FJ40 Rear to a Steer- axle build (1 Viewer)

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i don't know if this is truly hardcore tech but then i don't think too many stock FJ40 guys would want to do this either. if yall want to move it though it won't hurt my feelings any. I have no idea if what i did with this is right or even a good idea, i just kinda pulled it out of my azz as i went lol.

i've been wanting a 80 series width front axle for a long time but i wanted to be able to re-use as many of the parts that i've invested in my 40 front axle over the years- 6-shooter knuckes, longfields, detroit. I had heard of someone turning a rear axle into a front axle but never could find any thread about it, i know people have done it before though. i did some rough measurments and it looked like i could make an axle 8" wider than a stock 40 front if i cut the 40 rear axle right behind the brake plates. I had a set of axles laying around that i took out of my FJ55 so i stripped them down and got to work.

first thing i did was tear the rear axle all the way down and cleaned all the brackets off of it. then i cut the ends off flush with the brake plates with a chop saw.

i had to cut new notches for the ring gear so i cut the front diff cover off and then plasma'd the flange off the donor front axle to use it as a template, then i cut that ring up and used it to patch up the old ring gear slots on the new axle. i also decided to flip the axle so i wouldn't have to shave the drain plug and i can also use the old plug as a fill hole and also my vent. i took the plug and drilled and taped the middle of it for a bellows vent.

the ring off the front axle






i wanted to truss the axle before i welded knuckle balls to it so i made this jig to try and keep it from warping. i also put the 3rd back in it and filled it up with old oil to try and keep it cool. i also decided to flip it so i wouldn't have to shave the drain plug and i can use it now as a fill plug and my axle vent.







after i got finished trussing it i cut the brake plates off flush against up against them, again with a chop saw.

the truss-


After i got done with the truss it was time to work on the front axle some. Before i took the knuckle balls out i took a tape measure and got exact measurments from the inner axle seal surface to the side gear of my detroit on each side. i did this several times.


after that i cut the knuckle balls out and tried to put them in the rear axle....Oops, they didn't fit like i thought they would, too big. i tried to clearance the inside of axle tubes with a flap wheel but it didn't work. i wound up getting a buddy to machine the balls down a hair and press them in for me. i got my pinion angle where i wanted it and welded them on. i dont know if it was a good idea but i also drilled two holes top and bottom in the axle tube and made plug welds to the knuckle balls.

so then, i put my 3rd member in and got new measurements from the inner axle seal to the side gears of the detroit. i subtracted the original measurment from that one and i called up Bobby Long and ordered new inner axles for that amount longer then stock. i got him to make them about a 1/4 longer than my measurements and also to make the splines a little longer than normal just in case i had to adjust them. i also sent him my R&P for heat and cryo treating.

after that i reinforced the knuckleballs top and bottom put the knuckles, brakes etc on, welded up shock, link, and limiting strap brackets, added bump stop pads, built a mount for the ram and put a blue torch diff cover on it. i've been driving it for about a week now and plan to test it on the rocks this weekend at Morris Mt. in alabama. Wish me Luck!

i'll try and get a finished pic tonight.

This was a LONG project for me and could have gone horribly wrong at any point (and may still yet?) If this axle housing doesn't work out for some reason or another i WILL be buying a RuffStuff housing- i wouldn't do it again for anything!
 
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What did you use to cut the balls off? Just a grinder with a cut off wheel?
10-4

here's some pics of it finished






the final width wound up being 65.25....my rear axle is a 60 series with 2" wheel spacers putting it at 63"
 
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Interesting approach. You say that you had heard of others doing it before?

How much shorter do you think could you have reasonable made it by finessing the fit of the knuckles and the housing?


Mark...
 
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How much shorter do you think could you have reasonable made it by finessing the fit of the knuckles and the housing?
Mark...
not sure what your asking me here? if you mean how much narrower i could have made it? there's almost exactly 4" to play with on each side.

i tested it pretty good yesterday with no issues so-far!
 

orangefj45

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that looks like a helluva project and a lotta work. i like it, always good to see some tinkering that's a little different.

did you think about using dave's ( 4-plus ) axle extensions to widen the housing?

georg
 
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Thanks Georg......i actually did consider the extensions but if you think about it they are just as much work except for notching the housing for the ring-gear (which is no big deal with a plasma cutter). and the extensions imo add more opportunity to get things misaligned. and i'm cheap and already had the housings laying around.
 
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well i've run into the first problem with my custom axle housing. I experienced my first Longfield failure in about 7-8 years of running them. Sheared the splines off of a inner-axle where it meets the birf. Anyway when i pulled the shafts out the grease in my knuckles was fawking soup, both inneraxle seals are leaking like a mofo. I'm guessing that my knuckleballs got off just a hair when i welded them on. I'm trying some if those marlin crawler superseals next, if that don't work then i'm thinking i will probably going to have to get some custom seals made that fit into the diff end of the axle tube.

Btw, the breakage happened during the ECORS endurance race at DGP in NC a couple of weekends ago when i came around a corner going 30-40 mph probably and there was another racer (my teammate and friend :doh:) backed off the course on the outside of the curve. We bumped front tires, i bounced off and kept going, found out after the race that it tore his dana 60 knuckle completely off.

here's a pic of his rig and a couple from the race just for the hell of it :)


 
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dead crickets in a dead tree falling in the middle of an uninhabited forest are more interesting i guess.....

Middel Fangers:flipoff2:
 
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Looks good Mook, I had considered doing the same project but it seamed like too much work when an aftermarket straight housing can be bought for a pretty reasonable price. Are you alluding that your shaft stripped its splines because of leaking axle seals? I doubt it, stuff breaks. Who splined your longer shafts? Directly from Long?
 
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thanks man!

and no i think it happened when i bumped tires with the guy and broke his knuckle off.....and yes the shafts came from longfield.....i think rcv makes them and he splines them.

totally agree with you about buying a housing over making one.....ruffstuff has a really good price on them now
 
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Digging an old thread up here. Mookie, have you got any thoughts to add about this after the years have passed?


Mark...
 

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