60 axles in a 40

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Pros and cons to putting 60 axles under a 40?

What are the real gains over stock 40 axles and knuckles?
 
What are the real gains over stock 40 axles and knuckles?




Only width....for your application.


40/60 knuckles are the same, as are the outer axle stub/f-ing birf.





If you had a 08/75-12/78 you could upgrade to the larger studs and larger bolt pattern on the knuckles...
 
just fyi, disadvantage is they don't just bolt up. poser covered the advantages (except that in early models, the birfield is also a bit larger, and if you're pre 76, you'd get fine spline birfs)
 
Pro: as already discussed, width, and larger knuckle pattern, making hysteer applications stronger.

Cons: Ackerman angle gets all wrong, but I'd sure if you told a hysteer arm manufacturer your width and wheelbase, they could custom make a set of arms for you. I will be doing this sooner or later, just waiting for the 60 Axles to come off a friends truck.
 
I've done it. It is a little (3 inches) wider. Assuming you do crossover steering, cut and turn and SOA, the steering is perfect. The knuckles and birfs are all the standard late model stuff and so Longfields will fit.

It isn't worth it unless you are going SOA, and if you are doing that, you porbably want to lengthen the wheelbase and a few other tricks.
 
BTW, you have to consider spring spacing issues as well.
 
Thanks for all the prompt responses, much appreciated!
 
The 60 rear axle is a relatively simple swap to widen the wheel track to improve stability and eliminate rubbing in the rear wheel wells. Just need to re-locate the spring mounts. Not so easy in the front if staying SUA...
 
I'm seriously thinking about this swap on my 40. I have both axles from a 60 and will definitely go SOA with a cut and turn. I read several posts about outboarding the springs. I have just a couple of questions regarding this.

First, what spring should I use? A stock set of 40's or a stock set of 60's springs?
Secondly, would using Proffitts Spring outboarding kit ( New and Used Parts ) be the best method of attachment to the frame?
 
You can buy the 3" front axle tube spacer and extended axle shaft from lcwizard and install it when you do the cut and turn, then just buy the lengthened axle shaft for the passenger side. I did this and you could just use 1.5" wheel spacers for the rear. I know this sounds more complicated but it only costs about $300 in parts and you dont have to outboard the front springs, imop loosing some flex in the front suspension. lcwizard sold these parts, not sure if he still does. plus you cut the front knuckles off already to do the cut and turn for caster so its not really any extra work. Theres already post on this and I highly recomend it.
 
I already have the 60 series axles and picked them both up for uber cheap. I was going to use the knuckles for a disc brake conversion but after searching through the FAQ, I found that the axles would do the job so long as you outboarded the springs. I have a set of both 40 and 60 spring for the taking. I'm just trying to figure out which one to use.

I'm also trying to do this as fiscally responsible as I can!
 
you can also inboard the spring hangers on the diff. i have em under my 40, stock spring spacing, SUA
 
If your interested , this is what zcruz is talking about
The comparison is of a 40 widened both sides. A 60 housing would only need the short side extended


P7051309.jpg


P8131448.jpg


P7051310.jpg
 
If your interested , this is what zcruz is talking about
The comparison is of a 40 widened both sides. A 60 housing would only need the short side extended

That's what I would do next time. I became aware of it after I did this...
random 123s.webp
front axle.webp
 
spring selection should be based on what hangers your planning on using. personally i like 55 series springs...
 
Lcwizard do you have any more spacers? I have a 60 front I would like to install one of those in.
 
Lcwizard do you have any more spacers? I have a 60 front I would like to install one of those in.

Yes I have sleeves. They are $50ea
You will need an extended short side shaft.
The only ones I have made are Bobby Long's for the 30 spline birf
I also have them made in stock fj60 long side and extended FJ60 long side
 

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