How strong are the gearboxes?

[geg1992]

My cAr is a 55 plate with 39K miles.

 

In first and sometimes second there is a slight grinding noise. First and second are also hard to select sometimes and often clunk when changing, the clunk is sometimes there when changing into third too.

 

I drove to football earlier and got stuck in traffic, with first gear j was struggling to move, the car was juddering and the rpm went all the way down to 0 sometimes?! I thought it was going to stall. First and second gear just seem awful, the rest are really nice. Also the clunking sound when coming to a stop and pushing the clutch down in first and second as explained on another post. I'm really scared my gear box may be going wrong or something!

 

How much are near gearboxes? Or refurbished? Or even used?

 

Thanks!

[TimC]

My first gear box was terrible with grinding noises, clunking and just really hard to change gears. I had another one fitted from car of similar miles and age under warranty and this was ok for a few weeks but 2nd and 3rd gear started playing up on that one as well. I fixed it by changed the gearbox oil and putting in some Molyslip, it did not fix it straight away but after a week there were no horrible noises and changing gear was so much better. Only thing I get now is if its cold the first time I go into 2nd gear it just feels a bit stiff, but its fine after that. Not sure about the other problems but for the cost of the oil and Molyslip it may be worth a try. Others on here have fixed there gearbox issues by doing the same, its a real common problem. Try it, it may not fix all the issues but it may fix some of them.

 

Maybe the revs dropping could be a dirty throttle body, my revs go up when I change gear, I suspect that is the problem with mine. Another job to do in the future

Edited July 28, 2015 by TimC

[Zeezeebaba]

New oil and Molyslip helped mine too. Still nasty changing into second when cold but I find it goes in better revving past 3k when changing from first.

[Juggalo]

I think the syncros are weak in the 350z boxes. I understand they fixed it with the CD09 and CD0A HR boxes.

I've read posts by people on the US forums where they've refurbed the box, only to have the problem return after a few thousand miles or so. So I can only imagine the OEM syncros are made out of cheese.

 

I'd need to talk to a gearbox specialist, but the only real options I can think of is to adapt and fit a later model gearbox, or have custom, tougher syncros machined and fit those. Both options would be really expensive.

 

I imagine that's why people put Moly in. I put Millers 75-145w in mine and it's helped a lot, but not completely cleared the problem.

Difficult to understand how Nissan made a really great car, yet totally ballsed it up with the Gearbox....and it took 9 revisions to finally fix it!

[firemansim]

Get an auto, no problems then.

[geg1992]

I think the syncros are weak in the 350z boxes. I understand they fixed it with the CD09 and CD0A HR boxes.

I've read posts by people on the US forums where they've refurbed the box, only to have the problem return after a few thousand miles or so. So I can only imagine the OEM syncros are made out of cheese.

 

I'd need to talk to a gearbox specialist, but the only real options I can think of is to adapt and fit a later model gearbox, or have custom, tougher syncros machined and fit those. Both options would be really expensive.

 

I imagine that's why people put Moly in. I put Millers 75-145w in mine and it's helped a lot, but not completely cleared the problem.

Difficult to understand how Nissan made a really great car, yet totally ballsed it up with the Gearbox....and it took 9 revisions to finally fix it!

 

I wish I had seen this when researching to buy one. I thought it was just the 2003 cars which had the gearbox issues. I may try the gearbox oil change and moly. thanks!

 

How much would it be to put tougher syncros in? And why don't hundreds of people complain about the issues on here?

[geg1992]

My first gear box was terrible with grinding noises, clunking and just really hard to change gears. I had another one fitted from car of similar miles and age under warranty and this was ok for a few weeks but 2nd and 3rd gear started playing up on that one as well. I fixed it by changed the gearbox oil and putting in some Molyslip, it did not fix it straight away but after a week there were no horrible noises and changing gear was so much better. Only thing I get now is if its cold the first time I go into 2nd gear it just feels a bit stiff, but its fine after that. Not sure about the other problems but for the cost of the oil and Molyslip it may be worth a try. Others on here have fixed there gearbox issues by doing the same, its a real common problem. Try it, it may not fix all the issues but it may fix some of them.

 

Maybe the revs dropping could be a dirty throttle body, my revs go up when I change gear, I suspect that is the problem with mine. Another job to do in the future

 

I'll try this,thank you! I'm not mechanically minded though so will have to get someone else to do it! Is the stuff expensive?

[Toon Chris]

Always put in genuine Nissan oil rather than after-market - it really does make a difference.

[Juggalo]

 

How much would it be to put tougher syncros in?

 

Not sure, like I said, I'd need to talk to a GB specialist to see if that's even an option, I don't see why not. I know a refurb with new syncros is appx £600. So having a set machined by a precision engineering firm is probably going to cost 200 maybe?

So you could be talking just under a £1,000 for a uprated box. But it should be bullet proof afterwards.

 

or import the CD0A from the USA for £1085 + £208 shipping + 20% Customs. Then adapt it to your DE.

 

Or have your box refurbed for ~600 and hope it doesn't happen again.

 

And why don't hundreds of people complain about the issues on here?

 

they do if you look back in time

 

https://www.google.co.uk/search?q=currency&oq=currency&aqs=chrome.0.69i59j69i60.1432j0j7&sourceid=chrome&es_sm=0&ie=UTF-8#q=350z+gear+stiff

[geg1992]

How much would it be to put tougher syncros in?

 

Not sure, like I said, I'd need to talk to a GB specialist to see if that's even an option, I don't see why not. I know a refurb with new syncros is appx £600. So having a set machined by a precision engineering firm is probably going to cost 200 maybe?

So you could be talking just under a £1,000 for a uprated box. But it should be bullet proof afterwards.

 

or import the CD0A from the USA for £1085 + £208 shipping + 20% Customs. Then adapt it to your DE.

 

Or have your box refurbed for ~600 and hope it doesn't happen again.

 

And why don't hundreds of people complain about the issues on here?

 

they do if you look back in time

 

https://www.google.c...350z gear stiff

 

That's nowhere near as bad as I was expecting, but I fear I need a clutch and DMF soon too. I'm having a mechanic look at it today. Maybe refurb is an option if the oil change doesn't help. it's not as bad today, but it still takes out some of the driving pleasure.

 

Also, I thought the gearbox problems were with 2003/4 cars which is why I got a later model and paid extra, silly me!

Edited July 29, 2015 by geg1992

[ChrisB]

Box has got character. Mine's a CD005. It's very mechanical and likes rev matching to smoothly get a gear. Don't try to get into second unless you are doing exactly 8MPH satnav speed when it's cold. Feel every cog and mechanism meshing when you are changing and don't force it in and it works fine Personally I think it's old school cool that way

 

Yes fresh Nissan gear oil and Molyslip helps too.

[geg1992]

Just spoke to my mechanic about the clunking on pushing down the clutch, took him for a test drive and he said it's completely normal, just a bit of play in the input shaft? Or something like that? Is it normal?

 

I said I'll change the gearbox oil and put in the molyslip too and continue to monitor it. I'm worried though.

[Juggalo]

My original box was a CD05 and 1st gear was toast. So had it replaced, with a CD03, which was fine, but lately it's started playing up in 1st and second.

 

I spoke to a gearbox specialist tonight. He said fitting custom synchros isn't a problem, the problem is that the synchros can't really be made out of anything too hard because they have to grip the gear to slow it down. Harder material = less grip.

So we know the OEM syncros are junk, and probably made out of Nickel-Phosphor Bronze; nearly all synchros are, so I'll need to speak to a precision engineer to see what materials are available.

[geg1992]

My original box was a CD05 and 1st gear was toast. So had it replaced, with a CD03, which was fine, but lately it's started playing up in 1st and second.

 

I spoke to a gearbox specialist tonight. He said fitting custom synchros isn't a problem, the problem is that the synchros can't really be made out of anything too hard because they have to grip the gear to slow it down. Harder material = less grip.

So we know the OEM syncros are junk, and probably made out of Nickel-Phosphor Bronze; nearly all synchros are, so I'll need to speak to a precision engineer to see what materials are available.

 

It's rather strange how such a great car can be let down by something like a gearbox!! Thought they'd pay a lot of attention to that. So you say referb gearbox would be 600? Or is that just the syncro part?

[Juggalo]

Yeah, it's about 600-800 for new OEM synchros put in. You'd need to ring around.

[GriffGTV]

..'.or import the CD0A from the USA ':

Nissan OEM 32010-CD00A 32010-CD009 Manual Transmission - Nissan 350Z 03-06 Z33

 

Not clear what this 'CDOA' is precisely, Geg believed 05 onward would be clear of the CD05 and soft synchros and the CDOA appears to be referred to as 03 -06 So when precisely, if ever was a gearbox fitted that works properly? - GTR boxes seem to cope with torque ok, so why not the 350?

[GriffGTV]

...'https://www.google.c...350z gear stiff' ..

 

'i drive a 2008 hr engin 350z its just done 40000 miles and i am just about to replace the flywheel and clutch because of problems ive been having but also i have noticed 90% of the time when i change from 1st to 2nd gear i get a clicking/clunking

metal on metal noise but it isnt realy that loud but i does happen almost every time now and is getting quite concerning..'

 

..now this is one huge Achilles heel isnt it?!

 

If this issue is as rife as it appears, should it not be displayed prominently in a 'known issues & remedies' section....as No.1....above gas rams and paint chips?!

Edited July 30, 2015 by GriffGTV

[Juggalo]

Yeah, seems to be the one weakness of the 350Z. The guy to talk to would be ZMANALEX about gearboxes. I think he knows what fits what, and all about the revisions.

[GriffGTV]

Geg, I can understand you being royally pi**ed off having spent so much, in the belief that the HR would have ironed out all obvious design issues (engine, which worked pretty well gets 80% changes....gbox which has fatal flaw...didly sq**t...)...I dont get it - I also dont get why it isnt the major Sticky Warning - prob would have saved you over £2000 over top purchase price for an HR rather than earlier model - Clutch, DMF + recon box fitting.....and from all accounts, the problems will only return!

 

I think we need some expert guidance on most efficient (cost v longevity) cure to this clearly common issue - Just Google 350z stiff gears or similar if you are unaware of the issue so far

 

Has the 370 box been re-engineered .....or was the 'auto rev match' introduced to try and balance gear speeds to alleviate strain on weak synchro design?

[GriffGTV]

found this one within a few seconds search too. ..

Posted 25 March 2014 - 15:51

Hello,

 

I'm new to the forums and the site, but hoping you might be able to advise me re my 2008 350z (done circa 30,000 miles).

 

The car broke down recently at the side of the motorway - it wouldn't go into gear and I've had a new clutch fitted at a South London Nissan dealership (cost me £1k all in) which has fixed the problem. But they said when I picked up the car it was still notchy in third - and the gearbox can be notchy so I didn't think anything of it, but it turns out it graunches loadly whenever it goes into third - it's driveable but not on a long -term basis so needs looking at. The dealership said it may be the synchros but that by the time the gearbox has been stripped, synchros and bearings replaced as needed, that I may as well get a new gearbox. This seems excessive to me? They are quoting just under £3k for a new gearbox and £1k labour. I'm considering taking it to a gearbox specialist instead and seeing if they can strip it and fix it rather than just replace the whole thing.

 

Any advice gratefully received! Thanks Tom

[Juggalo]

Aye, there's loads. There's a guy in the USA that ended up putting a brand new 370Z GB in his 350.

Took some work milling the shaft to fit the main bearing, but he put the internals in a 350 gearbox, Cool write up and no where near as difficult as you'd expect.

"Smooth as butter" is his quote when driving

Love the American can-do attitude.

 

http://my350z.com/fo...conversion.html

Edited July 30, 2015 by Juggalo

[JEMAN]

I had the oil replaced in mine a while back with nissan oil........man it's louder and clunks big time than ever before. Lol. ..I can hear it when driving.....and it crunches into 6 th.....so synchro is knackered to......good job I don't use 6 th hardly. Can't afford new Box, so just havin to live with it for now

[GriffGTV]

good find Juggalo!

[GriffGTV]

....but there are those that agree that the auto rev match feature added to 370 is there to take heat off the weak synchros...also smaller idler bearing in 370 is a little concerning...guess will now have to research 370 gearbox failures..

 

How difficult could it be for Nissan to upgrade synchros and idler bearing during development testing before 350 was launched?

[GriffGTV]

in that conversion thread, they note that the later HR gbox is same as fitted to 370 (he was doing a 370 into DE mod...so looks like they didnt improve the 370 box over 350HR... They also mentioned that the boxes are good for 1000bhp....just a shame they fail when you tootle around town in first and second with 10% of that capacity..