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Hi there, 

I bought a R34, which was converted auto to manual in Japan. Apparently the previous owner put a rb20 gearbox in it ?

I must say, it drives pretty good and clutch feels great.... But I know they're not strong as a rb25det box. 

Is there any other reason then to just save money, that could've been why the previous owner chose a rb20 box over rb25? 

 

Last question, if I would want to put a rb25 box in it... Best to get a R33 gtst? Or R34 gtt. I know the R34 clutches are pretty expensive. And maybe the propshaft is different? 

Advice is welcome. Thank you! 

 

Jasper

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3 hours ago, Jasper34gtt said:

Is there any other reason then to just save money, that could've been why the previous owner chose a rb20 box over rb25?

The R34 NA box is the same box as the RB20DET box (except for one or two different ratios and maybe a tiny bit of modernisation in synchros or something equally trivial). So it is quite possible that you don't have an RB20 box, but instead have an R34 box, and maybe the car not just got a manual conversion. Maybe it also got a turbo engine transplant.

R33 box and R34 box are almost identical with the exception of the clutch actuation. They will both require a different front half of the tailshaft to the small box you have.

Thank you for this info. I do think it came with the neo engine and automatic from factory, but someone swapped a small manual gearbox onto it... And I feel somewhat scammed. I didn't expect anything other than just a rb25det box underneath my car. 

Is it wise to swap it out anyway? I've seen these boxes are quite expensive ?

You can run the small box against a 25DET for quite a while, but it will not have a long life if you increase the power much or if you lean on it hard a lot of the time. They're just not heavy enough in the bearings to take the torque. They wear out even with just a boosted 20. Ask me how I know.

I'd plan to swap it. At least keep an eye out for a box you can buy to start the process.

You can't easily buy the 33 box new any more, but you can buy the 34 box new. For >$AU3k. I'm thinking of buying one, because rebuilding the big box is also getting to be near impossible, owing to lack of internal parts.

In my honest opinion, i have a rb20det box on my rb25 and i make good boost about 12-15 psi for a good while now and so do my friends and we go drifting and push our cars. it can survive and their bad reputation is overdone. i would say enjoy it and use it. When it decides to let go then i would suggest buying the r33 rb25 gear box as the r34gtt gear box is harder to find, more expensive, and with the r34 gearbox being a pull type clutch... you have less options and they are way more expensive to get clutches. 

  • Thanks 1

5 months now yes, i can agree this isnt very long time but this is with pushing The car on the drift courses and meets every weekend. Many of my boys in cefiros been at it for a couple years with 20det boxes on 25’s and this is why i advocate the small box because its not shit by any means and is alot more capable then what most think

especially if your planning to keep it at modest/little over stock power. To me and my scene where i live..... around a  300wheelHP mark and even a little bit over 300, you got a good gear box for a hopefully some good  time. Obviously its best to get a new r34 box or r33 used box but i am sure that you can use your box for a while and enjoy it. 

Edited by Dil-Dog

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