Strudul Posted January 9, 2017 Share Posted January 9, 2017 I'm getting a grind when shifting into 5th / 6th from any gear unless I pause or shift (IMO) slow. This happens every time I shift into 5th/6th in a normal fashion, but to exaggerate the problem, I've demonstrated it in the video below without actually bringing the clutch up and engaging the gear at all. Can anyone confirm if this is normal / acceptable? As you can see, quickly swapping between 3rd /4th it is very quiet, but between 5th/6th there is a noticeable grinding sound unless I pause for a fraction where there is resistance (which is also demonstrated - watch closely, it happens quite fast, but you can see 2 distinct stages to the shifts with no grinding sound). I'm assuming this is due to worn synchros as I've been told before, and Molyslip may help, but in reality am I just shifting too fast for the gearbox? I assume not, since there is no problem with the other gears, but I don't understand gearboxes well enough... Can (or does) anyone replicate the same shifting speed without any problems, or is it an innate issue with the Z? Cheers Quote Link to comment Share on other sites More sharing options...
Commander Posted January 9, 2017 Share Posted January 9, 2017 Known Z problem. HR 'box is supposed to be better than DE, but neither is great. Mine (HR) is similar to yours (5th to 6th), though mine's nowhere near as bad. Synchros / whole box can be replaced, but it aint cheap and the problem will probably reoccur again in the future (after considerable mileage) 2 Quote Link to comment Share on other sites More sharing options...
RobPhoboS Posted January 9, 2017 Share Posted January 9, 2017 It's mounts - either gearbox (most likely), diff or engine. I changed all of my ones, doesn't happen any more. 1 Quote Link to comment Share on other sites More sharing options...
RobPhoboS Posted January 9, 2017 Share Posted January 9, 2017 (edited) It's mounts - either gearbox (most likely), diff or engine. I changed all of my ones, doesn't happen any more. Interesting. How would mounts affect the syhncro operation unless you get somesort of outer casing distortion. The shifter isn't on external cables/rods - it's attached to the gearbox directly. Did you change oil at the same time? I did the gearbox mount first, the oil had previously been done about 2 years before (I stick with the Nissan oil). That vastly improved it, no grinding. Then Kaizer/Sly did the diff mounts as the main one had popped, then several weeks later he did the engine mounts. It progressively got better and better each time. Fast forward about another 8 months and I just did the gearbox/diff oil again I've posted this before, so the OP can have a seach and see if they want to do this. I'd probably just start with a new gearbox mount, but my ones are poly just to clear any confusion (except engine mounts are vibratechnics). The reason I'd say try a new standard gearbox mount first is that a poly one will bring potentially unwanted vibration. Edited January 9, 2017 by RobPhoboS 1 Quote Link to comment Share on other sites More sharing options...
RobPhoboS Posted January 9, 2017 Share Posted January 9, 2017 It was certainly the case for me, the old OEM mount is rubber and certainly wasn't in top condition after removing. It really is worth trying first before expecting the worst ! (not to say that syncro might be damaged but it alleviates the horrid feeling). 1 Quote Link to comment Share on other sites More sharing options...
Strudul Posted January 9, 2017 Author Share Posted January 9, 2017 (edited) Never considered mounts, cheers. Do you know the technical reason of why it causes a problem? Why does it not happen if I pause? Edited January 9, 2017 by Strudul Quote Link to comment Share on other sites More sharing options...
Toon Chris Posted January 9, 2017 Share Posted January 9, 2017 A new diff mount will tighten up the power transmission and on high mileage / older cars makes a world of improvement to the driving experience. Regardless of the gear problem you have it's worth doing anyway. 1 Quote Link to comment Share on other sites More sharing options...
RobPhoboS Posted January 9, 2017 Share Posted January 9, 2017 (edited) Never considered mounts, cheers. Do you know the technical reason of why it causes a problem? Why does it not happen if I pause? Totally guessing, so no, I don't know - but guessing... if the gearbox mount is perishing, then the bits and bobs aren't lined up properly and within tolerance for smooth changing, it'll will get worse and worse. Hardrace make a rubber one, if your car is daily driven and you want comfort, try that or a new OEM one. H-dev were selling Hardrace iirc, or google, easy to get. If you don't care, go for poly like Torque Solutions (for ex). For now, take care shifting, and try and pause into N before, let it settle for that moment and then change. This is just from my experience, I'm certainly not claiming this is 100% the problem. http://www.350z-uk.com/topic/97960-transmissions-mount/ http://www.350z-uk.com/topic/95585-gearbox-diff-oil-changemolyslip/ try a search on google - for example copy and past this: site:350z-uk.com gearbox mount Edited January 9, 2017 by RobPhoboS Quote Link to comment Share on other sites More sharing options...
Irn Bru Posted January 9, 2017 Share Posted January 9, 2017 On my Zed...... 1 - 2, notchy when cold, ok once warmed up. 4 - 5 crunches if shift is quick, no crunch and smooth when paused for a split second. Well known fact the syncros are chocolate in the early boxes. Just adjust your driving style a bit to compensate for the crappy syncro Quote Link to comment Share on other sites More sharing options...
RobPhoboS Posted January 9, 2017 Share Posted January 9, 2017 Just adjust your driving style a bit to compensate for the crappy syncro Orrr spend about £90, and 40 mins to put in a new mount Quote Link to comment Share on other sites More sharing options...
Strudul Posted January 9, 2017 Author Share Posted January 9, 2017 Just adjust your driving style a bit to compensate for the crappy syncro Orrr spend about £90, and 40 mins to put in a new mount Sounds like a plan. Only bought the car a few months ago, so will see if the dealer will provide any assistance. I I do it, will I need a torque wrench though? Quote Link to comment Share on other sites More sharing options...
Strudul Posted January 9, 2017 Author Share Posted January 9, 2017 Whilst the new mounts are a good idea if yours have gone there is no guarantee it'll fix it. As I said, my hypothesis would be that propshaft loading is putting strain on the output shaft and moving it slightly. Otherwise, and I'd be astonished by the, the gearbox case is warping under load. My guess is that the Synchros are worn though and it'll be a rebuild required. An independent examiner apparently stripped the gearbox and found no signs of wear. :S Quote Link to comment Share on other sites More sharing options...
RobPhoboS Posted January 9, 2017 Share Posted January 9, 2017 I do it, will I need a torque wrench though? Yup, worth having anyway. Just remember to unwind it back rather than leaving it on the last setting you used 2 Quote Link to comment Share on other sites More sharing options...
RobPhoboS Posted January 9, 2017 Share Posted January 9, 2017 Just in case the OP didn't see how easy it is to do: 1 Quote Link to comment Share on other sites More sharing options...
Strudul Posted January 9, 2017 Author Share Posted January 9, 2017 (edited) Did he give you values of measurements he'd taken, or just said he saw no wear? Whilst you can get big chunks, you more likely going to get wear of particles suspended in oil and lost with an oil change. No only that, but the wear only has to be slight to hinder the performance to cause that grind. No doubting it is worth replacing your mounts if they're gone mind. Have a look under the car, take some pics for us! I didn't get a direct report, I just got told indirectly that "no wear was found". Will it be obvious from a quick glance whether the mounts need replacing? Just in case the OP didn't see how easy it is to do: Yup, seen and watched. Will have to try borrow some decent ramps / axle stands and a torque wrench if I do it my self. Edited January 9, 2017 by Strudul Quote Link to comment Share on other sites More sharing options...
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