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terrible shaking happening


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Ok well i have a 75 280z and everything is stock including transmission

 

my problem is this....when driving the car 1st and 2nd gear drive alright but once i get into 3rd and especially 4th gear the car shakes violently when i accelerate. Also when i push in the clutch to come to a stop, once i get down to around 15 mph and slower i can hear a tapping sound (seems to be coming from right behind the end of the tranny) that decreases with speed.

Also when i take a look through the shifter hole i do see quite a bit of oil and/or grease all over the place down there.

 

So tomorrow im going to take a more detailed look...but for you more experienced guys, can you tell me what might be the cause of this and/or possibly tell me how to just fix it all together.

 

I have no experience working with drivetrains so im not going to tear anything apart unless i can see something obviously wrong.

 

ive also done a search and know that i should check the u joints but im not sure how to tell if they are bad or not.....

 

Any help will be greatly appreciated!

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If the shaking happens at a certain speed, like if as soon as you hit a certain mph it starts to shake then it is quite possibly an alignment issue or wheels out of balance.

 

If it has a whirring sound associated with it then in my experience it it usually something out of balance which could mean something is not bolted snugly, I had that happen when a lug nut was loose also when the half shaft bolts werent torqued correctly.

 

I'm no expert by any means but that should at least give you a start.

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Ditto on the u joints/drive shaft. I had a similar issue with a vibration, shaking noise from inside the tranny tunnel. Turned out to be the driveshaft. Cant say anything about there being oil/grease. As for not dissassembling stuff, it is quite easy to just unbolt the 4 bolts from the driveshaft to the diff and slide off the driveshaft. You can then take it to a driveline shop to have them check it.

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  • 4 weeks later...

Alright guys. I havent been able to work on this problem yet because of being busy and what not. But i did find out something new to add and want to see if you guys have anything else to give as far as advice. I noticed that the shaking only happens at 45 mph or higher. Would that still be a drive train issue or maybe a balance issue on the wheels? or both?

 

Just trying to get an idea of where to look when i do find the time to start taking care of this problem

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Even though the noise is coming from the transmission, it's always good to make sure everything it nice and tight with your brakes. Check the grease spindle nut. It's right under the the gold cap that pops off on your front wheels. If it's too tight or loose, you will have shaking. Torque it to 20 ft lbs and back off 60 degrees. You'll also want to make sure all your bushings are in reasonable condition. Lets face it, most of our suspensions are 30 years old!!

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ok So here's an easy way to determine your issue.

 

First: you say it sounds like a noise from transmission.

Test: when you get to 60mph put it in neutral (dose it go away? is shaking still there?)

If so then you might have thrown a driveshaft weight (rusted off) or the Ujoints are going

 

Second: if the above did not solve shaking Check front wheel bearing play. There should be a little movement as these type of bearings expand with heat and tighten up normally but when cold they are semi loose (im talking barely lose)

 

Thrid: check lower ball joint is it moving back and forth when you grip tire and wiggle.

 

Fourth: inspect tie rod ends are they bleeding out grease and cracked boots?

 

Lastly: have a tire shop check the tires. Perhaps the alignment has been out long enough to cause Shoulder wear

Also if the front suspension was badly worn *IE bouncing up and down for awhile before you replaced* you could have tire cupping which would vibrate violently at almost all speeds but mainly low to mid.

 

thats all I got for now (I do alot of alignments & drivetrain so I have seen almost all of it including wreches stuck in things hammers in frames ect ect)

 

OH YEAH also do you hammer hard ont he brakes? maybe your brake rotors are warpped enough to cause imbalance while driving But this would be felt in wheel to when braking as a shudder from left to right..

 

ok its 330am im tired Night!!!!:burnout:

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wow THANKS for all the info. When i put it in neutral at 60, it does kinda solve it. I mean kinda because it still shakes but it isnt as bad. Once i put it in gear and even lighly o moderately hit the gas the sound and shaking comes back ten fold until i let off the gas.

 

Hope this makes it a little more clear. Not really sure how to explain it other than it is sort of like im constantly driving on those "cuts" or whatever they put on the side of some of these cali highways to wake up drivers that may have fallen asleep.

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sorry HOOV100 i didnt see your reply. No i havent had a chance to actually get a chance to crawl under the car yet. So im just trying to get ideas for when i actually do. The shaking is not through the steering wheel though. It is throughout the ENTIRE vehicle after 45 mile per hour.

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yeah sounds to me like your driveline is out of balance. the out of gear at 60 part says to me it could be your clutch plate may be loose. do you have any clutch problems, or does that seem fine? Really you need to check your driveshafts, that and balance on the tires. If you loose one of the 3 shafts at speed, it night not be pretty.

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  • 2 weeks later...

so yesterday i started the problem solving process for this.

 

I thought maybe i had gotten beyond my abilities an ALMOST sold the car to some kid that didnt even know what a Z car was! SO to all you die hard Z guys i apologize for the mistake i ALMOST made. lol

 

Anyways to the problem solving...

 

I decided to start with the obvious so i took the z down to my local big O tires for a simple balance of the tires. Knowing that the tires are about 8 years old i figured they need changing and a new balance couldnt hurt since its only 5 bucks a wheel. So i have that done and before the shaking happened at 45 mph like clock work no matter what gear or if its in gear at all. After the balance now it doesnt happen until 55-60 mph.

 

So im thinking that the tires are just too far gone and replacing them will solve it. So this week im going to go down to the local junkyard and get a cheap set of wheels and tires (that are obviously in better shape than mine of course) and balance them and see what happens when i put them on. If it solves the problem then i will be happy and just continue on with my plan of buyin all new bushing set and suspension set up and save up for new wheels and tires

 

If it doesnt i will look underneath at the rear and driveshaft and what not and see what the damage is (i am probably going to do it anyways but just with a different agenda).

 

I just wanted to update you all and for anyone else searching this topic with the same issue. Thanks to everypne for the ideas and help. I will still check all the other things you all mentioned also just to have my bases covered. i am getting closer and closer to having this a daily driver that i can taste it. But then after that comes the upgrades and where the real money goes away. what a vicious cycle these Z cars put us in!

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  • 2 weeks later...

one more UPDATE!!!!

 

took the rear end apart today to replace all the bushings and i find something shocking!

 

the driveshaft was NOT tightened to the diff!

 

only one bolt was more than finger tight and on top on that there was only 3 bolts holding it together....

 

so i think its safe to say that THAT was what was causing my problems....haha

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Looks like you found the true culprit. That said, let me chime in about tires. There are only four small patches of rubber that keep your car in contact with the tarmac. Don't short change yourself here. Tires only about 4-5 years old are more likely to grenade due to UV, ozone and heat. I had an older set of Pirelli's on my 240Z that looked fine with great tread, no cracks, etc. One rear tire decided to delaminate at 70 mph on a straight highway. The rear quarter was damaged heavily before I could get off the road. Minutes earlier I was winging through the Smoky Mountains at similar speed. Had it happened there I would not likely be replying to this post now. Even cheap new tires are better than old expensive tires.

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Thanks for the advice ezzzzzzz.

 

I do plan on getting new tires still because mine are still shot. At the MOST i will only keep the ones i have for about a month before getting new ones. I only drive this car on rare occasion right now as it is so thats the only reason That im willing to wait even that long. But having heard that i will most definately be getting them sooner than later.

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Looks like you found the true culprit. That said, let me chime in about tires. There are only four small patches of rubber that keep your car in contact with the tarmac. Don't short change yourself here. Tires only about 4-5 years old are more likely to grenade due to UV, ozone and heat. I had an older set of Pirelli's on my 240Z that looked fine with great tread, no cracks, etc. One rear tire decided to delaminate at 70 mph on a straight highway. The rear quarter was damaged heavily before I could get off the road. Minutes earlier I was winging through the Smoky Mountains at similar speed. Had it happened there I would not likely be replying to this post now. Even cheap new tires are better than old expensive tires.

 

I read this entire thread and was thinking this same thing. My friend at work recently acquired his dad's 76 280Z that he'd bought new (dad passed on to him), and the car is in great shape...but it's got many OLD components (rotted bushings, cracking tires, etc). He told me of a rattling at a certain speed (45-55 MPH, and then it's gone at higher OR LOWER speeds). I drive it around for a bit one day and told him that the bushings were shot and his tires likely needed to be replaced soon. He drove it home that day but his front right tire blew at 75 on the freeway and severely dented his fender in front of the door.....but it goes to show that new tires are important, regardless of how much they cost (compared to old tires).

 

this is a second car for him so he's got some time to save up money and do the proper repairs....otherwise it's a great car.

 

 

ezzzzzzzzzz - glad you were not hurt -that's a scary thought!

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