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RB30X

Shift kits for auto Zeds

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I found out some good news today for auto owners. The 280zx i was stripping was an auto and I never really took much notice of it until today. It turns out that nissan has used the same jatco auto throughout the nissan range from around this era, the 4n71b and the 3n71b (4 speed and 3 speed). The reason this is good news is many years ago I was involved in the development of a shift kit for the 4 speed which has the same valve body as the 3 speed. The goal was to strengthen the internals of the auto to increase lifespan behind an increased horsepower engine, especially the turbo. The shift kit for these valve bodies stiffens up and reduces shift time by increasing fluid pressure and the volume of fluid required for each shift. the result is a smooth firm shift, not a harsh shift, and otherwise normal operation. I have personally installed at least ten of these 'shift kitted' valve bodies and sold about 20 on an exchange basis (its easier to swap valve bodies yourself than install a whole shift kit).

 

Does anyone know what auto came out in the 240 and 260Z's???? Hopefully the three speeds are all the same.

 

Now what I'm saying is if you have an auto Zed (can't afford to swap to a 5 speed) and want to increase its life span while improving performance, and have basic mechanical skills, you can install a shift kitted valve body into your auto yourself.

 

I'll have to see how much interest there is in such a thing as I know most of you have manuals but I still have all the parts and information required to produce such a product from back in my Vl turbo days. I can transform the valve body I removed today from the 280zx auto and work from there. As far as cost goes, I'll have to see what existing kits go for these days from places such as Keas and B&M or if they're still available.

 

If you're interested let me know or ask questions here.

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With an $11,000 recondition left ankle (my clutch foot) Im bound to auto for a while linger.

I have the L4N71B in the Ti (luxo) R30 skyline

 

http://en.wikipedia.org/wiki/Jatco_4N71_transmission

 

currently its leaking trans fluid, looks to be fromn the o-ring on the kickdown solenoid?

 

but im VERY keen on the idea, i read that the net jurno Julian had a tinker with th VL units too

http://autospeed.com.au/cms/title_Tweaking-the-Shift/A_110682/article.html

 

But half the stuff on the site is shite.

 

Details most looked forward too!

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Ok. So to perform this conversion or swapping of valve bodies you do the following.

 

- Pick up a service kit from Repco or somewhere which includes a new bottle of trans fluid, a new filter and pan gasket. I also recommend running an external oil cooler if you live where it gets hot.

- Jack the car up, handbrake on and shifter in neutral.

- Undo the many bolts around the pan (sump for auto). Take note of how they aren't very tight. This is how they should go back on.

- Have a container ready to catch the fluid. Unfortunently there is no drain plug for this so it gets messy.

- Once the pan is off you should see this.

 

Picture250636787.jpg

 

-Take note of the two pins from servos/solenoids on the passenger side of the trans (yellow arrows). They stick into the valve body and one may fall out as you remove it. Also, take note of where the shifter linkage sits in the selector rod. (red arrow) These pins and rods must go back the same way.

 

Picture2506367871.jpg

 

- Undo the following 10mm bolts highlighted with the yellow lines (read on first). Do not undo the ones in red as this holds the two halves of the valve body together. These bolts are different lengths so make sure you record or remember where they came from.

 

Picture250636787-1.jpg

 

- As you undo the last few bolts the valve body should just fall out (don't drop it). Here is where you find out you haven't put it in neutral. (don't put it in neutral with no bolts holding it inside your trans).

 

Picture250636785.jpg

 

Picture250636764.jpg

 

- Remove the old filter by undoing the smaller 8mm bolts, as well as the one 10mm bolt with the nut. Ensure this goes back on the new valve body same way.

 

- The you get the modified valve body and install it the same way you removed the other one. Ensure the pins slide in to their holes as you insert the valve body and the shifter linkage sits in neutral.

 

- New gasket. trans fluid and you're away.

 

Clear as mud???

 

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Very good,

What is actually done on the modified valve body? Is it an off the shelf type thing or exchange?

DIY even?

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Well a spring is replaced inside the valve body to increase the fluid pressure obviously. And between the two halves of the valve body there is a seperator plate. Enlarging certain holes in this plate is the key to all of lifes mysteries. DIY?? Well it can be done from home if you are sent the stronger spring to replace and a template to enlarge the holes yourself, although pulling apart and putting back together the valve body isn't for the faint hearted. I was only thinking $100 exchange for the shift kitted valve body. I send you one and when your done, you send me yours to modifiy for the next person. Or, if you want a DIY option I could look into that. Any shift kits sold would see a donation to the site of course.

 

Any other questions?

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This is the modification that was done to my 3 speed auto By Gerard Gayle in Ballarat and the result is WOW. Thought i'd been hit from behind the first time it changed into second, third is not a strong a change but this is because the way the auto is designed. I have a spare auto in the shed if you's need a valve body to start this ball rolling.

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$100 exchange is quite reasonable, VERY reasnoable infact. Sounds good, count me in.

I know of a R30 Ti getting stripped, might put a bid in for the valve body.

 

Just a quick question, are there differences between different year or vehicles?

Like:

VG30e 300zx Z31

L24e R30 Skyline

L28 280zx

 

As I do have access to a Z31 that is for sale VERY cheap, it has receipts for a fully rebuiilt auto a few months ago, $2500 rebuild seems like it will last a good 15 years more than my 160,000km unit!

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Have a look on the ID plates of those cars, it should have the auto code.  Look for 3N71B or 4N71B.

 

I've got two valve bodies here waiting for the first person to put their hand up.

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Have a look on the ID plates of those cars, it should have the auto code.  Look for 3N71B or 4N71B.

 

I've got two valve bodies here waiting for the first person to put their hand up.

 

I have a few invoices waiting to be payed, once thats done I;ll let you know and arrange payment.

 

I think the valve bodies are the same throughout the 4n71b range, just the solenoids differ from vehicle to vehicle. some are hydraulic controlled and thge later R31/Z31 have an extra computer too.

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I have a few invoices waiting to be payed, once thats done I;ll let you know and arrange payment.

 

I think the valve bodies are the same throughout the 4n71b range, just the solenoids differ from vehicle to vehicle. some are hydraulic controlled and thge later R31/Z31 have an extra computer too.

 

Mate, I'll put my hand up!!!

 

Do you want me to PM you so we can exchange details? Let me know what you want us to do please. I've always thought that something like this would be cool....can't wait!

 

Cheers mate.

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Ok, in an effort to prove these valves bodies were the same I installed a shift kit into a local friends 240Z. He picked up a new filter and pan gasket kit for $24. His auto had 3N71B on the side but his valve body was a little different as the pin/rod from the vacuum throttle valve (connects to engine inlet manifold) were thicker than the 280zx ones. So a 280zx valve body is a tiny bit different to that of a 240Z. Good news is that the insides are the same, so once I performed the same mods to his valve body rather than swap in a 280zx one, the auto shifted firmer as expected. Could almost chirp a tyre into 2nd if the car had more power ;D

 

Anyway, what I'm saying is a couple of things.

 

Option 1: Because I have two spare 280zx valve bodies. I can offer 'exchange valve bodies' for 280zx's with the shift kit already installed for you to swap over yourself easily. Then you send your one to me.

 

Option 2: Providing you don't mind your car off the road for a few days, you can send me your valve body from your auto out of any Z family and I perform the shift kit install and send it back to you.

 

Option 3: I create a instruction document with a heap of pictures and information as part of a DIY kit for you to perform the shift kit install on your own valve body. I send you a seperator plate (same across all models) with the enlarged holes (or you drill your own) and a small spring to swap out on the pressure modifier valve.

 

Option 4: You drive your car to Townsville in sunny Nth QLD for a drive in drive out service.

 

Hey Scootag, which model Z is your valve body from. If I could see a picture of a 260Z one I would be able to tell if they are theysame as a 240Z or 280ZX.

 

Anyway, let me know what you guys think.

 

Also for reference, the following models use these autos 3N71B:

 

RX-2, RX-3, 1300, 808 (1300), 616 (Capella 1600), 808 (1600), 616 (US), and 618

Ford:

Courier

Mazda:

1200

1800

616

618

808

B110

B1600

Cosmo

Mizer

R100

R1200

RX2

RX3

RX4

 

Nissan:

1200

1600

2000

200sx

210

240z

260z

280zx

310

312

320

410

411

510

610

710

810

B110

B210

F10

Maxima

 

 

cheers

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Hey Scootag, which model Z is your valve body from. If I could see a picture of a 260Z one I would be able to tell if they are theysame as a 240Z or 280ZX.

 

It's a 260C box i have in the garage... says 3N71b on the housing... Can take a pic of the valve body if you like.

 

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Thanks for that mate. That is a very clean transmission. They (260C and 260Z) are the same as 240Z's and here is where I'm confused.

 

You see in your second photo, there are four lumps along the top section of the valve body for the four valves. At the end of the valve body on the center or longest valve there is no hole in the side of the plate, so it does nothing, which would make sense because that is for the 3rd-4th gear shift, on a 3 speed auto???? 4N71B's have them obvioulsy which would make sense because they are a 4 speed (overdrive). But the 280zx's don't have them, just before the actually branch into a 4N71B 4 speed gearbox?? Maybe the later 4 speed parts have been used to repair older 3 speeds, and for some reason you and I have two examples of this, I think not.

 

Picture250636785.jpg

 

4n71b-4.jpg

 

As mentioned before, the insides are the same and the shift kit dynamics remain. So let me know if this would be something you would be interested in.

 

cheers

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No doubt that this is a simple operation as it took me 14 minutes to take the valve body out and post up photos (granted the sump only had three bolts and it was out of the car).This will make a noticeable difference in the performance of your Auto Zed. Again if you do need or want this valve body it's yours. One of the best Mods i had done to mine.

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I'll send up a unit out of a R30 Skyline Ti soon hopefully.

 

AND where is the best place to get the gasket & filter kits?

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Not sure where you are in Aus but Repco, Super cheap or Autobarn up here would have them. Don't just let them look for a 240Z part, make sure they search the auto code (3N71B or 4N71B) and they'll find them  listed for heaps of cars inlcuding Mazda. The filter kit my mate got recently was actually for a Maxda listed as WCTK7 which was interchangable with FK-1500?? As long as the pan gasket size is the same as well as the filter.

 

I'm half way through writing out the whole thing on a document for those DIY nutters, including heaps of pics etc. I just have to go through and perform it myself and make sure everything is explained in the doc. That way I only have to send you a spring, regardless of if you have a 3 or 4 speed box.

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Here is a snippet from the doc I'm creating on how to perform a shift kit install DIY style.

 

8. On a cleanish surface, undo the 8mm headed bolts (and one 10mm) that hold the trans fluid filter to the valve body. Take note of the torque required to loosen.

 

3n71b01.jpg

 

9. Remove the remaining bolts, working from the outside towards the centre. As the very last bolt is loosened the valve body will begin separating. Hold it together with one hand as you remove the last bolt completely. With two hands holding it together like a burger, flip it over and lower it down on the surface where the filter was attached.

 

3n71b02.jpg

 

10. Remove the top half of the valve body ensuring the separator plate remains on top of the lower section.

 

3n71b03.jpg

 

3n71b04.jpg

 

3n71b05.jpg

 

11. Lift off the separator plate carefully and you will see a ball bearing sitting on a strong spring. There will also be one or two small cups sitting on very weak springs. It is important you remember where these go.

 

3n71b06.jpg

 

3n71b07.jpg

 

3n71b08.jpg

 

12. Remove the loose springs, cups and ball, and clean all the parts with petrol or Brakleen. There will be a lot of fine build-up in the small chambers of the valve body.

13. Using the diagram, identify side plate D and carefully remove the three 8mm headed bolts. Take note of bolt torque. Valves inside are spring loaded so the plate will eject itself.

 

3n71b11.jpg

 

3n71b12.jpg

 

3n71b13.jpg

 

14. Remove the pressure modifying valve and the spring. Replace the existing spring with the red spring supplied.

 

3n71b14.jpg

 

15. Compress the three valves against their springs so the plate can be reinstalled.

 

3n71b10.jpg

 

3n71b09.jpg

 

16. With a clean separator plate, mark the holes to be drilled out using the template provided.

 

 

Easy hey. 8)

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1x request for DIY instructions & spring. have access to drill press etc here. (scored a filter kit too, $26 bucks)

 

will be doing a tranny day VERY soon, fluid leaking out ov the overdrive solenoid o-ring (i think) so its on notice!

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Hey i dropped that valve body into the Express Post box today. Sorry for the delay. I think Dalee may be looking into this Mod, maybe you can help him with one. For reference a valve body is 2.4Kg, same weight as Four VB stubbies ... Kooky  :o

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