A&Q about 350Z
Q:
When I shift from 4th to 6th gear, I've lately been experiencing occasional grinding and/or difficulty getting it into gear.
Does anybody know what could be up and whether I should worry about it?
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guns and guitars, bikinis and fast cars - slide behind the wheel and GO!!
A:
for some reason every car I've owned seems to grind occasionally if you skip gears without double clutching...
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1985 300ZX n/a
A:
Shouldn't grind, especially if the car is warm. Is it grinding or just notchy? If you don't do it just right, it may be notchy which is acceptable occasionaly in a transmission like this.
19[TT]91
My TT beauty is gone.
2[00]2 Honda 954RR
Suzuki 1200 S; sportscar eater
19[I4]94 Integra GSR Sedan
Long live the Z...
aka SAHTT
A:
Yeah, it's grinding. I can tell that something is definitely different. I don't know what you mean by "notchy", but I do know that it's difficult to get the stick into that gear at times.
Then, after I shift to 6th a few times, it seems to get better and eventually return to normal.
Any ideas? Thanks for your help so far.
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guns and guitars, bikinis and fast cars - slide behind the wheel and GO!!
A:
Stank,
It sounds like either your tranny is low on oil or possibly it has too heavy of oil for the colder weather..
My cars shifting is really "notchy" when its cold, but as I use it and the gears get re-lubricated it starts shifting much better. Its because I have 90W-140 in my tranny when I should have something lighter like 80W-90.
Check your oil level first, and if its low add some generic 90 weight Gear oil to it to top it off. If its not low, have it drained and re-filled with 80W - 90 and some Lucas oil stabilizer. Its good to change it out every now and then anyway. It can only help.
oh, and by "notchy" we're meaning you can actually feel the teeth of the gears hitting through the shifter as the gear engages, but it doesn't actually "grind".
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1985 300ZX n/a
Post Edited (Nov 27, 9:31pm)
A:
Grinding is the internals of the transmission not aligning properly. You'll know the grinding noise when you don't put the clutch far enough down during high speed shifts, you'll never mistake the noise again. It makes a terrible grinding noise and sensation you feel through the shifter. If it's just notchy, it's the syncros not meshing correctly and the only realistic remedy is fluid adjustment like phx mentioned. If you are totally pressing clutch down and pausing for a second, and still having consistent trouble with the proper fluid in the transmission, then there is reason for some concern.
19[TT]91
My TT beauty is gone.
2[00]2 Honda 954RR
Suzuki 1200 S; sportscar eater
19[I4]94 Integra GSR Sedan
Long live the Z...
aka SAHTT
A:
Im almost positive there is a TSB for your tranny not going into gear. Seams like tons of our Zeds have this problem. Go get you free tranny courtesy of Nissan. BEN
2006 Acura TL, Black on Black, 6 speed Navi with Brembos.
A:
Guys,
Thanks for all your help. I will check that oil tomorrow after I get off work and the engine is good and hot!
tha stankanator
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guns and guitars, bikinis and fast cars - slide behind the wheel and GO!!
A:
The only thing is, the problem occurs intermittently. It seems like when the gear is turned to the "right" place, the teeth are messed up and the gear grinds; when the gear is turned to any other position, the teeth aren't in a place where they move improperly, so everything sometimes works fine.
Thanks again for the help.
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guns and guitars, bikinis and fast cars - slide behind the wheel and GO!!
A:
that seems to be consistent with lack of or improper lubrication.
the only other thing it could be in your synchros going bad, but unless you beat the hell out of your car I doubt that.
It could be the clutch going out, but it would affect all gears if that were the case. They would all start off as "notchy" and then eventually start grinding...
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1985 300ZX n/a
Post Edited (Nov 29, 12:18am)
A:
Hey, i just wanted to say thanks too... for explaining the "notchy" description... because i always though that the gears were "grinding" and that i was REALLY screwing something up... cause mine sometimes will have that notchyness going into 3rd... with the clutch full depressed... anyways i'm gonna take your advice and check out the fluid when it gets a little warmer...
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I don't think, I know...
Well, I don't think you know either
A:
Ok guys, get this. I've noticed that it's only when the RPM is high between shifts (as it usually is), the 6th gear will grind, but if I wait between shifts until after the RPM is down to idle THEN shift, it doesn't grind.
Any ideas?
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guns and guitars, bikinis and fast cars - slide behind the wheel and GO!!
A:
stankanator:
The three most likely causes of something like that are:
1) the synchro for 6th is wearing out
2) its cold outside and the oil is too thick
so the bearings on the drive gears won't
spin up/slow down fast enough
3) there isn't enough oil in the tranny and the
synchros aren't getting proper lubrication.
All of the synchro hubs and drive gears are on the output shaft, which is the higher of the two main shafts in a manual tranny. If your oil level is too low, shifting will be affected first.
The condition of the oil is extremely important with regards to shifting. If the oil is too light, it will not protect the synchros and other surfaces well enough and it will wear things out faster. If the oil is too thick (possibly due to very cold weather or improper viscosity) the gears will not be able to spin up or down fast enough and the teeth will hit or grind. The synchros must spin up or down not only the drive gear it touches but, also all the other gears in the tranny and the clutch disc because they're all connected together... And it has to be able to do it fast, it only takes half a second to switch gears.
Since they deal with a lot of friction, synchros wear can wear out pretty quick if they're heavily abused. But the difference in rotational speed between 5th and 6th gears is lower than between any other two gears in the tranny, so this synchro should not be worn out yet under most circumstances.
It can also be non-transmission related. It could be the clutch not releasing properly, still making some contact with the flywheel. Maybe its not releasing perfectly straight and just an edge is touching.
One other thing you may want to note:
When switching immediately between 5th and 6th will cause the speed of the moving parts in the tranny to drop. Basically, the output shaft (and all the synchro hubs) spin faster and faster as the car goes faster. But each time you shift gears, all the gears and the clutch have to slow down to match the engine, while the synchro hub spins faster to match the output shaft (bolted to drive shaft and differential)
When you pause and let the RPMs drop, you're actually letting the clutch spin down by itself. Now when you shift from 5th to 6th the gears in the tranny and clutch have to spin up instead of down.
I would check your oil level first. You may want to just have it drained and refilled for the heck of it... Its not too expensive if you have somebody else do it (jiffy lube? it may be a cheap joint but it don't take more than $8/hr of talent to change oil in a tranny) and that way it takes 10 minutes. If you want to do it yourself you can get some higher quality gear oil and make sure its done properly. Getting under your car will be the only hard part.
If changing or topping off the oil doesn't fix the problem, try doing an adjustment on your clutch pedal. Its super simple, and your description of not shifting at immediately but letting it spin down and then shifting makes me think that your clutch is much more likely the culprit than your syncros.
I hope that helps you come up with a diagnosis.
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1985 300ZX n/a
Post Edited (Dec 1, 12:15am)
A:
Great info there, phx!
Boy, I sure hope that all I need to do is change the oil! I looked for the dipstick yesterday for a second while I was filling up my gas tank, but I didn't find it. It should be red, right? All I saw was the yellow one for checking motor oil. But I need to look for it again, I was in a hurry! :)
It could also be the clutch as you mentioned. It could be- after all, I've been experiencing clutch chatter/judder for a while now, but it wouldn't ever do it in front of the dealer's service guy. It may be related to this chattering.
I'm going to have it checked out on Saturday and mention some of the things you said in your posts.
Thanks for all your help,
stank
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guns and guitars, bikinis and fast cars - slide behind the wheel and GO!!
A:
There is no dipstick for a manual transmission, only autos. Unfortunately, the only way to test the fluid level is to jack the car up and remove the FILL plug. The fluid level should be just high enough that it reaches the bottom of the filler hole without starting to pour out. If its low, I would drain it (by removing the drain plug on the bottom) and then fill it back up with new fluid. I also highly recommend adding Lucas Stabilizer to whatever oil you end up putting in. A good general oil rating for most transmissions and weather conditions is 75W-90 or 80W-90.
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1985 300ZX n/a
A:
Stank: I seriously doubt that it's the fluid. You could go ahead and check just to satisfy yourself that it's up to the mark. If you add or replace, consult your manual for the specific requirement.
Based on your post, I did some testing with my car, shifting from 4th to 6th at various rpms and road speeds. No grinding. I will say, though, that that is a PIA way to shift--the motion is awkward--and when I'm skipping 5th, I shift into 5th, keeping the clutch depressed, and then into 6th.
If you've got genuine clutch judder--or chatter--there should be no trouble getting it to happen at any time. Clutches I've experienced with that problem have simply done it, and almost no amount of left-footwork could prevent it.
Wish I could be helpful, but this one's an odd issue. Grinding into top gear is not a typical first symptom of gearbox trouble. It's almost always the 1st to 2nd shift, where the jump in ratios is the largest and where the synchros take the biggest load. On the other hand, I'm led to believe--by various posts elsewhere and here--that there are some design features of this gearbox that are a bit odd, to say the least.
A:
BTW, if you replace fluid, be damned sure to use GL-4 rated oil. GL-5 contains additives that can degrade yellow metals such as those used for your synchros. If you want, I can refer you to a series of postings on the 350Z-TECH website on the subject.