The ultimate gearbox thread!

[_Wing_]

Not exactly true because I am taking the rear of the Z32 casing and putting it on the RB25 bellhousing with RB25 internals and using Mazworx's short shifter kit for the Z32 rear casing means I wont need to trim any of the shifter housing where it comes through on the standerd 6 speed as their kit makes it come through at the same angle, I have been told this will work by one of the leading guys in the UK as he has done this before but will keep an up date on my members thread of how it goes

Please let me explain...

The facts so far...

• You know that the rb25 and z32 gearboxes are basically the same internally, which means the major differences are external, IE their housings.
• You also know that the rb25 and the z32 bellhousings / front housings are basically the same in length, and the housings can be interchanged freely with no modifications, therefore swapping bellhousings around is pointless for us as it will not change the shifter position.

So at this point, for the scope of this discussion, everything at the front of the gearboxes are basically the same.

You now know that the major difference is the rear housings - the rb25 rear housing where the shifter sits is TOO SHORT, whilst the z32 rear housing where the shifter sits is TOO LONG, therefore the shifter position is determined by the rear housing.


IE
Z32 rear = TOO LONG = shifter sits behind your shifter hole
RB25 rear = TOO SHORT = shifter sits in front your shifter hole


So.....

1. If you swap a z32 rear housing onto a rb25 gearbox, then you have a gearbox with a shifter that is TOO LONG because, as you know, the z32 rear housing determines the shifter position.
   
   
2. And likewise, if you swap a rb25 rear housing onto a z32 gearbox, then you have a gearbox with a shifter that is TOO SHORT because, as you know, the rb25 rear housing determines the shifter position.

The same thing will happen if you swap bellhousings.
I hope I make sense and hope that is helpful.



The shifter position solution that we at ALPHA OMEGA Parts and Services has came up with is to manufacture parts that will bring the z32 shifter position back into the standard shifter hole - this is another reason why we chose the z32 gearbox because the shifter design allows us to get the shifter in the shifter hole (and the rb25 shifter design does not)

 

[_Wing_]

RHD sell another six speed gearbox thats been modified by HPI and its rated to 430PS, I know its a wee bit expensive but if my box ever goes bang this is what im thinking about

http://www.rhdjapan.com/hpi-6-speed-cross-transmission-s13-s14-s15-silvia-180sx-58394

Yep as I mentioned earlier it's a modified NISMO gearset (both of which do not address or fix the circlip issues)...

...(there's also HPI that does an upgraded version of NISMO), and for the money you spend the results are... not what you'd expect.

 

[AllanOrr]

Dude I think we are getting a bit confused over what I am saying here, I know what the main differences are between the 2 set ups I am putting the Z32 rear case on to a RB25 Bellhousing with internals,
You are not the only supplyer that can supply these kits to fix this issue as I said before Mazworx do a short shifter kit that will change the posision of the Z32 shifter the reason I am using RB25 Internals and Bell Housing is they are easyer to come across in the UK,
So as I said before I will not need to trim any parts by using the Kit Mazworx can supply me the main reason for doing this is no one has made a driver friendly version of it for the RB25 in the UK with out it being a swan neck type set up which I have been told can feel a bit weird when changing gear.

 

[_Wing_]

Is this what you're talking about?
http://www.mazworx.com/index.php?l=product_detail&p=2766

 

[Hypnotik]

I just sent Mazworx an email regarding the specifics of their kit in a S15. That's most likely the kit I'll be using, I just picked up a Z32 transmission today. I just wish I didn't have to send the bellhousing in to be machined. When they email me back I'll post the info here.

 

[AllanOrr]

Is this what you're talking about?
http://www.mazworx.com/index.php?l=product_detail&p=2766

Hey dude sorry I never seen your reply

I think thats the one honestly not 100% I have a list that Polo gave me on what to order etc but its in the boot of my S15 so cant remeber exactly whats on it lol

I just sent Mazworx an email regarding the specifics of their kit in a S15. That's most likely the kit I'll be using, I just picked up a Z32 transmission today. I just wish I didn't have to send the bellhousing in to be machined. When they email me back I'll post the info here.

Lol the joys mate would be good to see what results you get back from them though

 

[_Wing_]

I just sent Mazworx an email regarding the specifics of their kit in a S15. That's most likely the kit I'll be using, I just picked up a Z32 transmission today. I just wish I didn't have to send the bellhousing in to be machined. When they email me back I'll post the info here.

Why not get a s15-to-z32 gearbox conversion kit that bolts straight on, no bellhousing mods needed at all and you get to keep your s15 clutch/flywheel too?

 

[_Wing_]

Hey dude sorry I never seen your reply
I think thats the one honestly not 100% I have a list that Polo gave me on what to order etc but its in the boot of my S15 so cant remeber exactly whats on it lol

Cool it will be interesting to see how things turn out

 

[AllanOrr]

Thats it dude its all part of the fun

 

[Hypnotik]

Why not get a s15-to-z32 gearbox conversion kit that bolts straight on, no bellhousing mods needed at all and you get to keep your s15 clutch/flywheel too?

That would be great if it didn't cost more than double the Mazworx kit. The Mazworx kit also allows my to keep my clutch/flywheel.

Mazworx
-adapter
-crossmember
-shifter
-shifter bracket
-1 piece driveshaft
-all hardware
= $1090

AO-PS
-adapter
-crossmember
-shifter + $290
-shifter bracket
-1 piece driveshaft + $750
-all hardware
= $2540

I'm sorry but I don't see the point of paying double for the same thing.

 

[AllanOrr]

Remember though dude Maxworx - USA // AO-PS - Australia.....I think?

 

[DeanS15]

still £683.00 vs £1588.00....................

i know RnD costs are added onto the product until they are recovered, but when you think of the cost of the matrials etc. all these kits do seem 'dear'...

 

[AllanOrr]

thats why I like the kit Polo can supply full RB25 box and fitting kit inc custom prop etc for around £1000

 

[_Wing_]

I'm not here to push AO-PS products although that may seem like it because of who I work for - if I didn't work here I would still recommend it over the others because I have personally used other gearboxes/conversions myself, including the mazworx one (well, a copy of it since I didn't know better way back then).

There are many differences between parts, much like comparing a Volk rim to a Rota rim... such as being a FULL adapter plate, thicker (meets minimum thickness), accurate CNC machined, uses genuine Nissan dowels, uses the strongest (stronger than anybody else I know) Spicer parts for the tailshaft...

I can talk about the mazworx one in detail, or the AO-PS one in detail, or the Polo one in detail, or others.

 

[Panda]

Hi everyone,

I've bought an S15 last year, second hand, no history at all with some parts and usual stuff. The clutch died after 6 months... So changed it.
When removing the gearbox, it appeared that there some radial play on the input shaft. You can move it like 2-3 mm.

On some boxes the play is normal, but I've never seen another S15 box so I can't tell. Should I worry, open it and check bearings and the rest, or is that play normal ?
I've read the 4 pages and if I understand correctly, it's one of the common failures... I don't really know what to do.

 

[craig8585]

It's normal mate. I have 2 good boxes and they both do it

 

[Panda]

Thanks

There is no info about that in the workshop manual, that's strange. Didn't know that gearbox had so many issues... Now I've started looking for info I find so many threads about that...

 

[craig8585]

If you have a Spec-S N/A you shouldn't have a problem. It's torque that kills them and N/A doesn't produce masses to torque.

 

[Panda]

It's a Spec R with some upgrades

 

[Benne]

6 Speed Info

Found this on the 240sx forums:

Part 1

Thanks to Boostin for showing me this. I figured I would go ahead and put in the legwork and post it on here and see if I can't get it stickied. This was pulled from a sister Nissan site, and I don't claim to have made it up, just copied it.

S15 6 Speed Manual Transmission (6MT)

Everything you wanted to know about the S15 6MT. A lot of this information is scattered all over the place. I'm just bring it together. I personally know quite a bit about the 6MT. I own and use two of them.

Please do not ruin this thread with a bunch of nonsense. Don't post information unless you are 100% positive that it is correct. Don't post how weak you think this transmission is, especially if you've never used or destroyed one yourself.. Any personal experience with this transmission is encouraged to be posted on this thread. For example, "XXXWHP and XXXWTQ, and I destroyed 3rd gear," or "XXXWHP and XXXWTQ, and she still kicks ass."

THE KA 5MT AND SR 5MT BELL HOUSINGS ARE NOT THE SAME.

I don't know everything, but I do know a lot. I'm not stubborn with what I am presenting to you. If you feel I posted incorrect or misleading information, I would be more than happy to hear you out and further research the issue.

To be covered:
- First look
- Comparison to the '5 Speed Manual Transmission' (5MT)
- Gearing and Specifications
- Gearing Comparison to the 5MT
- Necessities for Use
- VSS and Options
- Neutral Position and Reverse Switches
- Aftermarket Options
- Miscellaneous
- Final Notes
- Post Notes

Pre-notes:
- I am strictly providing information regarding the S15 6MT for the SR engine. But, always take information as opinion anyway, and fact-check the information yourself.
- When I say 5MT, it is with assumption that it has a SR bell housing for the S13 and S14 SR engines and not a KA bell housing.
- When I am referring to a specific chassis, I will state so.
- I am strictly referring to OEM parts, excluding the 'Aftermarket Options' and 'Miscellaneous' sections.

First Look(Pictures of 6MT)

Nissan guarantees that this transmission will not fail at or below an input torque of 209lb-ft.

Apparently this transmission was built by Borg Warner. (See the 'Sources' section.)

This transmission was designed with a Dual-Mass flywheel in mind. Watch this video for an animation on how the dual-mass flywheel works. The first half shows how it is assembled. The last half shows how it works.
YouTube - 3D animation of dual mass flywheel
Comparison to the 5MT
Similarities
- Bell housing pattern between the 6MT and 5MT are identical.
- The transmission mount is the same as the 5MT. However, the cross member is not the same.
- The slave cylinder, fork, pivot ball, release bearing, release bearing holder and pin are all the same as the 5MT.
- The starters are identical between the S13-S15 SR engines.
- The 6MT clutch disc and pressure plate are similar to the 5MT. (NOTE: Because the 6MT uses a dual-mass flywheel, the OEM clutch disc is unsprung. The 5MT does not use a dual-mass flywheel, so the OEM clutch disc is sprung.)

Starters may appear different, but seem to mount and operate the same.

Differences-
The 6MT flywheel is much thicker than the 5MT. Consequentially, the bell housing is also deeper by the difference in thickness.
- The copper pilot bearing is located in the 6MT flywheel, rather than in the SR engine for the 5MT.
- The 6MT is divided into three sections, rather than two for 5MT.
- The shifter and shifter plate are not the same between the 6MT and 5MT.
- The output shaft to the driveshaft is not the same as the 5MT. The splines are just slightly thinner.
- Shift knob threading is wider, but have the same thread pitch. 6MT = M12. 5MT = M10.
- The Vehicle Speed Sensor (VSS) is located on the differential rather than the transmission.
- The 6MT cross-member is opposite of the 5MT. (The AT cross-member is closer to the 6MT, but still will not fit.)

Slight difference in spline thickness.

Thicker Flywheel. (In this picture, both the OEM S15 Dual-Mass Flywheel and Autech Flywheel are shown.)

This is the OEM Dual-Mass Flywheel with OEM Unsprung Disc and Pressure Plate. (If I recall correctly, the OEM Dual-Mass Flywheel weighs about 28lbs.)

6MT Crossmember and Nismo Transmission Mount

The 6MT bellhousing is noticeably deeper than the 5MT

The shifter plate and assembly are completely different.