Mine happens at around 1100-1400 RPM's and also increasing gets worse if I go 90 or faster. I've been trying to locate this sucker for a good year or two and can't find the problem. Neither can dealerships. Its getting worse though. You won't notice it at first until the car has been driven for a good while and warmed up. Usually going about 70-80 for 20 min should do it and is very noticeable from then on.

I've got brand new wheels and pretty new rims, and they are all balanced. I've been getting this even before the wheels. New brake pads are on, too.

 

What you have in probably referred to as Cowl Shake. The C4 Conv. was notorious for it. There is nothing you can do. Its worse at some speeds than others. Its due to the lack of rigidity in the body of the Conv.'s. Coupe will tend to do it with the top's off. If you notice Chev. put an X frame under the conv.'s to try and help it, but no luck. Unless the car has been in an accident before and something in the chassis is still bent causing it to track wrong going down the road.

 

I don't believe this is the case. This started only 2 yrs ago and I've had it for 5. It pretty much started very small right after I threw on my Corsa's. I thought it was just the exhaust but its been getting gradually worse and within the past 6-12 months, its gotten really bad. I never had this problem with my stock exhaust; even when I hit my top speed of 136. I'm not sure if I ever attempted it with the corsa's on or not...

 

How old are the tires? Maybe a belt in a tire has come apart or something?

 

136 top speed :( what kind of vett is it :confused:

 

Maybe 2 months. The old tires I had for about 2-3 yrs. I went from no vibration before the exhaust all the way to a couple months ago when it was fairly bad. The tires are definitely not the problem.

 

See my sig

 

has the exhaust come loose at all or anything funny like that? keywords to me were that it all started when you put on the corsas.

 

That's what I thought too but I've checked it out and tightened up stuff. I've even brought it in to the dealerships about 7 times so far and they say its running like a champ. I don't buy it. :bs

During my installation, I ran into a snag. When I went to disconnect the exhaust from the driver side cat, all three bolts snapped off and I had to drill holes out holes. I then used longer bolts, washers, and self locking nuts (is that what they're called?). I even told the dealerships about this and they checked it out. They say its tight under there.

Could it be my cats or headers at all? I've never cleaned them out or replaced them. And I can feel the vibration in the seat, my shoes through the floor, and it even makes a small rattling of little stuff in the car. It feels like its on the drivers side but I can't tell for sure unless someone else took it for a drive and recreated the problem, which I've never done.

My engine sounds more "clicky" that other C4's. I've noticed on others, the engine sounds nice and smooth. Mine sounds like its coming from one of the cylinders. I don't know if this is related at all, but maybe its the cause of the problem. It may very well explain the previous power loss problems I've had in recent months but I haven't had that since my alternator was replaced.

LOL, that's a lot of guessing I'm doing but I'm throwing out everything I know in hope that you guys might get an idea from something I say. :smash:

 

Perhaps a misfire at certain RPMs?

Have you tried all the tricks to isolate the cause? You mentioned RPMs, but its still unclear whether you think its based on vehicle speed or engine speed?

Do both of these in gear and in neutral (and in gear with clutch disengaged if you have a stick):

1. Drive at same RPM in different gear.
2. Drive at same speed at different RPM.

 

Inspect your motor mounts closely. Also, Have you previously pulled the driveline out for repairs etc? Balance is crucial (sp). Just a couple of thoughts.

 

:withstupid:

 

I had the same thought but I know I've never touched them. I figured they would have rusted in place by now and wouldn't be coming loose.

 

Check out your driveshaft yoke, if it is off replace the driveshaft.Don't just replace the yoke it is impossible to balance to the old shaft.I had a vibration for 4yr this fixed it . Good luck. :chevy

 

Check out the July 2003 Corvete Fever issue. On page 92 Chris Petris goes into detail about a 92 roadster with a six-speed. He thinks it is a clutch/flywheel problem. I have set in on a couple of classes he taught at Bloomington Gold and he is very sharp. I think he owns the Corvette Clinic in Florida. You can also get answers from Gordon Killebrew (former Corvette factory troubleshooter) at 1-800-398-3883. He charges a fee for phone consults though. Sounds like a blitch, hope you can find the problem! :confused:

 

Check driveshaft.

 

Ok, I just took it for a test drive. It happens on all gears to some extent. I really notice it the most in reverse and 90+. The rest of the time, its usually around 1200 rpm.

 

Sorry did'ent want to offend I thought thay(vetts) are faster.I sold my 91dodge stealth rt/tt,no mods 14.0@98 and was 4000lb top out at 155 stable. The 92 300zx tt goes 13.7@102 was 3600lb top out at 153 bone stock,I belive the SUPRA and RX7 do better.I'm new to the vett info got tired of inports.I just thought it was faster even after all the mods.Sorry : :reddevil

 

From what I hear, they usually are. I hear I should be running mid 13's right now. I don't know what's going on with my car. I think I just need to learn how to launch better. :steering:

 

If you find out what the vibration is can you let me know maby it won't be to late to get mine.And when I learn more about's vett's hopefuly I can help someone.I do know a thing or two about RICE burners,and I love them cars to. :seeya