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Pritchet Canyon
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21 Road
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Gillespie Gulch
Gillespie Gulch - Gillespie Gulch 2004 Movie 11.3MB

Truck Modifications - February 7, 2005

  • Chromoly FJ80 Birfields

I had some worn birfields that didn't last long with my new 40's. I busted both of them at Carnage Canyon. This was the first time I have ever broke a birfield on the trail. I've done 21 Road, Billings, even broke a rear axle but never have I ever broke a birfield! I do admit I was doing lines I have never done in my 80 before and was pushing it to the limits that day. Funny thing is the only thing that broke was the inner cage holding the balls in place. I wish they would just make those cages more beefy. Here are some pics of what you can expect to see after breaking a birfield. Notice all the gear oil has mixed with the moly grease making a soupy mess. Yes those are the steel balls inside my knuckle. The cage was diced into little bits.

The timing couldn't have been better because the next Monday Bobby Long at LongfieldSuperAxles.com finally received their new FJ80 chromoly birfields. No other vendor has ever made chromoly birfields and I wanted to be one of the first to try them out :) So here are some pictures of these bad boys side by side next to my stock birfs.

I hope you can see which one is the chromoly one in the pictures above :) Looking at the overall dimensions these things appear identical. Same bell diameter, same size balls, same cage thickness. I had a spare birf lying around for camparison. The bell housing even looked exactly the same thickness. One thing for sure is the cage appears to cover more area than stock. Notice how the cage extends outward past where the stock one is tappered off. Bobby says the cage is made out of 300M material.

Also notice that if you want to keep using your front ABS system you need to take off the old teeth ring and press it on the chromoly birf. I decided to not re-use mine because my old ring was all chewed up. NOTE: If you don't install this ring your ABS will not work and the ABS light will be on even in high range since the sensor depends on that ring to function.

The install went very smoothly. I took the inner axle out of my spare birfs and pushed them into the chromoly axle. They snapped right in perfectly. I am very impressed so far with these birfields. I haven't done any real hard core wheeling on them yet but tomorrow I'm going back to carnage to test them out.

Some Advice - When you brake a birfield don't just wheel home on it. Not only are you chewing up the insides of your knuckle every time you steer but there are times when you literally can't steer in one direction or the other which can be very dangerous on the road. Even if you take off your front drive shaft and take off your hub covers your still gonna do damage by turning those wheels back and forth. You have all sorts of sharp metal in there plus the balls all getting in the way and binding up the knuckle.

Other Comments - I have questioned a lot of 80 owners who have broken at least one birfield and they all say it's the cage that goes. I'm not even sure anyone has ever broke the bell housing on an 80. Christo has broke an inner axle before but not the bell. I can see why they decided to stick with the same thickness bell and balls and focus on the cage. And with 4344 chromoly steel these have gotta hold up a lot better than a stock birfield. I'll let everyone know if/when I brake one of these :) Until then I'm gonna have some fun wheeling on 40's!!

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