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RB 26 GTR and RB20 gearbox- same ??

exXU1
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exXU1 Mentor

exXU1

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Just wondering if the above are the same , they look the same except for the front bell housing and case on the GTR R 32 box has more forged ribbed reinforcing on the outer cast.

Does this indicate that the rb 20 is structuraly inferior or weeker, clutch pak smaller or weaker or is it simply the same?

Need a concrete answer on this as doing a total rebiuld .

Fellas i may of made a mistake in the above question , keep an eye on this as i shall do a little more home work and ask the question again, sorry about that!

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SteveL Mentor

SteveL

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Just wondering if the above are the same , they look the same except for the front bell housing and case on the GTR R 32 box has more forged ribbed reinforcing on the outer cast.

Does this indicate that the rb 20 is structuraly inferior or weeker, clutch pak smaller or weaker or is it simply the same?

They are most definately not the same. RB26 gb is more-or-less the same as an RB25DET gb in terms of gear size, etc. RB20 gb is smaller in all respects and gear strength is less.

SteveL Mentor

SteveL

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Fellas i may of made a mistake in the above question , keep an eye on this as i shall do a little more home work and ask the question again, sorry about that!

I had a thought last night - perhaps your thinking of the R32 GTS4 gearbox (??). If that's the case then the answer is that the gearbox used in those cars is more-or-less identical to the R32 GTR type in terms of gear strength, etc.

TTT Grand Master

TTT

Posted
Posted

I asked this question before.

is the R32 GTS4 gearbox same strength as an RB26 gearbox and got the answer of no.

the reason I asked was this.

I've been told the Rb26 gears are pretty much on par with the RB25 gears.

rb25 gearbox costs about $2K

rb26 gearbox costs about $1K

GTS4 gearboxes are even less than the GTR ones.

so cut the transfer case and weld it all shut as required and for under $1K you have a really good box..

but it turns out that the GTS4 gearbox in the R32's are pretty much the same as the gtst gearbox in the R32..

in terms of strength anyway.

SteveL Mentor

SteveL

Posted
Posted
but it turns out that the GTS4 gearbox in the R32's are pretty much the same as the gtst gearbox in the R32..

in terms of strength anyway.

Don't know who led you to believe that.....R32 GTS4 gearbox has the same ID as the R32 GTR gearbox - FS5R30A. I have also confirmed using FAST that the same gears are used in each gearbox.....so they are nominally the same strength.

But yes, RB25 turbo gearbox is very similar to the GTR/GTS4 type in terms of strength.

exXU1 Mentor

exXU1

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My appologise, you two are on the money.

My original question is this :

I have GTS 4 rb20 box and a GTR R32 box. i want to sell my GTR box and rebuild the Gts 4 box with my new internals being a Pfitzner straight cut with large input shaft.

I have noticed how ever - the gts 4 box has less structural ribs on the front cast bell and box housing, this would indicate to me that it is of a lesser srenght?!

Would the clutch pak in the transfer be a strong or exactrly the same, could i put one of the clutches out of the Gts 4 transfer into the Gtgr box to make "stauncher "?

A few quetions here , but proper answers appreciated always.

blind_elk Grand Master

blind_elk

Posted
Posted

I would expect the ribbing to be indicative of the strength of the casing itself, not necessarily the internals.

I have a GTS4 fitted with a RB25DET pumping 180 kW at 4 wheels (I guesstimate 240 at the flywheel), through the standard GTS4 (manual) gearbox. It hasn't shown any sign of not being able to cope. In fact, I have burn marks on the HD clutch where the clutch slipped while trying to right a half-flipped car.

exXU1 Mentor

exXU1

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My appologise, you two are on the money.

My original question is this :

I have GTS 4 rb20 box and a GTR R32 box. i want to sell my GTR box and rebuild the Gts 4 box with my new internals being a Pfitzner straight cut with large input shaft.

I have noticed how ever - the gts 4 box has less structural ribs on the  front cast bell and box housing, this would indicate to me that it is of a lesser srenght?!

Would the clutch pak in the transfer be a strong or exactrly the same, could i put one of the clutches out of the Gts 4 transfer into the Gtgr box to make "stauncher "?

A few quetions here , but proper answers appreciated always.

My concern is i will be pumping around 900 thru mine hence the concern in regard to housing strength.

SteveL Mentor

SteveL

Posted
Posted
My concern is i will be pumping around 900 thru mine hence the concern in regard to housing strength.

I think you need to look at what the serious GTR drag racers use. I suspect they use the standard case but with strengthened internals.....or change over to some sort of mega-buck trans which comes as a complete unit. The stock GTR trans uses a cast casing, but despite that I think it would take a lot to break it and, at least theoretically, the more ribs the better.

At the end of the day it will depend on how deep your pockets are.....

Fitzpatrick Speed Works Mentor

Fitzpatrick Speed Works

Posted
Posted

the gts4 box is weaker on the internals side, they have a smaller input shaft and gearset runners are also smaller as are the actuall gearsets and the ratio on each gear is slightly different. Dont know on the transfere case side of things never had the two different models apart, but the part numbers from nissan on the clutch packs are different this could mean they are different i dont know??? As for casing who knows I think you would be alright running th gts4 casing there shouldnt be alot more stress on the casing it should rise in stress per horsepower like other factors might!

TTT Grand Master

TTT

Posted
Posted
so is the gts4 g box internally as strong as a GTR box, as in the gears

I'll make it a little easier for you.

the gts4 box is weaker on the internals side,  they have a smaller input shaft and gearset runners are also smaller as are the actuall gearsets and the ratio on each gear is slightly different.
exXU1 Mentor

exXU1

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From what I can tell it doesn't seem to matter which one has stronger internals, as the power you're planning on making is going to require a full rebuild of either anyway.

Yes that is correct, i have PPG full dog, but the question IS the gtst - 4 box as strong ( housing - front case ) as the GTR?

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