xTBIRDx

Hello, I am a new subcriber here and i have a "86" RX-7 and in the last few months i have noticed a stange vibration whenever i get on the throttle! The vibration seems to demenish when i let off the throttle, but the second i step on the throttle the vibration is just about unbarible, shakes so bad it makes my cd player skip. I know the tires are balenced, not sure if it's dew to engine mounts being bad or something wrong with the tranny? Manuel tranny, this is a plain RX-7 no turbo. any sugistions would be greatly appreciated!

silverFC

maybe driveshaft u-joints

xTBIRDx

I was told this RX-7 had no u-joints it has short shafts right and left, not sure how true that is since i am uncapable of getting under it and checking for my self, I have now jack or i don't know some one who has a garage i could use! I was told by a mechanic who test drove the thing that it seemed like the engine mounts might be bad, but i just wanted to see if anyone here has ever exsperianced the same thing i have! Thanks for the input and info! More is greatly appreciated!

Joonas

It does have U joints just there not replaceable. umm It would probably be motor mounts if there good try the diff mounts. I doubt it would be a tranny mount cuz mine was gone I I couldnt notice a vibration. But I would say motor mounts

Bigretardhead

yes, it has a U-joint in the drive shaft. could possibly be out of balance drive shaft also? hehe, I was going to say tire balance. motor mounts would also mae sense. try rocking the engine from side to side. if it moves a lot, motor mounts might be bad. anyone have better ways to check motor mounts?

oh yeah, could also be your wheel bearings(most likely front). if one is loose, it could rock from side to side while moving, creating massive vibration. my dad's Z had vibration. we re packed the wheel bearings, and no more vibrations. but this was mostly at high speeds.

good luck

XXX

xTBIRDx

never thought about it being the barings, Hmmm? It does seem to have a heavier vibration after about 40mph. Don't really have the $$ to put it in the shop and have some one else fix it! The barings would be inexspencive enough for me to do for now to see if it is the barings! Thnx much!

Pyrocloud

Yes, I have the same problem.

It just started. I changed my tranny two weeks ago (used) and the bushing that fits on the Bottom tranny plate was missing. So I used a peice of rubber to fill the void.

After I let the car down, I noticd the vibration.
I removed the rubber piece the vibration stoped but the tranny rummbled from the post of the tranny hitting on the bracket. I put the rubber piece back but didn't tighten it down all the way. The tranny stoped shaking but the vibration is back.

I plan on putting the rubber peice above the plate below the tranny. To see if that helps.

U-joints may also be going bad. Yes they are replacable, most aftermarket U-joints come with grease ports, as the OEM u-joints don't have grease ports.

xTBIRDx does it make the noise when the car is in neutral, clutch down. Rev the engine in nuetral, does it still amke the noise? If the drive shaft is not moving it can't be the U-joints.

When in neutral my car makes this vibration. So the drive shaft is not in motion when the vibration occurs. But the question remains. What's making that damd sound.

SureShot

One possibility:
Got high miles on the clutch?
It could be shedding bits & running out of balance.

T2R7

i have the same prob. i replaced my tranny and as soon as i drove it again i noticed the very bad vibration. i thought it might be the wheels, so i changed them and i didnt help. then i decided that it might be the brake rotors... i have yet to change them:-) Then my buddy suggested that it might be my motor mounts. But all along i though it was my u-joints. Untill i read this it never occured to me that since it doesnt vibrate during idle... it cant be my motor mounts, and it has to be a "while driving" vibration. lol. anyways anyother sugestion would be helpful. (are the u-joints changable, because you can by new joints for like $20 apiece, but mazda told me they could only sell me the whole shaft w/joints for like $600+, so clearification would be nice) thanks all, josh

Relisys190

iTrader: (4)

the stock drive shaft does NOT have removable u-joints. trust me i found out the hard way when i went to go replace non replaceable u-joints.

you can get an aftermarket driveshaft from mazdatrix... and alot of other company's. the aftermarket unit's come with replaceable joints, so down the road just replace them if need be.

I would check all your mounts first.. because just checking them is free.. rock everything back and fourth.. put a PRY bar near the diff and move it, see how far it moves. than rock the engine like someone said earlier, it should be pretty solidly bolted in. When i shatterd my clutch it vibrated pretty bad. how's your shifting? going into gear fine?
more than likely it's your driveshaft. sorry about the news, but it's gunna be couple $$$ to fix

let us know
=Markus

T2R7

ya i know its not the clutch cause i just put in a CF dual friction plate and disc. + the problem just started after i replaced the tranny so it must be in the drive system somewhere. who else makes aftermarket drive shafts, and what are some average going prices. thanks josh