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Rb20Det Box On Rb25Det

R3N3
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R3N3 Proficient

R3N3

Posted
Posted

Hi, i was wanting to know how much the RB20DET box can handle? i now it would be best to get the RB25det box, but at a third of the price its hard not to consider the RB20det box. my car is a relatively stock (for now) R33, my goal is one day to have round the 250-280rwkw mark, with track days etc in mind. will it be fine with just a better clutch or what?

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https://www.sau.com.au/forums/topic/352978-rb20det-box-on-rb25det/
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Birds Grand Master

Birds

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Posted

RB20DET is a piss weak gearbox. I wouldn't put one in a stock RB25 street car, let alone tracking @ 250rwkw.

Also, FYI an uprated clutch puts extra pressure on the gearbox, not the other way around. It's meant to be the weak link in the driveline. What's wrong with your current gearbox?

Sir Lord Van Von Vader'ham Veteran

Sir Lord Van Von Vader'ham

Posted
Posted

also depends alot on how you treat your car/box.

i have a 20box running behind a 30DET with 285rwkw and a bucket load of torque. its a track only car too, been going good for two years doing motorkhana's, texis, hillclimbs and normal track days.

i figured i could go through 5 for the price of one 25box, but yeah, so far so good.

Birds Grand Master

Birds

Posted
Posted

Yes, you would have to reconvert everything as the RB25 is a completely different box. Do it properly first time around and get an RB25...there's a reason Nissan didn't use the RB20 box in the R33. If you blow up even one or two boxes, the cost and time to replace won't have been worth it, not to mention how bad it feels retiring from the track with no gears :)

Sir Lord Van Von Vader'ham Veteran

Sir Lord Van Von Vader'ham

Posted
Posted

not to mention how bad it feels retiring from the track with no gears :)

you'd have to feel awesome but, like my car is sooo powerful it munches metal cogey spinney things!

Really is a valid point though.

Birds Grand Master

Birds

Posted
Posted

you'd have to feel awesome but, like my car is sooo powerful it munches metal cogey spinney things!

Really is a valid point though.

Hahaha, or the sad reality in most cases "I can't drive a manual for shit".

I'm very surprised you've lasted this long with the RB20 behind an RB30ET. Very lucky or you know how to take care of it I'd say. There are that many people who blow up the RB20 box with little more than factory boost. How much does your R31 weigh in race spec? Might factor into things, as you can run piss weak boxes behind lightweight Cobra kit cars with big V8s all day long and have no issues at all.

badhairdave Proficient

badhairdave

Posted
Posted

I also had a couple of years with a 20 box behind a 280odd rwkw rb25. Ended up removing it and selling it to upgrade to a 25 box before the inevitable death and zero resale.

This was in a full weight 32gtst.

It did get a little noiser over that time but still shifted fine.

Mechanical sympathy and a sprung centre clutch is the key.

Sir Lord Van Von Vader'ham Veteran

Sir Lord Van Von Vader'ham

Posted
Posted

Hahaha, or the sad reality in most cases "I can't drive a manual for shit".

I'm very surprised you've lasted this long with the RB20 behind an RB30ET. Very lucky or you know how to take care of it I'd say. There are that many people who blow up the RB20 box with little more than factory boost. How much does your R31 weigh in race spec? Might factor into things, as you can run piss weak boxes behind lightweight Cobra kit cars with big V8s all day long and have no issues at all.

just lucky i'd say. i break stuff alot.

when i last weighed it, it was 1150kg dry. so +100kg for me, say 40-60kg for cage and 35kg in fuel.

maybe 1300-1350kg

tyres are 235 fedi RSRs and a sprung centre 5 puk with 4000 pound clamp load & carbonic? pads. maybe combination of lighter weight, smaller tyre contact patch and clutch help

i actually dont want to break the box, i got a case of piss saying it'll last 12 outings.:rolleyes:

Ad's Mentor

Ad's

Posted
Posted

I have a rb20 (nics) if it makes a difference behind my rb25 in my coupe! Car makes around 180rwkw not to sure but im having it dynod friday! Has lasted about 2 months now. But i don't drop the clutch on it hard etc, but i think it comes down to the clutch too! I have a heavy duty clutch in it from when i bought it but i need a new clutch so if i went a too harsh clutch it would probally break after a while..

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