C4 No Flex Frame Stiffener Bar System
Thread Starter
Drifting
Joined: Apr 2007
Posts: 1,291
Likes: 33
From: Chicago IL
C4 No Flex Frame Stiffener Bar System
Burning Brakes
Joined: May 2009
Posts: 1,014
Likes: 7
From: Ft Wayne IN
No experience with this but I don't believe the design would be as strong as a true X-brace which would help more with body flex/articulation.This brace looks like it would only support front to rear load? Just my observation.
Safety Car
Joined: Jan 2004
Posts: 3,783
Likes: 15
From: Northern California
Yes, that was designed by C4 design engineer Gordon Killebrew.
It works as advertised!...
http://forums.corvetteforum.com/c4-g...me-braces.html
http://forums.corvetteforum.com/c4-t...s-stiffer.html
.
It works as advertised!...
http://forums.corvetteforum.com/c4-g...me-braces.html
http://forums.corvetteforum.com/c4-t...s-stiffer.html
.
Last edited by GKK; Aug 16, 2013 at 10:29 PM.
Race Director
Joined: Mar 1999
Posts: 16,950
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From: Stafford, Virginia Kittah, Kittah, Kittah...
Not these.
But is R&D Racing still around here? I bought their Cross Frame several years ago and it was awesome. I went 4 years or so without taking the top off because of the body flex. After adding the cross brace I had the top off all the time.
The only problem was it is hard to install because most vehicles that aren't convertibles don't have the rear holes for mounting drilled and threaded. I measured it incorrectly and messed up the hole locations so I'll have to have some work done to get it right, probably get a plate welded in to do it right. Currently it's sitting leaned up against the wall in my garage but I miss having it installed.
The only problem was it is hard to install because most vehicles that aren't convertibles don't have the rear holes for mounting drilled and threaded. I measured it incorrectly and messed up the hole locations so I'll have to have some work done to get it right, probably get a plate welded in to do it right. Currently it's sitting leaned up against the wall in my garage but I miss having it installed.
Team Owner
Joined: Dec 1999
Posts: 34,873
Likes: 487
From: Lacey WA RVN 68-69
NCM Sinkhole Donor
But is R&D Racing still around here? I bought their Cross Frame several years ago and it was awesome. I went 4 years or so without taking the top off because of the body flex. After adding the cross brace I had the top off all the time.
The only problem was it is hard to install because most vehicles that aren't convertibles don't have the rear holes for mounting drilled and threaded. I measured it incorrectly and messed up the hole locations so I'll have to have some work done to get it right, probably get a plate welded in to do it right. Currently it's sitting leaned up against the wall in my garage but I miss having it installed.
The only problem was it is hard to install because most vehicles that aren't convertibles don't have the rear holes for mounting drilled and threaded. I measured it incorrectly and messed up the hole locations so I'll have to have some work done to get it right, probably get a plate welded in to do it right. Currently it's sitting leaned up against the wall in my garage but I miss having it installed.
IIRC, they provided nutserts for the holes that had to be drilled in the coupe frame. I think that the RD brace also hung down a good inch or so below the frame compared to the factory brace.
Finding and installing a factory brace would work work but the rear mounting holes would still have to be drilled and nutserts added. The center portion of the brace can be bolted to the floorpan simply by drilling holes and using bolts and nuts. The OEM brace can easily be boxed using some pieces of steel flat stock and welded to the brace.
Race Director
Joined: Mar 1999
Posts: 16,950
Likes: 0
From: Stafford, Virginia Kittah, Kittah, Kittah...
RD Racing is gone. Their Cross Frame apparently worked well, but holes did have to be drilled as mentioned. There was also no attachment points to the floorpan like the OEM brace did on the 'verts.
IIRC, they provided nutserts for the holes that had to be drilled in the coupe frame. I think that the RD brace also hung down a good inch or so below the frame compared to the factory brace.
Finding and installing a factory brace would work work but the rear mounting holes would still have to be drilled and nutserts added. The center portion of the brace can be bolted to the floorpan simply by drilling holes and using bolts and nuts. The OEM brace can easily be boxed using some pieces of steel flat stock and welded to the brace.
IIRC, they provided nutserts for the holes that had to be drilled in the coupe frame. I think that the RD brace also hung down a good inch or so below the frame compared to the factory brace.
Finding and installing a factory brace would work work but the rear mounting holes would still have to be drilled and nutserts added. The center portion of the brace can be bolted to the floorpan simply by drilling holes and using bolts and nuts. The OEM brace can easily be boxed using some pieces of steel flat stock and welded to the brace.
Yeah, it did hang down about 1.5" so on a lowered car they would be a problem, even on a stock height vehicle I dragged it over speed bumps on occasion.
Racer
Joined: Aug 2006
Posts: 277
Likes: 8
From: Calgary Alberta
I have a '90 coupe and convertible. In an effort to make things more rigid on my coupe I installed the R/D camber brace and cross brace. I still had flex on the coupe and so I bought the vette2vette frame system .
That was a huge improvement over the R/D system in rigidity and less squeaks .
On my convertible I boxed in the factory cross brace and run the factory hardtop when doing an auto cross . So the convertible is pretty good for a C 4
That was a huge improvement over the R/D system in rigidity and less squeaks .
On my convertible I boxed in the factory cross brace and run the factory hardtop when doing an auto cross . So the convertible is pretty good for a C 4
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Race Director
Joined: Feb 2003
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From: Kingman AZ
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St. Jude Donor '06-'07-'08-'09-'10-'11-'12-'13-'14-'15-'16
Had it on m 91 and loved it. Selling the car so I sold the bars to another Forum member. Felt like it was showroom new after the install - even with the targa off and going over railroad tracks.
Safety Car
Joined: May 2002
Posts: 4,659
Likes: 82
From: Toronto ontario
I have it lying here in front of me just haven't installed it yet. Not sure if any holes need to be drilled for the install I haven't read the instructions yet. I have the camber brace on my 93 and its amazing. Helped the steering wheel jiggle and makes for a way better steering feel. I also have the harness bar in that car which helped a bit and was noticeable when going up a driveway on an angle (almost eliminated the few squeaks I had going up my previous homes driveway).
The setup is a bit heavy but its right in the middle of the car and right at the bottom which I think is the best place really to add any weight if you had to. I'm not happy about the camber brace adding weight on the nose but I will be getting one of those when I can find one for the lt5.
To those that added one.. Did you tighten or extend the bars to get the stiffness you wanted? Instructions are vague so I was curious which way people found had the most impact. Hopefully ill get to install it tonight and ill make a thread with pics of the install.
The setup is a bit heavy but its right in the middle of the car and right at the bottom which I think is the best place really to add any weight if you had to. I'm not happy about the camber brace adding weight on the nose but I will be getting one of those when I can find one for the lt5.
To those that added one.. Did you tighten or extend the bars to get the stiffness you wanted? Instructions are vague so I was curious which way people found had the most impact. Hopefully ill get to install it tonight and ill make a thread with pics of the install.
Race Director
Joined: Feb 2003
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From: Kingman AZ
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I too did not find any instructions on how much to tighten it. I just got the biggest crescent wrench I had (with about a 1' handle) and cranked it down real tight. I did not use a breaker bar but got the nut as tight as I could with that wrench. That amount of stiffness seemed to work nicely.
The guy that designed this is in the NCM Hall of Fame. If you have ever been to one of his seminars you will remember that he is a genius.
The guy that designed this is in the NCM Hall of Fame. If you have ever been to one of his seminars you will remember that he is a genius.
Race Director
Joined: Nov 2003
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From: Overland Park Kansas
2020 Corvette of the Year Finalist (appearance mods)
C4 of Year Winner (appearance mods) 2019
(OTOH...profit = margin x units sold. Hmmm.... I see they originally planned to sell this sucker for $700ish. Really?)Seriously, I see how it would help -- assuming the stock frame rails really flex as much as the product description implies. By attaching to a second point on the frame and tensioning that bar, the fore/aft can't flex "upward" (or downward) as much. The bar just looks SO flimsy in respect to the frame.
Based on the ability to reduce windshield-to-BPillar flex when jacked, that's how I see the car must actually flex "longitudally" as described in a linked thread. (And, that person said he wouldn't drive a C4 if it flexed like that. But, it must -- if the windshield/BPillar gap increases when jacked between the wheels!)
I actually question whether an x-brace would do less -- as one person suggests because it's accomplishing the same function. Strength of materials involved would affect the outcome though...and I gotta think tubular steel is stronger than flat-steel. That's must be the reason.
I might have to suggest this to RPP_Corvette for consideration.
Team Owner
Joined: Aug 2005
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From: Riverside County Southern California
Co-winner 2020 C4 of the Year - Modified
2018 Corvette of Year Finalist
2017 C4 of Year
2016 C7 of Year Finalist
St. Jude Donor '09 thru '20
We have a lot of members in here who DO RACE their C4s, and they do not have that crap installed.
Le Mans Master
Joined: Dec 2003
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From: Van Steel Corvettes
St. Jude Donor '12-'13
If only he was "smart enough" to have developed a unit for less than $500 a pop! It sure doesn't LOOK like it's worth that much in materials. Maybe profit is part of his genius? (OTOH...profit = margin x units sold. Hmmm.... I see they originally planned to sell this sucker for $700ish. Really?)
(OTOH...profit = margin x units sold. Hmmm.... I see they originally planned to sell this sucker for $700ish. Really?)
Race Director
Joined: Nov 2003
Posts: 12,221
Likes: 446
From: Overland Park Kansas
2020 Corvette of the Year Finalist (appearance mods)
C4 of Year Winner (appearance mods) 2019
Team Owner
Joined: Aug 2005
Posts: 34,988
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From: Riverside County Southern California
Co-winner 2020 C4 of the Year - Modified
2018 Corvette of Year Finalist
2017 C4 of Year
2016 C7 of Year Finalist
St. Jude Donor '09 thru '20
You obviously have no idea what Post #1 is about. I think only a dunderhead would think as an idea that racers remove a targa to race.
