Blackline ATB differential

[Nick Jones]

Ok. After some research and assistance on Sideways forum

It seems there is a simple way around this.  I think it is in fact possible to use any carrier with any body by choosing the right bearings, though I haven't yet looked for the bearing that allows the later 35mm carrier in an early body.

There are probably other variations out there (the 4.11s certainly have some differences) but among the parts I have:

Early (Vitesse Mk2) 3.89 has 62mm carrier bearing saddles with a maximum width of 130.6mm
The carrier with this has 31.75mm bearing spigots and uses 15123/15245 bearings with a width of 18.16mm
The carrier width between bearings is assumed* to be the same width as the Blackline one @ 91.5mm and adding two bearing widths gives 127.82mm which will fit within the 130.6mm housing width with just under 3mm for shims

Late  (Spit1500) 3.63 has 59.13mm carrier bearing saddles with a maximum spacing of 126.17mm
The carrier with this has 35.00mm bearing spigots and uses 68149/68110 bearings with a width of 15.875mm
The carrier width between bearings is assumed* to be the same width as the Blackline one @ 91.5mm and adding two bearing widths gives 123.25mm, which will fit within the 126.17mm housing width with just under 3mm for shims

Intermediate: Some in the middle (maybe even the majority in numbers made) are diffs with smaller 59.13mm bearing saddles and smaller 31.75mm carrier spigots. Using the LM67048/LM67010 bearing gives the smaller 31.75 ID in combination with the smaller 59.13 OD wioth the same 15.875 width.  It has a marginally higher (+3%) strength rating than the larger ID bearing. 

The early housing bearings 15123/15245 combination gives +30% strength though....... which is interesting.  However, I don't think the carrier bearings are noted failure points, so probably not worth wrestling with the pinion height issue for.

* Assumed..... all carriers are the same width between bearings @ 91.5mm (ish). I say this because I've only been able to measure the new ATB spool as the old carriers still have at least one bearing and the crown wheel on them which makes then well nigh impossible to measure with the kit I have.  Plus the increased width of the early casing bearing saddles seems to tally with the increased bearing widths....  Unless anyone knows different!

I can order bearings now.....

Nick