RB25DET Series 1 & Series 2 Gearbox Identification

[Ratsun]

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]

There's a difference?

[Ratsun]

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]

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]

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]

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]

how far would i need to pull it apart?

 

 

[hardsteppa]

Series 1.

[hardsteppa]

 

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]

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

 

[hardsteppa]

 

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]

@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]

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

[Ben C34]

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]

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]

JustJap will get one in for around $3400.

[admS15]

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]

@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. ?

 

[hardsteppa]

On 19/12/2019 at 10:55 PM, GTSBoy said:

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

If you call a completely different improved 2nd>3rd  synchro setup insignificant then, ...yes.

Just finalising an R34 RB25 gearbox swap into R33, couple of things to note.  If you are going with a push-clutch rather than the R34's pull, there are bosses moulded into the bellhousing you need to drill and tap to be able to bolt your clutch slave cylinder on. I put a stud into the hole closest to the clutch fork to make installing the slave easier, but up to you.

You need to change the front cover plate....obviously, as it's well-covered everywhere. If you were short of $$ looks like you could adapt the R34 front cover to be able to take the clutch fork ballstud/pivot bolt but, up to you, prob not worth it.

The neutral and reverse plugs on the sensors that the box comes with are likely to be different. You can get the loom side of the connectors here, and they are EXCELLENT quality.

https://www.efisolutions.com.au/2-pin-grey-connector-nissan-reverse-switch-fuel-ha

https://www.efisolutions.com.au/2-pin-black-connector-fits-some-nissan-neutral-swi~138383

The box comes filled with oil but it is a corrosion-protection oil only, do not run the box with it. Drain and refill with a good 75w-90 once box is installed.

[GTSBoy]

8 minutes ago, hardsteppa said:

If you call a completely different improved 2nd>3rd  synchro setup insignificant then, ...yes.

Wow. Pissy much? You on a mission to find old posts to argue with, or is this legitimately just because you're 5 years into a 1 day job?