transmission hypothetics

[Seaney_55]

may be a silly question and it's completely hypothetical so bear with me and fan your flames.. also, please no "why would you want to do that?" posts..

now is there any way that i would be able to go to a transmission shop and either gut the rb25 transmission and1) replace it with rb26 6spd gears2) have custom gears fabbed

and if i could could someone with knowledge on the subject tell me how much it would cost.. i know this guy in canada that makes trannies and they're strong as hell.. but at 1k for a transmission seems steep and the transmission that i've seen in action was for a crx.. (custom w/ a 6 gears, made for my friend shad)

any thoughts on this would be nice, but i would like a bit of informed advice..

[rbsileighty]

You might not want to consider custom anything if you think $1000 is to expensive. Why do you want 6 gears? Depending on your setup... having the 5 taller gears my be the better option (unless the 1-5 gears on the GTR's are the same as the 1-5 on the 25 trans, but I doubt it). Someone like Wulfgang might be the best to touch on this whole post/subject.

[Nameless EJ6]

I'm almost 100% sure you can't fit all 6 gears from the GTR gearbox into an RB25DET gearbox. If you were to have everything fabbed it would likely cost you as much as 8-10k+ for something nice. You're better off fabbing an adapter plate/bell housing and using a transmission from another make.. like toyota. Or invest in a serious fuken box that's already been fabbed for 10-20k.

You really don't need 6 gears anyways. Unless you trap over 170 or so mph, or you love cruising the highway all day long, the RB25DET gearing will be fine.

[rbsileighty]

Depending on how serious I really get with my car, I've considered a Jarico road racing 5spd which is a fully custom 5spd w/ a super light housing... it is ~$5k which isn't to bad considering what you get. Regardless, it is the same if not less than what it'd take to do custom work to an existing trans, and it can take heaps of power (they quoted me 800+... I'm not even going to touch that). Not to forget you can pick your gear sets and change them out with an access panel later if needed.

[Seaney_55]

um, sorry i wrote 1k but wanted to put 10k down.. but still, thanks for the imput.. keep it coming!

[IvoryJ30t]

you wont be getting the R34 GTR's 6 gears in a nissan case no matter how you slice it.

R34 GTR 6 speed = Getrag5 speeds [all others] = Nissan

[IvoryJ30t]

you better off having a Supra 6 speed transmission mated to the motor if your dead set on having 6 speeds.

theres no need for it though.

the R34 GTR uses a 3.545 rear diff and short gears. if you were to mate that transmission to a S chassis's 4.08 rear, you will loose top speed.

the nissan trannys use a .75 5th gear, and the getrag uses a .78 6th gear. makes no improvement.

your gonna be looking for a totally custom transmission.

besides the whole piont, with the nissan 5 speed, at 8K rpm, with a 3.916 rear, and a 255/40-17 tire, your going 202 mph.

[rbsileighty]

Ahh... that's right it's you Ivory, the resident transmission man. For some reason I was thinking it was Wulfgang.

[IvoryJ30t]

its what happens when you have too much time on your hands one day, and decide to go over all the transmission combo's

the getrag unit looks good untill you see the ratios, and the fact that theres 50 or so lbs of useless metal if your not going AWD.

personally, i think the nissan trannies are good enough considering the larger gearset withstands GTR's dumping clutches, you shouldnt have a problem in a RWD configuration.

i would bet that with slicks you would break the rear before you broke a gear/shaft.

[IvoryJ30t]

the only thing a six speed would be good for is adding an extra shift. unless of course, someone feels the need to exceed 200 mph. and in that case a custom transmission will probably be on the menu anyway.

the only difference between the RB25DET transmission and the GTR 5 speeds is the AWD. the gears are the same. if it will hold up to AWD, it will take RWD without a problem.