DIFFERENTIALS..or diffs

[ozbox]

These are the things under the back of your van/ute/car..there is quite a few diffs but the factory ones are either banjos which all 6 cylinders had up to hz or salisburys which were in the hq to hz v8s.we shall be looking at ratios and sizes and limited slip diffs.
lets start with...

LARGE 10 BOLT SALISBURYS..

Most people think the 10 bolt saying comes from the amount of bolts that hold the hat on at the back..its actually how many bolts hold the crown wheel to the hemisphere..
Utes,vans and 1 tonners have leaf springs and sedan,wagon statesman have coil springs so car stuff wont fit as a unit axle to axle straight in your ute/van without modifying the housing..
1 tonner will fit ute/van but the pinnion yoke has larger universals and larger u bolts,easlly distinguished in a car as the 1 tonner u bolts have 1/2 inch nuts and the v8 ute/van has 7/16th.
The ratios across the board are 2.60 2.78 these are usually a car type ratio 3.08 3.36 3.55 usually the ute/van ratio and optioned performance for other models..4.11 4.44..only a 1 tonner ratio and they tell me the 4.11 was used for racing in a9x but rarely seen..myth?
Note in the pic below that the diff at the front has no ears cast on it..this meens it is unique for ute/van/tonner..the hat on a large 10 bolt measures up and down 250 ml and side to side 290 ml..



SMALL 10 BOLT SALISBURY..

These were only in wb 6 cylinders and are refered to as small 10 bolts but technically the saying is wrong..yes there is 10 bolts holding the cover on but only 8 bolts hold the crown wheel..these are hard to distinguish from the heavier 10 bolt out of a car if you have no experience so it is always better to remove the hat and count the bolts holding the crown wheel..the gears in these are the same as banjo diffs..the hat on these measure 250ml top to bottom and 240 ml side to side..
Note the different shape of the hat to the large 10 bolt..






BANJO DIFFS..

These are in 6 cylinder cars [also in hktg v8 and torana lh lx v8 with larger pinnion yoke]from the beginning of holden production but are only useable in hq to hz from the eh model.[earlier in grey motor powered cars had a different pinnion yoke].the banjo is an unboltable drop out centre..its ratios are 2.78 3.08 3.36 3.55 3.90..3.90 is only found in lh lx 4 cylinder toranas..
hq and hj origianlly had coarse spline centres and axles and hx hz had fine spline..they do interchange so always check the axle spline before presuming that you have one or the other..





The crown wheel on most holden diffs has the ratio stamped into it...this one is a 3.55 ratio.



The crown wheel is the large gear in the pic below and those little gears are your sun gears or side gears and the pinnion gear is under them.the red thing is the hemisphere..



AXLES AND SPLINES

Large 10 bolt salisburys are all classified as fine spline..
Small 10 bolt salisburys are also all fine spline but the axles from a small wont work in a large and vice versa..
Banjos in hq hj should be coarse spline and in hx hz should be fine spline and both will have the same type splined centre to take the axles..BUT..dont take this as gospel because they can be interchanged as long as you use the right axles..
Large 10 bolt axle pic below...banjo fine spline looks pretty much the same just not as fat..



Coarse spline banjo axle pic below..



Popular conversions for holdens are the ford nine inch..these are a removeable centre like the banjo



This is what a 9 inch diff under a wb van looks like..this one has been shorthened to accomadate the 15x10 wheels.



This is the centre from the 9 inch..this one had 3.88 ratio and is a full spool like a v8 supercar..full spools or mini spools are illegal for street use as they lock the 2 back wheels up putting great stress on the axles..great for drag racing and drifting..



Spooled diffs do this to axles..the spline is supposed to be straight..:knockout::knockout:

[gypsy]

Thanks for the info. My diff has the 2 x ears / lugs on top for a sedan and I can see where it has been convertor to fit my van but some photos I've seen have holes in the ears like mine with a rubber bush inserted for the top trailing arm but others look like it's a solid casting can you confirm this and what the difference is for.

[ozbox]

some ute/van/tonner large 10 bolts do not have ears at all and are only used in that application..most have solid ears in ute/van/tonner but i have seen many that have the ears without bushes that were not sedan/wagon/statesman converted..if you have a ute/van/tonner diff with ears and it has bushes then its 100% been converted from a sedan/wagon/statesman...

[HK1837]

Greg

Couple of fixes:

The "mythical" A9X ratio 10 bolt was 3.90:1.

3.90:1 banjo was optional on some Holden 6cyl, at least for HK-HQ. Not sure about exactly which models and series.

[ozbox]

Greg

Couple of fixes:

The "mythical" A9X ratio 10 bolt was 3.90:1.

3.90:1 banjo was optional on some Holden 6cyl, at least for HK-HQ. Not sure about exactly which models and series.

byron thats not what the race car guys say..but they are old and may be mixing up there numbers..

3.90 banjo was optional in utes and vans from books ive seen and also standard in 4 cyl lx torana..then the 3.9 crown and pinnion was used in the uc 4 cylinders.

--- Updated ---

Okay, one question for you...

This diff is a "Small" salisbury from a 6cyl WB built 4/80.



Why does it have holes in the ears??? is it the holes for the bushes???

and then this is also a "Small" salisbury from a WB built 8/83, this one has no holes in the ears.

the centre is a cast unit and the axle housings were pressed into it so if they had no non holed ear centres for ute/van they would use whatever they had..that centre could have been used in uc torana or vb commodore...holden didnt stop the production line coz they ran out of something particular..

--- Updated ---

The one with no holes is a ute diff, the one with holes is sedan diff. You can convert a sedan diff housing by welding on the leaf spring brackets.

correct in principle but they didnt have small salisburys in wb sedans..see above explanation..

[83 WB_Ute]

Rightio, you learn new things everyday... lol

[ozbox]

Rightio, you learn new things everyday... lol

yep.. i still learn something new everyday ..

[gypsy]

Pull the inspection plate and my sedan 10 bolt that is modified to fit my van must have had the centre changed as well as it is a 3.08 centre and not 2.60 2.78 which are usually a car type ratio

[adam perth]

HK 1837, i think the early ones from humpy to EJ were actually 3.89 stamped crownwheel. then later they were stamped 3.90 (i mostly pulled them out of 4 cyl toranas, mainly LX sunbirds.)

greg have you got a pic of the holden banjo with 2 longer bolts at the bottom for 2.78 / 3.08? As you know, always a good thing to look fo when buying rollers / cars to wreck with GU4 on ID tag and 2 longer bolts underneath cause it means $250 for the 3.08 centre.

the 2.6 diff was standard on the WB statesman, and thats the only place i have ever found them

[HK1837]

HK 1837, i think the early ones from humpy to EJ were actually 3.89 stamped crownwheel. then later they were stamped 3.90 (i mostly pulled them out of 4 cyl toranas, mainly LX sunbirds.)

greg have you got a pic of the holden banjo with 2 longer bolts at the bottom for 2.78 / 3.08? As you know, always a good thing to look fo when buying rollers / cars to wreck with GU4 on ID tag and 2 longer bolts underneath cause it means $250 for the 3.08 centre.

the 2.6 diff was standard on the WB statesman, and thats the only place i have ever found them

From memory 2.78 Salisbury was dumped late in HJ as it was too noisy. 2.60 was then used from that time instead. I'll find the document later today that states it (features manual).

--- Updated ---

This is probably a gumby question to some but can you put the LSD centre out of a WB salisbury into a HX salisbury, i know they are different sizes physically but are the planetary, internal, gears interchangable

Yes you can use the WB large salisbury internals in a HQ-HZ salisbury. Just remember that there are 2 x different hemispheres theough (LSD and not LSD aside). 2.6 and 2.78 share a hemisphere and 3.08, 3.36, 3.55, (3.9) and 4.44 share a hemisphere. So you can't use a WB 2.6 hemisphere with 3.08 gears for example. You must use 2.6 or 2.78 gears on it.