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I didn't notice any difference when installing the whole pack.
You are a very rare case. The front brace is essentially useless, but the other two had a distinct effect on both of my cars.
 

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After I replaced my tunnel brace with my DIY version, my wife (who knew almost nothing of what i was doing) asked me if the car is riding better and how I got some of the squeaks out.

LOVE the way it rides with the tunnel brace replacement. 55k miles and stock suspension at that point.
Are you saying your home-made thicker/stronger tunnel brace (DDM Back Bone equivalent) eliminated many of the body squeaks? How thick is your home-made version?

To others here who replaced their stock tunnel brace with a beefier one, would you say it significantly reduced body squeaks? If so, then I would consider the upgrade.

DDMWorks offers a 1/4", 3/8" and 1/2" version.
Does their 1/4" version eliminate the body squeaks as well as the thicker ones?
Do the stock mounting bolts accommodate the thicker materials?

How thick is the stock brace? Is it thin sheet metal primarily there as a splash shield?
 

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I have a couple of decades experience in setting up cars for road racing and when I bought the Solstice immediately noticed some shortcoming which I proceeded to address. Sorry, I didn't do the tunnel brace separately so can't assist on the question of its separate effect. I have the 1/4" version. Yes, the original is fairly light in comparison.

The combined effect of the Probeam and ynnel brace was to settle the car in cornering and specifically eliminate a mid corner skittish feel that had been bothering me. The replacement of both sway bars and all of he shocks/springs completed my chassis tuning. There is no comparison between original and tuned handling.

Having said that, if you aren't a driver that is into handling, it is quite possible that you'll be quite happy with the stock setup. I also added the front brace but found the effect to be minimal - it would be interesting to know of that holds true if that is the only brace added to an otherwise stock car.
 

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Discussion Starter #26
I have a couple of decades experience in setting up cars for road racing and when I bought the Solstice immediately noticed some shortcoming which I proceeded to address. Sorry, I didn't do the tunnel brace separately so can't assist on the question of its separate effect. I have the 1/4" version. Yes, the original is fairly light in comparison.

The combined effect of the Probeam and ynnel brace was to settle the car in cornering and specifically eliminate a mid corner skittish feel that had been bothering me. The replacement of both sway bars and all of he shocks/springs completed my chassis tuning. There is no comparison between original and tuned handling.

Having said that, if you aren't a driver that is into handling, it is quite possible that you'll be quite happy with the stock setup. I also added the front brace but found the effect to be minimal - it would be interesting to know of that holds true if that is the only brace added to an otherwise stock car.
Did you replace shocks with new stock or custom shocks?
And BTW (sorry by derailing my own thread) replacing 12 years and 57k miles old shocks by new stock ones would improve handling that much?
 

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I have a couple of decades experience in setting up cars for road racing and when I bought the Solstice immediately noticed some shortcoming which I proceeded to address. Sorry, I didn't do the tunnel brace separately so can't assist on the question of its separate effect. I have the 1/4" version. Yes, the original is fairly light in comparison.

The combined effect of the Probeam and ynnel brace was to settle the car in cornering and specifically eliminate a mid corner skittish feel that had been bothering me. The replacement of both sway bars and all of he shocks/springs completed my chassis tuning. There is no comparison between original and tuned handling.

Having said that, if you aren't a driver that is into handling, it is quite possible that you'll be quite happy with the stock setup. I also added the front brace but found the effect to be minimal - it would be interesting to know of that holds true if that is the only brace added to an otherwise stock car.
The mid-corner "skittish feel" was almost certainly cured primarily by the ProBeam. I did that one by itself and the effect was day-and-night better. The BackBone (tunnel brace) may have had some effect, but the only difference I really noticed with it was a generally more solid feeling to the car. The positive of that (to me) was the more solid feeling, but the negative (again to me) was increased sensitivity to single-wheel bumps. I feel the same difference between the NA and RL spring/bar/damper difference, with the RL feeling more solid but also more sensitive to bumps. Overall, given my local roads and my driving style, bump sensitivity is a bigger negative than stiffness is a positive during agressive driving, and I was disappointed about that.

If I primarily used the car for "puttering around" and for only local driving, the BackBone would be a net positive, as it really did make the car feel "better" while cruising around. I don't, so to me it is not.

I installed a front brace in an NA with only the ProBeam and could not detect any effect whatsoever, so it either isn't there, the NA doesn't output enough torque to cause a problem, or I am not sensitive enough to detect it. Maybe my next step should be to bolt it into the RL as a test. I also have an LVDT that I have been meaning to adapt to that area to measure any actual flex, so maybe that needs to be prioritized also. Front braces are valuable for MacPherson strut front suspensions and for high-torque engines in relatively weak chassis. We have relatively stiff hydro-formed tube chassis and don't have struts, so i didn't expect much benefit and wasn't surprised by the result.
 
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Did you replace shocks with new stock or custom shocks?
And BTW (sorry by derailing my own thread) replacing 12 years and 57k miles old shocks by new stock ones would improve handling that much?
There would have been no point putting in stock shocks - my car had less than 1000 miles on it when I did this. I used BC Racing units with different springs. The sway bars were ZOK. I sold my original sway bars and shocks to an NA owner - they are an upgrade for them. He told me they made a significant difference to his car.
 

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I had hoped to get my hands on a thicker aftermarket version in used fashion to experiment with to see if I liked it. My logic says, thicker-is-better, but apparently "touring comfort" is sacrificed.
I know of one that may be available soon...

The mid-corner "skittish feel" was almost certainly cured primarily by the ProBeam. I did that one by itself and the effect was day-and-night better. The BackBone (tunnel brace) may have had some effect, but the only difference I really noticed with it was a generally more solid feeling to the car. The positive of that (to me) was the more solid feeling, but the negative (again to me) was increased sensitivity to single-wheel bumps. I feel the same difference between the NA and RL spring/bar/damper difference, with the RL feeling more solid but also more sensitive to bumps. Overall, given my local roads and my driving style, bump sensitivity is a bigger negative than stiffness is a positive during agressive driving, and I was disappointed about that.
You know John, I wonder what the result would be going with the softer base model suspension parts and a backbone brace? You would be stopping the chassis from soaking up bumps and transferring that duty to the suspension. If you then could get a slightly softer spring/shock setup, it may be better than stock and holding the tire to the road consistently. Just spitballing.
 

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I have a convertible and a coupe. I installed the DDM brace kit to both cars, years ago, and suggest to every kappa owner i meet, to get the kit. I think it makes a fabulous difference and is well worth installing. The tunnel brace and Pro-beam seem to me to do the best. The venom brace didn't seem to create as much change, but then I always installed the venom brace last. Our club, MKC, has installed many brace kits at our annual mod meets and I know of one kit we will be installing in a couple weeks at our event.
I know that before I installed the first brace kit my wife said "she wouldn't go on cruises with me anymore". I drive aggressive but not extreme and after I installed the kits, she has no problems with riding with me. I'm 100% satisfied. I do not do auto cross or race my cars. But love hilly twisty roadways!
 

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I know of one that may be available soon...



You know John, I wonder what the result would be going with the softer base model suspension parts and a backbone brace? You would be stopping the chassis from soaking up bumps and transferring that duty to the suspension. If you then could get a slightly softer spring/shock setup, it may be better than stock and holding the tire to the road consistently. Just spitballing.
It is certainly a reasonable idea, and if I was unhappy with the handling as-is I would likely try it. The bottom line is that handling is not what is limiting my speed in most cases, so since the car handles "well enough" I have other things that are more worthy of my time, energy, and money to work on.
 
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It is certainly a reasonable idea, and if I was unhappy with the handling as-is I would likely try it. The bottom line is that handling is not what is limiting my speed in most cases, so since the car handles "well enough" I have other things that are more worthy of my time, energy, and money to work on.
Oh no, I know. Just one of my tangents. lol
 

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The days of wooden frames where performance drivers used the flexible frames to help keep all 4 tires in contact with the road during spirited driving are long gone. It seems to me that the goal today in high performance is to have as solid of a frame/chassis as possible and have the springs, shocks, tires, and other suspension pieces tuned together to achieve the best ride and handling characteristics to suit the vehicle and driver's preferences.

We are limited not only by the platform we are driving but by the limited aftermarket to be able to do the tuning of the drive to what we want. This is not to say that our cars are poor performers in their handling aspects as most of us prefer the way the car handles and rides stock. I think the Sky Redline is a pretty good handling car for a stock car in it's price range. Remember, GM designed these cars to try to satisfy as many of us as they could within price limitations and you can't satisfy "all of the people all of the time".

I am on my second Redline. I've owned and driven many high performance cars (Mustangs, Corvettes, Porsches, Vipers and Jaguars) and with nominal changes (tires, springs and back braces) am very satisfied with the Skys.
 

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The days of wooden frames where performance drivers used the flexible frames to help keep all 4 tires in contact with the road during spirited driving are long gone.
Wood, yes but as for flexible chassis, they were made much later than many would think.

 

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The days of wooden frames where performance drivers used the flexible frames to help keep all 4 tires in contact with the road during spirited driving are long gone. It seems to me that the goal today in high performance is to have as solid of a frame/chassis as possible and have the springs, shocks, tires, and other suspension pieces tuned together to achieve the best ride and handling characteristics to suit the vehicle and driver's preferences.

We are limited not only by the platform we are driving but by the limited aftermarket to be able to do the tuning of the drive to what we want. This is not to say that our cars are poor performers in their handling aspects as most of us prefer the way the car handles and rides stock. I think the Sky Redline is a pretty good handling car for a stock car in it's price range. Remember, GM designed these cars to try to satisfy as many of us as they could within price limitations and you can't satisfy "all of the people all of the time".

I am on my second Redline. I've owned and driven many high performance cars (Mustangs, Corvettes, Porsches, Vipers and Jaguars) and with nominal changes (tires, springs and back braces) am very satisfied with the Skys.
 

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Are you saying your home-made thicker/stronger tunnel brace (DDM Back Bone equivalent) eliminated many of the body squeaks? How thick is your home-made version?
How thick is the stock brace? Is it thin sheet metal primarily there as a splash shield?
rjgramps: I do not know what it’s primary design was: chassis tie, debris shield? I can only guess. But, here is the link to my DIY Tunnel Brace from 2020 fall.

I used a plate of 12”x 40” @ 3/8” 6061 aluminum. Only need 36”, but the remnant I found on the shelf was the same price as the 36” long piece. Stock piece was stamped steel (I think) at about 1/16" perhaps.

yes, squeaks are fewer on the Michigan roads likely because it doesn’t seem to flex as much. The Sky feels better driving, IMO. Not being a professional driver or ever having it on a proper course, I can’t speak to the performance enhancements or degradation. I found it interesting that a supposedly stiffer chassis actually makes improves the ride feel as i would have thought a little flex would smooth things out. Not so!

DDM did the science, I just made my part. If you go to the DDM website, they have some videos of their "Backbone" eliminating flex. The name "Backbone" is really DDM's property, which is why I call the same part a "tunnel brace." Buy the DDM product if you are at all concerned about fabricating your own as they deserve it. Not sure if anyone else is making these, anyway.



(edited for Quatoes and better description)
 

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I can definitely feel the difference when I accelerate from 10 to 15 miles per hour....making those turns can be dangerous. I believe a thicker back brace will definitely help
 

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rjgramps: I do not know what it’s primary design was: chassis tie, debris shield? I can only guess. But, here is the link to my DIY Tunnel Brace from 2020 fall.

I used a plate of 12”x 40” @ 3/8” 6061 aluminum. Only need 36”, but the remnant I found on the shelf was the same price as the 36” long piece. Stock piece was stamped steel (I think) at about 1/16" perhaps.

yes, squeaks are fewer on the Michigan roads likely because it doesn’t seem to flex as much. The Sky feels better driving, IMO. Not being a professional driver or ever having it on a proper course, I can’t speak to the performance enhancements or degradation. I found it interesting that a supposedly stiffer chassis actually makes improves the ride feel as i would have thought a little flex would smooth things out. Not so!

DDM did the science, I just made my part. If you go to the DDM website, they have some videos of their "Backbone" eliminating flex. The name "Backbone" is really DDM's property, which is why I call the same part a "tunnel brace." Buy the DDM product if you are at all concerned about fabricating your own as they deserve it. Not sure if anyone else is making these, anyway.



(edited for Quatoes and better description)
Thank you for sharing your experience and dimensional thickness of the stock tunnel brace. The stock brace being 1/16" thick seems to function more as a strap and slash shield, than a brace.

Were you able to reuse the stock bolts on your 3/8" thick brace?

If I find a used one with a shipping cost that doesn't ruin the deal, I will buy it. I am open to either 1/4 or 3/8 inch material thickness. If I don't find a used one by the time I am done with everything else I want and need to do with our base Sky, I just may order a new one from DDMWorks. But that would be a number of months away. In the mean time, I will post my request in the "Wanted" section.

Thanks again!
 

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Thank you for sharing your experience and dimensional thickness of the stock tunnel brace. The stock brace being 1/16" thick seems to function more as a strap and slash shield, than a brace.

Were you able to reuse the stock bolts on your 3/8" thick brace?

If I find a used one with a shipping cost that doesn't ruin the deal, I will buy it. I am open to either 1/4 or 3/8 inch material thickness. If I don't find a used one by the time I am done with everything else I want and need to do with our base Sky, I just may order a new one from DDMWorks. But that would be a number of months away. In the mean time, I will post my request in the "Wanted" section.

Thanks again!
Yup - Stock bolts reused with a fresh application of thread lock.

The OEM brace is steel and although it is able to be twisted a bit when in your hands, it did have some rigidity due to the sides being bent over and a couple structural "corrugations" (for lack of a better term). Once bolted to the vehicle, I would think it's even more rigid. But still... there are a lot of forces working to flex that thin metal. The 3/8" aluminum plate is super rigid just being flat and probably weighs 3 or 4 pounds more than the OEM plate.

I would bet this piece is mostly structural, but like I said before: that's just a guess based on what I read. Why else would they put it in there? Adding material just for the sake of covering up the driveshaft seems like a waste of weight and money if it didn't have some sort of performance benefit. Without a roof, cars lose a lot of structure to counter twisting and flex. Other forums and discussions on this topic have comments made by some that were involved in testing these cars before production and they seem to indicate the tunnel brace is indeed structural.
 
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