R31 (Aussie) 5sp drivetrain strength?

[Cameron McDonald]

Hi, How strong is the Standard 5sp box and diff, driveshafts, etc in the R31?

I ask, as I am thinking of doing an rb30det conversion on an r31.

Would be running forged pistons, turbo mods etc, so realistically looking at 250+kw at the fly,

Will I destroy the running gear in short time? :flamed:

Honest answers required, as I dont want to have to switch to a 25det gearbox any time soon.

Thankyou,

Cameron McDonald

[rsx84]

rb25det box would be a good step in the right direction as you've got to think the N/A r31 box is just that and i'm sure not made to surrport 3x the power output... m2c

[relicr31act]

generally the "strength" of any component is less important than the manner in which it is used. If the question is can I multiply the power of the engine threefold, sidestep the clutch at 4,500 rpm and then flat change it through the cogs and have it survive the answer is NO. But if you are mechanically sympathetic and have some clues on advanced driving techniques that minimise damage to the more highly stressed drivetrain and the box was in good working order initially then the answer is probably YES.

[R31 POWER]

There's a dude over here with a RB30et in his Aussie GTS2 and that has 374rwhp with the N/A 5 speed,brass button clutch and still going strong.

The torque this thing has is way to much as he can cruz at 100kph in 5th then give it some and off he goes sideways in 5th,sounds hard to beleive but it does it.

Bit of a waste post coz that box is a freak.

[Adam 33]

Yeah got to love his driving style but the reason why it has lasted so long is because he still has pretty standard tread, nothing special, last time i checked they definately were not over 225/ as soon as he gets some decent tyre size on there then bye bye gearbox.

But yes 374 rwhp and no wider than 225 tyres creates some awsome driving;)

[SKY031]

Stock manual gearbox should be fine with RB30ET, but if you're spending the $$$ to go twincam, then fork out the few extra bucks to get a decent gearbox.

[shane_cummings]

A fella I know has a 240z race car with a VG30DET and 200KW @ the wheels, He runs a non turbo gearbox, I wouldn't say he abuses it but it does get a work out. As far as I know its stood up to the power, the importance would be not to put too much torque thru the higher gears, change down out of fifth!

[NismoR31Jet]

I ran an rb30et that hit over 200rwkw and I was using the stock Rb30 na manual box which was over 330,000 km old.

I have just got the rb26 running and am using the stock box for now, so I will find out the strength of the box real fast!!!

As for diffs. I only broke the spider gears on one diff. I belive there is a harlequin R31 running 10's? I spoke to the owner last year and he was still using the stock diff, just with a minni spool.

[predator]

250kw+ fly? if you are going for an rb30det with forged pistons and things 300rwkw (maybe 400kw fly) should be easy. Thats going to tear most things apart If you wanted 250rwkw just put get the bottom end converted to VL turbo pistons.

i think the torque would grind it pretty quickly. Apparently RB30e box and RB20DET box are very similar strength.. Some have killed their rb20det boxes at 180rwkw, others have got 250rwkw. So like people have said, its how you drive it and a bit of luck thrown in.

A diff specialist also told me similar about the borg warner diffs.. might make heaps of noise and not real too fancy.. but good for quite a big amount hp.

[cazz]

The only real weak link in any R31 is the tailshaft and diff. (Both ozzie made) Treat the Standard box nice, and it will be OK, a Series 3 manual box is stronger than a series 1/2 manual box. But if you want to have a car you don't have to worry about, no matter what, put a VL Turbo Box in or a RB25 Box, and a one piece tailshaft. Howdy by the way DVS-JET.

[Cameron McDonald]

Thanks for the replies guys, Still unsure about the project, just doing some thinking at this stage.

Predator, I would rather use the forged pistons, as the VL turbo pistons will create a very low compression ratio with the twin cam head (7:1? or so)= monster lag.

I work for Repco, so buying a new set of forgies and doing the bottom end properly would be slightly(i hope) more affordable for me compared to the average joe off the street.

How well would the standard rb25det turbo go on this combo, what sort of boost could it generate without disintegrating the ceramic turbine wheel?

Basically the idea is to take a stock r31, build the bottom end nice and strong, get an r33 gtst halfcut, slap on the head, wiring loom turbo, etc straight in.

Then take it from there, if more horses are desired.

Obviously if the r33 rb25det halfcut is a manual, I would use the box out of it, but I have a friend who has an r33 gtst with an auto on the way out, so the idea would be to go halvies, I take the head, turbo, loom,efi sys.

He gets the block, auto and rack,etc,etc.