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Let us kill the rb26 mated to rb25 tranny questions.


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#1 zilvia_gt

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Posted 26 November 2008 - 02:38 PM

First off, I've done my research... here, google, nico, zilvia, freshalloy, and so on...so let's end the questions and myths about using these tranny combinations. These are more confirmation and/or clarification questions.

Please correct or confirm me on these questions:

The rb26 and rb25 bell housing can be mated with any Z32 transmission (since both turbo and n/a are identical internally) without changing the input shaft to compensate for the difference in rb and z32 bell housing length. Although recommended, it is not necessary since the shorter z32 input will still work when mated to an rb motor. Yes?

However, this setup will not fit into a S30 chasis without modifying the shifter hole/area and/or the shifter itself since the Z32 shifter is a "linkage style" type shifter and the lengths are different. Yes?

You can also mate the rb bell housing to a Z31 transmission also (and the z31 has the same type of shifter and length as the rb25 tranny). Yes?

All sr, ka, and rb shifters are interchangable. Yes?

When mating the rb26 motor to the rb25 tranny, you can use any flywheel made for a rb20, rb25, or rb26 motor? Clutches that you can use with this setup are any n/a Z32 or rb25 clutch regardless of flywheel. Yes?

Rb26 and rb25 starters are interchangable and works with any of the flywheels mentioned. Yes?

Rb26 and turbo Z32 clutches will not fit the rb25 tranny because they are 250 (something) and the rb25 and n/a Z32 measure only 240 (something), but you can notch and grind the interior of the rb25 bell housing to use the larger 250 (something) clutches. Yes?

Rb26, rb20, and rb25 clutch pilot bearings (the one inside the engine) are the same. Yes?

You must use the matching clutch release bearing (the one mounted on the clutch fork) for the clutch being used (i.e...rb25 bearing for rb25 clutch and n/a z32 bearing for n/a z32 clutch). Yes?

Parts needed for pull to push clutch conversion include:
Rb26 (or Rb25) bell housing
Z32 front cover
Z32 throw out arm
Z32 throw out bearing
Z32 pivot ball
front cover gasket
slave cylinder
.
Yes? (Taken from http://www.nicoclub....s.php?id=288581)

For push type rb25 trannys, you can use a z32 slave cylinder as a replacement.Yes?

RB tranny sensors can be swapped out for a Z32 speed sensor for correct MPH reading. Yes?


Please add anything else I missed or omitted.

#2 Evan Purple240zt

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Posted 26 November 2008 - 03:00 PM

Ah crap, no good way to quote and edit.

Your answers are;

Yes
????
Yes BUT only Z31 turbo trans will work
No
Dunno bout' the 26 flywheel, but the others are fine
Not sure bout the 26' starter
That clutch scenario you laid out does NOT sound right to me.
Almost all nissan pilot bearings are the same
I don't remember.

No clue on push to pull conversion

z32 slave will NOT work on an rb25det bellhousing

You can use a z32 speed sensor, or just swap the plastic gear on the end to match your diff.

Happy thanksgiving lol..

Evan
1995 240sx....
1972 240z RIP

#3 RIPSNZ

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Posted 26 November 2008 - 07:59 PM

Or when using a RB20/25/26/30 why not just use a R33 RB25det tranny, a RB26 flywheel and push type clutch and save yourself a hell of alot of trouble, all bolts straight up without mixing parts.

Rob
RIPS Datsun 240z, RB30, Worlds quickest 240z and RB30 7.8/177.44mph on petrol.

RIPS RB30 FED 7.26 @ 179, NZ National record for DD/D.

Australasia's quickest RB overall.

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#4 Makenski

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Posted 26 November 2008 - 08:06 PM

Or when using a RB20/25/26/30 why not just use a R33 RB25det tranny, a RB26 flywheel and push type clutch and save yourself a hell of alot of trouble, all bolts straight up without mixing parts.

Rob


Sure, if everyone one did what was simpliest.. then discoveries of matching parts wouldn't be made.:tongue:

#5 zilvia_gt

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Posted 26 November 2008 - 09:07 PM

Or when using a RB20/25/26/30 why not just use a R33 RB25det tranny, a RB26 flywheel and push type clutch and save yourself a hell of alot of trouble, all bolts straight up without mixing parts.

Rob


Sure, but you didn't mention which clutch rb25, rb26, or n/a 300zx?

It's easier said than it is to actually source some of these parts together. Here in the U.S., rb parts are not common and are quite expensive.

I would like this post to be something that helps people who can't readily get "ready-to-go" swap parts that are already pieced together or for someone looking to replace a clutch or flywheel or any of the other parts. Also I've found that a lot of the info I came across on the internet is very vague as if people don't want to share their knowledge but just hints at it. No offense, but comments like "get a push clutch type" just brings up more questions. A comment such as "a push clutch type from a n/a Z32 or Rb25" would be more helpful. I started this post to clear up all the conflicting information floating around the net so I would like the answers to be specific here if possible.

#6 Racinjitter

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Posted 27 November 2008 - 12:20 AM

Yes BUT only Z31 turbo trans will work

Further, you will need an 4/87+ Z31 turbo only. All previous turbo transmissions were the weak 90a (t5) transmissions.

And to add the Nissan hard body pickup and pathfinder 2wd with a vg30e will also work. They are the fs5r30a variant. You will still need to swap out the bell housings.
RB25DET, RB30DET build in progress. 400whp Shiro Special # 981 build in tuning.
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#7 ktown z

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Posted 02 December 2008 - 08:18 AM

Will a RB25 flywheel and push type RB25 clutch work? In a post above it states a RB26 flywheel is needed. I was under the asumption that it just take the everyday aftermarket rb25 clutch/flywheel.

-Silver 350z 632whp- Greddy twins, FMIC, Arias pistons, Eagle rods, Cosworth heads and bearings, JWT cams, Carbonetics triple clutch, AAM full return fuel system, HKS v-pro, SVRT downpipes wastegate dumps, APS exhaust, Volk GT-s rims, and a whole lot more
-280z- 390whp, rb26dett, willwood brakes, T3 coilovers, ST sways, SSR professor rims,  carbon fiber 240z bumpers, hks f-con,
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#8 Careless

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Posted 02 December 2008 - 07:06 PM

Will a RB25 flywheel and push type RB25 clutch work? In a post above it states a RB26 flywheel is needed. I was under the asumption that it just take the everyday aftermarket rb25 clutch/flywheel.


RB20 and RB25 flywheels are the same, and I was told they are the ones that work if used with an RB25 clutch kit
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#9 RIPSNZ

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Posted 03 December 2008 - 11:39 AM

If you'd like some answers, list them below and I will only answer if I am 100% sure I am giving you correct information.

From what I read above, there's still a hell of a lot of missinformation or you guys sure like doing things the hard way, lol.

Here's a couple of basic's for ya..........

If you want a 2wd transmission for RB20,25,26,30 in a S13,S14,S15,A31,C33,C34,R32,R33,R34,240z,260z etc and you want something that can cope with up to 600hp pretty easy, go with a stock R33 RB25det box, it bolts straight up to the motor, uses the same starter etc etc.

Then................use a RB20 or 25 flywheel (any model, and there are no pull type RB25 flywheel/clutches as far as I am aware)....or R32 RB26 flywheel as they all take normal push type clutches, just be sure you get the flywheel that takes a 9 1/2 in clutch and it has 9 bolts holding the clutch cover on (some RB20s had a 9 in flywheel and a 6 bolt cover)

Then............use a normal push type R32 release bearing or whatever bearing suits the clutch you get.

Its so simple its not funny, why mess around with a VG30dett box???

If you have any other specific questions, go for it.

Rob
RIPS Datsun 240z, RB30, Worlds quickest 240z and RB30 7.8/177.44mph on petrol.

RIPS RB30 FED 7.26 @ 179, NZ National record for DD/D.

Australasia's quickest RB overall.

e-mail rips@inspire.net.nz
www.ripsracing.com

#10 RB26powered74zcar

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Posted 03 December 2008 - 12:02 PM


Its so simple its not funny, why mess around with a VG30dett box???

If you have any other specific questions, go for it.

Rob


Because those RB25det boxs are a reare and expensive item here in the States... :)

#11 RIPSNZ

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Posted 04 December 2008 - 11:05 AM

Fair comment, but surely by the time you muck around doing all this extra work it would be easier to just import a R33 RB25det box (or several of them and make them available)

Whats a VG converted to RB 2wd box owe you including all your time to swap it over??

Rob
RIPS Datsun 240z, RB30, Worlds quickest 240z and RB30 7.8/177.44mph on petrol.

RIPS RB30 FED 7.26 @ 179, NZ National record for DD/D.

Australasia's quickest RB overall.

e-mail rips@inspire.net.nz
www.ripsracing.com

#12 Evan Purple240zt

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Posted 04 December 2008 - 11:20 AM

Rob, a good rb25det box can go for north of 1,000 here. It is much cheaper and more economical to do the bell housing swap. It is common to find a z32 trans for around 300 dollars.

Evan

EDIT; and it takes no more than two hours to take both trannies apart and swap everything.
1995 240sx....
1972 240z RIP

#13 RB26powered74zcar

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Posted 04 December 2008 - 02:35 PM

Most of the guys that buy a rb26 motor set, end up with a awd box that they can use the bell housing off of, so it's just a matter of coming up with a z32 box to mate to.

Or better yet, find a z31T (88-89) and use that with the front bell from the awd. No shifter dramas that way...

rb25 guys usually get the correct rb25det box with their motor set, so they are good to go.

I know this is old, repeated info I just posted. I just wanted to put it all in one place again for those searching.


j.

#14 zilvia_gt

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Posted 04 December 2008 - 08:28 PM

If I recall correctly, haven't you tried the z31t tranny with your rb in your s30 (read it somewhere in nico)? How does the z31t tranny shifter align up to the s30 shifter hole?

On another thought. The z31t tranny seems to have taller gearing from gears 1-3 and a shorter fifth gear when compared to z32 and rb25 transmissions. I'm have no clue when it comes to gearing, but would this mean better acceleration (for dragging) in the first three gears, while having a higher top speed in fifth or do I have that reversed? I believe fourth gear on all the trannies are 1:1. Here are the gear ratios that I found for the FS5R30A, 1988-89 z31t transmission:

1st - 3.324
2nd - 2.077
3rd - 1.360
4th - 1.000
5th - 0.711

(info sourced from http://www.az-zbum.c...nsmission.shtml)

Most of the guys that buy a rb26 motor set, end up with a awd box that they can use the bell housing off of, so it's just a matter of coming up with a z32 box to mate to.

Or better yet, find a z31T (88-89) and use that with the front bell from the awd. No shifter dramas that way...

rb25 guys usually get the correct rb25det box with their motor set, so they are good to go.

I know this is old, repeated info I just posted. I just wanted to put it all in one place again for those searching.


j.



#15 zilvia_gt

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Posted 04 December 2008 - 08:36 PM

Thanks Bud,

Thanks for clearing a lot of things up. I know that there's a lot of this information on the net and this is an old subject, but all the information I've found were conflicting with no solid answers.

If you'd like some answers, list them below and I will only answer if I am 100% sure I am giving you correct information.

From what I read above, there's still a hell of a lot of missinformation or you guys sure like doing things the hard way, lol.

Here's a couple of basic's for ya..........

If you want a 2wd transmission for RB20,25,26,30 in a S13,S14,S15,A31,C33,C34,R32,R33,R34,240z,260z etc and you want something that can cope with up to 600hp pretty easy, go with a stock R33 RB25det box, it bolts straight up to the motor, uses the same starter etc etc.

Then................use a RB20 or 25 flywheel (any model, and there are no pull type RB25 flywheel/clutches as far as I am aware)....or R32 RB26 flywheel as they all take normal push type clutches, just be sure you get the flywheel that takes a 9 1/2 in clutch and it has 9 bolts holding the clutch cover on (some RB20s had a 9 in flywheel and a 6 bolt cover)

Then............use a normal push type R32 release bearing or whatever bearing suits the clutch you get.

Its so simple its not funny, why mess around with a VG30dett box???

If you have any other specific questions, go for it.

Rob


There's also another member who started a separate post after I did about using the n/a 300zx clutch:

http://forums.hybrid...ad.php?t=141802

The answer is yes. You can can us the n/a z32 with the rb26/rb25 tranny setup. It will bolt right up to the rb flywheels.

#16 fentin_fury

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Posted 05 December 2008 - 04:14 AM

Because those RB25det boxs are a reare and expensive item here in the States... :)


I would disagree with the expense of these - I bought two for less than the $1000 quote - in Canada. Have used both and they are both working fine with no issues. I believe I know where there are a couple more reasonably priced - around $600 CAD.

Q
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#17 Evan Purple240zt

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Posted 05 December 2008 - 07:23 AM

If I recall correctly, haven't you tried the z31t tranny with your rb in your s30 (read it somewhere in nico)? How does the z31t tranny shifter align up to the s30 shifter hole?

On another thought. The z31t tranny seems to have taller gearing from gears 1-3 and a shorter fifth gear when compared to z32 and rb25 transmissions. I'm have no clue when it comes to gearing, but would this mean better acceleration (for dragging) in the first three gears, while having a higher top speed in fifth or do I have that reversed? I believe fourth gear on all the trannies are 1:1. Here are the gear ratios that I found for the FS5R30A, 1988-89 z31t transmission:

1st - 3.324
2nd - 2.077
3rd - 1.360
4th - 1.000
5th - 0.711

(info sourced from http://www.az-zbum.c...nsmission.shtml)


This is the setup I currently have. I wish I had that taller 5th of the z32 tranny. As for the other gears?? I wish they were a bit shorter when I am on drag radials, otherwise it doesn't matter. I can spin 3rd gear from a roll without too much trouble. However, it would be nice to have shorter gears for launching at the track.

Evan
1995 240sx....
1972 240z RIP

#18 zilvia_gt

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Posted 05 December 2008 - 07:56 AM

This is the setup I currently have. I wish I had that taller 5th of the z32 tranny. As for the other gears?? I wish they were a bit shorter when I am on drag radials, otherwise it doesn't matter. I can spin 3rd gear from a roll without too much trouble. However, it would be nice to have shorter gears for launching at the track.

Evan


Is this setup in your s30 or s14?

#19 Evan Purple240zt

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Posted 05 December 2008 - 10:08 AM

S14.

Evan
1995 240sx....
1972 240z RIP

#20 badgti

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Posted 06 December 2008 - 07:33 PM

so everything from a rb25det gearbox inc thr flywheel and clutch will bolt up to a rb26dett right?




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