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How To: Mating an RB25 and Z32 Trans


Booztd 3

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Very nice write-up and you had me on a scare for a few minutes. I have a blown RB25 transmission which both 3rd and 4th gear syncro's went out and I purchased an 5spd. Z32 transmission and compared both bellhousing and bolt patterns and was pretty positive that it would switch right over....nice to hear that you think there wouldn't be a problem with that either.

 

Great information. If no one gets to it first I will let you know if I run into any problems with the RB25/Z32 bell housing conversion and the pilot bearing.

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Just got done actually swapping bellhousings. Might want to include that you have to remove the check ball plug, spring, check ball, and then interlock stopper. Here is the direct link to to what I am talking about: http://300zx.co.uk/cgi-bin/manual.cgi?list=mt&dir=&config=&refresh=&direction=forward&scale=0&cycle=off&slide=12&design=default&total=37

 

Also...I don't see why you would have to remove the two pins from the shift and selector lever and the pin from the striking arm......I would imagine that those are only if you are taking the rear housing out as well, but for those that are taking just the bell housing I would leave those alone. I punched them out, but didn't see how they helped one bit.

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Might want to include that you have to remove the check ball plug, spring, check ball, and then interlock stopper. Here is the direct link to to what I am talking about: http://300zx.co.uk/cgi-bin/manual.cgi?list=mt&dir=&config=&refresh=&direction=forward&scale=0&cycle=off&slide=12&design=default&total=37

 

 

You will begin by pulling the outter detent ball out of the trans. On the upper side close to where my bro's index finger is pointed in the picture above. Remove the 17mm bolt on the left hand side and remove the spring and then remove the ball. Keep these in a safe place.
Focus more closely on the text young one :mrgreen:
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  • 4 weeks later...
This is excellent if you have a spare RB25 transmission laying around to scavange the bell housing from... ;)

 

I think I'd be inclined to find one to use the Z32 tranny as well, if for no other reason than parts availability.

 

Does anyone have the breakdown on the gear ratios between the 2 transmissions?

 

 

These issues have been covered already but I'll reiterate....

 

The RB25 or RB26 bell housings are identical, so you dont have to go scavenge a bell housing from an rb25.

 

The gear ratios between the Z32, RB25, and AWD RB26 trans are all identical, and they all use the same synchros and internal parts.

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Nope - although if you have a choice, go for the NA tranny as there is less chance of it having the crap beaten out of it.

 

Correct

 

The only difference in the NA and TT Z32 bell housings are the inner diameter, since you're using an RB bell housing, this is negligible.

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  • 1 month later...

Sweet sweet sweet!!

 

As clean as that cuda machine is, I'll venture a guess you are surely not at a toyota dealership or that thing would be a skanky mess.

 

That RB tranny sure looks a lot like the implementation used in the pathfinders and Z31 turbo from late 1987 on.

 

Of course........they are rare and the Z32 tranny is not.

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05/87+ Z cars are FS5R30A transmissions.

all relatively identical to RB25 transmission, save for a few different lengths of the input shaft and different gear ratios.

 

All will receive any bell-housing with the proper interior plate seal from what I've learned here.

 

It's all starting to make my Z31 feel like a better RB30DE candidate. :?

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Just to clairify as I'm a little fuzzy on two things.

 

If i use a Z32 trans with an RB bellhousing in a 240Z will I run into shifter troubles or will it all line up the same as if I was using a RB25 trans?

I ask because one person said they would have to modify there shifter area if using the RB trans and another said the trannys were the same minus the bellhousings, so I'm confused.

 

Also this is for all Z32 trannys, correct? I noticed someone specify JDM Z32 trans, so I was wondering if the USDM ones were the same or not.

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Im not sure how the shifter setup works in the 240's however the RB25 shifter setup is definitely different than the Z32 shifter setup (this is accomplished by different linkages and tail section)

 

The reference I made to the trans being the same internally, was meant to concern the actual gears, ratios, synchros, shift forks, etc

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The FS5R30A was used in the z31 turbo from 5/87 until the end. Used again in the Z32 both n/a and TT. Also was used in all 5spd skylines (r32-r34). The differences are shifter position, input shaft total length, individual gear ratios and if GTR (yes, same transmission) the addition of tail section to apply AWD. That is why all the bell housing are interchangable.

 

Personally I used the 87 turbo transmission (swap going into 87 z31) and the 1/8th inch offset was not an issue. Along with that, the shifter position after final mounting was still in near stock position where as if using the z32 transmission I would have had to modify the tunnel so the shifter would be reachable.

 

But then another option I have heard of is using the R34 GTR bell housing attached to the 6spd Getreg transmission from MK4 Supra TT. Can any vouch for this being correct? I know the MK4 used the V160 or V161 (Getreg 233) but what did the R34 use?

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