Pic of C4 frame brace stiffness demo
06-23-2012, 06:36 PM
#81
Max G’s
Sorry, but still don't see the validity of this upgrade. Even if it was hooked to a machine to measure deflection, there has to be a small amount of deflection or the moment will be too rigid and crack. As far as the statement about welds cracking, a good weld can be 2X the strength of the material that is being welded.
I've been autoxiong and recently tracking this car for over 5yrs and have not experienced a problem with frame flex. As a matter of fact, I rode in a fellow racers C6 coupe and it had a lot more squeak than my C4 does.
http://s1172.photobucket.com/albums/...etteframe1.jpg
I've been autoxiong and recently tracking this car for over 5yrs and have not experienced a problem with frame flex. As a matter of fact, I rode in a fellow racers C6 coupe and it had a lot more squeak than my C4 does.
http://s1172.photobucket.com/albums/...etteframe1.jpg
Last edited by l98tpi; 06-23-2012 at 06:41 PM.
06-23-2012, 07:28 PM
#82
Racer
we're in trouble.
06-23-2012, 11:48 PM
#84
Instructor
Is this what I am feeling from 30 to 60 when I have top off. This comment makes it seem like a common issue which is actually a relief.
I have been blaming this shake or shimmy on flat spotted tires and the Z07 package and not understanding why it goes away completly with the top on; I mean I get the added stability but was shocked at the significant difference.
Will anything mentioned in this thread cure cowl shake? Leaning toward the vert cross brace.
I have been blaming this shake or shimmy on flat spotted tires and the Z07 package and not understanding why it goes away completly with the top on; I mean I get the added stability but was shocked at the significant difference.
Will anything mentioned in this thread cure cowl shake? Leaning toward the vert cross brace.
06-24-2012, 12:14 AM
#85
Le Mans Master
Is this what I am feeling from 30 to 60 when I have top off. This comment makes it seem like a common issue which is actually a relief.
I have been blaming this shake or shimmy on flat spotted tires and the Z07 package and not understanding why it goes away completly with the top on; I mean I get the added stability but was shocked at the significant difference.
Will anything mentioned in this thread cure cowl shake? Leaning toward the vert cross brace.
I have been blaming this shake or shimmy on flat spotted tires and the Z07 package and not understanding why it goes away completly with the top on; I mean I get the added stability but was shocked at the significant difference.
Will anything mentioned in this thread cure cowl shake? Leaning toward the vert cross brace.
06-24-2012, 03:53 AM
#86
Melting Slicks
Personally I think GM could have fixed this easily and just were not given the money to do it. If they used the trans tunnel as a central spine tied to the front and rear firewall like Lotus and other do and have done for a very long time the cowl shake would not exist. If you look at something as cheap and pedestrian as a Mazda Miata they have a stiff trans tunnel with a cover bolted under it to form a box. There are loads of good books on chassis design and how to test them. The most down to earth ones are from Carroll Smith. On either this forum or the tech one there was a post about doing a nut and bolt check on all the various frame parts and was sort of dismissed and in my mind on a 20 something year old car a good idea as well.
07-23-2012, 10:45 PM
#87
Racer
This appears to be a good product. It's effective and it's hidden compare to a roll cage or the targa top brace.
The alternative is to go purchase a C5 or C6 Corvette and lay out large chunk of cash. The $500.00 is a small price to pay.
My recently purchased 1994 LT1 Admiral Blue Corvette is my first. This is my first and will not be my last Corvette. I plan to own a C4, C5 and one day a C6 or C7 Z06. However to be honest...this chassis design is disappointing. It's feels great over smooth surfaces but on rough roads it sounds like its about to fall apart. If I could improve the ride by spending $500.00 so be it. I will purchase the vette to vette solution sooner or later, however it's not if but when. If and when I sell the car, the new owner WILL pay for the upgrade or I will remove it and sell it separately.
I'm a proud GM consumer...but they should have remedied this problem.
Yours truly,
sNaKeDr
The alternative is to go purchase a C5 or C6 Corvette and lay out large chunk of cash. The $500.00 is a small price to pay.
My recently purchased 1994 LT1 Admiral Blue Corvette is my first. This is my first and will not be my last Corvette. I plan to own a C4, C5 and one day a C6 or C7 Z06. However to be honest...this chassis design is disappointing. It's feels great over smooth surfaces but on rough roads it sounds like its about to fall apart. If I could improve the ride by spending $500.00 so be it. I will purchase the vette to vette solution sooner or later, however it's not if but when. If and when I sell the car, the new owner WILL pay for the upgrade or I will remove it and sell it separately.
I'm a proud GM consumer...but they should have remedied this problem.
Yours truly,
sNaKeDr
Last edited by SnAkeDr; 07-23-2012 at 10:59 PM.
07-24-2012, 08:36 AM
#88
Le Mans Master
07-24-2012, 10:29 PM
#89
Safety Car
Dave fixed this in the C5 which is HIS car not Dave Hill's.
Even with its flexible chassis they did such a good job with the suspension the C4 was a world class handling sports car until it was replaced with the C5.
Dave wanted to do many of the C5 concepts on the C4, management, time, money, all constrained him and the team. Keep in mind the C4 was a Night and Day departure from what had been done before. Had it incorporated some of the C5 concepts its impact would have been even more profound. The C4 was the first modern Corvette and paved the way for all other modern Corvettes C5, C6, C7.
It STILL is a very good handling sports car.
Last edited by 93Rubie; 07-24-2012 at 10:32 PM.
07-24-2012, 11:06 PM
#90
Racer
It was going to be, until the last minute with prototypes/calculations built and done. Lloyd Ruess decided it had to be a targa. The car got higher door sills and reinforcements to compensate but this was NOT enough. Dave McLellan admits in his book Corvette from the Inside, that the car should have been delayed another 2 years (that is how late the ORDER came down for a targa) to find a good solution.
Dave fixed this in the C5 which is HIS car not Dave Hill's.
Even with its flexible chassis they did such a good job with the suspension the C4 was a world class handling sports car until it was replaced with the C5.
Dave wanted to do many of the C5 concepts on the C4, management, time, money, all constrained him and the team. Keep in mind the C4 was a Night and Day departure from what had been done before. Had it incorporated some of the C5 concepts its impact would have been even more profound. The C4 was the first modern Corvette and paved the way for all other modern Corvettes C5, C6, C7.
It STILL is a very good handling sports car.
Dave fixed this in the C5 which is HIS car not Dave Hill's.
Even with its flexible chassis they did such a good job with the suspension the C4 was a world class handling sports car until it was replaced with the C5.
Dave wanted to do many of the C5 concepts on the C4, management, time, money, all constrained him and the team. Keep in mind the C4 was a Night and Day departure from what had been done before. Had it incorporated some of the C5 concepts its impact would have been even more profound. The C4 was the first modern Corvette and paved the way for all other modern Corvettes C5, C6, C7.
It STILL is a very good handling sports car.
07-25-2012, 08:45 AM
#91
Le Mans Master
Yep, I certainly concur 93Rubie. Would love to try these out on my car for autocrossing, but I've got too much money sucked up in just keeping tires on it and keeping it running!
07-25-2012, 10:31 PM
#92
Safety Car
On a side note, but related one, my car is SCCA B Stock Legal if I put this frame brace on, JUST the brace. It would bump me straight to a Prepared Class. Yeah, HUGE jump. PAX index would really hurt.
I remember reading an article that they took a national champion auto-x driver and put him in a C4 and tested the lap times with roof on and roof off. No significant difference. So while this brace MAY help with feel/flexing it has NO improvement as far as performance goes on a otherwise stock C4.
The Solo Chair in the club local to me sets FTD a lot of the time with his roof out. He cannot drive the car with it in.
Its a BSP C4. That being said, I bet most of the folks that are interested in this don't auto-x or race at all. Kinda of ironic, don't you think?
Note: I notice my roof/etc...creaking on the public roads as they really stink. I never noticed this on smooth/flat parking lots/road courses. I bet the frame flexes less due to less twisting from road imperfections.
To each their own, though.
Just my 2 cents worth.
Last edited by 93Rubie; 07-25-2012 at 10:34 PM.
07-26-2012, 04:29 AM
#93
Melting Slicks
I think a few things have to kept in mind. First if the wheel rate is greater than chassis stiffness the the chassis is the suspension, no sense in making anything stiffer as far as springs go just hope for a smoother surface.
Second a Corvette is a produtcion car built for a price. Market people decide what the buyer will spend then everyone else has to fit in that budget. A high end exotic is built with what designers want then they tally it up and hang a price tag on it. GM needs to sell 20 or 30 thousand cars to make it worth the effort and an exotic needs to sell 50 or 100. Complete different game.
Second a Corvette is a produtcion car built for a price. Market people decide what the buyer will spend then everyone else has to fit in that budget. A high end exotic is built with what designers want then they tally it up and hang a price tag on it. GM needs to sell 20 or 30 thousand cars to make it worth the effort and an exotic needs to sell 50 or 100. Complete different game.
07-26-2012, 07:35 PM
#94
Burning Brakes
Ok - just wondering... If someone already had the RD Racing X-brace, could you still add the V2V frame brace as well? If so, I wonder if you might then cure both the fore/aft flexing that seems to occur as well as the torsional flex. What do you guys think?
03-23-2013, 05:32 PM
#96
.....Update on V2V Torsion Bars
Digging up an old post here but between work and a new baby boy, its been hectic. Found some time to get in the shop and I wanted to post some updates on the Vette2Vette C4 torsion rods.
The original frame kit I installed on my ZR-1 last year had brackets that located the rod parallel to the bolt holes on the rear control arm, but, too close to the floor pan and not aligned parallel to the body. The bars rubbed slightly on the floor pan fiberglass
Jason and Dan are great to work with and they fabbed me up some replacement brackets with additional offset. These fit perfectly in terms of rod alignment, but, now they are off center from the rear control arm mount. Not a big deal, but, the additional offset could potentially cause bending torsion in the brackets under load.
Jason and Dan cut the brackets so that there was extra metal covering a strong area of weld seam immediately behind the bracket. I drilled a hole through this seam and used a short grade 5 bolt to provide 2 mount points for the bracket. This is a solid setup. The only drawback to doing this is the steel used on the C4 frame is TOUGH. Not sure what spec GM used for this, but, I ruined 4 titanium drill bits getting the holes drilled. Not sure if Jason and Dan are going to recommended drilling the holes in the revised kits, but, I think it is necessary. See below pics for details.
I drove the car over to a client who has a XFinity XMS laser alignment system. Someone asked about this in an earlier post. The XMS is primarily used in aerospace applications, but, depending on the configuration size it can be used to precision measure any object in three dimensions. Laser targets can be affixed to the object at strategic points using mechanical and/or adhesive mounting and then a baseline target scan is performed.
With these revised brackets, the measured deflection and torsion improvements were similar as the results from last year. Without getting into a lot of complicated math my estimates would be approximately a 40% reduction in side beam deflection (longitudinal and angular) and a 30% reduction in L-R torsion deflection differential measured 18 deg above the axle centerline.
The kit works as advertised, and from what I have been told, a similar setup was used on all the factory SCCA, LeMans, and Corvette Challenge cars back in the day.
The original frame kit I installed on my ZR-1 last year had brackets that located the rod parallel to the bolt holes on the rear control arm, but, too close to the floor pan and not aligned parallel to the body. The bars rubbed slightly on the floor pan fiberglass
Jason and Dan are great to work with and they fabbed me up some replacement brackets with additional offset. These fit perfectly in terms of rod alignment, but, now they are off center from the rear control arm mount. Not a big deal, but, the additional offset could potentially cause bending torsion in the brackets under load.
Jason and Dan cut the brackets so that there was extra metal covering a strong area of weld seam immediately behind the bracket. I drilled a hole through this seam and used a short grade 5 bolt to provide 2 mount points for the bracket. This is a solid setup. The only drawback to doing this is the steel used on the C4 frame is TOUGH. Not sure what spec GM used for this, but, I ruined 4 titanium drill bits getting the holes drilled. Not sure if Jason and Dan are going to recommended drilling the holes in the revised kits, but, I think it is necessary. See below pics for details.
I drove the car over to a client who has a XFinity XMS laser alignment system. Someone asked about this in an earlier post. The XMS is primarily used in aerospace applications, but, depending on the configuration size it can be used to precision measure any object in three dimensions. Laser targets can be affixed to the object at strategic points using mechanical and/or adhesive mounting and then a baseline target scan is performed.
With these revised brackets, the measured deflection and torsion improvements were similar as the results from last year. Without getting into a lot of complicated math my estimates would be approximately a 40% reduction in side beam deflection (longitudinal and angular) and a 30% reduction in L-R torsion deflection differential measured 18 deg above the axle centerline.
The kit works as advertised, and from what I have been told, a similar setup was used on all the factory SCCA, LeMans, and Corvette Challenge cars back in the day.
Last edited by gsvette; 03-23-2013 at 07:10 PM.
03-23-2013, 06:39 PM
#99
Le Mans Master
Thank you gsvette for sharing your experience and test results with the V2V/ Killebrew kit. Some forum members posted concern over what they thought was a high cost for the few parts they can see. The part they do not see is any project requires analysis of the size of the potential market for which this one will certainly be limited and the original engineering expense involved to develop properly working reliable parts which has to be shared among all purchased kits. Others posted they believe they can easily copy the kit for $100 or so. What tubing type (chrome moly?) and wall thickness will they choose to achieve the results Gordon Killebrew is getting? How will they design the brackets to properly attach to the frame pick-up points. Who will do the Tig-welding? How much will the tubing, materials, welding and heims ends cost? It appears the V2V kit is a bargain. Well done!
Last edited by Greg Gore; 03-23-2013 at 06:42 PM.
03-23-2013, 06:59 PM
#100
Thank you gsvette for sharing your experience and test results with the V2V/ Killebrew kit. Some forum members posted concern over what they thought was a high cost for the few parts they can see. The part they do not see is any project requires analysis of the size of the potential market for which this one will certainly be limited and the original engineering expense involved to develop properly working reliable parts which has to be shared among all purchased kits. Others posted they believe they can easily copy the kit for $100 or so. What tubing type (chrome moly?) and wall thickness will they choose to achieve the results Gordon Killebrew is getting? How will they design the brackets to properly attach to the frame pick-up points. Who will do the Tig-welding? How much will the tubing, materials, welding and heims ends cost? It appears the V2V kit is a bargain. Well done!
Time is money......I bought the kit from V2V. Dan and Jason are hard working guys selling (and supporting) a product at a fair price that works as advertised....which is actually quite rare these days.
Last edited by gsvette; 03-23-2013 at 07:11 PM.