FJ45 axle widening, can it be done?

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Hi everyone,

A 45 series front axle is 55.7" WMS to WMS and I wondered if it is possible to widen the front axle to the width of an 80 series front axle (63.3" WMS to WMS)? Adding about 3.8" to each side of the axle tube. Also, would 80 series axle shafts fit into the 45 series 3rd member?

I was wondering about this since I possibly want to do an SOA conversion in the future and the extra width would look better and also help a lot with the added height of the conversion.

Sorry if this is possibly a stupid question or in the wrong place, just wanted to ask if anyone else has attempted this or knows if it would work.

Thanks!
 
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simple answer is Yes you can widen it. There used to be a kit to do ~3" to one side, sure you could add it to both sides. Might be better off ordering a custom housing that will be much stronger. 80 shafts should fit the 3rd you have. Length might be another question. Why not use a 80 front?
 

GLTHFJ60

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Those widening kits @lcwizard used to make almost necessitated a truss, with how much width you were adding.

I had wanted to widen a 60 front to a ~63" width, and bought the kit from lcwizard, but it was cheaper to put a Dana 60 in, so I sold it all. If I *had* to stay Toyota I'd opt for a custom housing, diamond or other, to avoid having to truss the whole thing (if staying with leafs).
 
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simple answer is Yes you can widen it. There used to be a kit to do ~3" to one side, sure you could add it to both sides. Might be better off ordering a custom housing that will be much stronger. 80 shafts should fit the 3rd you have. Length might be another question. Why not use a 80 front?

The main reason for wanting to widen the 45 axles is to try and keep the 45 knuckles. It's hard and expensive to find a high steer kit for an 80 series axle and much easier to get high steer or double steer arms for the 45 axles. Would I be able to still use the 45 knuckles if I widen the 45 front axle and use 80 series axle shafts?

Those widening kits @lcwizard used to make almost necessitated a truss, with how much width you were adding.

I had wanted to widen a 60 front to a ~63" width, and bought the kit from lcwizard, but it was cheaper to put a Dana 60 in, so I sold it all. If I *had* to stay Toyota I'd opt for a custom housing, diamond or other, to avoid having to truss the whole thing (if staying with leafs).

Trussing the axle would not be a problem, it would be something I would want to do while doing the SOA conversion. Having custom axle housing made would not be something that I would go for, all the parts that I would use doing this project I would be able to source locally and not have to deal with importing parts.

So basically what I want to know is if I would be able to use the 80 series axle shafts with the widened 45 front axle and then still be able to use the 45 knuckles?
 
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So basically what I want to know is if I would be able to use the 80 series axle shafts with the widened 45 front axle and then still be able to use the 45 knuckles?
If you do your measurements correct, yes the inner shaft will fit into the diff and the the 45 birf. I would go with the larger bolt pattern on the later series knuckle (mini truck and 60 series). Tons of options for steering arms. '78 and down knuckles have a smaller pattern. For that matter I would find a 60 series front axle and widen that one.
 

GLTHFJ60

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The 80 shafts will mate with the 40/60/mini birfs. The star gear spline count is the same, that's what the question was.

EDIT: it appears matzell and I are mistaken.
 
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cruisermatt

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The 80 shafts will mate with the 40/60/mini birfs. The star gear spline count is the same, that's what the question was.

No they don't if they are OEM axles. 80 is 24spline, 40/60/mini is 27.

Now if everything was aftermarket 30 spline, maybe, but I seem to recall that the inner snap ring or inner shaft diameter was slightly different, there was some reason it doesn't work, I feel like I looked into this a few years ago
 

cruisermatt

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So basically what I want to know is if I would be able to use the 80 series axle shafts with the widened 45 front axle and then still be able to use the 45 knuckles?

No. 80 inners not fit 40/60/70/mini birfields. and 80 birfields will not work with a 40/60/70/mini knuckle ball/spindle
 
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No they don't if they are OEM axles. 80 is 24spline, 40/60/mini is 27.

Now if everything was aftermarket 30 spline, maybe, but I seem to recall that the inner snap ring or inner shaft diameter was slightly different, there was some reason it doesn't work, I feel like I looked into this a few years ago

Thanks, I just looked this up as well and saw that the spline count was different.

If I was maybe to go the 80 series axle route, what would be the stronger axle to use? I've heard that the high pinion axle is not very strong??
 
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paging rustynailjustin - search that user name , very helpful thread on his axle build somewhere
 
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Thanks, I just looked this up as well and saw that the spline count was different.

If I was maybe to go the 80 series axle route, what would be the stronger axle to use? I've heard that the high pinion axle is not very strong??
The HP diff is a strong diff. it has reverse cut gears
 

GLTHFJ60

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The HP diff is a strong diff. it has reverse cut gears

Not nearly as strong as a 9.5" diff. See blown up fzj80 front 8" diff.

1648068224733.png


The 80 knuckle balls are larger than a 40/60/mini, but the axle shafts are the same diameter, so you're not gaining any strength there either.
 
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You can use aftermarket 80 series 30 spline inner shafts with mini/40/60 series birfs. If you used the 2-5/8" tube sleeve spacer that LC wizard used to sell you can turn a 40 series axle into a 60 series axle or a 60 series axle into a an 80 series axle as far as width is concerned on the long side. Unfortunately, I don't think he makes the sleeve anymore as he told me I purchased the last two he made. You could make` them quite easily yourself though with a lathe.
Trail gear makes a bunch of different length 30 spline chromoly shafts that will aid in the process. I used the spacer sleeve on my 60 series front axle in my 40 series on the short side and used the mini truck short side +5" -30 spline axle to make it so I could turn 40" tires on the factory leaf spring mounts. It also matches up pretty close to the 80 series rear axle I have in the back.
If you do a bit of research there are a lot of options as far as width you can get to. You don't need an aftermarket housing and if you are crafty you can make a stock housing quite strong.
I have lots of pics of quite a few of these axle housings I have built over the years.
 

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9.5 is only marginally stronger the hi pinyon 8”diff with reverse cut gears. And the extra clearance is a plus.
If you’re not 38-40” tires I don’t see a issue.
Even then they hold up just fine as long as you don’t hammer down in reverse.
I’m running 39s on my 80 and there holding up to hard core trail use and rock crawling !!
 
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When your a fabricator anything is possible .. It gets real expensive real fast building out 8 x Axles. I disagree with broski on the strength of a 8 inch HP front. but I have been beating on one like it owes me money for years in my daily.I modded a semi float 8x rear axle turned it into a frt so I could have the larger ring gear. This is in my buggy.


78772338_2495670217195340_6003075544806064128_o.jpg
 
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why dont you just do the IFS mini truck hub mod?? that will give your 4x axles 6 x width. Plus you can do killer brakes . Be warned this is geeky Toyota nerd s***!!

277794167_10221180218878217_2196864560576378826_n.jpg
 
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EWheeler

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why dont you just do the IFS mini truck hub mod?? that will give your 4x axles 6 x width. Plus you can do killer breaks . Be warned this is geeky Toyota nerd s***!!

View attachment 2984410
Thats a unique way to get double shear on that tie rod! Cool stuff
 

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