Rx-7Doctor

iTrader: (13)

I forgot to ask if you had recently done anything to the car?

riceyepie

Well, we can eliminate tires as the problem. A set of new Faulkens no help. I needed new tires anyway.

I'll look drive shaft / u-joints next. I don't know..my instincts say exhaust.

rx7-doctor, the car is bone stock except for a drop-in K&N air filter and the BD headlight harness.

Rx-7Doctor

iTrader: (13)

If the steering wheel is shaking back and forth then I would do a full inspection of the front end including the wheel bearing play.

Also inspect those bolts that secure the driveshaft to the diff flange.

Box_Man

My car does the same thing, it's definitely in the drive train somewhere. The driveshaft is a new Mazdatrix unit, and it still does it on all three of my sets of wheels and tires. I do have a bad bearing in the rear end, the outer right side bearing, but I think the vibration is somewhere in the transmission. BTW, it does it at 40-45mph constantly, and intermittently at other speeds, especially decelerating.

wanklenoob

I have a similar problem, when I hit 60 MPH car shakes violently. I hit 85 the other day, trying to outrun another car, and the whole car felt like it was going to rip apart, looked in rear-view mirror and the highway behind me was a blur of shakiness....haha it got me to slow down for once! even at 60 it's rather annoying, and I took out of gear and still felt the vibration. I would get new tires, alignment Balancing, the whole bit...but in about a week my little 7 is going to her winter home in the garage, so I suppose I might as well wait until spring. Probably be easier on the wallet anyway. I hope that'll fix her, if not then I suppose a new Driveshaft with bushings and U-joints is in order. (never actually replaced one of those before lol) I'm correct in thinking I just make the back wheels easily turnable, and drop the exhaust from the cat, and proceed to pull the old one out stick new one in, while making sure everything is lined up properly? Pretty straight froward right? any way, guess I'll keep riding the rough for the next week or so, she's fine at lower speeds 55 and below, so she's not bad through town. Just no Highway racing for me eh?

wanklenoob

*bump*

I said..."eh?"

85 FB

I'm guessing that it could be possible U-joints. I had that problem on my old pickup. Only at a certain speed would it vibrate; around 40mph. Replaced the u-joints and the problem went away. I also had that kind of problem with my FB at higher speeds, turned out the tires needed rebalancing.

Check your driveline first, along with suspension.

Box_Man

I'm pretty sure my problem is internal, in the transmission, because my wheels and tires are balanced, and the driveshaft is brand new (I looked for any new wear, there is no play in the u-joints)

85 FB

I've just never heard of a transmission giving that kind of problem before. You'd grind gears from a bad synchro link but not a vibration like what you're describing.

riceyepie

Just to follow up. I just installed a new clutch and new drive shaft (mazdatrix after market) no help..

Vashner

Take the car to a tire shop and get rebalance and or rotation.

There also is a way to test the transmission mounts. I read about it the other day.

Sometimes tires also get bulges and or have internal defects in construction.

Directfreak

iTrader: (2)

If it's not the U-joints (my first guess), and not the tires, - Then you probably have a bent rim.

djessence

^I had a bent rim from the PO. A rear one, i think he curbed it trying to drift. Definite vibration at certain speed but usually got worse at higher speeds.

That being said i could visibly see the rim was fucked

defiant13

iTrader: (-1)

Mine was doing that. I had a bad idler arm, which I replaced the bushings in it.

Vashner

Yea time to get that puppy up on a lift and let someone find the problem for you. Don't throw money into it till you figure out wtproblem is.

fbatman

also- sounds dumb- but i had exactly what you are describing in my old FC - and it turned out i had WATER IN THE TIRE again may not be your problem but couldnt hurt to check it out....i replaced u joints, shocks, a driveshaft.....etc lo and behold when i thought it was the tire i went up to a buddies place we pulled it off... and there was no joke like 2 inches of water in the tire- so after that came out everything was fine- but THAT was the cause of my problem.......just an idea.

good luck with it
zach

F-MECH-PHIL

I also say its the driveshaft Ujoints

twinkletoes

iTrader: (17)

I'm going with alignment, tire balance and possibly bent rim. I need new alignment and I have a bent rear wheel that I'm swapping out for a new one. I can feel the wobble when slowing down in the rear, so I know the new wheel is going to help a lot with that and at top speed. Alignment will/should help greatly too. If not these then I'm going with what everybody else said. Good luck with it, and I know i have the shake too from 65 to 130.

Can the u-joints really make the whole car SHAKE?

RX-7 Chris

iTrader: (19)

Yes it can and it gets worse as you go faster.

What about wheel barrings.

djessence

Yes u-joint cause the whole car to shake rumble. Its actually quite concerning the first time your u-joints start to go and you dont know what it is

twinkletoes

iTrader: (17)

I'll have to check them then. How do you know if they're bad?? Can't search busy all day.

Maniacmikey

You will be able to grab the shaft and give it a good shake. should not be able to move it.try both ends.

djessence

I dont know how to check them but i do believe they are not actually replaceable cuz they are pressed in.







Maybe I'm missing something but how does a water pump cause a vibrating car......?

riceyepie

Original poster

Replacing the tires is the first thing I did..no help. And again, new clutch and drive shaft were no help.

The vibration is almost exactly at 60mph. It is not affect by what gear I'm in or RPM.

It's a heavy rumbling type vib, present both on accell or decell but worse on decell. The steering wheel is steady, but I do have a significant pull to the right. Perhaps it is a bent rim.

RX-7 Chris

iTrader: (19)

It is a bent rim or the rear end.