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Rb20 Gearbox In An R33 Gts-t

SoFreshSoClean
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SoFreshSoClean Proficient

SoFreshSoClean

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Gday, well Im doing to do a transmission swap in my turbo auto R33 because auto is teh sucks for throttle control.

Seeing as RB25 gearboxes are going for 1500 plus lately I was considering using an RB20 box. I was wondering if this was possible, ie a straight bolt in or would I have to stuff around to make it fit? Keep in mind I'm not building a power monster, ie im only aiming for 250-300rwhp MAX once I'm done with the car. I'm building it for response, not for massive straight line go.

Im just not sure if the RB20 box would cope with the increased torque. Also, I'm very sympathetic to my drivetrain, there will be no flatshifting or 7k launches etc.

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SoFreshSoClean Proficient

SoFreshSoClean

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Thanks Munna1 yeah I understand that its torque that kills em..

I've heard of people using them for VL turbos, with varying success. What would an average 250rwhp car be putting out in terms of torque? Keep in mind this is probably running stock turbo or a highflow item.

So it would bolt up, but require a custom driveshaft?

Anyone running big torque/power through a RB20 box?

brizzi Collaborator

brizzi

Posted
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;) I would not bother dude! I just changed mine to a rb25det box, cos rb20det boxes dont handle much!

I know some people arnt made of money, whatever your cash flow is? Save your coin, and get a rb25 box!

Tailshaft slipyoke on a rb20det box is heaps smaller than an rb25 one :wave: So you will need tailshaft mods!

I want to change mine to auto cos i am sick to death of manual boxes! Me and them dont mix! ;)

People think manuals are quicker,but i think you have to be a perfect driver to make a difference shift times etc.. :)

FATGTS-R Experienced

FATGTS-R

Posted
Posted

In theory it shouldn't cope as Nissan themselves saw fit not to use it behind the RB25 but many people have used them with success.

Will all depend on how you drive it though and what condition the box is in when you get it.

R31NISMOID had a 20 box behind his RB25 (over 300rwhp) and it lasted a long time.

Also plenty Of R31 guys turbo the NA engine (3 litres = more torque than 25) and keep the standard box which is near on identical to a 20 and make them last, although some smash them every 6 months which again comes down to driving style, clutch choice and tyre choice.

If your car is still running with the auto I would just save a little longer and get the Rb25 item.

The 20 box is cheaper, yes, but you will need custom tail shaft, custom/modified gearbox mount and sort out the speed sender. Obviously with 33 box it will all be factory parts you can source s/hand.

R32 Driver Mentor

R32 Driver

Posted
Posted (edited)

play R 32 (i think thats his user name on the forums) is running in his R32 GTST with a RB26 conversion with a rb20 gearbox at over 300rwhp

since its an auto your going to need a custom tailshaft, centre console, clutch master/slave cylinders n shit done, if your not a bastard on your gearbox then a rb20 box would hold up fine

btw what is the price difference between a rb20 and rb25 box coz 1500 sounds cheap as last year when i enquired i was gettin quotes of 2-3k

1 more thing, C-red does a drive in drive out deal on this for $3800 using a 25 box, takes approx 4 days i THINK (quotes from last year so might be a outta date)

Edited by R32 Driver
dangerous_daveo Grand Master

dangerous_daveo

Posted
Posted

Two things to look at here. The condition of the box, you would expect an RB25 box to be in better condition as in most cases they are newer, and they are stronger. That and where your rb20 box is coming from, they might have done the same thing you are thinking of...

The other is resale (might not be thinking of it now but you should), I can tell you now if you car was identical to another price, colour extras etc, but yours had the rb20 box and the other was rb25... I wouldnt be buying your car.

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