I am having a strange issue I thought I would share. When I rev up to and over 5000 rpm my ’82 shakes or vibrates at a high frequency, not with great amplitude or violently but enough to make we wonder if I should be running that high.

Any ideas?
Thanks

 

the vibration that ur taliking about is that an engine vibration, or a chasis/steering vibration....

 

I'm assuming your just in neutral with the car sitting still. I would check to make sure the your getting consistent spark at those rpms by using a timing light. It could be its a miss on one of the rotors as the rpms go up. That could be number of issues, cap, rotor, ignitor, wires etc.

 

it is at speed but I will try reving in neutral, I will check out the ignition as well

 

If its at speed I would check the u joints on the drive shaft then.

 

If it does it at idle too, then start looking at your exhaust system. Make sure that it is not in direct contact with any part of the chassis. The system should be isolated using rubber donuts and such. If it is pressed up against any part of the chassis, then you will feel bad vibrations.

 

Do you feel the shake in your hands on the steering wheel or through your butt, this indicates front or rear problem.

Sort of sounds like an out of balance tire though. Does it go away as you get faster?

 

I had a similar vibration on my project '85 recently, though in my case it was intermittent with speed and unrelated to rpm as far as I could tell. Former hack job on one of the front struts and fossilized connections between the Chassis and suspension. One thing I've noticed my rex does that I probably wouldn't notice if I hadn't pulled out all the interior carpets is that she hums like a tuning fork if she's been driven at speed for any time. The longer and faster, the higher she sings. Something about that rotary engine puts a lot of vibration into the car. In some cases I'll bet that means if some little thing ain't right, even the small wave patterns in the road, the rex can start resonating all wrong. Just a theory. Maybe check engine mounts, struts and axles.

 

id say bad u joints in driveshaft!!!

 

Change the Transmission mount, it's collapsed. It may looked OK. IT's only about $50.00 and 15 min. labor

 

any one of the above suggestions could be valid as the car is 20 somehting years old, and any of the above suggestions could be correct (or many of them )

FWIW 5000 rpm is just a drop in the bucket, 7500 on a stock motor is very do-able, and on a race prepped 13b bridge I built a few years ago, we often turned over 10,000 rpm (clutch eventually exploded though)

kenn