R34 Gtt Manual Conversion (not The Same As Every Other Topic)

[Sivvy96]

Hi Everyone,

New to this forum I decided to sign up as I coud'nt find the answer I was after and after searching many pages of forumns aswell as not being halfshitted going through 247 pages I came to this result.

Right now on topic. As most of you know and from what I've seen theres a heap of R34 Manual conversions topics on here and not many of them are very informative. I'm new to skylines but Ive got a background with cars so I dont really suffer the costs of labour charges. Now I've got myself a repariable write off with minor damage. It's an R34 Gtt auto with most parts included except the engine & auto trans. I currently have a RB25det Neo motor on the way and am hoping to convert it to a manual.

The question is whats the best manual gearbox to run on one of these motors that can handle the torque with out shitting itself?

I currently have a N/A Rb25de Neo 5 speed manual box and am curious if theres much difference between that and the manual the origionally comes with the R34 GTT and if that can handle the turbo'd engine?

If not then whats the best recommeneded Manual box to use?

I also believe the diff ratio is different between the GTT autos and manuals? If so will it hurt to use the auto diff if i go ahead with this conversion? Otherwise I'll replace it if the anyone knows the ratio.

I picked up this car cheap as so I don't mind spending some dollars for a unreal car.

Appreciate any answers guys, Thanks very much.

[GTSBoy]

The ONLY gearbox you should put behind the 25DET is the big box. That is the actual 25 turbo box. All the small boxes will break from the torque. The 33&34 boxes are essentially the same thing. 33 used a push clutch (conventional) and the 34 takes a pull clutch (less common& more expensive). Either can be used, SFO get what gearbox you can based on clutch preference or not!

You will not notice the difference between 4.11 and 4.08 gears in the diff. Hell, I've recently been swapping back& forth between 4.11 & 4.3 and barely notice the difference.

[iruvyouskyrine]

Can use the small frame box if you keep the engine relatively stock and treat the gearbox nicely. Should last a fair while. But if you plan on giving it a hard time save your money and sell the small box while it's still worth something and put it towards a proper rb25 box.

And same as gtsboy. I didn't notice a difference going from 4.3 to 4.11.

[V28VX37]

Since you've got a GTT base car I'd recommend going with a turbo box. The power bug inevitably bites and you'll kick yourself later if your put in the weaker N/A 5-speed.

R33 boxes are easier to come by but are older/more abused than the R34 ones (surprise). Clutches for them are cheaper.

R34 boxes have a better heat sink built into them based on side by side comparison photos.

R34 boxes can be converted to a push style clutch by replacing the bellhousing with an R33 item from what I've read.

R34 auto ECU can run a manual car no worries. Same goes for a Nistuned auto ECU.

Factor in some $$ for buying a manual harness or splicing into the auto one.

Also this thread is your friend: http://www.sau.com.au/forums/topic/139916-diy-r34-manual-conversion-using-r33-parts/

[Sivvy96]

Thanks heaps for the replies guys ,Appreciate it. I thought that would be case being on a N/a vehicle. I managed to find and order an R34 Gtt 5 speed manual so its on the way! I think I'll end up running the car off the auto ecu for now. Shouldnt be too hard to wire up hopefully. Any of you guys had much trouble with it?

[GTSBoy]

If the car originally was turbo then there will be no hassle plugging in the engine side of things.

You would be best off getting the harness that runs down the side of the engine to gearbox from a manual. So much easier than trying to build on and replace all the auto stuff.

The auto ECU is effectively a manual ECU with the TCU built into it, so it will run an engine on a manual just fine.

[Duncan]

Just wanted to say I agree with Josh, the smaller gearbox would not be a problem if you are genuinely just going to use standard power and drive like a human being. The problem is, standard is never enough......unfortunately the big gearboxes are hard to find and very expensive because every hectic drifter breaks one a week.