RB25DET Series 1 & Series 2 Gearbox Identification

[Ratsun 0]

Hi all,

apologies if this has already been covered previously (i have searched but could not find a definitive answer), how do identify if i have either a series 1 or series 2 RB25DET manual transmission without knowing the donor vehicles VIN?

Thanks in advance

[GTSBoy 2,397]

There's a difference?

[Ratsun Topic Author 0]

according to my local Nissan parts dude there is, the internet also implies there is but does not elaborate what the differences are nor how to identify one from the other. 

[GTSBoy 2,397]

Let's just suggest that the differences are insignificant. Just because it has a different part number doesn't mean it's functionally different.

[BK 198]

You can't know unless you're familiar with the transmissions once disassembled. Coming from GTR boxes (which are the same as R33 Gts turbos Gearset and synchro wise), the only difference will come with the synchros, shift fork and gear with 3rd like 97+ stuff which translates to any FS5R30A transmission. Not sure which years are series 1 and 2 you're referring to in R33 gts,t. In GTR, 89 - 96 is same, 97 -98 upgraded (R33 GTR series 3), but not much of an upgrade really like people make out but are not interchangeable. Old mate Hardsteppa just went through this on a non GTR on this page.

[hardsteppa 660]

I did indeed. I would say its unlikely you have a series 2 box, as i gather the vast majority are series 1. As above you would need to pull it apart and look at 3rd to see for sure.

[Ratsun Topic Author 0]

how far would i need to pull it apart?

 

 

[hardsteppa 660]

Series 1.

[hardsteppa 660]

 

this bit circled. So you are extremely unlikely to find a brand new 3rd gear, 4th gear,  2>3 coupler or synchro hub, but should be able to find everything else new. 

[Ratsun Topic Author 0]

Whoa, how did you get series 1 from those pics and how sure are you?

 

[hardsteppa 660]

 

see how these clips are broken and missing? Later models ditched this type and moved to the same type as you will see on the 1st>2nd synchro hub.

[Ratsun Topic Author 0]

@hardsteppa thanks heaps

It appears that I have the following options, any advice would be a appreciated

a) rebuild the series 1

b) source a series 2

c) transplant the internals from GTR

The box is being mated to a mildly worked RB26 and then shoe-horned into a 240z street/track car, so its going to get a bit of a hard life and therefore needs to be somewhat reliable.

[hardsteppa 660]

If you can afford it, buy a new r34 rb25det box from japan, would be my choice.

[Ben C34 2,392]

23 minutes ago, hardsteppa said:

If you can afford it, buy a new r34 rb25det box from japan, would be my choice.

Do you know ballpark what that would cost?

[hardsteppa 660]

Around 3g aus i believe. Between buying a box and buying parts for rebuild i spent over 2g, and still have all old gears, beat up casing etc. So all brand new for that price is worthwhile IMO.

[GTSBoy 2,397]

JustJap will get one in for around $3400.

[admS15 1,280]

I bought a brand new r34gtt box for 3k at the end of last year when there was heaps of stock. Price rose a bit in the next few months. I have been told recently they are now made to order and it's around a 3 month wait. 

[Ratsun Topic Author 0]

@hardsteppa my aim was to undo every nut and bold on this resto, but given the shortage of parts and price of a new box it might just be more cost effective to purchase new.

thanks heaps for the help. 🙂