1991 300ZX 2+2 Vibration Help!

[etsl90]

Hello, all.

I just bought 300ZX last week. The car makes vibration/Humming above 45 mph through a whole body. No vibration on steering wheels. I suspected tires and bought two new ones. I tried rotstion between front and rear, but no luck. New tires and old tires does not make any change. When it vibrates, I tried different gear and different rpm, also, step on the clutch. It does not change anything. No matter what, it just vibrates/humming above 45mph. I can feel it through the seat very much.

How can I find the cause and fix?
Could it be rear drive axles, or drive shaft out of balance, or its u-joint? I just want to know how to find what's wrong and fix rather than replacing everthing untill it is fixed.
Can anyone help me, please.

[k3smostwanted]

Originally Posted by etsl90

Hello, all.

I just bought 300ZX last week. The car makes vibration/Humming above 45 mph through a whole body. No vibration on steering wheels. I suspected tires and bought two new ones. I tried rotstion between front and rear, but no luck. New tires and old tires does not make any change. When it vibrates, I tried different gear and different rpm, also, step on the clutch. It does not change anything. No matter what, it just vibrates/humming above 45mph. I can feel it through the seat very much.

How can I find the cause and fix?
Could it be rear drive axles, or drive shaft out of balance, or its u-joint? I just want to know how to find what's wrong and fix rather than replacing everthing untill it is fixed.
Can anyone help me, please.

are all of the wheels/tires combos balanced???

it could possibly be the driveshaft...i would suspect both. i guess the worst case scenario, you could have something fubard in your suspension.

[DeleriousZ]

yeah... get an alignment done... does it get worse when you step on the brakes? do you have the stock driveshaft in there?

[etsl90]

Yes, all tires are balanced. Bought two brand new and got all 4 balanced.

No, brakes does not matter.

FYI, my Z has 186K miles on it.

It feels like vibration coming from rear or center of the car, and sounds like a bee, Zeeeeee when it vibrates.

Thanks.

[k3smostwanted]

Originally Posted by etsl90

Yes, all tires are balanced. Bought two brand new and got all 4 balanced.

No, brakes does not matter.

FYI, my Z has 186K miles on it.

It feels like vibration coming from rear or center of the car, and sounds like a bee, Zeeeeee when it vibrates.

Thanks.

pull down the driveshaft...sounds like the carrier bearing has gone. if it does indeed looks bad...check out http://www.z1motorsports.com

they offer 1-piece driveshafts for reasonable prices. typically, 1-pieces have more vibration then 2 pieces but these seem to be wvery well balanced and i havent heard any complaints.

[etsl90]

What's the carrier bering? Is it the one that is called midshaft bearing on z1motorsports website?

If one piece drive shaft has more vibration, is it be easied to get stock 2pc on the vehicle rebalanced than buying one piece shaft?

Oh, well, if this uncomfotable viration is gone, my car will run like a champ.

I guess I'll check the bearing around drive shaft first. Is it common on older Z? Is it easy to enough replace? (I'm not be able to take anything heavy off since I'm thin and skinny. My weight is 110lb. My weight is more effective than taking parts off car to reduce the vehicles weight, lol)


Thanks,

[k3smostwanted]

Originally Posted by etsl90

What's the carrier bering? Is it the one that is called midshaft bearing on z1motorsports website?

If one piece drive shaft has more vibration, is it be easied to get stock 2pc on the vehicle rebalanced than buying one piece shaft?

Oh, well, if this uncomfotable viration is gone, my car will run like a champ.

I guess I'll check the bearing around drive shaft first. Is it common on older Z? Is it easy to enough replace? (I'm not be able to take anything heavy off since I'm thin and skinny. My weight is 110lb. My weight is more effective than taking parts off car to reduce the vehicles weight, lol)


Thanks,

well the carrier bearing isnt universal and is not replaceable because nissan built it that way so you will need to sourace a brand new driveshaft from Nissan which will probably cost you well over $500 or risk buying a used one from someone and have the same thing happen.

and yes, this is very popular with Z32 owners. that carrier bearing tends to go after 100k miles, hence alot of Z32 owners running 1 piece driveshafts.

when i say the 1 picee has more vibration. this is because there is no flex in the driveshaft so if it isnt balance perfectly you will run into problems but there are alot of people with Z1 driveshafts and i havent heard a complaint yet.

you should be able to remove the driveshaft easily with a couple of metric sockets, straight wrenches, jack, and stands. . pretty simple stuff.

[Hodo]

K3 I would have to dissagree with you on the 1 peices haveing more vibration than a 2 piece. I can say if your tranny mounts are ok then the vibration issue, isnt a issue. But if your tranny mounts are shot, then a 1 peice will just make the problem more evident.

Now to the original poster, when you take off from a light or a standing stop, do you feel and clunking or hear anything like clunking or even a squeeking noise when you back up. These are also signs that your center support or midship bearing has failed.
Look on the brite side, it takes about 2 hours if your REALLY slow to change your drive shaft. And if my memory serves me I think its about 10 bolts total. The hardest to get out will be the 17mm bolts in the body of the car that holds the midship bearing in place. I suggest a breaker bar with a cheater handle. (or a breaker bar with a 4ft metal pipe)

If you need any more help just drop a post on here, if K3 cant answer it then I can, or someone can. I just changed my drive shaft about 3 weeks ago so I still have it fresh in my mind.

Good luck.

[k3smostwanted]

Originally Posted by Hodo

K3 I would have to dissagree with you on the 1 peices haveing more vibration than a 2 piece. I can say if your tranny mounts are ok then the vibration issue, isnt a issue. But if your tranny mounts are shot, then a 1 peice will just make the problem more evident.

i was theoretically speaking. if something doesnt have a bearing in the middle that can flex just a tad then there will obviously be more vibration due to drivetrain movement and such. 2 pieces have to be perfectly balanced, just imagine how precise a 1 piece does.

but like i said, i have never heard of any complaints with the 1 pieces offered for the z32 so they must be well made.

[etsl90]

Thanks for a lot of info. I have additional question about this issue.

1. How can you tell carrier bearing is bad? I understand that I have to take the drive shaft off and see, but how can you tell it's worn? Is there any visual signs that people can tell that it's bad although I do not know how it look when it's new? Does any one has a picture of it?

2. When you install one piece drive shaft, how do you put it on? I guess 2pcs one can be bent at joint so it would slip in, but do you have to remove additional parts to put 1pc shaft?

3. Has anyone here had the same problem as I have and have sucessfully fixed? What part was the problem?

I still do not know what to do unless I replace all suspective parts untill it gets fixed.

There is no clunking noise or squeeking noise.

Thanks.

[TeamRedLine23]

I hear a clunking sound. its coming from the passanger side. It sounds like its coming from cat converter or around that area. I need help with this problem because its bugging the shit out of me. One more thing how hard is it to change the transmission mount, mine are shot. Im guessing thats why Im getting some vibration. Thanks for your help. you guys/girls have helped me make my car run flowlessly. if anyone lives in Oceanside,CA maybe we should meet up because there are some things that I cant explain only show you.

[k3smostwanted]

Originally Posted by etsl90

Thanks for a lot of info. I have additional question about this issue.

1. How can you tell carrier bearing is bad? I understand that I have to take the drive shaft off and see, but how can you tell it's worn? Is there any visual signs that people can tell that it's bad although I do not know how it look when it's new? Does any one has a picture of it?

2. When you install one piece drive shaft, how do you put it on? I guess 2pcs one can be bent at joint so it would slip in, but do you have to remove additional parts to put 1pc shaft?

3. Has anyone here had the same problem as I have and have sucessfully fixed? What part was the problem?

I still do not know what to do unless I replace all suspective parts untill it gets fixed.

There is no clunking noise or squeeking noise.

Thanks.

1. the bearing could be cracked, the rubber surround could cracked. i seen a picture of a bad one the other day, i will search.
2. there are 4 bolts that hold it to the rear differential and slides right in the yoke of the transmission. so slide the spline in the yoke first then bolt it to the diff. you will not need the center support bracket and that is the only other thing. make sure you put the exhaust shield back in place and your good to go.
3. i cracked the surround on my stock driveshaft when i pullde it down but the reason i pulled it down was with intentions to replace with a 1 piece anyways. but yes, it is very common for people to have this driveshaft problem and it seems they always fix it by replacing it with a 1 piece because it is the most cost effective way.


there may not be a clunking noise but just a bad wobble. the bad wobble in the driveshaft is causing the vibration.


TeamRedlineZ: when do you hear this sound? your problem could possibly reside in your shifter, transmission, shift control arm, rear diff. kind of hard to diagnose without more detail.

[TeamRedLine23]

I only hear the sound when the car is at idle.

[Hodo]

etsl90, ok like K3 said you can tell when the center support bearing is shot by looking at it but its not the easiest thing to see from under the car. But you can check it by getting under your car and grabbing the driveshaft and pushing up and down and left and right. If it gives more than about a half a inch or clunks when doing this then odds are the bearing is torn or starting to tear.

Its easy to replace the drive shaft. There are 4 bolts holding the drive shaft to the rear diff. And there are about half a dozen holding the exhaust heatshield. But you will need to lower your exhaust about 6-8 inches, this will mean undoing the rear exhaust hangers and the middle ones. It also helps to disconnect them from the transmission too. Then you will have enough room to get the 19mm bolts that hold the center support bearing in place. Once thats out then you can pretty much just pull the old driveshaft out then, line up the new drive shaft and push it into place. It is splined so it will have to line up with the output shaft on the transmission, you can sort of twist the driveshaft and it will pop into place. Then just center it up on the rear diff then bolt it back in. Make sure to get them tight, the torque specs can be found online. Then put your heat shield back and rehang your exhaust. Then you are done. Like I said not more than 2 hours if you take your time.

Its pretty easy. On a scale of 1-10, 10 being hard. I would say this is a 3, its just a bit tricky if you have a automatic and you have to keep getting out from under the car to release the e-brake to turn the driveshaft to get to the top bolt on the driveshaft.

All you will need is 4 jack stands, basic socket and wrench set, a half inch breaker bar about 30" long helps, and maybe some breakfree penetrent oil. Just take your time and it will go smoothly.

[etsl90]

Do you guy's think my problem is a driveshaft?

I also find one on NyxMotorsports.com. Which is better, Z1 or nyx?

Thanks,