I have a 1966 fj40 that I dont know much about and am curious about what kind of axles it has. I read somewhere that cruiser axles this old dont have birfields, if this is true does this mean that the axles are weaker or not as good or what? How big of tires can i go up to on these axles and what can i do to make them stronger? Tell me anything else i need to know about these axles too please since i dont know much. Thanks in advanced!
1966 axles? (1 Viewer)
- Thread starter i<3fj40's
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i<3fj40's said:
The rear axle housing is the same as other FJ40s except I think the shock mount is in a different spot, but I can't remember how it's different. The axle shafts are 10-spline, so they aren't as strong as the later (post-68 or so) 30-spline shafts, but still decently strong. If you're worried about them, the newer ones will interchange if you swap out the spider gears in the diff to match.
The front axle is a unique creature. The housing is completely unique, but the third member is the same as newer cruisers. It doesn't have birfields; it has ball joints. In the knuckle, there's a brass(?) ball with 2 longitudinal circumferential grooves perpendicular to one another. The inner and outer axles have two-pronged 'forks' that engage the grooves on the ball. They're supposed to be weaker than birfields, but I've never broken one and haven't ever heard of anyone breaking one either. I would be interested in knowing what actually fails; I have my own guesses, but no experience. There's basically no practical way to make the front any stronger short of having your stock shafts cryo-treated - waste of money for this axle IMO.
The biggest drawback is that there is no (AFAIK) way to convert the front to disk brakes. I currently run 33" MTs and have wheeled them pretty hard with no issues. I just recently got a locker up front, but haven't tried to break it yet
Eric
the ball joint isn't the problem...it's the course spline that usually fails.
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I have the 10 spline axles in two of my rigs and LOVE THEM. Size matters too. The 10 spline are MUCH BIGGER SPLINES. The shafts and the spiders NEVER get the kind of wear that the fine spline ones do. I have only seen one 10 spline rear axleshaft fail, and it was behind a V-8.
I had a buddy that ran them for 10 years behind his big block 396 with no problems. He would still be running them now if he hadn't sold the rig.
MAF and JTO now offer disc brake kits for the drum spindle front axles. The shafts will not matter to the kit.
So it's up to you.
I had a buddy that ran them for 10 years behind his big block 396 with no problems. He would still be running them now if he hadn't sold the rig.
MAF and JTO now offer disc brake kits for the drum spindle front axles. The shafts will not matter to the kit.
So it's up to you.
Depends really how you use your rig. I would recommend running it until you find its' limit and can't live with it anymore. Then start worrying about upgrading.
I ran that axle with no locker and 33x12.5 Super Swampers for a number of years. I had to replace the housing because I bent it (40's tend to land with a thud), but other than that, never a problem with the guts.
I ran that axle with no locker and 33x12.5 Super Swampers for a number of years. I had to replace the housing because I bent it (40's tend to land with a thud), but other than that, never a problem with the guts.
65swb45 said:
ARE YOU ON CRACK!
First off, size dose matter, and larger spline count with smaller splines is better. This decreases the stress concentration on the axle shaft. When you run smaller spline count with bigger splines you are in essence necking down the axle at the splines. This creates a huge stress concentration at this point the axle shaft leaving your axle shaft much weaker.
This is common knowledge in the 4x4 world. That is why spline count is so talked about.
I personally would not bother buying a locker for these axles. Just weld up the rear spiders and get some fine spline replacement on hand for when they go.
As for the front, get a drum front end as people are practically giving them away.
e rock said:The biggest drawback is that there is no (AFAIK) way to convert the front to disk brakes. I currently run 33" MTs and have wheeled them pretty hard with no issues. I just recently got a locker up front, but haven't tried to break it yet
Eric
You actually can convert the ball joint style axle to disk brakes using the mini truck swap. My 68 had ball joints and I did the mini conversion. You have to pull the brass seal out of the housing (kind of a pain) and put an actual seal in there. As with other cruiser axles, you have to grind the knuckle a bit to get the bigger birfs to fit. I think you have to grind a little bit more than a birfield axle, but it will work. That also of course leads to you having to get fine spline inner shafts wihich then leads to having to get fine spline gears for the diff, or a whole new diff. I would say convert it over to mini disks and run it.
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Thanks for all the infor so far guys. Do you think I can run 35's with stock axles? or will i be at high risk of breaking axles verytime i offroad? Also if i do break a axle shaft can i just replace it with a new 30 spline shaft? Thanks once again.
you will need 30 spline spider gears.
