Jump to content
SAU Community

Recommended Posts

I am currently doing a RB26 swap to my R32 gtst. I have searched on this in all the silvia forums regarding on making the rb26 rwd. There are different method but i wonder which one will be better. Should use the GTR tranny and cut the transfer case? then weld a plate on top? or should i just get a RB25 tranny? i am asking because i know it will take some work to get the rb25 to work with gtst cluster. Also, the engine will come with a gtr tranny so i dont want to sell it and buy another unknown condition rb25 tranny. Is the GTR tranny going to work? whts the bad side of cutting the transfter case off?? thanks

Link to comment
https://www.sau.com.au/forums/topic/164613-rb25-tranny-vs-rb26-tranny/
Share on other sites

Why exactly do you want to cut the transfer off when it unbolts from the rear of the transmission??

Generally the easist way is to remove the Transfer open it up and have it modifed to suit. Most places compentant with transmission work can do it. What area are you located in?? By far the neatest and probably more simple solution is to buy an RB25 box even if its stuffed. You can use the RB26 gearset minus the ouput shaft and build a good RB25 box out of it.

what i mean to cut the transfer case of its that i want to remover the part that sticks out. and bolt a plate over to cover the hole. I am located in Canada and there is no one doing a rb26 swap to a gtst that i know of. My plan was orignially save the money of getting a rb25 box n use it to rebuild the engine. i know the cutting part sounds weird but i have seen some people doing it, don't know if it is the best way though.

Charles W,

GTRBen did exactly what you are talking about and was goign to fit it in to his RB30DET S13.

I remember seeing some pics with it in the tunnel but for what ever reason he ended up not finishing the *rb26 g/box* project and bolting up an rb25t box.

I don't see Ben around here all that much any more but it wouldn't hurt to drop him a PM.

Be sure to update the thread with any issues etc and why he decided to not go with it if he responds. :blink:

25 & 26 box are basically identical im lead to believe.

Obviously one has a transfer case, one doesnt etc. But internally they are the same thing.

So... just use a 25 box and sell the GTR box off. You'll come out infront cost wise as opposed to having the transfer case removed etc

it depends on your usage, i have modded a few GTR transfers to RWD only see pic. i even have a spare in the shed.

The benefit of using a GTR trans is they are dirt cheap on average i would pay between 500-800 for a complete setup. The gtr box and modded transfer has much better support (4 bearings vs one) on the output shaft so takes abuse like drifting far better, in fact TRUST japan uses a GTR box and modded transfer behind their sr20 D1GP car as it lasts far longer than the GTs-t equivalent. (something to do with the way the load travels up the output shaft).

the downside is the time and effort to make it happen, i built one up for our RB26 powered s13 but found that due to some other issues i was unable to fit it in the tunnel without reworking the custom handbrake setup and so forth. I ended up using a R34 gtt box.

only the R34 is a 6 speed and it wont fit.

R33 gts t and R34 GTT are the same box but the R34 has some nice subtle upgrades ive noticed.

post-34927-1177048228.jpg

post-34927-1177048779.jpg

Edited by URAS

There is aheap of info around now about the 25/26 boxes.

They are the same gear set, identical in every single way. Like Uras has said the output shafts are a different length and supported slightly differnt but other than that they are the same same.

You can't take the GTR gear set out and drop it straight into the GTs't housing because the shaft differences for the trasnfer. You need to get a GTS-t output shaft and have the gear set fitted onto this shaft then fitted into the housing.

Ive dont plenty of them its not a hard thing to do with the right tools.

Risking, I reckon there is money to be made there. As mentioned above, GTR boxes are dirt cheap and GTST boxes are getting hard to find I've been told. I guess this only helps where you have a dead r33 box though and doesn't address the shortage of r33 boxes.

Uras, in a bigger car with stock handbrake setup (eg R33gtst) would you think the modded GTR box will fit? Also I remember reading about your car in HPI I think where you said you thought the R34 box was stronger than the R33 one (pretty sure it was you). What makes you think that? What are the subtle differences you talk of?

I'm certainly no expert so I'm not being a smart arse with these questions. The only thing I've noticed from the outside is the R34 box is much lighter as the casing is made with much more aluminium in the alloy. The down side is that it's very soft and easy to thread the bell housing bolts.

Yeah I agree hence why we do the conversion. If you have a dead GTS-t box and can get a GTR box fro cheap its really very simple to re-build the GTS-t box with the GTR bits using the original output shaft.

Unfortunatly alot of people tend to do exchange R33 boxes with wreckers and they end up being lost or dismantled for parts making it very difficult to get the housings.

You may remember seeing a box in bits near your diff that I was actually building at the time to go into an R32 RB25.

I have fitted full sized GTR boxes into the R33 GTS-T before but im not sure about the 34. From memory the floor pans are very similar and Id say it would fit.

R34 boxes are very similar to the Z33 gear set all bar the extra gear and selector obviously, id be interested to hear Trents opinion on the R34 5 speed as im not a fan of the Z33 box at all

Could be a few things. Probably fimd the previous owner of the box rested a little pressure on the gear stick in 5th and may have put some premature wear on the face of the selector fork so it wont engage, Could have a problem with the Gate on the selector.

I have this same problem with my GTR from time to time and I know its cause I rest my hand on the stick with a little presure whenever I drive it to work cause im lazy

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

    • I'm looking for some real world experiences/feed back from anyone who has personally ran a EFR7670 with a 1.05 exhaust housing or a .83 I'm leaning towards the .83 because its a street car used mostly for spirited driving in the canyons roads. I"m not looking for big numbers on paper. I want a responsive powerband that will be very linear to 8000 rpm. I dont mind if power remains somewhat flat but dont want power to drop off on top. The turbo I've purchased is a 1.05, although the mounting flange T3 vs T4 and internal vs external waste gates are different on both housings, I not concern about swapping parts or making fabrication mods to get what I want. Based on some of the research I've done with chat gpt, the 1.05 housing seems to be the way to go with slightly more lag and future proofing for more mods but recommends .83 for best response/street car setup. AI doesn't have the same emotions as real people driving a GTR so I think you guys will be able to give me better feed back 😀   
    • Surely somebody has one in VIC. Have you asked at any shops?  Is this the yearly inspection or did you get a canary?
    • This is where I share pain with you, @Duncan. The move to change so many cooling system pieces to plastic is a killer! Plastic end tanks and a few plastic hose flanges on my car's fail after so little time.  Curious about the need for a bigger rad, is that just for long sessions in the summer or because the car generally needs more cooling?
    • So, that is it! It is a pretty expensive process with the ATF costing 50-100 per 5 litres, and a mechanic will probably charge plenty because they don't want to do it. Still, considering how dirty my fluid was at 120,000klm I think it would be worth doing more like every 80,000 to keep the trans happy, they are very expensive to replace. The job is not that hard if you have the specialist tools so you can save a bit of money and do it yourself!
    • OK, onto filling. So I don't really have any pics, but will describe the process as best I can. The USDM workshop manual also covers it from TM-285 onwards. First, make sure the drain plug (17mm) is snug. Not too tight yet because it is coming off again. Note it does have a copper washer that you could replace or anneal (heat up with a blow torch) to seal nicely. Remove the fill plug, which has an inhex (I think it was 6mm but didn't check). Then, screw in the fill fitting, making sure it has a suitable o-ring (mine came without but I think it is meant to be supplied). It is important that you only screw it in hand tight. I didn't get a good pic of it, but the fill plug leads to a tube about 70mm long inside the transmission. This sets the factory level for fluid in the trans (above the join line for the pan!) and will take about 3l to fill. You then need to connect your fluid pump to the fitting via a hose, and pump in whatever amount of fluid you removed (maybe 3 litres, in my case 7 litres). If you put in more than 3l, it will spill out when you remove the fitting, so do quickly and with a drain pan underneath. Once you have pumped in the required amount of clean ATF, you start the engine and run it for 3 minutes to let the fluid circulate. Don't run it longer and if possible check the fluid temp is under 40oC (Ecutek shows Auto Trans Fluid temp now, or you could use an infrared temp gun on the bottom of the pan). The manual stresses the bit about fluid temperature because it expands when hot an might result in an underfil. So from here, the factory manual says to do the "spill and fill" again, and I did. That is, put an oil pan under the drain plug and undo it with a 17mm spanner, then watch your expensive fluid fall back out again, you should get about 3 litres.  Then, put the drain plug back in, pump 3 litres back in through the fill plug with the fitting and pump, disconnect the fill fitting and replace the fill plug, start the car and run for another 3 minutes (making sure the temp is still under 40oC). The manual then asks for a 3rd "spill and fill" just like above. I also did that and so had put 13l in by now.  This time they want you to keep the engine running and run the transmission through R and D (I hope the wheels are still off the ground!) for a while, and allow the trans temp to get to 40oC, then engine off. Finally, back under the car and undo the fill plug to let the overfill drain out; it will stop running when fluid is at the top of the levelling tube. According to the factory, that is job done! Post that, I reconnected the fill fitting and pumped in an extra 0.5l. AMS says 1.5l overfill is safe, but I started with less to see how it goes, I will add another 1.0 litres later if I'm still not happy with the hot shifts.
×
×
  • Create New...