Do any of you know at what tire size birfields really start breaking? What tire size limit would you put on stock fj40 axles? Thanks.

mostly anything over 35'tires are really hard on Birfields - obviously it is impacted by many factors, such as lockers, engine power, gearing, etc and last but not least, driving style. Many recommend backing the bumpstops all the way out as a way of limiting stress at steering lock positions. The other thing I have heard is that the short side tends to break more than the long side - maybe it has to do with the longer axle being able to "take-up" sudden torque situations <IMG SRC="smilies/confused.gif" border="0">

From my own experience, they started bustin'
back when I had 33" TSL's & an ARB <IMG SRC="smilies/frown.gif" border="0"> If you
can forsee yourself ridin' 4+ trails & have
a tendancy to "gas it", don't spend your hard
earned $$$ fixin' up an LC front axle. I
wished someone had pounded this into my head
years ago <IMG SRC="smilies/mad.gif" border="0"> <IMG SRC="smilies/beer.gif" border="0">

So far, 3 birfields and one 2nd gen newfield with 33x12.5 Swamper Radials. One 2nd gen newfield with 38.5x14.5 Swamper SX's.

4th Gen newfields in there now....3 HARD trips and no breakage...

There is no magical tire size....just situations!

They can realy break with any setup if you wheel a lot. the biggest contributor to breakage is a locker. then tire size. If you have open difs it is pretty hard to break them with anything smaller than 33's.

when I get within 5 feet of them <IMG SRC="smilies/biggrin.gif" border="0">

The other thing I have heard is that the short side tends to break more than the long side - maybe it has to do with the longer axle being able to "take-up" sudden torque situations

Yep. Everyone of my breaks were short side
& mostly in a binded situation (between rocks
or in a hole) <IMG SRC="smilies/mad.gif" border="0"> One time I sheared the
inner shaft & the birf. was okay <IMG SRC="smilies/confused.gif" border="0">

Is there a difference in the 79 vrs. 76 outer. I might be able to pick up some 79 birfields for spares, but heard they were a tad longer and would not work with my Selectro hubs? Can someone clarify this?

Is there a difference in the 79 vrs. 76 outer. I might be able to pick up some 79 birfields for spares, but heard they were a tad longer and would not work with my Selectro hubs? Can someone clarify this?

Yes, the '79 birfs are a little shorter &
therefore would not provide enough spline
engagement w/your '76 hubs. <IMG SRC="smilies/beer.gif" border="0">

Pretty much when you start a thread about them. :flipoff2:

Is there a difference in the 79 vrs. 76 outer. I might be able to pick up some 79 birfields for spares, but heard they were a tad longer and would not work with my Selectro hubs? Can someone clarify this?

Pick up a set of the stronger Asain hubs and you can run all the 79+ birfs. (light grind in axel housing, well documented on the web) The 79+ are a bit stronger as OE.

Mark

This is some old sh!t. Who dug up this thread?:D

Pick up a set of the stronger Asain hubs and you can run all the 79+ birfs. (light grind in axel housing, well documented on the web) The 79+ are a bit stronger as OE.


The Aisin hubs are definitely the way to go. My 40 had Warn hubs and when I put minitruck birfs in the axle I didn't have the money to get new Aisin hubs. If you have Warn hubs you can still run them with '79 or later cruiser/minitruck birfs if you just use a washer/bolt in the end of the birf instead of the snap ring.

try backing up over volkswagen rock with the locker on , :nuke:
did not really know it till buck island tho , it siezed up there.
I say the front locker is the worst punisher.

" When do birfields start breakin' "


Right after you hit the key...


Last one of the three that I broke was on the starter...


I like to run my junk, not pull a wrench on it while on the trail.


They suck, period.