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Tailshaft Mods To Go From Rb20 To Rb25 Gearbox

k_d
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k_d Mentor

k_d

Posted
Posted

So this has been covered before, but everyone has different theories about this.

I am about to convert my r32 gtst from a rb20 and box to an rb25 and box and have been told I need to mod the tailshaft to fit. I want to keep the cost down, so im looking at doing this the cheapest way possible. Im not going to be running crazy power, so I just want to modify the stock tailshaft to fit instead of going custom. Now I dont want to know your theory on it, just want to know what worked for you. I know I need a new yolk to fit the box, but do i need to shorten the shaft as well? If so, how much? Because the car is my daily, i cant have it off the road for any longer than a weekend, so i cant put motor and box in then measure it. I need to have it done and all ready to drop in.

Thanks in advance.

bubba Grand Master

bubba

Posted
Posted

As a quick fix for a short time I got away with bolting the front half of the 33gtst shaft to the rear half of the 32gtst shaft (I was waiting for my big custom shaft to be finished). You could just do this and get it balanced, I don't think new centre bearings (for piece of mind) are very expensive either.

nick81xd Community Regular

nick81xd

Posted
Posted

just spend the money get a front shaft made up its cheap enough. i had to shorten my front section to make it fit.

BUBBA. what did you do about the centre bearing cause bolting a 33 front onto a 32 rear eliminates the bearing???. postive you had a them model shafts??

k_d Mentor

k_d

Posted
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just spend the money get a front shaft made up its cheap enough. i had to shorten my front section to make it fit.

BUBBA. what did you do about the centre bearing cause bolting a 33 front onto a 32 rear eliminates the bearing???. postive you had a them model shafts??

How much did you have to shorten it by?

Cheddle Enthusiast

Cheddle

Posted
Posted

Dont get one made the stock one worka...

The front shaft is the same between rb20det and rb25de. But rb25det uses a larger yoke and the rb20det box wil not use it

i have an r33 gtst with an r31 series 3 box (VERY similar to r32 gtst) and i use an r33 gts front half shaft and r33 gtst back half shaft

bubba Grand Master

bubba

Posted
Posted

just spend the money get a front shaft made up its cheap enough. i had to shorten my front section to make it fit.

BUBBA. what did you do about the centre bearing cause bolting a 33 front onto a 32 rear eliminates the bearing???. postive you had a them model shafts??

Kept the centre bearing from the 32 shaft, bolted 33 front half to it.

Did the job putting around to work but it was horribly unbalanced. New shaft was a custom 2-piece with a brand new slip yoke, centre bearing and spicer unis.

  • 2 weeks later...
nick81xd Community Regular

nick81xd

Posted
Posted

my shaft was pretty much the weld thickness on the standard yoke too long so around 7mm at a guess. i can remember the exact measurement fromt output shaft to centre bearing mount

bubba Grand Master

bubba

Posted
Posted

you better hope everything goes 100% smoothly doing a engine and gearbox swap in 1 weekend lol

I did a 30 conversion in a weekend, it's all about the 6 P's...

Prior preparation prevents piss poor performance :P

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