C4 frame flex [Forums - C4 Technical]

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flyboy	C4 frame flex	#1
Elite Guru Westmont, Il. 2632 Posts Member since: 2008/9/28 12:47	The April issue of "Vette" has an article on Corvette frames. Regarding the C4, it states that the new frame was welded together to form a single unit. When the 5th gen. was under development they studied the C4 to see what needed improvement because the frame would flex under spirited driving. The frame side rails are 3 pieces welded together and THE WELDS were where the flex occurred. That is something I didn't know, if it in fact is true. Attach file: P1010006.JPG (0.00 KB)
	Posted on: 2011/2/12 14:51

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pianoguy	Re: C4 frame flex	#2
Guru Emeritus Apple Valley, MN 14762 Posts Member since: 2007/12/29 0:00	I read that as well. I'm still thinking about those bars that were being sold last year (I already have a Cross-Frame).
	Posted on: 2011/2/12 15:42
	_________________ 1996 LT4 �Before you criticize someone, you should walk a mile in their shoes. That way when you criticize them, you are a mile away from them and you have their shoes.�- Jack Handey
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flyboy	Re: C4 frame flex	#3
Elite Guru Westmont, Il. 2632 Posts Member since: 2008/9/28 12:47	The C5/6 have the 1 Piece hydroformed frame rails. Haven't read much about those "tension rods" lately but this kind of makes a case for them. I don't think I'll be adding those along with my cross frame brace though.
	Posted on: 2011/2/12 16:22
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bogus	Re: C4 frame flex	#4
Grand Imperial Pooh-Bah San Pedro, CA 20859 Posts Member since: 2005/9/7 0:00	Anytime you weld metal, you weaken it as much as bond it. I stand by my prior theory on how to reinforce the C4 frame - fill the damned thing with autobody expandable foam. Make that thing dense as MDF. Dick Guldstrand did his GS90 custom C4 in 1990 and reinforced the frame. He removed the hatch floor and welded in reinforcment rods, then welded in a b-pillar roll cage reinforcment. It still doesn't solve the lack of a binding reinforcement from the a- to b-pillars. Which is why the entire thing shimmies! Dave McClellan wanted to have a t-bar. Marketing didn't. He protested, and asked for $1m to reengineer it, they threatened to have him fired. I hate old GM; more concerned with the marketing than a safe and stout vehicle. However, he had to scramble without the added cash. He then came up with the high sills. The problem? The firewall STILL cantelevers off the sills! ugh. That's where the tension rods and the xbrace come into play. By tying those points to gether, they simply can't flex. The other obvious solution is the targa truss. This is also why we shouldn't drive these cars with the roofs out for extended periods of time. The hood and firewall will feel the effects over time...
	Posted on: 2011/2/12 19:08
	_________________ The single biggest problem with communication is the illusion that it has taken place. - George Bernard Shaw Education is the best tool to overcome irrational fear. - me
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flyboy	Re: C4 frame flex	#5
Elite Guru Westmont, Il. 2632 Posts Member since: 2008/9/28 12:47	[quote] bogus wrote: Anytime you weld metal, you weaken it as much as bond it. I stand by my prior theory on how to reinforce the C4 frame - fill the damned thing with autobody expandable foam. Make that thing dense as MDF. I saw a discussion about drilling into the frame rails at the door sill and filling the cavity with the 16# version of this stuff. I may look into it someday. http://www.shopmaninc.com/foam.html
	Posted on: 2011/2/12 20:44

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-=Jeff=-	Re: C4 frame flex	#6
Master Guru Bartlett, IL 573 Posts Member since: 2007/12/20 0:00	Which Bar? These:
	Posted on: 2011/2/12 22:59
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flyboy	Re: C4 frame flex	#7
Elite Guru Westmont, Il. 2632 Posts Member since: 2008/9/28 12:47	Yes. http://www.corvette-guru.com/modules/ ... id=129762#forumpost129762
	Posted on: 2011/2/13 1:20

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pianoguy	Re: C4 frame flex	#8
Guru Emeritus Apple Valley, MN 14762 Posts Member since: 2007/12/29 0:00	I love my AFSB targa bar - wish I didn't need it, but even with the Cross-Frame the cowl shake is unnerving.
	Posted on: 2011/2/13 6:46
	_________________ 1996 LT4 �Before you criticize someone, you should walk a mile in their shoes. That way when you criticize them, you are a mile away from them and you have their shoes.�- Jack Handey
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flyboy	Re: C4 frame flex	#9
Elite Guru Westmont, Il. 2632 Posts Member since: 2008/9/28 12:47	Quote: pianoguy wrote: I love my AFSB targa bar - wish I didn't need it, but even with the Cross-Frame the cowl shake is unnerving. The camber brace really helped with the cowl shake topless or not. Yeah, the targa bar is a slick piece.
	Posted on: 2011/2/13 13:23

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corvetteronw	Re: C4 frame flex	#10
Senior Guru Lowell, MI 646 Posts Member since: 2007/2/19 0:00	If anyone wants to drive my 91 coupe to see how it feels with the Gordon Killebrew-designed bars I will be at Bloomington Gold in June and probably FunFest in September. I think they have made a greatly noticeable difference in how stiff the car feels. Just shoot me a PM and we can meet up.
	Posted on: 2011/2/15 4:53
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Steve40th	Re: C4 frame flex	#11
Elite Guru 1114 Posts Member since: 2005/12/20 0:00	I wont drive mine without my RD RACING targa truss. Even with the S/T Frame is still flexes.
	Posted on: 2011/2/15 22:50
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Steve40th	Re: C4 frame flex	#12
Elite Guru 1114 Posts Member since: 2005/12/20 0:00	Quote: bogus wrote: Anytime you weld metal, you weaken it as much as bond it. I stand by my prior theory on how to reinforce the C4 frame - fill the damned thing with autobody expandable foam. Make that thing dense as MDF. Dick Guldstrand did his GS90 custom C4 in 1990 and reinforced the frame. He removed the hatch floor and welded in reinforcment rods, then welded in a b-pillar roll cage reinforcment. It still doesn't solve the lack of a binding reinforcement from the a- to b-pillars. Which is why the entire thing shimmies! Dave McClellan wanted to have a t-bar. Marketing didn't. He protested, and asked for $1m to reengineer it, they threatened to have him fired. I hate old GM; more concerned with the marketing than a safe and stout vehicle. However, he had to scramble without the added cash. He then came up with the high sills. The problem? The firewall STILL cantelevers off the sills! ugh. That's where the tension rods and the xbrace come into play. By tying those points to gether, they simply can't flex. The other obvious solution is the targa truss. This is also why we shouldn't drive these cars with the roofs out for extended periods of time. The hood and firewall will feel the effects over time... So, does the X brace really make a difference?
	Posted on: 2011/2/15 22:52
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bogus	Re: C4 frame flex	#13
Grand Imperial Pooh-Bah San Pedro, CA 20859 Posts Member since: 2005/9/7 0:00	It makes a big difference! I drove a 92 vert (verts and Z07s came with) and it was almost as tight as my 92 coupe with the top in.
	Posted on: 2011/2/15 23:32
	_________________ The single biggest problem with communication is the illusion that it has taken place. - George Bernard Shaw Education is the best tool to overcome irrational fear. - me
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pianoguy	Re: C4 frame flex	#14
Guru Emeritus Apple Valley, MN 14762 Posts Member since: 2007/12/29 0:00	Quote: flyboy wrote: Quote: pianoguy wrote: I love my AFSB targa bar - wish I didn't need it, but even with the Cross-Frame the cowl shake is unnerving. The camber brace really helped with the cowl shake topless or not. Yeah, the targa bar is a slick piece. Agreed, I could notice the difference with or without the top after installing the Camber-Brace, particularly going around bumpy corners.
	Posted on: 2011/2/15 23:32
	_________________ 1996 LT4 �Before you criticize someone, you should walk a mile in their shoes. That way when you criticize them, you are a mile away from them and you have their shoes.�- Jack Handey
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pianoguy	Re: C4 frame flex	#15
Guru Emeritus Apple Valley, MN 14762 Posts Member since: 2007/12/29 0:00	Quote: corvetteronw wrote: If anyone wants to drive my 91 coupe to see how it feels with the Gordon Killebrew-designed bars I will be at Bloomington Gold in June and probably FunFest in September. I think they have made a greatly noticeable difference in how stiff the car feels. Just shoot me a PM and we can meet up. Do you know where these are being sold now?
	Posted on: 2011/2/15 23:43
	_________________ 1996 LT4 �Before you criticize someone, you should walk a mile in their shoes. That way when you criticize them, you are a mile away from them and you have their shoes.�- Jack Handey
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Steve40th	Re: C4 frame flex	#16
Elite Guru 1114 Posts Member since: 2005/12/20 0:00	Quote: bogus wrote: It makes a big difference! I drove a 92 vert (verts and Z07s came with) and it was almost as tight as my 92 coupe with the top in. RU Serious. I would have put one of these things on yeas ago by RD Racing, if I knew they would make a difference. My ST Frame is pretty tight though, but not with the roof out. Of course, I have 140Kmiles and a zo7 suspension installed.
	Posted on: 2011/2/15 23:54
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pianoguy	Re: C4 frame flex	#17
Guru Emeritus Apple Valley, MN 14762 Posts Member since: 2007/12/29 0:00	The Cross-Frame helped quite a bit on my car, but it still feels a little sloppy unless I have the targa bar in. And the Cross-Frame is fairly heavy, and kind of a PITA in that you have to remove it in order to do various repairs. If the tension bars were at least as good as the Cross-Frame, I'd think those would be the way to go.
	Posted on: 2011/2/16 0:05
	_________________ 1996 LT4 �Before you criticize someone, you should walk a mile in their shoes. That way when you criticize them, you are a mile away from them and you have their shoes.�- Jack Handey
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Ultraman	Re: C4 frame flex	#18
2015 Memorial Day Car Show Winner! Huskerland 14738 Posts Member since: 2009/9/12 19:16	Where do you go to see pics of the cross frame and the targa bar?
	Posted on: 2011/2/16 1:14
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bogus	Re: C4 frame flex	#19
Grand Imperial Pooh-Bah San Pedro, CA 20859 Posts Member since: 2005/9/7 0:00	Targa Truss: http://www.r-dracing.com/targa-truss.htm Cross Frame: http://www.r-dracing.com/CROSS-FRAME.htm
	Posted on: 2011/2/16 1:19
	_________________ The single biggest problem with communication is the illusion that it has taken place. - George Bernard Shaw Education is the best tool to overcome irrational fear. - me
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flyboy	Re: C4 frame flex	#20
Elite Guru Westmont, Il. 2632 Posts Member since: 2008/9/28 12:47	Weight=40#. Attach file: X brace.JPG (840.89 KB)
	Posted on: 2011/2/16 2:08

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pianoguy	Re: C4 frame flex	#21
Guru Emeritus Apple Valley, MN 14762 Posts Member since: 2007/12/29 0:00	The last few pics here are of the AFSB Targa Bar - there's a couple partials of the cross-frame, too: http://bradprestonmusic.com/Photos/Ve ... ect_Spring2008/index.html Here's the link for the AFSB bar (I bought mine used): http://www.prostreetcustoms.net/CorvettePage.html
	Posted on: 2011/2/16 2:18
	_________________ 1996 LT4 �Before you criticize someone, you should walk a mile in their shoes. That way when you criticize them, you are a mile away from them and you have their shoes.�- Jack Handey
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-=Jeff=-	Re: C4 frame flex	#22
Master Guru Bartlett, IL 573 Posts Member since: 2007/12/20 0:00	Quote: pianoguy wrote: Quote: corvetteronw wrote: If anyone wants to drive my 91 coupe to see how it feels with the Gordon Killebrew-designed bars I will be at Bloomington Gold in June and probably FunFest in September. I think they have made a greatly noticeable difference in how stiff the car feels. Just shoot me a PM and we can meet up. Do you know where these are being sold now? here is a link for contact info on the bars both Ron and I have http://vettextc.net/MY_ZR-1/Frame_Brace.html
	Posted on: 2011/2/16 15:33
	_________________ -=Jeff=- 1990 Corvette ZR-1 #1051
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flyboy	Re: C4 frame flex	#23
Elite Guru Westmont, Il. 2632 Posts Member since: 2008/9/28 12:47	Quote: -=Jeff=- wrote: here is a link for contact info on the bars both Ron and I have http://vettextc.net/MY_ZR-1/Frame_Brace.html Great job making your ZR-1 look like it does!
	Posted on: 2011/2/16 15:44

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ggrassmid	Re: C4 frame flex	#24
Guru Newb Edgewood, KY 18 Posts Member since: 2010/3/25 13:26	[Here's the link for the AFSB bar (I bought mine used): http://www.prostreetcustoms.net/CorvettePage.html[/quote] I LOVE my AFS Bar from Prostreet. The guy is top notch too!! Huge difference in how my car felt on the road and autocross, even someone driving my corvette for first time noticed the difference. This is my planned order for stiffening; 1. AFSB - completed 2. Camber brace - this used more to tie the front cambers together for racing 3. Stock 'Vert x-brace boxed 4. 4pt + 2pt welded roll bar I had an issue with mounting the AFSB and Tom helped me work through it, which also included shipping the bar back to him for some additional machining. He is top notch, if/when I buy another C4 Targa, I will purchase another bar for that car as long as he keeps making them. They definately look better than the R-D Racing one!!
	Posted on: 2011/2/16 15:57

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CentralCoaster	Re: C4 frame flex	#25
Senior Guru San Diego, CA 9454 Posts Member since: 2007/10/28 0:00	That's nice and all, but what's the point? I'm still waiting ot see the tangible benefit. It's just warm fuzzies, like with the camberbrace.
	Posted on: 2011/2/16 16:12
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flyboy	Re: C4 frame flex	#26
Elite Guru Westmont, Il. 2632 Posts Member since: 2008/9/28 12:47	I don't have a picture without the brace for comparison but here's one with the jack under the R.R. mounting point. Attach file: P1010012.JPG (141.31 KB)
	Posted on: 2011/2/16 20:05

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Steve40th	Re: C4 frame flex	#27
Elite Guru 1114 Posts Member since: 2005/12/20 0:00	Quote: CentralCoaster wrote: That's nice and all, but what's the point? I'm still waiting ot see the tangible benefit. It's just warm fuzzies, like with the camberbrace. I know RD racing used allot of their produts in his C4 he raced. But as far as numbers, ie slalom times down to chassis stiffness, what kind of numbers can we get to validate these products before and after? RD Targa Truss realy does stop the dash from shaking while driving. The RD ST Frame definitely is stiffer as my chassis doesnt flex when I jack jack it up. Camber brace. Dont know the difference, but I understand what it is supposed to do, keep the control arms from flexing inwards therefore keeping camber steady. X brace. Well it was a band aid for convertibles.
	Posted on: 2011/2/16 20:14
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CentralCoaster	Re: C4 frame flex	#28
Senior Guru San Diego, CA 9454 Posts Member since: 2007/10/28 0:00	Quote: Steve40th wrote: But as far as numbers, ie slalom times down to chassis stiffness, what kind of numbers can we get to validate these products before and after? Lap times, or at least feedback from a racer experienced enough to benefit from the difference. I know it makes the chassis stiffer, but what effect will that have on the track?
	Posted on: 2011/2/16 21:09
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Steve40th	Re: C4 frame flex	#29
Elite Guru 1114 Posts Member since: 2005/12/20 0:00	Quote: CentralCoaster wrote: Quote: Steve40th wrote: But as far as numbers, ie slalom times down to chassis stiffness, what kind of numbers can we get to validate these products before and after? Lap times, or at least feedback from a racer experienced enough to benefit from the difference. I know it makes the chassis stiffer, but what effect will that have on the track? The original owner of RD racing made all his stuff to improve his times.
	Posted on: 2011/2/16 21:58
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Aardwolf	Re: C4 frame flex	#30
Senior Guru Fremont, WI 209 Posts Member since: 2008/4/30 15:21	Quote: Steve40th wrote: The original owner of RD racing made all his stuff to improve his times. Last I knew they were not winning.
	Posted on: 2011/2/16 22:58

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Steve40th	Re: C4 frame flex	#31
Elite Guru 1114 Posts Member since: 2005/12/20 0:00	Quote: Aardwolf wrote: Quote: Steve40th wrote: The original owner of RD racing made all his stuff to improve his times. Last I knew they were not winning. Well, that is a different topic altogether. From what I understand, the people running RD Racing are not the original owners. But, the original owner said it improved his car. So...whatever that means. So many teams dont win, only one can win.
	Posted on: 2011/2/16 23:17
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pianoguy	Re: C4 frame flex	#32
Guru Emeritus Apple Valley, MN 14762 Posts Member since: 2007/12/29 0:00	Quote: flyboy wrote: Quote: -=Jeff=- wrote: here is a link for contact info on the bars both Ron and I have http://vettextc.net/MY_ZR-1/Frame_Brace.html Great job making your ZR-1 look like it does! +1, and thanks for the link!
	Posted on: 2011/2/16 23:29
	_________________ 1996 LT4 �Before you criticize someone, you should walk a mile in their shoes. That way when you criticize them, you are a mile away from them and you have their shoes.�- Jack Handey
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CentralCoaster	Re: C4 frame flex	#33
Senior Guru San Diego, CA 9454 Posts Member since: 2007/10/28 0:00	Quote: Aardwolf wrote: Quote: Steve40th wrote: The original owner of RD racing made all his stuff to improve his times. Last I knew they were not winning. And they're selling the stuff too. I doubt after tooling everything up they're going to say it doesn't perform.
	Posted on: 2011/2/16 23:29
	_________________ 1985 Z51, ZF6
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BillH	Re: C4 frame flex	#34
The Stig Moderator Reno 22702 Posts Member since: 2007/12/25 0:00	Quote: CentralCoaster wrote: Lap times, or at least feedback from a racer experienced enough to benefit from the difference. I know it makes the chassis stiffer, but what effect will that have on the track? It makes a noticable difference in the corners when you're racing at 100%+. Slight changes (like a camber change)will make you correct the wheel just a hair. That's good for a couple hundredths. The flex ultimately affects the tire contact patch which means more corrections in the corners and slower lap times. The flex in a corner wil also affect how the car handles bumps and ripples in a corner. Obviously, it's only part of the equation, the entire suspension & steering must be tight. If you run enough, you gat a feel for things like this, you'll notice flex because the chassis won't take a proper set in the corner.
	Posted on: 2011/2/16 23:35
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bogus	Re: C4 frame flex	#35
Grand Imperial Pooh-Bah San Pedro, CA 20859 Posts Member since: 2005/9/7 0:00	There are two things I need before I go on track with my C4 - one is brakes; the other? A targa truss type upgrade. I am too tall in the body to fit right with a helmet on. Oh, and a tire budget would be nice, too.
	Posted on: 2011/2/16 23:45
	_________________ The single biggest problem with communication is the illusion that it has taken place. - George Bernard Shaw Education is the best tool to overcome irrational fear. - me
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BillH	Re: C4 frame flex	#36
The Stig Moderator Reno 22702 Posts Member since: 2007/12/25 0:00	Quote: bogus wrote: There are two things I need before I go on track with my C4 - one is brakes; the other? A targa truss type upgrade. I am too tall in the body to fit right with a helmet on. Oh, and a tire budget would be nice, too. Got a glass top?
	Posted on: 2011/2/16 23:50
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bogus	Re: C4 frame flex	#37
Grand Imperial Pooh-Bah San Pedro, CA 20859 Posts Member since: 2005/9/7 0:00	nope. glass top died years ago. only have painted.
	Posted on: 2011/2/17 0:31
	_________________ The single biggest problem with communication is the illusion that it has taken place. - George Bernard Shaw Education is the best tool to overcome irrational fear. - me
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BillH	Re: C4 frame flex	#38
The Stig Moderator Reno 22702 Posts Member since: 2007/12/25 0:00	Quote: bogus wrote: nope. glass top died years ago. only have painted. There's a decent bit of height advantage with the glass. How tall are you? Seat the whole way down? Tilting it back helps too. I'm 5'10" and don't come close to hitting. You only need 1/4 in. of clearance.
	Posted on: 2011/2/17 1:34
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bogus	Re: C4 frame flex	#39
Grand Imperial Pooh-Bah San Pedro, CA 20859 Posts Member since: 2005/9/7 0:00	I am about 5'11, but with only a 30" inseam, it's all in my upper body... I should be 6'3", but I have short legs!!!
	Posted on: 2011/2/17 2:17
	_________________ The single biggest problem with communication is the illusion that it has taken place. - George Bernard Shaw Education is the best tool to overcome irrational fear. - me
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jonszr1	Re: C4 frame flex	#40
Senior Guru Lone Pine, CA 453 Posts Member since: 2010/10/25 22:42	Quote: -=Jeff=- wrote: Quote: pianoguy wrote: Quote: corvetteronw wrote: If anyone wants to drive my 91 coupe to see how it feels with the Gordon Killebrew-designed bars I will be at Bloomington Gold in June and probably FunFest in September. I think they have made a greatly noticeable difference in how stiff the car feels. Just shoot me a PM and we can meet up. Do you know where these are being sold now? here is a link for contact info on the bars both Ron and I have http://vettextc.net/MY_ZR-1/Frame_Brace.html are these a bolt on deal? if so they might be nicer than the x brace under the car as i wouldnt have to remove the brace when i wanted to do work on the underside of the car . do these decrease ground clearence . they sure do look nice
	Posted on: 2011/2/17 3:43

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-=Jeff=-	Re: C4 frame flex	#41
Master Guru Bartlett, IL 573 Posts Member since: 2007/12/20 0:00	yes bolt on
	Posted on: 2011/2/17 13:14
	_________________ -=Jeff=- 1990 Corvette ZR-1 #1051
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ggrassmid	Re: C4 frame flex	#42
Guru Newb Edgewood, KY 18 Posts Member since: 2010/3/25 13:26	Quote: BillH wrote: Quote: bogus wrote: nope. glass top died years ago. only have painted. There's a decent bit of height advantage with the glass. How tall are you? Seat the whole way down? Tilting it back helps too. I'm 5'10" and don't come close to hitting. You only need 1/4 in. of clearance. I'm 6'3" and with helmet on I have to take the bottom seat cushion out to fit nice in car. I have the glass top, but definately perfer the targa truss from ProStreet Customs. I noticed a big difference in racing and just driving on the street. I am going to get a Kirky seat to put in the car and basically almost sit on the floor... cant wait to never hit my head on the roof again :-)
	Posted on: 2011/2/17 14:53

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BillH	Re: C4 frame flex	#43
The Stig Moderator Reno 22702 Posts Member since: 2007/12/25 0:00	Quote: ggrassmid wrote: I'm 6'3" and with helmet on I have to take the bottom seat cushion out to fit nice in car. I have the glass top, but definately perfer the targa truss from ProStreet Customs. I noticed a big difference in racing and just driving on the street. I am going to get a Kirky seat to put in the car and basically almost sit on the floor... cant wait to never hit my head on the roof again :-) Ha, ya can't fight mother nature. You'll really like the Kirky compared to sitting on the carpet.
	Posted on: 2011/2/17 15:37
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BillH	Re: C4 frame flex	#44
The Stig Moderator Reno 22702 Posts Member since: 2007/12/25 0:00	Quote: bogus wrote: I am about 5'11, but with only a 30" inseam, it's all in my upper body... I should be 6'3", but I have short legs!!! Yea, it's the upper body not the inseam. I just sat in the 92 with a helmit on and have 2" of clearence with the glass top. Probably 1" with the painted top.
	Posted on: 2011/2/17 15:46
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bogus	Re: C4 frame flex	#45
Grand Imperial Pooh-Bah San Pedro, CA 20859 Posts Member since: 2005/9/7 0:00	Quote: BillH wrote: Quote: bogus wrote: I am about 5'11, but with only a 30" inseam, it's all in my upper body... I should be 6'3", but I have short legs!!! Yea, it's the upper body not the inseam. I just sat in the 92 with a helmet on and have 2" of clearance with the glass top. Probably 1" with the painted top. Here is the deal... I am about 5'11". My brother Paul, is 6'1", and my late brother Roy was 6'8"! When the three of us sat next to each other, Paul and Roy were about the same height; I was only 1" shorter or so, even I was 9" shorter than Roy. He wore a 36 or 38" inseam, I don't remember for sure now. Paul wears a 32" inseam. So as I said, I am really tall in the body and it screws me up for wearing a helmet. I had zero room; it felt very claustrophobic in there.
	Posted on: 2011/2/17 18:48
	_________________ The single biggest problem with communication is the illusion that it has taken place. - George Bernard Shaw Education is the best tool to overcome irrational fear. - me
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BillH	Re: C4 frame flex	#46
The Stig Moderator Reno 22702 Posts Member since: 2007/12/25 0:00	Quote: bogus wrote: So as I said, I am really tall in the body and it screws me up for wearing a helmet. I had zero room; it felt very claustrophobic in there. What you could try is to pull the seat cushion and sit in the car with a helmit like ggrass. If that feels OK, you could pore a 2 part foam seat that would be much lower than stock. You could probably get away with using a 2 pint kit which, on line is only $20. Much cheaper than buying a race seat. I've pored 30-40 full seats doing this but have switched to poring beadseats. If you're interested, let me know, I'll give you the full procedure.
	Posted on: 2011/2/17 19:50
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flyboy	Re: C4 frame flex	#47
Elite Guru Westmont, Il. 2632 Posts Member since: 2008/9/28 12:47	Hmmm, The seat cushion pops right out doesn't it. Maybe I'll pick up a block of foam to put on the webbing for the occasional drag strip day.
	Posted on: 2011/2/17 21:14
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BillH	Re: C4 frame flex	#48
The Stig Moderator Reno 22702 Posts Member since: 2007/12/25 0:00	Quote: flyboy wrote: Hmmm, The seat cushion pops right out doesn't it. Maybe I'll pick up a block of foam to put on the webbing for the occasional drag strip day. I wouldn't recommend it,Joe. A block of foam will let your but slide all over the place. 2 part foam is molded yo your ass.
	Posted on: 2011/2/17 21:20
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flyboy	Re: C4 frame flex	#49
Elite Guru Westmont, Il. 2632 Posts Member since: 2008/9/28 12:47	Gotcha, the tech guy might not like it either.
	Posted on: 2011/2/17 21:24

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CentralCoaster	Re: C4 frame flex	#50
Senior Guru San Diego, CA 9454 Posts Member since: 2007/10/28 0:00	Quote: bogus wrote: There are two things I need before I go on track with my C4 - one is brakes; the other? A targa truss type upgrade. I am too tall in the body to fit right with a helmet on. Oh, and a tire budget would be nice, too. Those sound more like excuses than reasons. Stock brakes are fine if in working order. Have you pulled the headliner? Also some helmets are bigger than others. I have a SA rated helmet that's huge. Then I have a motorcycle helmet that is much smaller. Both are Snell rated and acceptable at a HPDE.
	Posted on: 2011/2/18 1:34
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