Jump to content
SAU Community

Recommended Posts

As per topic but expanded a bit more.

If I were to buy an RB26 GTR gearbox, with transfer case and all, how would I go about moding it to put in to a RWD RB20 application. Is it just a simple case of unbolt transfer case, and bobs your uncle (I wouldnt have thought so, but who knows).

Really Im lost with this one. Ive just done a quick search and got no where.

All I know is it can be done, and the reason is it is normally a cheaper option. If anyone has done it can you please post in here asap. I REALLY need to know.

I'm really keen to hear back on this one. ;)

I know GTR-Ben has done this and fitted the g/box up to his Silvia and RB30DET.

From what I remember you basically cut off the transfer case and weld a plate over the hole. Bobs your uncle.

Does the GTR box have a longer first gear? (compared to rb20/25)

I can't see how you just "chop off" the transfer case and weld it shut.. as there must be some gears that are driving the transfer case there.. ??

gtrgearbox.jpg

GTR's do a higher speed in 1st.. thats either the gearbox ratios or the diff ratios at play..

I have never done it but I have seen one done, looks/sounds like simple stuff. Unbolt the transfer case and remove the chain drive from the gearbox output shaft. Cut off the ATTESSA extension and weld an aluminium plate in its place.:(

You would need a custom tailshaft and almost certainly the same for the cross-member. At the very least you should check the position of the GTR cross-member compared to the GTSt type as well as the position of the shifter (eg distance from the bell-housing face).

You would need a custom tailshaft and almost certainly the same for the  cross-member.   At the very least you should check the position of the GTR cross-member compared to the GTSt type as well as the position of the shifter (eg distance from the bell-housing face).

I can answer a few of those;

I know the shifter is in the same place, I checked that.

The front tailshaft was the same as the "R33GTST gearbox in R32GTST" tailshaft.

(That's basically an R33GTST yoke and front shaft (shortened) with the mounting flange off an R32GTST).

The rear tailshaft was the standard R32GTST tailshaft.

I am not so sure about the cross member, I believe it was an R32 auto one. That needs to be checked, although I had heard (not seen) that it is simple to modify/move the standard R32GTST cross member.

:(

Yep I have done it alright. It was a tight fit into my S13.. and I have yet to do the cross member and tailshaft. Those are the simple parts though.

Basically you need to open it up, remove all the gears and chain etc so you are left with a straight shaft, put the speedo drive back on.

Then weld an alloy plate on the side. I just welded the complete transfer case up.. as the bearing press outwards there is no real need to get in there once it's sealed up. :(

You need to block the chain oil feed in the middle of the shaft as well as leave the oil pump there so it can supply oil to the rear bearing..

The cleanest way would be to make a new section so you can bolt it up and seal etc.. I did it the fast way as a test. If it starts to leak etc I know it fits now so I can re do it if needed.

The GTR's gearbox mount is quite different to the GTS-T etc.. but I am thinking a combination of the 2 would almost bolt up. The GTR box is also longer and I will be using a one piece tailshaft. Making tailshafts fit is as easy as cutting and welding then balancing..

My photo's are not so flash.. will get some more.

gearbox.jpg

under1.jpg

what do you mean the rear tailshaft is the same???

Mine didnt have a yoke, it had a flange?

It had a two piece tailshaft, the rear piece was the standard R32GTST.

Yep, there is a flange at the end of the GTR gearbox that the tailshaft bolts to, the GTST box needs a tailshaft with a yoke as it has a splined output shaft.

:(

I spoke to my mechanic today, he wasnt keen on the idea. Mostly because he has to charge me money to do it, and he doesnt want to charge me that much :) His words were ''its not that bad yet''.

I hope your not suggesting that anyone 'do this at home'  (cut and weld).   Basically the GTR flange output needs to be mated to the 'rest' of the GTSt shaft.

:confused:

Thats what you pay a Tailshaft expert to do.. who do hundreds a day and can supply with paper work to say it's legal...

I have had dozens done like this.

Yeah I know I said simply cut and weld.. which is simple and cheap for an expert to do.

Doing that at home would be on the stupidest things I could imagine.... lol

dangerous_daveo: Your Mechanic is right.. and the difference in price between a RB25DET box and modded RB26 Box will come a whole lot closer if you have to pay for other peoples time to do it...

It cost me nothing to do.. and GTR gearboxs are so much cheaper, I know when I blow one up, I can simple unbolt my transfer case and bolt it to another GTR box and away I go ;)

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now


  • Similar Content

  • Latest Posts

    • A 1.5 way is a 2 way. It is just a 2 way with a less aggressive ramp on overrun.
    • The ABS and/or TCS being missing/broken will not cause the engine to misbehave. It just casues CEL to come on and annoy you. The CEL is useless if it is always on, so you have to do the things you have to do to get rid of it, so it can be useful. Being a Stag ECU, then yes, it will not expect TCS to be present. But it will expect ABS to be present and working. You will need to either make the ABS CU talk to the ECU (don't ask me what that will take on an NA R34), and make sure the hardware is working....or, you just need to blank it out in Nistune. Do not persist with the stock ECU. You will just have problems. Gte it Nistuned. Start from there. DO YOU HAVE A BOOST SENSOR? The ECU's boost sensor that it. It is connected to the loom at the rear of the coil cover. Usually rides on the firewall on an R34, but is usually bolted down to a bracket along with all the other crap at the back of the coil cover when a Neo is dropped into another car. If you do not have it, the ECU will shit the bed. So, do you have one?
    • So sadly the fuel pump etc was not it. The pump and filter is new and it is still cutting around 4000 rpm. A read something about ABS/TCS (engine is from stagea and ECU too so no TCS) and i dont know for 100% that my car has ABS. It has ABS "cube" in engine bay but i dont think it works(or at least from my braking experience). Can be something like that?  I will be driving the car next week to Nistune tuner to properly see what is wrong...  
    • the Tomei LSD fluid with lsd kit. frustrated that it was shaking the car to crap and affecting everything else negatively, I pulled the diff last night, and removed the lsd carrier, could not find anything wrong, however it seem to be 100 locked up acceleration, and deacceleration, wondering if they sent me a 2 way not a 1.5??  either way I installed the stock open carrier back in place. test drove everything smooth as butter again. no shake, shutter, random, what felt like clutch slip and grab or drive shaft play, etc. something differently wrong in side the lsd. I might bother taking it apart (if possible) to figure out what's going on inside this carrier, as bought too long ago to return.  only draw back is its back to a one wheel wonder.
×
×
  • Create New...