Ok i'm getting a shaking in my car at around 60 mph to 65 mph, then it stops. It doesnt do it before those speeds or after. I have replaced the motor mounts, the tranny mounts are fine, all tires are balanced, and I also have a new driveshaft. Any ideas what could be causing this?

 

Where do you feel the shaking? In the steering wheel or is it just a vibration in the seat of the pants?

 

Seat of the pants man, feels like the freaken car is shaking. It's not really violent, but definitely noticeable, even for the passenger.

 

maybe the wheel bearings...at that speed its probably the natural fequency of the bearings

 

Ok well i'll take a look at them. What's the easiest way to tell if they are bad? The car doesnt squeek or anything and when I just rotate the wheel when it's in the air it's fine.

 

Rx-7's have really stiff suspension dude. If the pavement isn't pretty smooth you're gonna feel jarred.

 

I agree with Torean....although I'd check shocks for any case.

....it might a be time to change them....

 

The shocks are fairly new. All I know is that there tokico and they're gas. I know the shocks are ok. This shaking sensation comes around even on smooth roads, like when I'm accelerating onto a highway or even cruising down a smooth newely paved road.

 

Check the tires, particularly the rears, for flat spots or other irregularities. Find a shop that has a Hunter GSP9700 balancer (go here to find a shop: http://www.gsp9700.com) and have them check all the wheels. Ya gotta completely rule out the wheels before looking into something more serious and this machine will check for tire as well as wheel problems.

 

Something odd I've noticed is that this tends to happen moreso when it's warmer. Today when I was driving to church (it was 40 out) the car didnt do it once. Remained smooth the entire time.

 

Simple questions now.

Was the engine ported (like street ported...that kind of thing)?

If not, when engine is warm how high your RPMs are?

When did you do the tune-up?


Now the reason I'm asking you this is because the first thing that came to my mind once you mentioned, "...this tends to happen moreso when it's warmer. ", is your timing.

Check your timing...

In general any car runs smoother on colder weather, once it's warmed up.

 

Ok it's definitely not a timing problem. I adjusted the timing a few months ago to avoid detonation with the winter fuel. As far as the motor is concerned, it's got about 5k on a rebuild. No porting. The RPM's dont seem to effect the shaking at all. I can push the clutch in and have the tach drop to idle and I still get the vibration. It seems to mainly be due to speed. Thanks for the help though.

 

did it act like that before you did the rebuilt?



no problem.....sorry to hear that though.

 

i know its not the wheel bearing ... i just replaced mine and at higher speeds it still feels like my car is loose or shaky ... its a possability of tie rod ends of ball joints .. he said its under acceleration either that or it could be oil pressure .. or just not enough power .. its thrange that it only happins at 65 thoe .. thats doesnt make any sense the only that that would cause such a vibration would be mechanical and not be intermittent as he is describing

 

The more I think about it the more I think it would be a bushing or something that can expand and contrast with the change in tempreture. I just recently rotated my tires and that didnt seem to help the problem. It still feels like it might be coming from the rear

 

Have your tires been rotated / balanced lately?

iSP33D-for-J3SUS

 

Could be from the drivetrain, check the diff and tranny. Your yokes might be going out.

 

Ding Ding Ding

Same problem with my first gen, turned out to be the driveshaft was completley fubared...

 

I recently replaced the driveshaft, but I will check the yokes as I'm certain there is some play in them.

 

With one from Mazdatrix? Our stock drive shafts have non replacable ujoints...which is why when I go to get my new drive shaft I have a buddy down south who's going to custom make a carbon fiber driveshaft for me for free.