42 replies to this topic

[TerrA LX]

FYI falcon does not run 3.08 and Commodore V6 and V8 3.08 gear sets are different, V8 are shot peened OEM for strength.

[TerrA LX]

Fraud run 3.07 i believe

holden 3.08 are same diff/gears just shot peened for H/D use.

[76lxhatch]

If your mate can convert whatever then they're all much the same diff as mentioned. The later Falcon 4 spider ones use a 7.8 inch crownwheel and larger rear pinion bearing so the gearsets aren't interchangeable with the Commodore and Skyline 7.5 inch crownwheel versions without machining the housing to increase the pinion depth (the centre is identical and there is space in the housing for the larger crownwheel).

Housing probably makes little difference but its nice not to have to shorten axles so Skyline is handy in that respect. However they are still a little wider than standard (20mm) and the down side is that you need to weld and re-drill the flanges to change the four stud pattern to something useful. The Falcon obviously has Ford stud pattern on the axles but that is possibly useable, and they have 1/2" studs.

I am a little hazy on the Ford options but as far as I know there is no such thing as a 3.07 in these Borg Warners (3.07 superseded 3.08 in the change to M80 VT2 onward) - Falcons had 2.92 and 3.23. Some common ratio options (not a complete list):

2.92 - Falcon
3.08 - standard option on Commodores of all types from VN-VS, readily available for next to nothing
3.23 - VK 1/2 injected six, Falcon, Valiant
3.45 - VL Commodore, XR6 (with bigger crownwheel)
3.7 - manual Skyline
3.89 - auto Skyline, manual Pintara (noisy old version, superseded by 3.91)
3.91 - auto Skyline, manual Pintara
4.11 - auto Pintara

Commodores up to VL (except some V8s and VL Turbo), Falcons up to XF, Valiants and the Pintaras only have two spider 25 spline centres and axles but everything else still interchanges.

The Skyline disc brakes are a nice compact unit with less offset and integrated hand brake in the caliper, although slightly smaller diameter rotor than the Commodore ones. The Skyline and Commodore housing end flanges are the same but on different angles. The XR6 Falcon one I have (EF-EL I think?) has a different flange on the housing with similar sized disc brakes to a Commodore (and similar calipers again with integrated hand brake) but a stupid big alloy caliper bracket.

If you're looking for an LSD centre then the Ford ones seem to be let go the cheapest and are also the newest so not a bad bet (Commodore ones are few and far between in that era).

[76lxhatch]

The Salisbury gear is of no use to interchange with the Borg Warner stuff. If you can find a good Skyline housing and 28 spline axles (the Pintara only had 25 spline) then you can get a good centre and 3.08 gears for bugger all from any old VN-VS Commodore. If you want an LSD that will be the hardest part to track down a good one at a reasonable price.

[76lxhatch]

Yes that's right, plus get the stud pattern changed on the R31 axles (this is the expensive part) (or get custom axles)

The Commodore driveshaft flange would be useful if you don't have one, the Commodore shafts are quite small diameter so the yoke itself won't be much use but any yoke that takes a standard 1 1/16" cup uni will attach to the flange.

[76lxhatch]

They're pretty much all 3.08, that was the only ratio that came as standard. You can always count the turns without pulling anything apart.

That's a pretty reasonable price too

[dattoman]

R31 brakes fit R31's ... Skyline and Pintara the same

I haven't tried to use the Commodore backing plates onto an R31 diff yet so can't say for sure thats a bolt in
But whatever brakes you choose make sure you get the right axle bearings to suit that configuration

And R31 rotors are 4 stud as the axles... so if your changing to 5 stud and use the R31 brakes... redrill

[76lxhatch]

The Commodore brackets would definitely bolt on to the axle tubes but they would be on an odd angle (so clearance may be an issue) but the main problem is I don't think the R31 axle flange has the correct offset for the Commodore brakes. Rory didn't have any hassle re-drilling/slotting the four stud rotors, no need to fill the existing holes or anything.