Shaking RX-7... can't figure out the problem! HELP!
 

I am having troubles with my 85 rx7 gs....
When I'm am accelerating my car shakes really bad. I've looked at the U joints and it it fine... I can't think of what it would be.

Can anyone help me trouble shoot this problem please!

When did you last have your wheels balanced? Can you feel it in the steering? When did you last replaced your wheel bearings?

Is it only when accelerating? Or cruising along at higher speeds? Lower speeds? Decelerating?

http://mazdatrix.com/g2.htm

Also verify that the bolts that secure the drive shaft to the differential are tight and there are none missing.

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First off thank you both for replying so quickly...

about the bolts. I checked them and they looked tight and were all there, but i will further test to see if they are tightened.

Also this car is an automatic. So I am not sure if that makes a difference.

It is only when it is accelerating... when i let off the gas it stops shaking... and even cruising at speed it shakes pretty bad. Decelerating seems like it is better.
and you cannot feel it in the steering wheel really... it's the whole car that shakes.

I bought it with 100k on it and have put 10k on it since... So the wheel bearings is unknown. And I haven't done anything really with wheels or bearings.

It leads to the U-joint, but those are fine...

Alright, I had a similar problem, have you checked your tires? Mine were very unevenly worn when I bought mine, causing horrible vibration at highway speeds, and when accelerating. Check the tire wear, and if they are uneven, invest in some new tires. Can you hear any bearing noise coming from the wheels?

has it done this ever since you bought it? Does is do it more at higher rpm's?

Then time to get her up in the air and inspect the whole steering and suspension components including the front wheel bearings.

Does it shake when the AT is in neutral and the engine is running? When you rev the engine?

Does it shake When you are stopped with the front bumper against a wood barrier and the parking brake is ON and the motor is running with the AT in Drive?

May be your tranny mount... I had a a similar problem replaced the drive shaft and all that good stuff... Once I replaced the tranny mount it fixed everything... mine would shake to 40mph go away and then come back at 60mph

oh and you cant just take a look at your tranny mount.. cause before I took mine out I looked at it and it looked fine.. but once I took it out, it seperated into two pieces.. Replaced it and its as smooth as silk

My AT 83 RX-7 vibrates in third. I can pop it into neutral for a second and sift back to drive and the vibration goes away. Don't know what causes it but I figure the trans has something failing in it. Possibly rear bearing in the trans. Mine hasn't gotten bad enough for me to swap in the 5 speed yet. Good luck.....

Transmission mounts is a good bet. IIRC, the side mounts go first and that leads to the rear mount failing.

Thanks to all...
 

I'll be doing some further investigation on all of your suggestions today....
I'll update tonight if I find out where the problem lies...

Thank you all again.

No it's just been doing this in the past few weeks.
And about the tranny mount, all I need to do it take em out and check so i'll go do that.

Thank you all.

get your driveshaft balanced at a local shop? my buddy had that problem, and balanced, it ran wonderfully.

Thanks!
 

I've decided to take it to the RX7 store in Columbus and have him look at it. I'm definitely not an expert on cars andd really just want this fixed. Thank you all for your help. I'll post what it was after friday!!!

Thanks!:)

Engine Mount
 

I took my rx7 too the rx7 store in columbus and and owner Jason believes I have a loose right engine mount that i am ordering today! So hopefully I'l have this fixed next week. Thanks for all your help and suggestions. I'll update again after i get everything fixed.

-Hanna