Rb20det Gearboxes

[Roy]

PPl have told me the weight difference is typically about 20kgs

[Oosh]

Just been looking at my broken box at the mechanics less than an hour ago.

Okay, my reverse selector fork broke, leaving the gear to float back and forth, chipping teeth and sending them floating about and gunking up the works.

The hardening on all the other gears was chipping away.

The input bearing and another one were also shot.

[boostin_r33]

Its only a few kilos difference wouldn't make a difference in performance though just the rb25 boxs can handle more pwr

[AzzurrA]

every kg helps, boostin_r33

[The Dan]

I smashed my Rb20box....still drives.

Typically the problem areas are as follows.

Gearset too weak

Synchros too weak

Bearings too weak

Input shaft too weak

Pretty much the best way to strengthen an RB20 box is to throw it away and buy an RB25 one. Unless you have about 6-7 grand to play with. The standard 20 box can handle 200rwkw day in and day out as long as you don't smash second too hard. Mine went 2 years on 200rwkw and about 6 months on 240 then it was getting hard to select 2, 3, 4 and 5.

I have the RB20 box which you can have for $50..... plus freight unless you wanna pick it up from Brissy.

[Oosh]

Already source and had installed a RB20 item.

Cheers.

[Roy]

I smashed my Rb20box....still drives.

Typically the problem areas are as follows.

Gearset too weak

Synchros too weak

Bearings too weak

Input shaft too weak

Pretty much the best way to strengthen an RB20 box is to throw it away and buy an RB25 one. Unless you have about 6-7 grand to play with. The standard 20 box can handle 200rwkw day in and day out as long as you don't smash second too hard. Mine went 2 years on 200rwkw and about 6 months on 240 then it was getting hard to select 2, 3, 4 and 5.

I have the RB20 box which you can have for $50..... plus freight unless you wanna pick it up from Brissy.

What fluid and clutch...i was makign about 190-210rwkws for about 12 months (150,oookms to 165,000kms), then between 215-235, ocassionally 250 odd rwkws for about 8 months with plenty of track work thrown in and my box isnty even makign any funny noises....and i run semi slicks

Im forming the opinion that its a combination of luck, the way i drive and the fact that i only have a baby single plate clutch and am using very good fluid, (not redline...but Castrol) ?!?!?!!

That said i no i wont cheat death forever...but trust me, if the box is 20kgs heavier, thats half a tank of gas, and at the track you can feel when you go out in the morning on a full tank, then syphon 30L from the tank and go back out...the lap times dont lie

[Bl4cK32]

Then u need to shed 20 kg's from somewhere else in the car to offset the larger box then Roy Have u still got aircon, carpets, and a rear seat?

[Roy]

Well i can lose 10kgs, and im losign that cause im now a fat fark, forget the car. But i want to keep the air con and all that because it still is a street car, and if it happens to go quick one day, i dont want ppl copping out and saying its stripped...it would be so much easier/cheaper if i didnt care what ppl thought of the car

[dangerous_daveo]

I guess if your not snapping them it doesnt matter. And to be honest most of it is probably your clutch not snapping them.

But if you do start snapping them, you have to start to think. The extra 20kgs might be worth it. If you have to constantly replace or rebuild rb20 boxes, it kinda takes the fun away. That is assuming you are still doing track days for mostly fun, and not some form of paid competition.

[GTS20X]

If the RB25DET box weighs an extra 20kgs than the weight benefit will be more as for every kilo of rotating mass has the equivelant of 10kilos in the car.

Carlos

[predator]

That's if the actual gears are heavier... Then you'd also have to work out any differences in design to work out differences in energy lost in the gearing action. Then you'd need to know how much extra was in the actual casing compared to the gears.

Don't think it would be that simple.

[ellie]

My gearbox was tempremental shifting into 2nd. When dead cold it would have a slight choke when engauged the first couple of times then would be fine.

I've now canged the oil with a nulon additive and it engauges from cold alittle smoother but after a couple of spirited shifts that didn't quite engauge 2nd and munched it, it now has become a tempremental gear all the time so now I have to baby second which is begining to grate on me.

I highly suspect 99% of the damage had been caused well before I got my hands on the car and second gear as it cops a fair whack of torque and usage has lost the effectiveness of its synchros so is now crunching on engaugement. Unfortunately there's only one way it can go from here!

Which puts me in the same boat as you guys = 2nd hand gear box (unknown condition)

Reconditon (pricey at best)

Rb25 box (same as GTR, strong but once again

risky and pricey)

[huddy]

hi guys i'm a victim of blowing the rb20box - with 230rwkw clutched it in 3rd and 3rd exploded :S

i've done a 25box conversion and having major issues with clutch slipping, if anyone has any advice please read my thread and some feedback

http://www.skylinesaustralia.com/forums/in...howtopic=117570

thanks

-Matt

[brizzi]

I have exploded three of them! This neo r32 one is dying verry fast i think... My old rb25 powered r32 blew two.. I reved it to limiter and grabbed second then it exploded... I pulled it down with dad i slit second gear in half... Not bad boxes,but they dont like rb25 power and torque..

[Oosh]

RowdyR32 managed to make his survive a RB26 @ ~250RWKW, you just have to be aware of it's relative fragility, and drive accordingly.

[mr_rbman]

i have an RB30 in my 32 now still with the 20 box and naturally i'm looking to upgrade, I have spoken too PPG and they can rebuild my gerabox with the works but the price is a hefty $6100, I think the 25 box is the way to go!

[MANWHOR3]

One of my friends has smashed 3 rb20 boxes with about 250 rwkw.

The weak links in the box appear to be as mentioned above, basically everything in it. The ways it was smashed was:

1. shifting hard into 2nd.

2. near the top of 3rd gear, foot planted. Once the torque/power came in, the gearbox literally just exploded.

[T04GTR]

cool. just had to put one in a 32 non turbo!

was klnocking at all revs regardless of wich gear.

it turnes out that gay little bearing on the sandwich plate failed.

countershaft.

(bearing race ball cage came apart.) suprise suprise.

so it seems it really is luck of the draw really. concidering a na. rb20 completly stock lunched it lol

[fat200sx]

Mate works for birrana racing they have looked at an sr box, same as rb20 box and he says that the casing slightly flexes and loads the bearing in a way that the gearbox fails.