Upgrading front axle

[GreenBomber]

I'd like to start gathering parts to swap out my stock 66 front axle so I can have the 30 spline shafts, large style knuckles and disc brakes.

What I want to know is if I can get a 30 spline 3rd member (I guess just the side gears are different?) use the axle shafts from a mini truck, along with the spindles, knuckles, hubs, etc. in my current housing?

If I want to do this swap with my current housing, do I need to buy gaskets for the newer style axle or older style?

I aks this because I can piece together this stuff as of now. I haven't seen a late model FJ40 axle with disc's complete, and I would assume that it would be expensive.

Last thing on my mind was gear ratios. Are the stock ratios year specific?

Any insight would be appreciated. Whate exactly are the differences between the coarse spline and fine spline axles? (Besides the spline count and shafts and side diff gears)

[BELMONT148]

Leave your 3rd member alone. Do the mini truck knuckle swap, with a knuckle service kit for a mini, and order a set of 30 spline axles set from Longs. Call it good, unless you want a locker, then you will need to remove the 3rd and install that. The side gears are already 30 spline, the splines inside the birf are 27 spline, and the splines going into the hub are coarse 7 spline or something like that. The 30 spline set gives you 30 splines from the side gears to the hubs.

Jeremy

[GreenBomber]

Oh wow, so the outer spines are only 10 spline, and the inners that go into the 3rd member are 30 spline?! That makes things a lot nicer.

Thanks for your quick, clear response. I was starting to get mixed up with all the things I been hearing.

[BELMONT148]

Actually I just caught that you have a 66', this should be ball and claw style axles, so you will need a new housing. It might be better for you to source a complete axle from somewhere.

[JJS]

I think the side gears in the '66 carrier are 10-spline.

[BELMONT148]

Hence my correction above.

[GreenBomber]

Awe man, you got me all excited. :(

Ugh so I gotta find a newer style axle. D'oh!!

[e rock]

Originally Posted by BELMONT148

Actually I just caught that you have a 66', this should be ball and claw style axles, so you will need a new housing.

NO YOU DON'T.



Everything will swap to your existing housing just like a standard DB swap, whether you get Cruiser stuff or MiniTruck stuff. In addition to the regular swap, you will need to get a set of inner shafts from a 68+ FJ40/55 and the differential side gears to match (or a locker, which replaces those side gears). Granted, it may be cheaper to just get a whole axle, but for me the minitruck parts were almost free by the time I parted the axle out and sold the leftovers. And I bought inner shafts and side gears from someone on here for cheap.

The axle rebuild kit will include new inner axle seals, which install in the place of the brass support bushings that are currently there.

Your steering may require a little work to figure out. There are too many variables to consider depending on how you choose to set yours up. I may be able to hook you up with my 'custom' setup from a minitruck swap soon, depending on when I get started on my SOA/PS work.

[GreenBomber]

My plan so far is this:
1) Get mini truck axle ~$150
2) Find side gears/locker and axle shafts ~$75
......
3) Get 4x4 Labs hysteer setup for large style knuckle stud pattern.

I have a SOA at the moment, so I would like to go ahead and upgrade everything before getting the hysteer setup. (Its at stock right now...eek)

Thanks E-Rock!

[camcruiser13]

get the 6 stud knuckles and 4x4 labs stuff, bullet proof

[Poser]

Originally Posted by e rock

NO YOU DON'T.



Everything will swap to your existing housing just like a standard DB swap, whether you get Cruiser stuff or MiniTruck stuff.

Well-


His current 1966 ball and claw front axle assembly will have bushings in place of the inner axle seals, and I know that people have talked about a seal that can be installed into the housing after the bushing is removed, but I have yet to see a part number for the seal, or pictures of anyone that has done this.






If it were me, I would try and locate a 1979 or later 40/55 series front axle assembly, as this would have the larger studs and bolt pattern on the knuckles from the get go.


You can easily find a drum brake front axle housing that has the inner axle seal instead of the bushings, and then simply swap the knuckles from the later 40 series, the 60 series or the solid axle mini truck parts onto it when you find them.


Your axle side gears in the differential will not be compatible with the later 30 spline axle shafts and will need to be swapped out with the later side gears.

[e rock]

Originally Posted by Poser

I have yet to see a part number for the seal, or pictures of anyone that has done this.

I'll take some pictures for you next time I have mine apart.

I spent a long time trying to find seals that will fit in the inner bore where the bushing sits before learning that the sealing surface is further out toward the knuckle. The seals I got are tiny and I still have 6 of them in my garage, but they're useless because the shaft isn't machined smooth there. The standard inner axle seals fit just fine in the outer machined surface of the bushing and line up with the sealing surface on the shaft. I'm not sure if the new Marlin seals would fit or not.

The point about the larger studs is valid, but then he'd need a whole new third member as well and possibly have to deal with driveshaft incompatibility.

Since his current housing is already set up for his SOA, and I assume he's happy with however it's set up, I think it makes sense to re-use his current housing.

[mustardfj40]

Originally Posted by camcruiser13

get the 6 stud knuckles and 4x4 labs stuff, bullet proof

x2! When I did mine there was no 6-shooter knucles otherwise I would go this route after seeing many broken studs...I would add the Longfield 30-spline superset...If you do all this you don't need a whole mini-truck axle, all you need is the wheel hubs and Aisin locking hubs, everything else is you will be replaced anyway such as new FJ60 rotors and 4Runner V6 braking calipers.

Oh and don't forget either ARP knucles studs and ARP hub studs...With an ARB locker you could spend up to 3 grands into your front axle by the time you finish

[wr-ecks]

sorry to jump in but....i have a very similar problem. i have the course spine stuff and a pretty tough 350 and im worried about breakin the axles. i hear they are very weak. i have a complete straight axle from an 83 minitruck sittin at a friends house (he borrowed some stuff when his broke) could it just be swapped under the fj?(the whole thing?)

[GreenBomber]

Well, I wasn't all that stoked on swapping housings, but, its that big of a deal.

I actually do not have a cut and turn on my current setup, but, I have flat springs, so its not that big of an issue.

I'm sure I'll find a front disc axle here soon enough and hopefully it will be close to me.

I just found a front axle from a 74 that I could go ahead and buy for $100... But, that involves buying another mini truck axle for $200. Would I be spending that anyways on a post 79 axle?

Lastly is my concern with gear ratios.... ugh.

[Degnol]

A '79> axle will have 3.70 gears in it.

[Poser]

Originally Posted by e rock

I'll take some pictures for you next time I have mine apart.

I spent a long time trying to find seals that will fit in the inner bore where the bushing sits before learning that the sealing surface is further out toward the knuckle. The seals I got are tiny and I still have 6 of them in my garage, but they're useless because the shaft isn't machined smooth there. The standard inner axle seals fit just fine in the outer machined surface of the bushing and line up with the sealing surface on the shaft. I'm not sure if the new Marlin seals would fit or not.

Pictures and part numbers would be great as this is something that has come up out here often enough that there is an unfinished thread in the FAQ about it….

Originally Posted by e rock

The point about the larger studs is valid, but then he'd need a whole new third member as well and possibly have to deal with driveshaft incompatibility.

He would be able to reuse his current differential center section/third member, provided he changes the side gears out for the 30 spline units.

Provided the proper inner axle seals can be installed to at least try and keep the gear oil out of the knuckle, then reusing his current front axle housing, swapping the disc brake knuckle components onto it, and modifying the inner knuckle ball area for the larger birfs to clear would be the best direction.

[Poser]

Originally Posted by GreenBomber

Lastly is my concern with gear ratios.... ugh.

It is not that big of a deal.....



Again, your current center section will work with the later 30 spline axle shafts, provided you change the axle side gears in your differential.....which have been offered up to you out here already...and is also something that you should not have a difficult time locating locally.


Post something up in the Wanted section.

[GreenBomber]

Ok, well, reguardless, I'll get a new axle, but, I can just keep the center section and replace the side gears and wont worry about ring and pinion gear changes. Sweet. Thanks for the clairfication!

Right now, it seems like the best option to just get a new housing and swap in my modified diff. I don't like the idea of modifiying the inside of the knuckles to accept the larger birfs, and then worry about the axle seals failing.

I can rebuild the new axle, and while its bare, go ahead and do a cut and turn, my neighbor is a fab/mechanic guy who can help me out... just gotta pay him with beer. :/

Guess I'll try the wanted section. Sure seems that finding a post 79 axle would be superb.

[JJS]

Originally Posted by BELMONT148

Hence my correction above.

You posted that entirely too fast for me.