Reliable HP limit for GTS-T boxes

[JustenGT4]

Howdy,

I've done the usual FAQ and forum search and come up with some info but not exactly what i'm chasing.

As background i'm from the dark side with a GT4 Celica running a twin turbo lexus V8. The Supra boxes i running aren't cutting the mustard (W58) and the next step up is ugly (R154) and the step up from that is hell expensive (V160 6 speed).

The 300ZX box and R33/34 GTS-T boxes seem to be very strong so thought i may as well give them a try.

I'm looking at 350rwkw but it's the big torque from the 4lt V8 that's destroying things...guestimating 700+Nm at final tune.

So, what's the low down on these boxes or can a GTR box lose the transfer case for straight RWD use only?

[Sydneykid]

R33 GTST (RB25DET) gearbox is the same internally as an R32/33 GTR gearbox. We are up to 725 bhp (460 rwkw) without any problems, after having run 650 bhp for 12 months on the same gearbox.

[GTS-t VSPEC]

Geez, you guys must drive soft, I've broken the 4th gear synchro in mine at only 330rwkw.

[JustenGT4]

Sweet, that's good to know. I'll be 100rwkw shy of what you are produced and i'm pretty sympathetic with the gear changes so looks like this type of box might meet my needs.

A couple more questions then. What would be a fair price for a box ? and is any model preferred over any other or just fine the newest i can? I have heard that a batch of R33 boxes was a bit suss but could just be web goss?

[Sydneykid]

Geez, you guys must drive soft, I've broken the 4th gear synchro in mine at only 330rwkw.

Oh dear, you really left your self open for this one.... :wassup:

Gear failure is the sign of excessive torque loading, but you had synchro failure. Any data logging analysis will tell you that is unsympathetic gear change technique. :thumbdwn: You just gotta cut out those flat changes, it's not a dog box

[GTS-t VSPEC]

I agree I'm not sympathetic to my gearbox, but neither do I flatshift alot. Seen a few 3rd gears blown out of ND4SPD's boxes at similar power to yours. Just don't want to give the guy false hope about there strength. For a stock gearbox there brilliant, but certainly not indestructable.

[rb25]

Geez, you guys must drive soft, I've broken the 4th gear synchro in mine at only 330rwkw.

thats just stupid. you're being a showpony/dynoqueen again! whats your 1/4 time or are we still waiting for warmer weather?

-rb25

[Cubes]

It all depends on how well the gearbox was previously treated. Oil used etc.

I've heard of some RB25 gearbox's having synco problems yet some never have a hint of a problem.

[Sydneykid]

I agree I'm not sympathetic to my gearbox, but neither do I flatshift alot. Seen a few 3rd gears blown out of ND4SPD's boxes at similar power to yours. Just don't want to give the guy false hope about there strength. For a stock gearbox there brilliant, but certainly not indestructable.

All joking asside, when you say "seen a few 3rd gears blown out of ND4SPD's boxes", what do you mean exactly? We strip the teeth right off 4th gear, starts with torque loading on one or 2 teeth and then chews its way through the rest. :throwup: I have never seen a gear "out" of the box, just a bunch of mush in the bottom.

[Fitzpatrick Speed Works]

there are inherent design problems within the gtr box and from what i have seen from two apart boxes on a bench one a gtr and another a gtst they are a little different!!! The problem with 3rd gear in a gtr box is that nissan set the countergear on third gear 3mm too far foward so if a gear change is rushed ie. drag racing, and throw in big revs they dont ingage all the way down the spigett or cog and thus when you are loading up the gear with full power they tend to shear the teeth right off the end of the gear!!!! Its never a problem if the gear is carefull and fully engaged but this often doesnt happen in a motorsport situation or with sloppy gearchanging or flat changes!!! It doesnt help that 3rd gear is also in the middle of the stack either!!!!

[JustenGT4]

Thanks for the debate guys,

It's a turbo V8 remember (4lt) so i won't be pulling the bigv revs you guys do. I think the syncros will be fine as i'm not having probs with those at present. It's bearings and gear sets i'm worried about and i'm not hearing horror stories about those at the hp levels i'm looking at.

Good to hear. Anyone point me in the direction of a fair price for a RWD box and any model better than any other?

[rb20-calais]

GTS-T boxes generally cost $1200-$1500 privately but are worth it as they are great boxes, getting one from a wrecker you may be looking at close to $2k depending on who and availability.

I picked up one in perfect condition with tailshaft and almost new extreme single plate for $900, so awesome deals can be found.

Evan

[JustenGT4]

Thanks Evan,

Now to search for that elusive swesome deal :-)