turning 25 spline xy diff to 28 spline

[jak 11]

hi

i have a xy van that is a factory v8 Windsor it still has its factory fitted 2.92 25 spline 2 pin Borg-Warner 

i am contemplating do this conversion my self 

turn it to 28 spline axle with either new custom axles or use the 28 spline axles out of a xd 2.77 lsd 4 pin 351 diff i have/ no one wants these as you cant change the ratio and the lsd hemisphere is non useable in 2.92 and up ratios so I'm willing to rob some parts off of it.

things i need to check

1./ if there is enough spline on the factory 28 spline axels to cut them down to fit the earlier xy width.

2./ if the area between the housing end and the face of the axle is the same from a disk brake and drum brake axle

 

we have a lathe so shortening is easy and turning the bigger spigot on the later axle down to the earlier xy size is simple enough

 

questions:

 

things i need to find out before buying parts is do the latter BTR hemispheres from late model 90's cars  fit into the earlier xy housings ?????????????

 

i'll just get a 4 pin LSD 28 spline hemi and 3.08 gears from a vn commodore.

 

from my under standing the 2.77 axle is a M75 but nothing 2.92 and up M75/8 fits them or vice verser ....the 2.92 and above are either M75 or M78 (definitely M78 from xd onwards)2.92 and up  M75 & M78  parts are interchangeable 

i may need to machine down the 3.08 pinion to fit the falcon housing 

 

[jak 11]

one thing has me worried is the xw/y diffs don't appear to have the crushable pinion spacer they have selective shims in the xy parts book to get the pre-load.

 they also shim between the pinion bearing and behind the pinion gear and the large bearing( two shims go on before the first big bearing is pressed onto the pinion gear)

 

so will the newer gears that work with the crushable sleeve  work in the old housings???????

 

i also have a xw 3.5 gear set i pulled years ago and that has no crushable spacer on it so that backs that up.

 

 

 

this diff has to look original to the car other wise id do it different 

[the miracle stick mechanic 47]

Hey m8, Dunno if it helps but >

Many years ago , had to change ratio in two diffs from a new Ford Louisville .

The final check on the pinion shaft shims was done by measuring the torque required to rotate the installed shaft.

You could use a 1/4" torque wrench. But if my memory is correct I used a small spring balance and some string.

 

Good to have another vanner onboard. There are not many on the road anymore. 

[jak 11]

Yes I have the inch pounds wrench to measure the drag 

 

you also have to use string wrapped around the hemisphere and a different type of scale to measure the hemisphere bearing preload without the pinion installed 

[the miracle stick mechanic 47]

Yep, I thought you would know that and about Bearing blue to check the tooth contact.

Rare pano you have there .