Poor handling with top
Thread Starter
Intermediate
Joined: Aug 2012
Posts: 30
Likes: 0
Poor handling with top
I have a 93 Vette with a targa top. When I remove the top I get poor handling and the shakes. I have read several threads concerning this problem but most of them are live with it. Anything new on this topic.
Thanks
Jim
Thanks
Jim
Team Owner
Joined: Oct 2004
Posts: 81,241
Likes: 3,062
From: altered state
St. Jude Donor '05
If there was a way to tie the front firewall area in to the front frame rail somehow like some race cars do I bet that would cure it for the cost of metal some welding and probably do a lot better job. Or a bolt in deal?
Burning Brakes
Joined: Apr 2011
Posts: 917
Likes: 25
From: College Station Tx
You know, you can buy a broken/cracked top, remove the glass and use it as a targa top brace. It might look kind of odd, but it would be a whole lot cheaper than buying the one from CC.
Pro
Joined: Mar 2005
Posts: 666
Likes: 0
From: Walton KY
I get the shakes when I let my car sit a long time. Generally once I get tires warm, most of the shimmyshakewigglerattle goes away. I have a targa frame with no panel in it I use sometimes. It looks stupid but works.
Racer
Joined: May 2013
Posts: 297
Likes: 0
From: Stowe VT
Something else is not right, its plexi glass, i find it hard to believe, that a 1/4 piece of plexi glass, like on my 86 can make a 3200plus lb car stiffer and handle better. Under twisting load, i would think the roof would twist also, so in or out would be the same. I dont mean to step on anyones toes, its just me personally would find it odd.
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Racer
Joined: May 2013
Posts: 297
Likes: 0
From: Stowe VT
Are the convertibles stiffened from underneath? All im saying is i think GM would have spent the 45 extra bucks to stiffen the targa top cars a little more from underneath. Id be very interested,to see if there is a way to mesure the targa opening before and after jacking it up, to see if the car deforms or not. My see thru blue targa has all spyder cracks in it from me lifting up on it ,when the PO glued the weather stripping in and put the top on while wet, so in essance i flexed the plexi enough to spyder crack it, thats why i say i think the tube steel frame it sits in isnt all that strong and doesnt provide the strengh ,you think it would, or maybe im just that strong,lol.
Pro
Joined: Nov 2011
Posts: 542
Likes: 2
From: Miami FL
I would say the spider cracks are from sun baking. When the plexiglass cracks from stress, it is a visible crack most of the time.
I have a canvas top that I do not use due to the shaking, but I would like to make a modified version of the canvas top (rain coat) to fit over the targa truss.
I have a canvas top that I do not use due to the shaking, but I would like to make a modified version of the canvas top (rain coat) to fit over the targa truss.
Last edited by speedycat3; Jul 26, 2013 at 12:00 AM.
Burning Brakes
Joined: May 2010
Posts: 941
Likes: 10
Its strange, but some cars dont have this problem. I had a 87 that was rock solid with the top off. I now have a 95 that is a train wreck with the top off. I hate to run in the summer with the top on......but
8Valve
8Valve
Le Mans Master
Joined: Mar 2010
Posts: 8,170
Likes: 17
From: Eugene Oregon
I believe in the Beer Fairy
St. Jude Donor '15,'19
My 93 is the same way, I will get around to building my own tubular brace for the top this winter. I have the loose steering wheel and door window adjustments to do first. 
Safety Car
Joined: Sep 2010
Posts: 3,752
Likes: 190
From: Indiana PA
First off, many of the structural reinforcements in convertibles are in the coupes as well. The later coupes got the stiffer K-frame bits for example. No X-brace however. They don't do much for you in the coupe.
Second, its a C4, they flex, if you don't like it, buy a C5 or later. The plexiglass does not give it any stiffness its the aluminum frame the plexiglass is attached to. The plexiglass flexes with the rest of the frame as it twist some taking the chassis loads. Hence, the cracks, etc...
Third, the flex is only a subjective thing, yes they creak, groan, and pop more with it out and you get cowl shake. That being said, they DO NOT handle worse or better with the top in or out. The chassis flex is so that it does not matter. Tests have been done comparing lap times with top in and with it out. The difference is negligible.
Finally, the braces that install with the top out work just fine to bring it back to top on stiffness, which is already lacking anyhow.
Second, its a C4, they flex, if you don't like it, buy a C5 or later. The plexiglass does not give it any stiffness its the aluminum frame the plexiglass is attached to. The plexiglass flexes with the rest of the frame as it twist some taking the chassis loads. Hence, the cracks, etc...
Third, the flex is only a subjective thing, yes they creak, groan, and pop more with it out and you get cowl shake. That being said, they DO NOT handle worse or better with the top in or out. The chassis flex is so that it does not matter. Tests have been done comparing lap times with top in and with it out. The difference is negligible.
Finally, the braces that install with the top out work just fine to bring it back to top on stiffness, which is already lacking anyhow.