Welcome to IsuzuPiazza.com :: Uniting Isuzu/ Holden Piazza Enthusiasts since 2002

The Piazza uses the same 5 speed gearbox as the 2.3L 2x4 Rodeo and the 2L Shuttle bus. It is an updated version of the MSG gearbox with a larger output shaft than was used in the Gemini and the earlier 1.8L shuttle and the G-series powered Rodeos. The internal rotios will vary according to the application. As yet i havent found a way to externaly identify which ratios where in what box.

If you wanted to you could use the MUA type box out of the later TF 2.6L Rodeo. It shares all the same important mountings and measurments as the Piazza box. It is physically bigger in size and is stronger.

Pics and ratios to follow. Will up date soon.

When the large output shaft is mentioned or refered to it is infact the same size and spline as the common "trimatic" spline. Used in a high percentage of cars and in the bum end of a lot of boxes. The Trimatic of course, the T5, the TH350 & TH700R, Holden 3 and 4 speeds the list goes on.

The 2.3L Rodeo thats rated at 500kg carrying capacity has the same gearbox ratios as the Piazza. The only way to know for sure what ratios are in any Isuzu box is to know that the box was fitted in the vehicle it came out of from the factory.

All others have "Commercial" ratios.
Having said that, "fat chance" of finding a Rodeo box thats not noisy. Its seems to me that the MSG series boxes, more so the latter ones mentined in the psot above with the larger output shaft, have some serious issues with hard facing somewhere in the input cluster. From what im told what would sound like a stuffed input bearing is infact the hard facing worn off where the main shaft meets the input shaft in the front of the box.
With the clutch out the box "whines" and "grumbles" but if you push the clutch in it stops.
Ive replaced the box in my Rodeo because of this and i have another Rodeo here that suffers the same problem. With the console and shifter boot out of my Piazza it has the same noise but could be exadgerated due to the lack of noise insulation. I would say its on its way out as well.

I am planning on stripping the box that came out of my rodeo and looking into weather it can be salvaged and by what means.


The MUA box from the TF Rodeo has a deeper Quadrant hole for the shifter to bolt to. Its also a different bolt pattern for this reason. The earlier MSG boxes have the mounting face for the gearstick/remote shifter sloping back on an angle, on the TF MUA box its flat and runs pretty much parrallel to the main shaft in the box. The only shifter that will fit on the TF box with out modification is the TF one as the actual selector that goes down into the box from the quadrant lid is longer by over 10mm. The TF remote shifter is approxamately 8" shorter in the stick location than the Piazza's shifter.

Due to the age of the Piazza and the fact that the uni joints in the tailshaft arent replaceable i think the Gemini box idea has merrit. Offset the cost of getting a tailshaft made/modified against the availability of Gemini 5 speeds and their relatively low cost and its a worth while proposition especially if your tailshaft has loose unis. Even more so when you take into account the fact that you can use a 4 speed at an even cheaper price if you have to. You still run into one problem, the Gemini used both a fine and coarse spline on the ouput shaft in the boxes fitted to them.
I myself would look at getting a two piece tailshaft from a Rodeo or Jackaroo (all jacakroos are large output size) and getting it shortened to the same lengths as the Piazza shaft. All the Commercials appart from the early Shuttle use replaceable uni joints. If you hunt around you would be able to find both a fine and coarse small yolk so your prepared for any box you can get.

Bob.

i have a TF rodeo box and i snapped a tooth off 2nd gear.

can i switch 2nd gear with 2nd out of a gemini 4 speed??

cheers
chris

D1FromAdelaide wrote:i have a TF rodeo box and i snapped a tooth off 2nd gear.

can i switch 2nd gear with 2nd out of a gemini 4 speed??

cheers
chris

No because the gears in a TF box are half as big again. Depending what year the box is you could probably still get new parts for it at Holden. You will have to know the year of the box.

Bob.

ok thanks. what gearboxes if any do piazzas share with any rodeo's?

D1FromAdelaide wrote:ok thanks. what gearboxes if any do piazzas share with any rodeo's?

Read the posts above.