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BASHERnissan

Rb20det gearbox in a r33 gtst coupe

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Hi all I have a r33 coupe rb25det, it has a big turbo box in it but it crunches and whines now. I have a spare rb20det gearbox and would like to put it in. And yes I KNOW it not the best option and all that but I just want to put it in to tie me over while I get my good one rebuilt 

what is required for the swap? Is it straight swap? 

Seen a lot of r33s with small boxes in them but can’t find any solid info on how to do it.

cheers guys !

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It'll go in. You will need to modify your tailshaft - which should be enough reason to not do it. The 20DET box is the same box as the 25DE, so they do fit natively in the R33. So you can use the front half of an NA car's tailshaft to mod yours. You will probably need to choose the appropriate gearbox crossmember from the available options (A, B or C) and you will need to consider whether you could make the speedo work (hint, unlikely). And....if you have boosted the RB25 at all, expect the box to last about a year before the input shaft bearing starts to carry on.

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31 minutes ago, GTSBoy said:

It'll go in. You will need to modify your tailshaft - which should be enough reason to not do it. The 20DET box is the same box as the 25DE, so they do fit natively in the R33. So you can use the front half of an NA car's tailshaft to mod yours. You will probably need to choose the appropriate gearbox crossmember from the available options (A, B or C) and you will need to consider whether you could make the speedo work (hint, unlikely). And....if you have boosted the RB25 at all, expect the box to last about a year before the input shaft bearing starts to carry on.

Thanks for your answer bro

can I used the speed sensor from the rb25det or do I have to modify the rb20 one ?

also can I just use the front half of the NA drive shaft or do I have to cut the existing one and connect the two ? 

Sorry new to drivetrain stuff ! 

Shop said 2k for rebuild on big box WTF!!! 

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I would pay the 2K for the rebuild. It's $3300 for a brand new R34 box (which you could use but only with the cost of another clutch).

No, you can't use the RB20DET speed sender. The R32 was cable drive. To use an R33 box in an R32 we have to make a cable drive adapter using something from a Navarra. I'm not sure that work has been done to try to fit an electronic sender into an RB20DET box.

Having said that, the same box was used in NA R33s, so maybe they had an electronic drive. Just don't know, because don't care about NA cars!

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I had a small box on my ecr33 rb25det running about 300 hp (bpu) for 2 years without a problem. Only developed a whine after going rb30.

 

Youll need:

 

- front half of tail shaft

- Gearbox mount

- clutch slave cylinder (I got a braided clutch hose aswell to remove the OEM hard lines, which apparently are a bitch to bleed).

- Shift knob default_biggrin.png&key=3179abbc31fa8dcb0030377446c69ae9371908a7acd2283c706671f656288530

 

Most likely youll have to do some fidling to get the speedo working. The box bolts straight to the engine and starter, clutch etc work just fine.

 

Edit:

 

Personally I wouldnt bother with the small box either. Sell the box and add the money you'd have to spend on making the small box work and you arent far from the 2k repair. And you'll have a good condition, much stronger box to enjoy.

 

Worst case is you spend lots of money making the small box work and it shits itself after a short while so you end up repairing The big box anyway.

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You just need to buy an appropriate speed sensor to make the speedo work. The part number is 2501071T00  just make sure it has 21 teeth . They are still available and were used in a variety of Nissan's. Amayama can supply for about $100 plus freight New. But as GTS Boy said its the same sensor in a N/A 5speed box so possibility of second hand.

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After looking further that part number applies to the following models- So you already may have a sensor that fits

(RB20E+RB25DET).MT,F5 +(GTS25+GTS25.S).MT,F5   08.1993 - 01.1995 

(RB20E+RB25DET).MT.F5 +(GTS25+GTS25/S).MT.F5   01.1995 - 01.1996 

(RB20E+RB25DET).MT.F5 +GTS25/S.MT.F5   01.1996 - ...

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I'm not sure how that can be true. I put an R33 RB25DE box into my R32. The R32 cable drive sender went into that one as if it was the same same. Which it, of course, was. But you still have to make a cable speedo drive for the big box, which I did when I put the R33 turbo box in. So I can't see the elec sender for the R33 DE box being the same piece as the R33DET box.

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/\ NA box definitely has a smaller different drive, NA manual R33 etc onwards have the electronic drive for the small box.

S14 & 15 SR 5 speed should work but will need a different gear.

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17 hours ago, GTSBoy said:

So I can't see the elec sender for the R33 DE box being the same piece as the R33DET box.

Info came direct (cut and paste) from parts catalogue all care taken but no responsibility.

Edited by Rusty Nuts

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6 hours ago, WMDC35 said:

S14 & 15 SR 5 speed should work but will need a different gear

And the S14 parts catalogue quotes the part number as 2501071T00  same part number

Edited by Rusty Nuts

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There are a couple drift cars in nz that are running 350kw with a 20det gearbox.
Not sure why there lasting but seems to be abit of a hit or miss with them

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