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HOLD64

RB25DET gearbox ratios

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I'm trying to decide which box I should use behing my RB30.

Does anyone have the gear ratios for the RB25DET box (R33 if there is any difference?)

..stretching for info here but does anyone know the differences between the MX7(VL Commodore Turbo 5speed) and the RB25 box? I have an MX7 box but am thinking about purchasing an RB25 box as I've heard it may be better suited to my 4.11 diff. Would also like to know if it is any stronger than the MX7?

I know the RB25 box will be younger which is an advantage.

Cheers

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don't remember were i got this info from but it was from one of these skylin sites:

1st 3.592 : 1

2nd 2.057 : 1

3 1.361 : 1

4 1 : 1

5 0.813 : 1

from memory the vlt box has a lower ratio for the 5th gear due to our top speed in australia is higher then that of japan, and we also run lower final drive ratios

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This might help:

http://www.nitroware.net/~tony/skyline_book.pdf

Not sure that it has RB25DET ratios, but I am sure it has some in there - just my server is a bit slow at the moment, so got bored waiting:D

The skyline uses a 4.11 final too if I am not mistaken, so it should be a good match.

Not too sure about the strength comparsion, sorry.

Hope it helps anyway

Steve

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The RB25DET gearbox is basicaly the same as a GTR gearbox (gear width, bearing size, shaft diameter etc) so it is a very strong gearbox. It's been a few years, but from memory a VL box looks to be smaller than a RB20DET gearbox which is way smaller than a RB25DET box.

We have used RB25DET boxes up to 620 bhp with no problems, so they are way tough.

This is my understanding of the ratios;

1 3.321

2 1.902

3 1.308

4 1.000

5 0.759

R 3.382

Diff 4.363

Hope that helps

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my NA R33 started life with a factory 4.3 lsd but it developed a bad whine. The only replacement i could find was an R33 turbo lsd diff (4.11) (How's ya nuts slip?) :D

Rpm seems approx 100-200 lower now at the same speed (according to the speedo which is no doubt now out from the swap also)

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Originally posted by Sydneykid

It's been a few years, but from memory a VL box looks to be smaller than a RB20DET gearbox which is way smaller than a RB25DET box.

The normall aspirated VL box is small and weak - around the same size or smaller than the RB20. But the MX7 or VL turbo gearbox looks pretty much the same as the RB25 box, same physical size. If you have the two of them sitting side by side you'd be lucky to tell them apart. I'm wondering if there is much difference inside them.

Might stick with the MX7 for the moment as I already have one - they are always a straight swap later if I feel the need.

Thanks for the info guys.

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