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RB25DET NEO , AWD vs RWD trans

rx-line

By rx-line,
in Engines & Forced Induction

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rx-line Enthusiast

rx-line

Posted
Posted (edited)

RB25DET NEO , AWD vs RWD trans

Looking to swap my RB20det with an RB25det NEO and run the RB20 nistune wiring / ecu as it is in an rx7. Push to Pull Conversion, Intake manifold, shaft yoke etc. differences aside. 

However the dilemma arises when shopping the Canadian market for the engines. My biggest issue has always been the weak Rb20 gearboxes. Keep in mind I have the ability to modify the transmission & oil pan and that I will have to increase the driveshaft tunnel size anyway.

All long blocks with trans, turbo, ecu etc.

RB25det RWD S2  - $3200.00 (Don't really want anyway)

RB25det RWD Neo - $2800.00 (Preference)

RB25det AWD Neo - $2200.00

 

First question, do the AWD versions only come in Stageas? Or was there an R34 GTS-4? As it is advertised as coming from a skyline. 

Does the AWD version feature the same transmission from a R34 GTR? I.e same transfer case, gear set, 6 speed, etc. If so is it stronger than the RWD box?

Lastly is there any mechanical / electrical differences from AWD / RWD besides oil sump? I heard something about Traction control on factory ecu being different, but likely won't effect me unless I maintain current harness for some reason. 

 

Edited by rx-line
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KiwiRS4T Grand Master

KiwiRS4T

Posted
Posted

I take it you want a 2WD system.

To my knowledge there are no Stageas with manual trans and 2wd (traction control only came with 2wd).

The gearbox on the manual Stagea is the same as the R33GTR and GTS-4 (five speed not 6 speed Getrag)

People have converted the above boxes to 2wd use (mainly because the RB25 big box is hard to find).

You will have to cut and shut to get rid of the diff in the sump and the transfer case.

The only difference in the loom that I know about is that there is a signal from the TPS for the AWD but that shouldn't create any problems for you.

If you get the ecu with the neo engine you should be able to run the proper Nistune board (not RB20) so that it can control the VCT

 

Cowboy1600 Grand Master

Cowboy1600

Posted
Posted

The important point, which I think is what Kiwi was getting at, is the interchangeability not if they are actually the same box.  Stag, R33 GTR and GTS-4 boxes are all interchangeable.

blind_elk Grand Master

blind_elk

Posted
Posted

Don't understand why people keep saying RB20 boxes are weak. In my experience, Nissan boxes in general are pretty much bullet proof. Sure, if you start fitting massive clamping-force clutches, then it's possible you might break the box. But then that's like using a 6" nail as an electrical fuse, and complaining that your kettle blew up!

I still have the original (over 250k) box in my R32 GTS4, although the engine has been replaced with a RB25DET that originally punched 180kW @ all four. Gearbox is still pretty much perfect.

GTSBoy Grand Master

GTSBoy

Posted
Posted
3 hours ago, blind_elk said:

Don't understand why people keep saying RB20 boxes are weak. In my experience, Nissan boxes in general are pretty much bullet proof. Sure, if you start fitting massive clamping-force clutches, then it's possible you might break the box. But then that's like using a 6" nail as an electrical fuse, and complaining that your kettle blew up!

I still have the original (over 250k) box in my R32 GTS4, although the engine has been replaced with a RB25DET that originally punched 180kW @ all four. Gearbox is still pretty much perfect.

Trouble with your example is that the 4WD box you have is strong like a GTR box.....effectively the same as the R33 25DET box.

The normal RWD RB20DET box is definitely nowhere near as strong as the R33 turbo box.  It's about half the size and weight.  I trashed the input shaft bearings on 2 of them with only mildly more power/torque from the RB20.  There was no way I was going to run a 25 without the matching.

To the OP....you _might_ get away with running the 20 box because the RX7 is so small and light.  It immediately presents that much less load to the box.

A Stagea engine will work.  The AWD sump is the biggest hassle.  As you were told above, don't use the 20 ECU.  Just use the Neo ECU with Nistune.  Much better.  If you use either engine (2WD or AWD) you have to use Nistune to keep the Neo ECU happy with the lack on inputs from the original car's ABS/TCS anyway.

rx-line Enthusiast

rx-line

Posted
  • Author
Posted
1 hour ago, GTSBoy said:

Trouble with your example is that the 4WD box you have is strong like a GTR box.....effectively the same as the R33 25DET box.

The normal RWD RB20DET box is definitely nowhere near as strong as the R33 turbo box.  It's about half the size and weight.  I trashed the input shaft bearings on 2 of them with only mildly more power/torque from the RB20.  There was no way I was going to run a 25 without the matching.

To the OP....you _might_ get away with running the 20 box because the RX7 is so small and light.  It immediately presents that much less load to the box.

A Stagea engine will work.  The AWD sump is the biggest hassle.  As you were told above, don't use the 20 ECU.  Just use the Neo ECU with Nistune.  Much better.  If you use either engine (2WD or AWD) you have to use Nistune to keep the Neo ECU happy with the lack on inputs from the original car's ABS/TCS anyway.

Yeah, making more sense to pay for the rb25 box.

Have killed 3 RB20 boxes so far. Running launch control,slicks, 6 paddle clutch and 1.5sec 60 foots royally dicks them. Usually Synchros wear off making the shift to second at full load near impossible, shift to third is none to great. I have broken shift forks as well. At the power I'm pushing in the 20 you'd be lucky to get weekend at the strip. Car weighs 2600 or so, ford 9" rear.

I've gone so far as to do the 6-8 hour job of re-building one, didn't last a whole lot longer than other spares I had.

I was going to continue with the 20 but the r25 tranny is a must and at that point it's too cheap not to get the engine. I like to idea of the using R34 ECU and wiring harness, hopefully they will send me a fuse box with the harness.

Just trying to get into the 9's

 

 

  • 6 years later...
andres14oj Apprentice

andres14oj

Posted
Posted (edited)

old thread but i think relates to my question:

i bought a 5 speed awd transmission that was removed from an rb25det neo. supposedley the combo had come put of an r34, but the sellers didnt really know shit, so who knows. engine really was a 25de neo, i saw it when they were still mated 👀

im mating that transmission to an s2 rb25det, 'cause it's already hard enough to find parts here in the US, let alone for a neo...

question is, what transmission do i have and how strong is it? i had read that awd rb25det r33's came essentially with an r32 gtr transmission, and i had the chance to get an r32 gtr transmission for the same price, but i opted for this one instead 'cause i was also getting the engine from them and being newer i thought it would be better.

it's stamped 344#1 on the left hand side of the bellhousing and has way more ribs that the regular r32 gtr one.

been looking for info on it like crazy for hours and havent found anything. 

finally, who manufactures it?

will post pictures tomorrow

TIA

Edited by andres14oj
GTSBoy Grand Master

GTSBoy

Posted
Posted
3 hours ago, andres14oj said:

supposedley the combo had come put of an r34

If it did, it wasn't stock. There were no RB25DET AWD Skylines. Only in Stageas. The difference between a Stagea AWD Neo and an R34 Neo is the Stagea doesn't have the TCS throttle that the R34 does, because Stageas don't need traction control (because they're so bloody heavy....plus ATESSA).

3 hours ago, andres14oj said:

engine really was a 25de neo

That woudl make sense, because GTS4 type things were all NA in the 33s and 34s.

 

3 hours ago, andres14oj said:

question is, what transmission do i have and how strong is it?

All AWD transmissions are the same. Same as GTR.

andres14oj Apprentice

andres14oj

Posted
Posted (edited)
8 hours ago, andres14oj said:

old thread but i think relates to my question:

i bought a 5 speed awd transmission that was removed from an rb25det neo. supposedley the combo had come put of an r34, but the sellers didnt really know shit, so who knows. engine really was a 25de neo, i saw it when they were still mated 👀

im mating that transmission to an s2 rb25det, 'cause it's already hard enough to find parts here in the US, let alone for a neo...

question is, what transmission do i have and how strong is it? i had read that awd rb25det r33's came essentially with an r32 gtr transmission, and i had the chance to get an r32 gtr transmission for the same price, but i opted for this one instead 'cause i was also getting the engine from them and being newer i thought it would be better.

it's stamped 344#1 on the left hand side of the bellhousing and has way more ribs that the regular r32 gtr one.

been looking for info on it like crazy for hours and havent found anything. 

finally, who manufactures it?

will post pictures tomorrow

TIA

 

5 hours ago, GTSBoy said:

If it did, it wasn't stock. There were no RB25DET AWD Skylines. Only in Stageas. The difference between a Stagea AWD Neo and an R34 Neo is the Stagea doesn't have the TCS throttle that the R34 does, because Stageas don't need traction control (because they're so bloody heavy....plus ATESSA).

That woudl make sense, because GTS4 type things were all NA in the 33s and 34s.

 

All AWD transmissions are the same. Same as GTR.

sorry, i meant to say "engine really was an rb25det neo", site wont let me edit my post again... and going back to look at the pictures on their site, you're right, the rb25det neo it was originally mated to doesnt have the traction control throttle body, just has like a block off plate.

and not all awd transmissions can possibly be the same. r34 gtr is the only one with six gears for starters. mine has a ribbed case that's different than the 32 gtr one.

did nissan build its own transmissions other than the getrag?

is this thing as strong as a r32/33 gtr one?

im attaching pictures of the original 25det neo/5 spd awd combo, the tranny now in my possesion, and the 25det s2 as a plus just to show off how clean of an engine i scored. i still cant believe it  😭

almost makes you want to baby it... almost 😈

5AE4481E-0194-47CC-8C69-3B430C7D18DD.jpeg

6EFA3852-A70D-469C-B59D-0ED55728F2EE.jpeg

FE698B93-6808-49A8-932C-2084004566C1.jpeg

662AA083-7BBC-40DA-BFDC-814E97B69CD9.jpeg

242961F0-A393-4CC4-A8A9-214D0B72CB3F.jpeg

B9FE3E55-E5F2-479B-8379-0292B1F080EE.jpeg

Edited by andres14oj
GTSBoy Grand Master

GTSBoy

Posted
Posted (edited)

OK, so, except for the Getrag in the R34, which was obviously not a Nissan gearbag, all AWD manual transmissions ARE the same. Ribs don't matter. They are the same basic box with the same basic strength. There are incremental differences from R32 to R33 and R33 S2 and S3. They picked up better synchros and such. But they are essentially the same box with the same ratios and it doesn't matter if they had an RB20 in front of them or an RB25 or 26.

In fact, the core of the 5 speed is essentially the same thing as the RB25DET box, and very similar to the VG30 box which is also closely related but has big differences externally at the back end for the remote shifter.

Edited by GTSBoy
RB36 is a badass engine, but not real common.
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