shaking when Topless

[32valvesftw]

This is a puzzler for me. We just got back from taking the Vette for a drive in the country. Along the way we stopped to remove the Targa top. It was then stored in its place. When I went to pull back not he road, the car was shaking badly, noticeable through the wheel. The shaking was pretty bad so much so that I did go over 50, cause I thought I had a wheel falling off. I did stop and check every lug nut was tight. I did visual of the drive shafts as best I could. I had the wife put the car in gear with he hood up, the engine did not jump, so no broken motor mounts. Then we proceeded on our trip and shaking resumed, I drove slowly for about 10 more miles. Then I stopped to put the roof panel back on, so I could hear better in the car. With the roof in place and bolted in, no more shake???WTH I am puzzled, How could the roof panel have that much to do with it?

[secondchance]

Has the car been sitting for awhile? Temperature today? You may have flat spots on your tires. Taking the roof off may be just amplifying the vibration from flat spots.

[32valvesftw]

I had been driving for quite a while so the flat spots were definitely not an issue. I get those and know what they are. I did some research and it appears C4s do loose some rigidity with the top off. I never had an issue in the past but perhaps the newly added HP and perhaps a tire issue made it more noticeable??? I have not checked up on tire balance but I just had them balanced less than 2000 miles ago.

[gbrtng]

Corey broke it for you - or maybe it was W. .... - oh, never mind ...

TGF

[Gunny]

no answer for why it's suddenly worse than before but my 90 has always been "looser" with the top out. Several years ago I bought a cross bar that allowed a video camera to be mounted, 5 point seat belts, and maybe something else. The big surprise was how it stiffened the body up so much that I no longer had the "looseness" and shake when I took the top off. That "feature" has been much more valuable than the camera & seat belt mounts. Couldn't find a photo of my install but did locate one when I googled it. The cross bar uses the existing holes/bolts from the seat belts and the clips that hold the top inside (the photo I found didn't retain the top clips but you don't have to lose that functionality). This is not a roll bar but I expect a properly installed roll bar would have the same effect. I'm not sure whether this cross bar is still available. Maybe someone else will chime in.

http://www.corvetteforum.com/forums/attachments/c4-tech-performance/47595671d1153394503-halo-brace-dsc02234.jpg

[Gunny]

found another photo

http://www.fastcoolcars.com/images/1994-corvette-6spd/crossbar2.jpg

[Kevin]

sounds about right. I can't drive the car with the top off. feels like its going to fall apart. I can tell a difference in the glass vs painted top

[Vette73]

This may help,maybe...Try the rear glass vent hook....It raise the rear glass at lest two inches which makes the incoming air escape faster....I used mine all through the spring and summer months....Also on the highwzy you will notice less wind noise because the air has an escape route...It costs around thirty bucks and I like it..

Forget where I got it from....I know I did not order it from Eklers or Mid-America because I heard some complaints about there design ...

Google it you should find it...Like I sId it's just a suggestion..
They install very easily...

[G8nightman]

In my None z C4 with the top off over 130 mph the rear would lift off the ground.

[Hib Halverson]

This is a puzzler for me. We just got back from taking the Vette for a drive in the country. Along the way we stopped to remove the Targa top. It was then stored in its place. When I went to pull back not he road, the car was shaking badly, noticeable through the wheel. The shaking was pretty bad so much so that I did go over 50, cause I thought I had a wheel falling off. I did stop and check every lug nut was tight. I did visual of the drive shafts as best I could. I had the wife put the car in gear with he hood up, the engine did not jump, so no broken motor mounts. Then we proceeded on our trip and shaking resumed, I drove slowly for about 10 more miles. Then I stopped to put the roof panel back on, so I could hear better in the car. With the roof in place and bolted in, no more shake???WTH I am puzzled, How could the roof panel have that much to do with it?

Significant steering column and windshield shake is typical of any C4 with the roof of. Unfortunately the C4 has pretty weak structure and when you have the roof of it's even worse.

[Billy Mild]

I have noticed this as well. I have heard the Vette2Vette solution really helps the chassis flex quite a bit. I have still wanted to run either that or X Brace from GM.

[Hib Halverson]

The C4 convertible "braces" on a coupe don't do much in a practical sense to improve the C4 structure, however, the improvement might be noticeable as a slight decrease in steering column shake.

They do increase weight and decrease ground clearance but, heck, they are easy to install.

I've never tested the product, but the "Vette2Vette" chassis reinforcement, looks like a better choice than the OE convertible braces.

[-=Jeff=-]

I have noticed this as well. I have heard the Vette2Vette solution really helps the chassis flex quite a bit. I have still wanted to run either that or X Brace from GM.

The C4 convertible "braces" on a coupe don't do much in a practical sense to improve the C4 structure, however, the improvement might be noticeable as a slight decrease in steering column shake.

They do increase weight and decrease ground clearance but, heck, they are easy to install.

I've never tested the product, but the "Vette2Vette" chassis reinforcement, looks like a better choice than the OE convertible braces.


From my personal experience the Vette2vette chassis brace works as advertised.

I have the prototypes on my car and very happy with them and I know they have made some improvements since they installed mine

[Kevin]

From my personal experience the Vette2vette chassis brace works as advertised.

I have the prototypes on my car and very happy with them and I know they have made some improvements since they installed mine

I still need to install mine....they've been sititng in the garage for a year

[BigJohn]

My roll bars work quite well, but makes the rear view mirror useless.

[Z51JEFF]

Welcome to C4 ownership. The car with the top off is about as ridged as a wet piece of toast. My car tries to shake the turn signal stalk off with the top off but I still take it off at times. I have a set of Bill Bs beam plates just need to get them on the car.

[Fully Vetted]

While it's completely normal it tends to be worse in some cars. I have the V2V No Flex Frame Stiffeners (basically a long subframe connector with heim joints on both ends) and I still notice some cowl shake but it did improve quit a bit. I also have beam plates. Again, it still shakes but not nearly as bad. I would definitely be interested in the cross bar if anyone knows where to get them.

[Mystic ZR-1]

My roll bars work quite well, but makes the rear view mirror useless.

you've been upside down in the LM?

[Livin' in the 80's]

I took the top off for the first time yesterday and experienced this shake. I took me a little bit of time to get used to it. It certainly scared me at first. The steering wheel and dash shook on all minor and major bumps. Has anyone made a X designed metal brace that fits in place of the targa top? Would this work?

[Z51JEFF]

I took the top off for the first time yesterday and experienced this shake. I took me a little bit of time to get used to it. It certainly scared me at first. The steering wheel and dash shook on all minor and major bumps. Has anyone made a X designed metal brace that fits in place of the targa top? Would this work?

Welcome to the wonderful world of C4 ownership. The things about as ridged as a wet piece of toast with the top off. The targa truss bar will tighten things up a bit but just can't get past the looks of the thing,I can deal with the shake.

[rush91]

I have minimal shake with the targa panel out..... The steering wheel has a bit more shake in it, but nothing to where I was like OMG what broke.

Sent from my XT1585 using ZR-1 Net Registry mobile app (http://r.tapatalk.com/byo?rid=90383)