R31 Local G/box Stength

[funky monkey]

Ok got a bit of an odd idea lately.

Doing a rb30 conversion in my 32 soon (gts-t) and as my original rb20 gearbox is slowly on its way out ie buggered syncros etc ive decided i will change that at the same time. I was just wondering if anyone has used a 31 box in a 32.

also if anyone has a turbo (local) 31 out there how much power can the box take.

I know a 25 box is a much more sensible proposition but at this point in time i would simply like to know if a 30 box could handle the punishment as im building a turbo SOHC rb30 for my brothers Datsun and he doesn't really want to fork out the extra cash for a 25 box.

any help would be much appreciated thanks guys

[VB-]

do it till you smash the MF5, then fork out for an upgrade. those boxes are worth f*ck all second hand, so might aswell use it till its no good. i *think* you can still use the same clutch and flywheel when you change the box over too, so theres no issue if you want to buy a tough clutch. although double check on that as i cant be sure

the R31's i believe should have pretty much the same box as the 32, just with a single syncro on first and second, overall strength, im lead to believe, is pretty similar

[NateR31]

they are crap, and yeh they are similar just less syncros, afew people do a rb20 conversions to 31's and keep the box, but with some decent power the box will just shag itself.

[CEF11E]

I have an R31 box with a hardened gearset in my R32 that is powered with a RB30det making 260odd rwkw and well over 600nm of torque.

I bought the box recoed and the gearset had been hardened, cant remember if it was nitrided or what was done to it but its been in there for 15 months doing its duty. the syncros are not fantastic but it has held the power fine.

probably not an ideal box but should hold together for a decent amount of time if it is treated with respect.

[NZM.031]

what is exactly about the rb20 boxes that break?? stripped gears?? snapped shafts?? etc??

i use my 32 for drift mainly... not much for drag.

just wondering what it is that is crap about the rb20 boxes and under what treatment?? snapping gears?? dumping clutch?? clutch kicking?? or is just shear power??

and yes rb25 and rb20 have same clutch.

cheers

Linton

[CEF11E]

I have busted 3 of them

1. input shaft bearing shat itself and the box became super noisy and crunchy.

2. blew iself to bits and a hard chance into 3rd. i was un able to tell what went wrong woth it as it was shattered. gearsets and syncros everywhere

3. stripped the teeth of 2nd gear..

all these were done with rough treatment and a heavy single plate with an rb20 making 240rwkw. if you treat the box well and no flat shifting it will last quite well

[RB30-POWER]

i have built an rb30det that has the r31 box behind it, holding up fine under moderate power.

however the car doesn't have an lsd and uses street tyres and organic clutch, so more then likely the reason it is still alive.

slicks/semis, lsd and button clutch would equal instant bye bye i reckon.

by the same token there was a guy with a turbo r31, slicked and lsd, launched it and actually popped the 4 pinion diff, how the diff went before the box is anyones guess, but i put it down to luck more then a testament of the stock r31 box strength.

[CEF11E]

not really

I have a button 5 puck ceramic clutch and 255 semis on the rear and a 2 way lsd on mine and she is still holding together

[battery]

i have a 31 box in my r32, the clutch and flywheel's are different and are not interchangeable with r32 or r33 boxes.

i have just done a clutch swap 10000k ago and im starting to get a noise when its engaged im thinking its the input shaft as the thrust bearing was replaced not long ago...

it likes to slip out of 5th sometimes too.

[toffy]

^ thats funny , i've put a r31 gearbox in an r32 before and it bolted in just like the r32 box

the syncros are the main difference , other than that its the same box as the 20 so it should handle the same power

Edited December 28, 2008 by toffy