Full Float build using early centered fj40 housing (1 Viewer)

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Tank5

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I thought this might be the best place for this but if not let me know.

In the back of my mind I have been planning on building a full float rear axle for my 2001 tacoma. This would be the first time I have tried to build an axle like this, so I am hoping to get some advice from those that have done aiming similar. I have read plenty of similar threads so far but this is a little different.

I have an early 1963 centered fj40 semi float housing that can take a 9.5" differential. I have a set of full float ends from an 80 series axle that I plan to attach in place of the current semi float ends. Then use all 80 series end and ebrake to complete it. I have a full float 80 series diff that I would use with an Eaton blocker or possibly source a toyota locker diff. In hopes it would plug into my existing factory harness.

The tacoma wms is just under 61".
The fj40 wms for the axle I have is 55".
The 80 rotors and hub assembly will add some width and the remaining if needed will use the 80 housing tube extending from the hub.

I read that the differential to housing studs are smaller on the early axle housings. I would plan to drill and tap them to take 80 series studs.

I expect I might have to modify the housing to accept the 80 diff but not sure. Definitely would if I went with a factory 80 e locker.

I am thinking it is an older housing and I have not compared it structurally to new housings for thickness. So I am thinking I would add a truss.

I would plan to mock it up the way I want and tac it together then get a shop to finish welding it. Plan B would be to build and buy jigs to weld it myself - Not ideal.

This is as far as I have gotten in my head. What do think?
 
I know the the early housings are weaker. But not sure how much weaker. Have you thoughtried about centering an 80 series housing instead? That is a pretty common modification.
 
I have not looked at centering an 80 series axle. I don't have a lot of cash to throw at this. If I did I would just buy a ruffsruff housing and add my ends. The reason I am looking to use the parts listed is because I have them already. I don't have a spare 80 housing.

That said if the early housing is really weaker and cannot be modified to improve the strength I won't use it either. I don't want to east my time on it if won't hold up. This is certainly one of my concerns and why I started this thread.

Thanks for the comments.
 
A centered fj40 housing has got to be worth some coin, you may be able to trade for an fj60 rear housing which are stronger and a dime a dozen.
 
I would sell it if I thought I could get a decent start to put towards a custom built housing but I just read where another member is selling one complete for 100.00. If I can use it for my needs it is money saved since a ruffstuff housing costs 695.00 p!us shipping.
 
I have just spent hours searching the forum trying to find reference to the strength of early fj40 housings compared to later models. I found a thread asking about housing strength but the answer was never given. If anyone knows if there is a strength difference please share.

Eventually I will disassemble the housing I have and compare it to a later model to see if the material construction is different.
 

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