Reinforcing the 6MT transmission

NissanZ34

Hello fellow Z owners. My car has about 50 000km and 4th gear is starting to show wear signs such as being clunky when shifting and not being smooth.

Is there a way to bullet proof the manual transmission? I don't want to buy another OEM transmission that will fail the same way over time.

It's a street car but I'm hard on it. I like speeding and found out my car was speed limited at 240 kmh in 5th gear. Would there be a way to remove the speed limit at low cost? (The dealership is a relative and probably told the mechanic to put the limiter)

Modifications done so far:
I already have a Stage 2 clutch kit with the lightweight flywheel from Zspeed along with their CSC delete kit. GReddy GT Evolution catback exhaust and Fast Intentions HFCs are on the way. Also have a Mishimoto oil cooler kit. K&N drop-in filters with Mishimoto silicone intake tubes.

Sport and Touring package

Thanks

crazy4oldcars

150mph in 5th sounds about right. I think you hit the RPM limiter, not the speed limiter. Top speed is supposed to be around 165 mph (~265 kph).
I have heard tales of people having their 6 speeds rebuilt with Ford synchro's, making them more durable. A search in the tech part of the forum would reveal more on that. Haven't needed the info, so I haven't researched it. From my limited reading, the rest of the transmission seems to hold up well.


Kirk B.

Spooler

Nothing really out there in the aftermarket world for our 6MT's. Just get a brand new one from Nissan and don't miss any shifts or abuse it.

SouthArk370Z

No transmission is bullet-proof - if you abuse it, you're gonna break it. The 6MT is pretty stout - some people on this site are FI'ed and running stock 6MTs with no problems. You should be able to find more than one thread on this site about beefing up the 6MT (IIRC, there's not a lot you can do) and how to use the 6MT properly. Personally, I'd get a reputable shop to rebuild the trans; might be able to find some beefier synchros to put in there.

The speed/rev nannies can be adjusted when you get your tune.

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Spooler

LOL, this is true. No issues with 824hp at the wheel. You just have to drive them properly.

Rusty

There was one member who was redoing the trannies. But he hasn't been on for a few years.

The Z is speed limited to 155 mph. To remove it. You have to use UpRev, or Ecutek tuners.

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BettyZ

Zingston does trannies every day?

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Rusty

I'm disappointed. There's nothing about Jar in the tags.

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NissanZ34

No I still had about 100 rpm before hitting the rev limiter which was set at 7600 rpm by the dealership. It was speed limited because the speed and rpm wouldn't budge.

Thanks for your imput.

NissanZ34

Is it possible the clutch kit was not properly installed or adjusted and that way it would not fully disengage? But thinking of this, it should not affect the transmission but it should affect more the flywheel and shift shaft?

There are no transmission shops nearby as I live in Eastern Canada and pretty far from Montreal.

I think I might be obliged to buy another OEM transmission.

Would the dealership be able to "rebuild" my current transmission by replacing the synchros with OEM?

Rusty

The stock rev limit is 7,800. You can change that with Uprev or Ecutek. Why would the dealer lower the rev limit? Plus I don't think the dealer has that option with their software.

Are you talking about when the rev light flashes? If you are. You can change that yourself.

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NissanZ34

My car was rev limited at 7500 rpm when I purchased it. I asked the certified mechanic to raise it to 7600 which he did.

The certified Nissan mechanic said he can change the speed limiter, rev limiter and timing but he did not want to change the timing when I asked him to advance it.

All the modifications were installed by that mechanic.

Rusty

How did he raise the rev limit? On the dash on the right side, where the gas gauge/water temps lights are?

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NissanZ34

With the dealership ecu management computer.