old Birfield joint that gives out.

If you get a wheel stuffed hard, best thing to do (if the situation is safe enough) is pop the t-case into 2WD and adjust your position so that wheel is no longer stuffed, then adjust your line so the wheel will not get stuffed again. The nice thing about the Birfield rings is that sometimes you don't realize that a front wheel is stuck and a ring will keep a minor incident like this from ruining a good day of four-wheeling.

Contact Rocky Road Outfitters (see information at left) for your own set of Spidertrax Birfield Rings. Retail is about $62. Newsletter
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