C4 Body Rigidity
Thread Starter
Instructor
Joined: Oct 2006
Posts: 246
Likes: 1
From: Elk Plain WA
St. Jude Donor '11
C4 Body Rigidity
I had noticed a lot of body shake in my 86 C4 coupe. Even had the tires rebalanced because I felt a heavy shaking of the body at around 50 mph. Shake appeared to be induced by minor road irregularities or the drive train.
Over the weekend I was out for some open top cruising and I noticed the shake again. Thought to myself "what is different today" ?
Hummm.....top is off!
Bolted the glass top back in and went out driving again. Shake disappeared!
Have others noticed how much flexing the body shows without the glass?
Over the weekend I was out for some open top cruising and I noticed the shake again. Thought to myself "what is different today" ?
Hummm.....top is off!
Bolted the glass top back in and went out driving again. Shake disappeared!
Have others noticed how much flexing the body shows without the glass?
Last edited by tdf; Jul 6, 2009 at 10:33 AM. Reason: clarity
Thread Starter
Instructor
Joined: Oct 2006
Posts: 246
Likes: 1
From: Elk Plain WA
St. Jude Donor '11
Makes Sense - Now That I Know
I don't know why it took me 2 years to figure this out....LOL
Guess because it's only Summer Days that the top comes off.
Nice job building the brace bar setup or is that an after market item? I may have to steal that design!
Guess because it's only Summer Days that the top comes off.
Nice job building the brace bar setup or is that an after market item? I may have to steal that design!
Burning Brakes
Joined: May 2008
Posts: 1,057
Likes: 2
From: Ohio
The targa top brace is an aftermarket item. I've seen a couple of manufacturers. There is also an aftermarket X brace for the bottom of the car. It's similar to the brace the verts got. I would consider that, because it would be one less thing to carry around.
Thread Starter
Instructor
Joined: Oct 2006
Posts: 246
Likes: 1
From: Elk Plain WA
St. Jude Donor '11
Top Removal
The top is easy enough to remove replace. However, I really don't like the shake, rattle and roll ride without the top. Will be looking to buy or build something to stiffen the body.
My C4 has become my DD. I like the open top in Summer. We don't suffer many extremely hot days here in WA, so the open top is nice. I leave it off for days at a time.
My C4 has become my DD. I like the open top in Summer. We don't suffer many extremely hot days here in WA, so the open top is nice. I leave it off for days at a time.
Last edited by tdf; Jul 6, 2009 at 11:25 AM. Reason: add
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Instructor
Joined: May 2009
Posts: 135
Likes: 0
I noticed what I thought was a vibration on my 85 and after all the conventional fixes, wheels, tires, brakes, shocks, etc, I realized it was not a vibration but harmonic wind buffeting when Targa was off. It goes away if you crack the back hatch with the aftermarket spacer. Also sucks your hat off.
Safety Car
Joined: May 2007
Posts: 3,651
Likes: 10
From: Apple Valley MN
That is an AFSB Targa Bar, from ProStreet Customs (I bought it used on the forum). R-D Racing makes a similar brace, but it is made of rectangular tubing. I like it a lot, makes the car as solid if not more so than with the fiberglass top in.
Le Mans Master
Joined: Jul 2007
Posts: 5,356
Likes: 2
From: No HOA, New Hampshire
Cruise-In X Veteran
St. Jude Donor '09
I learned my lesson the hard way. I installed the acrylic top on my 88 while in a dirt road school bus turn-a-round. I parked on my level driveway later and the next day the top was split right down the middle.
I guess they do flex a bit.
I guess they do flex a bit.
Burning Brakes
Joined: May 2008
Posts: 1,057
Likes: 2
From: Ohio
CF JASOC Member
Joined: Feb 2006
Posts: 8,040
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From: Downtown Annapolis, MD. The Future is where we all have to live. Let's not screw it up.
St. Jude Donor '08-'09-'10-'11
Never had this problem with my '88 Z52, but I drove my neighbor's '86 coupe with the targa off and I noticed the shake/flex almost right away.
Le Mans Master
Joined: Dec 2004
Posts: 5,230
Likes: 418
The C4 was originally designed as a t-top much like the C3. Late in the program Lloyd Reuss dictated that the designers replace the t-top with a targa design. The t-top design didn't have the rattles or body flex, but the targa design did. Engineering did what they could to make the car better from an NVH perspective, but it was late in the program. The convertible was always considered marginable when intruduced. And, obviously a targa car without the roof panel will flex just like a convertible.
Burning Brakes
Joined: May 2008
Posts: 1,057
Likes: 2
From: Ohio
I've owned a Camaro with T-tops. It feels just as open as the targa, without the flex. I WISH my C4 had T-tops versus the targa. (Also, T-tops are easier to remove and replace.)
Race Director
Joined: Dec 2003
Posts: 14,134
Likes: 935
From: Fremont Ca
2022 C4 of the Year Finalist - Modified
These cars are about as ridged as a wet piece of toast with the top removed.I had an 84 for 20 years and cant remember it being as sloppy as my ZR-1 with the top removed.With the top removed the turn signal lever looks like it could break off it flops around that much.