Pfadt Coilovers ... These are a good bit heavier than the stock shocks. The total weight of the stock shocks and springs are about the same as the coilovers. I'm a little concerned about adding that much unsprung weight, but so far I've only seen an improvement....
I strongly disagree with your assessment of the shock weights. I weighed my stock springs, brackets, bolts, and shocks when I put on Aaron's coilovers. The Pfadts are almost exactly 5 lbs lighter front and back. For a total savings of 10 lbs. The difference is the weight of the stock components was closer to the center of the car. So the Pfadts offer better performance, lighter overall weight, and adjustability. The only downside is that the springs(weight) are now closer to the corners of the car. My guess is that the 10 lb loss is more important than the weight moved to the corners.
Pfadt Coilovers ... These are a good bit heavier than the stock shocks. The total weight of the stock shocks and springs are about the same as the coilovers. I'm a little concerned about adding that much unsprung weight, but so far I've only seen an improvement....
I strongly disagree with your assessment of the shock weights. I weighed my stock springs, brackets, bolts, and shocks when I put on Aaron's coilovers. The Pfadts are almost exactly 5 lbs lighter front and back. For a total savings of 10 lbs. The difference is the weight of the stock components was closer to the center of the car. So the Pfadts offer better performance, lighter overall weight, and adjustability. The only downside is that the springs(weight) are now closer to the corners of the car. My guess is that the 10 lb loss is more important than the weight moved to the corners.
Dog
My concern was unsprung weight and these coilovers are substantially heavier than the stock shocks. Twice as heavy if I remember correctly.
The little weight savings you get is in the removal of the leaf springs and I don't think that really counts as unsprung (correct me if I'm wrong) due to the design.
Technicalities aside, I've only felt an improvement over the stock components for the way I use my car.
Maybe Aaron will chime in here and educate us on this subject.
Raise the CG (albeit only slightly since they are mounted higher than the stock springs)
Unsprung weight is any mass that is not supported by the springs such as the shocks, a-arms, spindles, wheels, tires, brake calipers and pads, etc. Coilover springs thus add unsprung mass as there are no springs supporting them and the springs themselves are part of the shocks since they are integral to them.
The stock springs are actually a rather brilliant design. Springs support the body of a car, right? What is the body attached to? Correct, the chassis. And where are the stock shocks attached to on the upper end? That's right, the chassis of the car. Therefore, their mass is partially supported by the leaf springs, indirectly.
The stock leaf springs are also mounted as low as possible, and thus their mass is also as low as possible which helps keep the CG as low as possible in return.
They are also easy to adjust for ride height, although they don't have the range of motion coilovers offer.
In addition to offering a greater range of adjustment, coilover springs are less expensive than the stock leaf springs. If one changes spring rates frequently they offer are a definite cost benefit. However, changing springs on a coilover, although not difficult, is not as quick nor easy as some may think. Changing leaf springs is about the same level of difficulty. Neither is hard so it's virtually a wash.
Adjusting corner weights on the stock leaf springs is simplicity itself: turn a nut after first lifting the spring end off the lower a-arm. With coilovers you use a spanner wrench, which is often unique to the coilovers, and turn the perch adjusters. Simple enough, but not as simple as the OEM design. Try and find the right spanner wrench in anytown USA...at 10 pm on a Sunday night. It's no problem finding a wrench to turn the stock adjusters. If you think this is a non-issue, think again and ask me how I know. Again, it's a compromise. More of one thing for less of something else.
The GM engineers did a good job designing the suspension. There are reasons they have stayed with it for this long. Likewise, there are reasons Pratt & Miller use it on their $200,000+ C6RS, although in addition they use airbags for ride height adjustment on the fly. They could have used any almost suspension they wanted at that price, yet they didn't. There are reasons Callaway uses the leaf springs although they also use a coilover helper spring to aid the shock damping. Here's what Callaway says, in part....
Quote:
"Callaway engineering's position is that the stock C6 Corvette chassis is not adequate to support the stresses transmitted through the shock absorber mounts once the leaf springs are eliminated. The issue isn't the ability to carry the car's static load or its ability to withstand the dynamic stresses applied to the shock mounts with a new chassis. The engineers' concern is structural fatigue that can result in and around the upper shock mounts after typical forces are applied repeatedly through the mounts over an extended period of time."
Perhaps the most important aspect of that statement being "structural fatigue that can result in and around the upper shock mounts after typical forces are applied repeatedly through the mounts over an extended period of time."
That is due to the fact, with the C6Z at least, the chassis is aluminum vs. steel. The fatigue life of aluminum is less, often much less, than steel depending on alloy and other factors and there is no avoiding that fact.
I'm not going to go into the mettalurgical properties of various aluminum alloys, hydroforming processes and the structural design aspects of the aluminum chassis vs. a steel one, nor start speculating about detailed design criteria. If one really wants to get into it then I suggest contacting Mr. William Kroppe, director, product engineering, Dana Structural Solutions, Inc. who produce the Z06 aluminum frames and inquire.
Seriously, call Pratt & Miller and ask 'em: "Why don't you use coilvers on the C6RS?" You saw what Callaway says; you know what GM is using. Maybe they're all wrong and have no idea what they're doing. However, ask yourself this: If they're all wrong and are terrible engineers who couldn't design a proper bicycle suspension, then why did you buy the car??? Mind you, a car that lapped the Nurburgring how fast (although only one lap) and it isn't good enough? I agree there were issues with that lap and in fact the car, as no car is perfect, but it sure gets touted a lot for a car needing so many modifications in order to be improved upon. That strikes me as being rather illogical.
My concern was unsprung weight and these coilovers are substantially heavier than the stock shocks. Twice as heavy if I remember correctly.
The little weight savings you get is in the removal of the leaf springs and I don't think that really counts as unsprung (correct me if I'm wrong) due to the design.
Technicalities aside, I've only felt an improvement over the stock components for the way I use my car.
Maybe Aaron will chime in here and educate us on this subject.
Basically our shocks weigh about the same as the factory shocks. Because they are non-inverted like the factory parts, the unsprung mass of the shocks should be very similar to the stock parts.
When you begin to account for the springs it gets more fuzzy. Most people treat coil springs as half sprung mass and half unsprung mass for simplicity. It is a good assumption. The leafs are a little heavier than the coil springs, so the overall mass is less in the coilover system. The leafs probably are more sprung mass than unsprung because they are held to the chassis and a smaller portion of the spring actually moves with the control arms.
The actual 'pounds' of unsprung mass is probably very similar. This discussion is primarily academic when dealing with production based cars. The difference from one system to another is very hard to quantify in analysis and even under testing.
The important differences between coilovers and leaf spring setups (functionally at least) involve some friction differences and practical issues of spring rate choices. You are very limited in spring rate choices with leafs and if you are tuning a race car it is nice to be able to change quickly in small increments.
Trying to equate what is 'best' to what GM puts on the car is an exercise in delusion. As a former GM engineer, I can tell you that many factors go into the decision about what makes it into a car and what does not. What works best is not generally one of those factors. What costs less is. Cars, even Corvettes and the C6RS are very subject to meeting the performance benchmark and meeting the cost target. When push comes to shove, the cost target does not move. The C6RS is especially handicapped in terms of new parts because they only have 200 units to amortize any additional tooling costs over. I'd bet money that it got Z06 suspension bits.
Cars can be fast and work well with either leaf springs or coilovers. Our Pfadt coilovers happen to be a one stop solution several suspension shortcomings on the Corvette. Those being poor damping from production shocks, too soft of spring rate and limited ride height adjustability.
We're always available to chat about this stuff personally. Just drop a PM or give a call.
Very nice and juicy. The paint looks like it's gonna drip....
Love the look at 2 fingers I can barely get in and out of my driveway with 3 fingers.
<edit> ... AND a response after reading further and getting a lesson on the benefits and negatives of coilovers... Excellent stuff. So, what about a combo coil over and light duty leaf. Splitting the difference between the two. Although I guess this is more applicable to the C6 than a C5.
Stock bars for now. I will consider the adjustable ones if & when I start doing HPDEs. According to Aaron, the stock ones are fine for spirited street use and low speed auto-x. A little body roll is good for the slower stuff.
Seriously, call Pratt & Miller and ask 'em: "Why don't you use coilvers on the C6RS?" You saw what Callaway says; you know what GM is using. Maybe they're all wrong and have no idea what they're doing. However, ask yourself this: If they're all wrong and are terrible engineers who couldn't design a proper bicycle suspension, then why did you buy the car??? Mind you, a car that lapped the Nurburgring how fast (although only one lap) and it isn't good enough? I agree there were issues with that lap and in fact the car, as no car is perfect, but it sure gets touted a lot for a car needing so many modifications in order to be improved upon. That strikes me as being rather illogical.
Thanks for your input, No Doubt. I appreciate your knowledge about these cars, but I can't understand why your so hellbent on insisting any deviation from the stock suspension is a mistake
The stock suspension is quite adequate and I've never stated otherwise.
The whole reason I switched to the Pfadt setup is because I wanted to lower my car beyond what is achievable with the stock components and not get a bumpy, jarring ride. I read several reviews on the Corvette Forum from users that were raving about them. It's all true... better ride quality, better (SOP) handling and elimination of wheel hop.
As far as safety is concerned, show me one C5 or C6 that has broken an upper shock mount using coilovers.
I have Pfadt coilovers and sway bars front and rear and the difference is like night and day. The car is much more responsive now and the ride has not suffered.
Congrats on the mods, car looks BAD!
I have the Pfadt C/O's, Pfaddy bars amd poly bushing too.
I like this shot the best.
Frank
Quote:
Originally Posted by Z06phile
I just hit my Z with another round of mods.
Pfadt Coilovers (stay tuned for a full street review) adjusted to 2 fingers worth of fender gap. The C/R settings are at 8 F & 8 R now, but I'll be changing the rear to 5 or 6. These are a good bit heavier than the stock shocks. The total weight of the stock shocks and springs are about the same as the coilovers. I'm a little concerned about adding that much unsprung weight, but so far I've only seen an improvement.
The iForged Aeros are beautiful and pictures don't really do them justice. I had to wait 11 weeks for them and yes it was worth it. The rear 19x11 weighs about 25lbs and the front 18x9.5 is 22lbs. They are much lighter than they appear. The tires are 305/30/19 and 265/35/18 Yokohama Advan Sports.
I haven't really pushed the Advans yet, but I can already tell that they're no match for the stroker. Traction isn't anywhere near the Nitto RIIs, but this is my street setup and I was prepared for this.
The SLP Power-Flo Exhaust is awesome. Very easy install, perfect fit and no more misaligned tips. This is my 3rd exhaust system and so far I like it the best. They nudge the Borla Stingers out for my favorite sounding exhaust. These have a crisper and more mid-range tone... kinda exotic at WOT, but still rumbly at idle.
The DEPO Black/Amber Corner lenses are nice. The fit is perfect and this looks like it could've came from the factory. Not too dramatic, but a nice subtle change. The stockers look dull in comparison.
I'll make a vid soon, so y'all can hear the new pipes.
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