1990 300zx (Z32) N/A 5 Speed Transmission Issue

Nissan 300ZX technical discussion forum: Maintenance, performance, installations, modifications, how-to's and troubleshooting.
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frootiebootie
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Car: 1990 300zx (Z32) N/A - Aztec Red
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Just bought a 1990 300zx with a 5 speed trans. Car only has about 127k miles on it. Car was fine for a few days after I took it home, and all of a sudden I started to notice a weird noise. When I accelerate from a stop, the trans will make a grinding noise once the clutch is fully disengaged. The noise only happens when I'm at a low RPM. if I ride the clutch from a stop and disengage at a higher rpm, there is no noise. Additionally, if I shift up into third from second/fourth from third/etc, at too low of a speed, the same grinding noise occurs if I accelerate. Any other time, there is no issue. I did a few tests to diagnose the issue. I put my car in gear, put the clutch in, and revved to 5-6k to see if the car would move, which it did not. If I put my hand on the gear shift while driving in gear, I can wiggle it back and forth about 2 inches. I also can't go into a lower gear without being at the speed to match it. I.E, if I throw my car in neutral to take a turn in 2nd gear, I have to slow all way down to 2nd gear speed to get it in. If I don't slow down, the car won't go into gear. This happens with any gear I try to go into. I asked a few people for their opinions, and I got a few different answers. I was told that the issue can be with the clutch/throw out bearing, synchros, shift fork. Just wanting to seek some more wisdom from the experts. Thanks in advance.


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lexcrob
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Id say its just the throw out bearing is bad. Im pretty sure that model has a fork for the throw out bearing and the pivot ball. Those will likely all need to be replaced as well. While you are there you might as well put a new clutch in it. Maybe upgrade depending your later plans for the car.

As far as it being synchros drain the fluid look for chunks if it looks good fill it back up and just do the stuff above. It likely could use synchos shift fork blah blah but its impossible to tell based on everything you got going on. Use a fluid that others recommend for that transmission.

nissanfreak12
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HOnestly check these two things;

This will give you a lot of slop.
https://conceptzperformance.com/nissan- ... _p_608.php

This is at the bottom of the shifter to the shifting fork. This can cause all sorts of havoc as to not getting in gear, excessive movement, odd noises due to slightly being or trying to be in gear. A lot of side to side movement.

This is when you can move the shifter up and down, will also cause all kinds of issues like you described.
https://conceptzperformance.com/nissan- ... p_1877.php

nissanfreak12
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Also make sure your master and slave cylinder are not shot, this will also make it very tough to put in gear.

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frootiebootie
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Haven't checked any of these yet, but thanks for the replies. Thinking the throw-out bearing is a likely culprit. It grinds audibly, almost as if I'm trying to change gears without the clutch, but it does it at speed, in gear, clutch fully disengaged and ONLY at a low rpm. It's so strange honestly. If I had someone who knew Z's to drive it, they might be able to tell me more. but I don't. Anyone feel like taking a trip to Phoenix, AZ?

nissanfreak12
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frootiebootie wrote:Haven't checked any of these yet, but thanks for the replies. Thinking the throw-out bearing is a likely culprit. It grinds audibly, almost as if I'm trying to change gears without the clutch, but it does it at speed, in gear, clutch fully disengaged and ONLY at a low rpm. It's so strange honestly. If I had someone who knew Z's to drive it, they might be able to tell me more. but I don't. Anyone feel like taking a trip to Phoenix, AZ?
Check out Projectz32.com, they are mainly in Phoenix and have recently started a club in different states. Besides, no one wants to go to phoenix right now. WAY too hot, used to live there.

If the throw-out bearing is bad you will only notice it when you press the clutch in, that is the only time it has pressure on it, otherwise it just hangs there. It may also be a bearing in the trans that is going out if you have grinding while driving. Also should check the center carrier bearing on the driveshaft.

Here are a few questions so I may hopefully help

Does it make the noise not moving clutch out?
Clutch in?

Is there a particular gear it makes noise?
Particular speed?

Do you have any vibrations?

Lets start with those.

Jessica1984
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My vote is going to the slave cylinder!!

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frootiebootie
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@nissanfreak12 - I'll visit the site when I get home. I don't blame you for not wanting to come to Phoenix. As far as the throw out bearing, the noise is only when it's not engaged, so pretty much means that's out. If I'm not moving, clutch out or in while in neutral, there is no noise. It makes noise in any gear if I am not going fast enough, but mostly it is in first gear that I have the issue. I slowly disengage the clutch to move the car forward in first, when the clutch is all the way out, there is no noise UNTIL I start accelerating. It only happens for a split second, but it grinds as I accelerate and then stop. No vibrations that I can think of. It's 26 years old, so it vibrates a little lol.

@Jessica1984 - Why would the slave cause this issue?

Thanks guys.

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lexcrob
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Get a big cup of coffee and a strong buddy.
Roll out the jack, bricks, and a simple socket set.
Rip that tranny outta there and look.
Then drink beer and think about why you hadn't done it already.

Stuff like that is normally pretty cut and dry. Yup thats messed up new one dones.

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frootiebootie
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@lexcrob , Yeah I wouldn't mind doing that if I had a place to do it. Honestly don't wanna drop the tranny in my apartment parking lot. Trying to convince my buddy to let me use his shop.

Also I'd like to rephrase my OP. The grinding noise is only when the clutch is ENGAGED while moving in gear. No noise in neutral, no noise at any gear with clutch in. If I drop into 2nd gear at about 10 mph (or anything less than 15 really) and accelerate, it grinds. As soon as I reach the right speed for the gear (about 15 mph), the grinding stops. It only grinds momentarily in first gear, once the clutch is fully engaged and the car is moving, and quickly stops after I gain speed. Input shaft bearing, maybe?

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DCaff300ZX
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Before mindlessly replacing things a few tests and checks would certainly be cheaper, and possibly insightful.
Your situation OP is an odd one, and hard to diagnose from conversation. From what I carefully read and re-read I think I'd concentrate on the carrier bearing first since it is prone to issues due to age, and really is the most likely culprit. Next would be trans and lsd input shafts, but those would possibly show issues from leakage or heat under inspection and could also probably be checked on a lift and creating driveline slack. Other possibilities are cheap aftermarket shifter, and possibly even shifter linkage wear. Check the entire system over carefully, and see about an inspection/advise from a trans shop. Also, another valuable source of tests and info is the online service manual.
Hope this helps.

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frootiebootie
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@ DCaff300zx Yeah I didn't plan on replacing anything just yet. Got a good quote for a new trans for about 800 with less than 60k miles (allegedly) so depending on what happens I might go with that. I don't wanna spend two hundred dollars on a trans shop to diagnose it (wrong, most likely) anyway. It's pretty stressful. If I take a video of the noise, would that help you diagnose the issue? Thanks.

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DCaff300ZX
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I understand cost constraints, I myself have enough contacts now that I can generally get answers to most questions I have without going through an actual inspection but that comes from already "spending" to that status. I guess I just mean that there are ways to present a problem you have to a shop and questions that can be asked that may be helpful to your own efforts...guys often remember oddities and so asking the right questions about an oddity can sometimes beat past the profit factor since they never will or can claim to know for sure in those cases but it can let you know if anything like that exists in their knowledge.
As for a video, sure, if you can make one that accurately portrays the noise I'd listen and see if anything sounds familiar, and others could too. I've had exhaust shrouding make weird noises, odd brake/suspension clicking, and plenty of other odd noises here and there over the years as our beloved ladies do seem to enjoy keeping things lively due to aged suspensions and our driving habits with them.

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frootiebootie
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Well I will check with local shops in my area to see what they charge for an inspection. I will also do my best to get a video that portrays the issue this weekend on my day off (Sunday). Thank you so much for your insight.

nissanfreak12
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I know it sounds stupid, are you sure your not just lugging the engine/. Espesicially at that low mph in 2nd. It still shouldn't lug, or make a rattling sound(the lug Im talking about). I just know the older the engine gets the more odd sounds it could make.

Is the grind sound you are talking about like one you make when you miss a gear?

Also, be careful when taking it to a shop, some will tell you the trans is shot. MOst trans shop will give a free estimate if you tell them you are looking for a repair. Do not tell them you are going to do the work yourself, then some will charge you. May not be the best advice to cheat shots out of money, I just hate shops, especially trans shops.

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DCaff300ZX
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nissanfreak12 wrote:I know it sounds stupid, are you sure your not just lugging the engine/. Espesicially at that low mph in 2nd. It still shouldn't lug, or make a rattling sound(the lug Im talking about). I just know the older the engine gets the more odd sounds it could make.

Is the grind sound you are talking about like one you make when you miss a gear?

Also, be careful when taking it to a shop, some will tell you the trans is shot. MOst trans shop will give a free estimate if you tell them you are looking for a repair. Do not tell them you are going to do the work yourself, then some will charge you. May not be the best advice to cheat shots out of money, I just hate shops, especially trans shops.
I agree about inspections, I meant that you call the shop(s) and get someone who can talk about transmissions (owner/operator hopefully like a trans shop I used years back) and present your issue in such a way to try and highlight the oddity that's holding things up, hoping he sees this thing and realizes the potential of your theory, or discounts your theory for whatever reason. Either way you get info to use in your own research hopefully, and maybe also lose a theory or bad thought process that holds you back. The trans shop I mentioned had an owner who did high end Mazda's and such which I knew, and figured this kind of guy would know about little things and not just about major trans stuff and was right...when I mentioned my need for no trans flush in my Nissan and the need for higher quality fluid he said to bring it in and he'd set me up with some better fluid and cleanup with no flush, which restored my aging A/T for two years until he went into custom only work and I couldn't use him any longer. 10 minutes conversation about trans details and my needs netted a huge return for me, and some decent business for him. Doug Smith at Fairlady is a similar guy I met many years ago now, I got a lot of good info and some great part finds and deals from him that way before now using him for everything I can't handle any longer. Doug is now hunting down a car for my niece and will get it all ready to go and for a great price that we agreed on, at his own suggestion and VERY short notice...the point being that you can get a lot more out of shorter, focused conversation sometimes than from a process such as inspections and full diagnosis where you are basically admitting you know nothing of what's going on, the repair guy realizes that and as a business man has to make some money somewhere. Play your cards right and you may net MORE than a solution for your current problem.

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frootiebootie
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I called Aamco and got an estimate. Anywhere between free and 95 depending on what they find. I'll take it Monday.

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DCaff300ZX
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Good Luck!
And, do your best to stay involved to learn the actual problem and solution for future reference. :dblthumb:

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frootiebootie
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Honestly, I would much prefer not to get the shop involved whatsoever. I am very much a DIY kind of person. If I knew what parts to replace, I would tear the tranny out tomorrow and get to work, but I don't know, lol. No matter where I go for info, no one seems to know whats going on.

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DCaff300ZX
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frootiebootie wrote:Honestly, I would much prefer not to get the shop involved whatsoever. I am very much a DIY kind of person. If I knew what parts to replace, I would tear the tranny out tomorrow and get to work, but I don't know, lol. No matter where I go for info, no one seems to know whats going on.
Honestly, that is exactly what I have been trying to do here- highlight how you would use the resources available to you do learn about and do the job yourself, or as much yourself as possible.
To do this, you have to beat past some problems to get to your answer/solution- most notably you have to use communication skills to work past a shop needing to make money, and your need to not spend money unnecessarily. To do this you have to be able to talk to people in such a way that illustrates you are working on a problem and have run into a rare/odd issue that no one seems to be able to pinpoint or know about, and not be coming across like just another potential customer and especially to come across as uneducated on the subject at hand. This way you try to have a different kind of conversation with this person where they are able to focus on a smaller thing and not be looking at your issue as too complicated to deal with verbally, and just another potential job...you do not indicate any need for their services, just information and possibly a direction to go or other person/shop to talk to.
Look at it like wanting to talk to some hot chick- you don't just walk up, gawk at her and make inane comments, you think it over about what you'll say and do, and even some thoughts about what to do if this or that happens. Same deal with your car, have a clue about things and don't waste time with anything that isn't required with your problem- talk straight to your issue and give any and all supporting info and such as possible, including any opinions and such so that person is right where you are and not feeling like they would have to do a lot of their own diagnosis and such to even talk about the problem- in other words, a regular job versus sharing specific info.
Rare and odd problems are just that- rare and odd so generally they stand out for that to guys who do work on things. I myself remember the odd things I've fixed over the years and so sharing that in a conversation is easier and I don't feel a need to make money off that like I would if someone drops their entire problem on me- THAT'S a job, sharing info is not.
Sure I've spent money at shops, but DEFINITELY not as much as the work I have done to my Z's, and really all other cars I have had. I am NOT rich or well-heeled in any way, do not have many tools or places to work, but have ALWAYS gotten anything I need done in similar ways- finding the true and best solutions, copying things that definitely worked and avoiding lesser solutions, and ALWAYS know what the problem is before work and always doing the right work, correctly, if possible.
The ONLY way to do this (and it doesn't always happen easily, or sometimes at all like before my total teardown) is to use all of the resources out there carefully, and generally with good communication and the right approach...and willingness to keep at it until you get it, and not worry about time spent researching/problemsolving or taking shortcuts.

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DCaff300ZX
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OK, waaaaay back in the past I had Ford 10" lsd issues and foolishly wanted to fix it (eventually found replacing it is way easier and cheaper always) and did, but it was a huge pita and required help from a highly knowledgeable diesel mechanic family friend to even contemplate and eventually do the detailed inside clutch plate setup and gear alignment work...dial indicator, shims, shims, and more shims, critical detailed measuring...basically we did what a rebuild shop would do.
This old family friend was a super-anal and detailed mechanic, but also a huge DIY guy and is the one who taught me about how to go about all of this and is the basic idea I have used to do ALL of my TT work.
So here's what I'd do:

1. You seem to have a lot of specifics about the lsd sound and possibilities, the info that I mention from above, so call/look up online any and all trans sources you can find looking for actual people to talk to or online chat with I suppose about specific conversation or tests/specs for the specific lsd internals, and about any further shops/people that do rebuilds and other internal rear end work that the normal trans shops don't do- the guys THEY send their units to for major repair/ rebuild service or new replacements.
2. Check the osm for any and all lsd tests and service procedures. Possibly even contact Nissan, but probably best online and not through a dealer directly although possibly certain dealers may have the info and be willing to share it...Ford would.
3. Follow up on ANY info from #1, and any further osm/test info.
4. Try and find anyone you know (or find via above) with ANY close experience or insights, including looking through old threads here and keeping us up to date on any results from above. BTW, after any diagnosis or such from any shop, you are not bound to have the work done there if you feel you can or want to do the work yourself and can simply use any info for your own purposes.
5. Compile all available info when things slow down, hopefully a solution becomes clear and is the solution you want. Continue if possible if not your preferred solution, or rethink things and make the New Plan.

Good Luck!

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frootiebootie
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Well I ended up not taking it to the trans shop because I was busy, but I plan to take it this coming Monday. Of course I'll take the free diag, and of course I'll use the information to determine my next step. A buddy and I went driving the other night, trying to get an idea of what was going on. We noticed that the noise is coming from in front of us while driving. After looking under the hood with a light, we could see exactly where the trans and engine bolt up, and the noise is definitely coming from somewhere in between the gear shift, which is at the back of the trans, to the back of the engine, where it bolts up to the housing. I had thought about the possibly of a diff issue at one point, but I disregarded that after realizing how far up the noise was. I need to take a video for you guys, but it's hard to tell whats happening from inside the car unless you're driving, and almost impossible from a drive-by video. I want to get it on a lift/jacks and accelerate in gear to gear where the noise is coming from, but I don't wanna risk it falling off my jack stands. Also, after driving around the other night, I noticed that the noise happens more often now. It happens higher through the RPM range than before, although it is much quieter the higher the revs. I got a quote for a new trans at about 700-900 USD, which is looking more and more tempting as time goes on. At the same time, I'm looking for some TT's at a good price, cus I want to do a swap, but I've been told to just buy a TT instead. Though my N/A is in really good shape (except the trans).

nissanfreak12
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Are you absolutely sure its not the center carrier bearing? Have I asked this already? Noise can radiated drastically, especially the way it is mounted. Its easy to figure it out, just lift it and see if the driveline moves. Try it up, down, left, right.

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frootiebootie
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Now that you mention it, when we drove it around a bit, there was one instance where I shifted and it felt like the whole trans moved forward. Scared the s*** out of me.

nissanfreak12
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Check your motor mounts and trans mount when you look under there as well. When checking the motor mounts, use a small piece of 2x4 inbetween the jack and oil pan and slowly lift the engine. Any separation and it is bad. Trans mount is roughly the same, but it will look sagged

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frootiebootie
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Heading to AAMCO tomorrow to do a free diagnostic test. I'll try to take a look at the car while it's on the lift as well. We'll see what happens. I will take some videos and pictures.

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frootiebootie
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Time to revive the thread. A lot of stuff has happened since the last post. I sold this car in September of 2016, as I just did not have the time to diagnose it. Well I reached out to the owner, and bought my baby back last week!!! Now I have to find out why the transmission sounds like it's going to fall out.

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Ace2cool
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Oh wow! That's uncommon to get the car back from the new owner! I'd definitely check the driveshaft center carrier bearing.

Zcarvert
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LOL ! Glutton for punishment ..I'm doing a complete rebuild


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