driveshaft or tires out of balance
 

I have a 1986 rx-7 that I recently bought. the car has set in one spot for a while which is not good for the tires. The car drives smoothly around my town but when I get on the freeway and get into speeds above 50 the car starts to vibrate. Normally this means my tires need to be ballanced which would make since, since the car has set for so long. I also read that the U-joints on the drive train tend to go out which would also make my car vibrate. Is there a way I can tell if it is the Tires or the drive train?

Are you any relation to Chuck?

anywho, the best thing to do is start with the small things first. take it and get a set of tires on it or get the old ones reblanced. Driveshafts will also cause that, but the stock driveshaft doesnt usually have many problems.. I am not 100% sure on this but i do believe that you cannot change the u joints on the stock driveshaft.

Also, since you just bought the car, I would recommend reading the FAQ and changing all the fluids and belts on your car..

hope this helps

--james

Rebalance:
When I first got my RX7 last summer, it had a noticable vibration in the steering wheel, but only on the highway. My first course of action was to get my wheels rebalanced ($). The garage said that the original balance was perfect but he noticed one rim was bent. We rotated the tires so the bent rim was on the rear rather than the front. This helped alittle.

Hubcentrics:
I'm running aftermarket rims which didn't fit the wheel hub perfectly. This causes the rims to be mounted off center to the hub and can also cause vibrations. So, I got hubcentrics ($) to fit the rims to the hub properly so now the rims are properly centered. This helped alittle too.

Replace Bent Rim:
Next, I eventually replaced the bent rim with a new one ($$$)which also helped alittle more. Another option is to just get the bent rim repaired ($$).

Driveshaft:
I still have a little vibration. My car is in storage now, but in the spring I want to assess the U-joints to see if they need replacing. If it is the stock driveshaft, the u-joints are not replaceable so the whole shaft has to be replaced.

+1!

also, proper tire air pressure too. i suggest between 32-35 PSI. I work at Discount Tires and we do this everyday. everytime there's someone pulls in asking for a rebalance and rotation coz theiy're getting vibes, when we check their tire air pressure, it's around 20-25 PSI.

I have had the drive shaft go bad on my car. The u joints are non replaceable. Get underneath the car and grab the drive shaft. Try and turn the shaft, if it has a lot of play than its probably bad. If so get an after market shaft that has replacable u joints. My car also had crappy tires that had flat spots. A new set of meats cured that too.