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Thanks JohnWR and the gang for your input.

With exception to drivetrain and exhaust noise, my rear half is quiet. All of my creaks and squeaks appear to originate up front. Can anyone comment on DDM products (Backbone, ProBeam, Chassis Brace) positively or negatively effecting the "front half" of your Sky?
 

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....after removing the GM backbone....u can view how cheap it was made...not saying that the GM backbone did not do it's job....just indicates how GM made all parts to a minimum standard....cost engineering
Actually, that GM part was quite sufficient for what it was designed to do. Remember it was a "tunnel cover", nothing more. Just a substantial layer of sheet metal placed there to protect the driveshaft from getting gunked up with road debris. Originally not intended to be a brace of any kind.

No "creak or squeaks" from this 2007 Redline.
 

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Actually, that GM part was quite sufficient for what it was designed to do. Remember it was a "tunnel cover", nothing more. Just a substantial layer of sheet metal placed there to protect the driveshaft from getting gunked up with road debris. Originally not intended to be a brace of any kind.

No "creak or squeaks" from this 2007 Redline.
Never let facts get in the way of a good GM bashing!
 

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Actually, that GM part was quite sufficient for what it was designed to do. Remember it was a "tunnel cover", nothing more. Just a substantial layer of sheet metal placed there to protect the driveshaft from getting gunked up with road debris. Originally not intended to be a brace of any kind.

No "creak or squeaks" from this 2007 Redline.
Perhaps it served a double purpose....
 

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I just installed the DDM brace set with the 3/8" back bone last month after I got a good price from someone selling it NIB. It was on my list of future mods, but I wasn't in any hurry, of course when a good price comes along that changes things. Since I installed all 3 at the same time I can't really speak to what did what, I have my suspicions though. Driving my RL prior to the brace install it felt like there was a lot of excess body roll and the rear end wanted slip a lot when I was going around a corner quickly, this was even more exacerbated after I had the tune done. After the brace set installed, it still feels that way, but maybe not as noticeable as before I don't know if it's placebo or not. The biggest difference I have noticed, is the side to side going down an uneven road. The body has less roll and flex IMO. I pulled the front Venom brace a couple weeks ago to paint it and I didn't notice any difference on or off. I'm sure if I autocrossed it would be more noticeable, but otherwise I would argue the braces do address a need, but other than converting to a coupe I think there is only so much improvement that can be expected. If someone has the time and money, then by all means go for it would be my recommendation.
 

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What does "converting to a coupe" have to do with it?
but other than converting to a coupe
What does that have to do with this issue?

The coupe is nothing more than a two piece top installed on a convertible body. I doubt that it stiffens up the body at all.

:dunno:

.
 

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What does "converting to a coupe" have to do with it?


What does that have to do with this issue?

The coupe is nothing more than a two piece top installed on a convertible body. I doubt that it stiffens up the body at all.

:dunno:

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I wasn’t inferring slapping on a Smooth Line hardtop and calling it a coupe. Convertibles will always have more twist in the body than a coupe. I was iterating that someone shouldn’t expect to have a convertible and then slap on a stiffening brace and expect to have the same results of that of a coupe.
 

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If anyone is selling a second hand heavy duty backbone brace near Chicago at a deal of a price, I would buy it and replace my thin stock tunnel cover with it to see if it helps to reduce any of my creaks and squeaks. I don't want to spend much on something that may have no positive effect.

If I could pick and choose, I would like the 3/8" solid version to fully enclose with higher strength.
 

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I’m not going to say it.... I’m just going to think 🤔 it...... with my luck a TOS violation. Just think 💭 what Johnny Carson or Groucho Marx would say..... in response to marlboromikes reply...
Karnak would open the envelope....and Groucho, You Bet Your Life.... (y) But Al Bundy would look and run away from Peg
 

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I don't suppose we have any actual evidence of what the stock pan was meant to accomplish? Like what it was called in the parts list, or....

A lot of modern cars use thin sheet metal panels under them for streamlining to lower air resistance and increase fuel mileage, and I'm sure that some have stiffeners but it isn't always easy to know what they intended with a given item. I'd probably guess that the stock Solstice panel was just to keep road garbage out of there, maybe to aid lowering air resistance, but I wonder about it being a stiffener.

I can, however, imagine the conversation around the development of the factory rear suspension cage when they got the torsional stiffness results on the stock chassis. "Well that's really crappy - we need to do some serious work if we are going to have these cars run in competition" "Yup, but we saved X millions by building a Flexible Flyer and the average buyer is too thick to realize the car could have been better."
 

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It is called a "floor closeout panel" or just a "panel" in the service manual.

So, Bill, what is your opinion as to why I find the car to be faster on roads (not on the track) without the backbone than it is with it? Am I not a good enough driver, or am I too thick to properly use my stopwatch?
 

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Maybe if I were a suspension engineer I could venture an opinion that meant something, but best to admit ignorance and join you in wondering why that phenomenon you have observed happens and how it is explicable if we only knew enough about engineering.

It would be interesting if what you observe also happens if you run the cars on a parking lot slalom course (i.e. lower speeds than on a track).

I'm still scratching my head trying to figure out how Morgans I raced against, that have a sliding pillar front suspension invented in 1898 could possibly have handled as well as they did.
 

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My opinion is that stiffer isn't necessarily faster, and that what "feels fast" frequently isn't. The introduction of "real world" ie: uneven or broken surfaces to the operation of a vehicle complicates the situation well beyond the textbook operation of the suspension.

Slight variations in suspension geometry from chassis twist can cause significantly smaller handling issues than can the rapid loading or unloading of a particular tire when a single-wheel bump is encountered. That is in addition to the harsh movements that can result in the driver having to concentrate on maintaining position in the car rather than controlling the car on the road.

I have worked with a lot of amateur race drivers in the capacity of amateur race engineer, and the hardest thing to do with any of them has been to get them over the concept that "feeling fast" equates to "being fast". The stopwatch (or g-tech, or GPS) always trumps the seat of the pants.
 

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That is for sure. When I started racing, whenever I'd come in and say 'that sure felt fast' most of the time it wasn't. I found that as I got to be a smoother more observant driver less prone to great looking (but slow) sliding through corners, I just kept getting faster. The process took me maybe a half dozen races. I had competition that was just enough faster than I was that it induced my inclination to try harder, but that was often counter productive.

You are right that many racers opt for too stiff suspension setting on the track and if you are on a bumpy surface that just isn't useful. I saw a guy in our MG club run a slalom (not serious, just for fun) and do quite well with an MG TC, which had a beam axle up front. On a course s smooth as a billiard table it did amazingly well. Put it on a bumpy track and it was a handful.

Another interesting thing I noticed was that on our local fairly bumpy track, when they allowed the larger engined karts to run on the big track (they normally ran on an adjacent smaller track) the ones with the stiffest chassis had a hard time while the ones with the flexible chassis did quite well (for those not familiar with karting, they ran engines with enough power to get them up near 100 mph on the big track but had absolutely no suspension - chassis flex was it.

I think that your observation that the less stiff Kappa suspension makes for a just as fast/faster and more comfortable street ride than the uprated suspensions makes a lot of sense, actually. I've seen quite a few people having a great deal of trouble with overly stiff settings (why do people that buy fancy shocks immediately want to set them to full stiff???)

I have corresponded by PM with several Kappa owners that went to the same shocks I recommend, the BC Racing units, and they almost always ignore my advice on stiffness settings (which in my case are fairly soft for compliance on the street). Guess they, too, figure that being 'racy' requires the stiffest settings....
 
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