Ode to the Aussie 4 Speed

[HK1837]

Yes they can, but nowhere near a sized Muncie layshaft. I think they use a smaller shaft from a top loader or something like that. A Muncie layshaft and needle rollers would probably be bigger in diameter than the trough of the gears on 1st/Reverse on the aussie boxes. Aussie boxes last a lot longer if you use a bronze bush in the cluster, a bigger circlip on 1st gear and a new or aftermarket shifter. If I was going to run a 4spd in a HQ-WB I'd be fitting a brand new Muncie with 4th gear overdrive and 3.36:1 diff gears. You can actually fit a Hurst shifter and not foul the floor, and one of these boxes will fit using a HT-HG 253/308 Saginaw bellhousing which looks just like an aussie 4spd one and will take the standard HQ-HZ clutch setup. Only odd one out is late HZ with full cable clutch where you have to run an aftermarket belllhousing.

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Slightly off topic, but is the 3 speed just as weak as the 4 speed?

No, these are heaps stronger. Lots of speedway blokes use them. Aussie 4spds normally wear out the cluster end with 1st and reverse on it and 3spds don't have this problem. They also don't have the 1st gear circlip issue, plus they don't use the awful Aussie shifter. These three things alone cause probably 90% of aussie 4spd failures. Often breakages are because of wear elsewhere in the box.

[agr071]

Does a 3 speed would have different ratio's compared to Trimatic/Turbo.

Might have to find a 3 speed and floor shifter to keep in case i decide to put out the trimatic and put a manual back in the HJ.

[HK1837]

Most M15 3spd synchro are the same ratio, except for a close ratio one fitted to HT V8. 1st gear on the normal ones is about the same as an M20 aussie.

3.07:1 1.68:1 1:1 Reverse: 3.59:1

Where the 3spd is better is its reverse. You can get away with running a 3.08 (or even 2.78 behind a 308) then 1st will be about the same as M20 wirh 3.08 but reverse is lower, whereas all aussie 4spd have reverse the same ratio as 1st. You can use an aussie 4spd shifter with one too, reverse is where 1st is. This is how 3spd Bedfords were done. From memory I think the 4spd extension housing fits straight on a 3spd so the shifter fits exactly as per on a 4spd and uses the same shift rods etc. Only hassle is the reverse switch, it'd have to be something like the Bedfords used.

[Robbo]

Are these Aussie 4 Speed boxes, the same boxes that were used in the LJ series Torana?

[HK1837]

Aussie 4spd were used in HQ-WB, VB-VK, late LC (from HQ release) to UC and CF Bedford. The 3spd upon which the 4spd was based was used in HK-WB, LC-UC and CF Bedford. Available mainly as M20, M21 and M22 ratio sets plus two other ratio sets used in XU-1 and L34.