RX-7Havik

I have been noticing more & more vibration in my 88 N/A over the past several months. I thought at first it was a out of balance driveshaft, but it does it when the driveshaft is not engaged...(neutral)...so when I rev the engine in neutral it makes the same vibrations as when I am driving. How serious is this? Does it have something to do with the rotors and counterweights?? I have no insight on this matter. Any input would be great. Do I need to take it easy on here?

Thanks

RX-7Havik

bump

Wyznewski

Could be motor mounts.

turbine

iTrader: (1)

i have the same problem. when its the drive shaft its usaly speed related when its rpm the problem lies else where
where i dont know. when i rebuilt my motor i wanted to get the esentric shaft ballanced but i was told it cannot go out of ballance. i wonder if it colud be a trans mount. after the rebuild the vibration went away but now its coming back. after about 3000 miles have no clue

HOZZMANRX7

iTrader: (43)

Vibration in drivetrain when starting off in first gear, and decreases once car is moving. Front U-joint is bad.

Vibration in drivetrain that gets considerably worse the faster you go. Rear U-joint is bad.

Vibration in car when not moving that increases / decreases with engine RPM. Bad transmission mount.

Sounds like a tranny mount problem to me..............

RotaryEvolution

iTrader: (30)

so if you are sitting in your driveway and rev the engine in neutral you can feel an RPM vibration or is it only while moving? if it is while moving i would suspect a drivetrain vibration because there isn't many ways the engine could go out of balance, only real way would be mud packed into the front crank pulley are some foriegn object stuck to your flywheel/flexplate or the retaining nut for the flex plate has come loose or the flex plate has cracked or the torque converter has become out of balance.

Smoken'

iTrader: (1)

yeap, sounds like some kind of mount, probably the tranny mount like hozzman said

RotaryEvolution

iTrader: (30)

also to note, some people don't realize this but tire balance is very pronounced in these cars, i found my tires had flat spots in them and this caused some very nasty vibrations that occur at all driving speeds but faintly go away at over 70MPH, you should have your tires rotated and balanced every now and then anyhow, if you can't remember the last time you had it done then it is a good indication you should just have it done for peace of mind and it may cure your problem.. my tires need to be replaced but in some milder cases a balance is all they need, mine used to be way worse but it is tolerable now until i get some new rubbers put on.

RX-7Havik

I feel it when in neutral & reving RPMS, but then it does the same while a drive. It is not a drivetrain problem. If it was then how could it do the same in neutral when nothing is engaged.....
My tires are good, engine mounts are good. No foreign objects that I can see. The only two things that seem to make the most sense are a bad tranny mount or the counterweights on the rotors....

RX-7Havik

Good tips there, but can I rule out the counterweights then.
How can it be the tran mount if it's in neutral while I rev the RPMS.....it is not engaged....

HOZZMANRX7

iTrader: (43)

If you just put in the motor, and noticed the vibration from that point on, then the counterweight could be the problem. The rebuilder might have used a S5 front counter weight. It's possible to replace the front counter weight, but pretty much have to remove the motor to be successful. One slip, and you'll need to take the motor apart and put back together. So, I really hope for your sake this isn't the case unless you have a warranty on the engine work that is still in force.

But, if all was smooth prior to the vibration showing up, then keep your focus on the rear tranny mount. Second focus on the engine mounts.

Good luck!!

dorkman52000

Just because you're in neutral DOES NOT MEAN your driveshaft is not spinning....if you are still moving forward, but you are in neutral, your driveshaft is spinning because it's being turned by the rear wheels, not the transmission.
It may be a problem with your tranny mount, but it could still be a balance-related problem due to counter-weight or driveshaft.

RX-7Havik

No no rebuild here. I have been noticing an increase in vibration over the past few months. Is there any way the counterweights can become faulty? Or once they are put correctly on do they stay on? I will look at the rear t-mount this weekend.
Working two jobs eats up your time ya know
Thanks

RX-7Havik

I am talking about sitting still and in neutral. I know what turns the driveshaft bud, maybe you misunderstood me. IF it is the tranny mount....how does that effect the vibration when I rev, sitting still, in neutral? Will that still cause my vibration even if the tranny is not engaged?

RX-7Havik

Anyone else? How critical is this if it is counterweight problem? It really feels like it is coming from inside the engine that is causing the vibration.

boosted1205

iTrader: (9)

Well, I've never heard this happening to anyone but it COULD be your needle bearings. That's the only thing come to mind by reading your post. The problem here is it's not something you can see without removing the front cover. I've never heard of a needle bearing failurebut it sounds like it. Has anyone removed the front e-shaft bolt at anytime???

zbrown

is your car an auto? because back when i first got my car it was an auto, and it had the exact symptoms that your describing, vibration that got progressively worse over several months.

In the end it turned out to be the flexplate, it was cracking slowly more and more all the way around the inner circumfernce, there was only about a three inch stretch of steel holding the flexplate together once i finally figured it out. the flexplates are perty flimsey.

I can about gaurantee this to be your problem if it is an auto, id check it out as soon as you can. The vibes drove me crazy till i finally figured it out

1SxyRXy

your drive shaft is still gonna be spinning when the car in the netural because the wheels are still spinning. it possibly coudl be your tranysmision. your main shaft could be bent, i highly doubt its your counterweight. thats olmost impoosible to mess up, maybe its your clutch, it could be alot of things. try reving it in nutral wih the clutch out then try it with the clutch in

HOZZMANRX7

iTrader: (43)

Tranny mount stabilizes the rear of the engine/tranny as a "unit" (since they are bolted together). A little vibration from the engine becomes a lot of vibration when it gets to the end of the tranny. Hold a golf club out and move you hand a little and watch the greater movement in the golf head at the same time. You'll see what I mean.

Adam

I have this vibrations that gets worse when i put it in nutral at any speed above 20 ... Anyone have this problem? if i shift it in nutral then back in drive! sometimes it go's away..then comes back later! not tires not motor..its an automatic.. can the torq Converters go out?

Aaron Cake

iTrader: (1)

I doubt it's the counterweight.

-Engine mounts? Remove and inspect them.
-Transmission mounts? Very common for the lower mount to fail.
-Clutch fan? Cracked or broken blades?
-Flywheel/clutch assembly? Cracked, broken, bad pilot bearing?

That's about it, not considering the slight chance of internal engine problems (thrust bearings).

jamie k

replace your pilot bearing

RX-7Havik

Okay.....

I will rule out the counterweights then.....whew!

I will focus on the mounts and look into the needle bearing. Last time I put a new clutch in the N. bearing was so brittle it just fell apart, but it was still a mother to get out.

Aaron, now what is all this about thrust bearings inside the engine?

Thanks all!!!

RX-7Havik

Also, one more thing....

This vibration I am getting...it is not a bumpy or loose vibration. It's more like a fast vibration. I'm talking if I am parked, clutch not engaged, and I rev the engine I can feel & hear things rattle, such as my dash and my deck faceplate. Definitely not as smooth as it used to be.

I hope it's mounts and not anything involving clutch componants.

Aaron Cake

iTrader: (1)

Doubtfull it's the thrust bearings. They don't tend to randomly fail.

You can test this by checking the eccentric end play. No play at all will indicate bad bearings, as well as excessive play (some engines with thrust bearings will have more then 1/4"!)