Rockwell axles. Help needed on specifications please!

Dont waste your time......nothing is interchangeable,except standard parts....nuts ,bolts ,bearings..................The diffs were completely redesigned to eliminate serious faults with the earlier ones,and to make provision for a power divider...............the main alteration was the bevel pinion was mounted on two taper rollers ,instead of straddle mounted............if you take the top cover from your rears ,you will likely see the bevels are chipped from load deflection.........the other fault was the keyed tapers were eliminated in favor of splines.

Wow John,
You really know your stuff. I'm impressed.

What you said lines up with the SFDD parts diagrams I have seen and I understand what you have pointed out.

Oh, well, back to what I already have. I know that these diffs fail due to inadequate oil supply to the pinion shaft bearings. I have seen 3 like that now, my Heavy wrecker included. The give away clue is an unused truck with the leading rear diff axle shafts removed = failed pinion shaft bearings in the top of the housing every time! It is always the leading diff, they do most of the work, I'm told.
In the Heavy Wrecker, I just re-bearing-ed the pinion shaft and off we went. Mind you, it is yard truck with a surprisingly underpowered Leyand 600 in it!

I contacted the bloke who did the safety certificate and explained the pre-1970s GVM issue and he has agreed to do another certificate without a GVM, but 'pre-1969' instead. Then it is off to the transport office!
Exciting times.
Have a nice day.
Sam.

my experience of these diffs is that mismatched tyre sizes put the gears under massive load............even the Tank PMs ,Ive seen the interaxle flange keyway sheared ,and the flange spun on the taper.The later diffs would often have cross shaft failures,causing just about all the gears to break teeth........PMG/telecom /telstra had both a Kenworth and a NM Mack........and the morons used to have pulling competitions between the trucks ..........did a good trade selling second hand diffs and axles to them.

kw573 wrote: ....
I did print a document from Canada that listed 'Out of Production Axles' and it included the SFDD series. The SFDD is, it seems, and SFD with a power divider/inter-axle diff. The SFDD tandem assembly is rated at a whooping 63000lbs = 29tons!!!!.
.....
Sam.

Any chance of sharing the link to that info.... I'm doing some research on Pacific trucks in Australia and some models used those diffs

Cheers

Werk

bryants on the gold coast had a very big Pacific,with big double reduction Rockwell diffs and 24" duals............they used to load over 40 ton on the jinker and pull out over rough bush tracks in the ranges behind the coast...................I remember it hit a car once ,wasnt a mark on the truck,the front guards were 1/4" chequer plate.............but they did regularly bust diffs in it,generally broken teeth on the bull gears.

I can only guess that if you were doing this in NSW
I don't know who would confirm the details that you put on the counter at what used to be called called the RTA as there are no qualified mechanics or inspectors jumping up and down behind the counter. Put almost anything on the counter and get them to work out if it is right or not. They have to carry some burden of proof at some stage. All you can do is your best and leave it up to them to disprove what you have put on the counter.

Problem is its outside the square........the person behind the counter puts the detail into the computer ,if the system says some required data is missing........they cant go on ..........whats then needed is someone with the authorization to override the system.....and often they dont know what to do.........so the application is just rejected...

What if the "wrong" axles details are listed but you do know the details they require? Honest mistake?