[Z06] Why does Chevy use transverse leaf springs?
05-09-2016, 10:32 PM
#21
Well damn, I had a lot typed out then my battery died and took my edits with it.
Anyway, short(er) version:
I think it's safe to assume at Corvette type volumes any coil spring would cost GM less than the leaf springs they are using. Also, if you read All Corvettes are Red the author notes that GM was looking at even using pushrod-bell crank setups to get the packaging they wanted.
I suspect that basically any coil spring that the aftermarket fits to the car would probably fail at least one of GM's longevity tests. I'm guessing that either the springs are stressed to the point that they wouldn't survive GM's cycle life requirements (increasing the stress in the spring effectively allows a smaller/lighter spring to act like a bigger one but reduces the cycle life). I could also see issues with corrosion resistance being an issue. Most Corvettes are going to live pampered lives in terms of exposure to salt and the like but GM probably doesn't relax specs just because the car is a Corvette and probably will be treated better than a Cruze. So an aftermarket spring might be made from a type of steel that, when subjected to what ever GM tests, rusts in "12 years" or fails due to fatigue after "12 years" of simulated driving. For an aftermarket produce a "12 years of use" test is a lifetime or two. For an OEM part, expected to last under daily use, that's a class action lawsuit in the making.
The Kappa chassis has been mentioned as a point of comparison. I agree with those who say the Kappa was clearly related to the C5-C7 designs. I don't think GM would call it the same architecture but one look and you can tell the engineers had Corvette CAD models on their computers.
Anyway, one of the places where the designs differ a bit is the height of the spring perches. I suspect the Kappa got away with the coil springs because the upper shock mounts are a few inches above the upper A-arm mount and the hood height of the Kappa was higher.
C7
Kappa
Note that it looks like the mounting point of the Kappa damper is higher with respect to the upper A-arm mounts. Also note that thanks to the large coil diameter the edge of the mount is quite a bit higher. I'm assuming if GM wanted they could probably fit the same diameter coil on the Corvette (maybe) but we also need to remember the Kappa is a lighter car thus can get away with a lighter spring.
One final note, the article linked above (copied below)
http://tech.corvettecentral.com/2012...vers-vs-leafs/
sadly contains some serious BS engineering claims by the aftermarket vendor.
A quote like that should make anyone run away because either the guy has no clue or he isn't telling you the truth. The Corvette spring is clamped in two locations so that pulling up on one side "pulls up" the other side. Earlier in the article they got it right (ie the anti-roll bar effect). Why the author didn't challenge the BS claims I don't know. Anyway, that cross-talk sea-saw discussion was total bullsht. The "cross talk" is true but it's the exact same cross talk you get from a sway bar.
Anyway, short(er) version:
I think it's safe to assume at Corvette type volumes any coil spring would cost GM less than the leaf springs they are using. Also, if you read All Corvettes are Red the author notes that GM was looking at even using pushrod-bell crank setups to get the packaging they wanted.
I suspect that basically any coil spring that the aftermarket fits to the car would probably fail at least one of GM's longevity tests. I'm guessing that either the springs are stressed to the point that they wouldn't survive GM's cycle life requirements (increasing the stress in the spring effectively allows a smaller/lighter spring to act like a bigger one but reduces the cycle life). I could also see issues with corrosion resistance being an issue. Most Corvettes are going to live pampered lives in terms of exposure to salt and the like but GM probably doesn't relax specs just because the car is a Corvette and probably will be treated better than a Cruze. So an aftermarket spring might be made from a type of steel that, when subjected to what ever GM tests, rusts in "12 years" or fails due to fatigue after "12 years" of simulated driving. For an aftermarket produce a "12 years of use" test is a lifetime or two. For an OEM part, expected to last under daily use, that's a class action lawsuit in the making.
The Kappa chassis has been mentioned as a point of comparison. I agree with those who say the Kappa was clearly related to the C5-C7 designs. I don't think GM would call it the same architecture but one look and you can tell the engineers had Corvette CAD models on their computers.
Anyway, one of the places where the designs differ a bit is the height of the spring perches. I suspect the Kappa got away with the coil springs because the upper shock mounts are a few inches above the upper A-arm mount and the hood height of the Kappa was higher.
C7
Kappa
Note that it looks like the mounting point of the Kappa damper is higher with respect to the upper A-arm mounts. Also note that thanks to the large coil diameter the edge of the mount is quite a bit higher. I'm assuming if GM wanted they could probably fit the same diameter coil on the Corvette (maybe) but we also need to remember the Kappa is a lighter car thus can get away with a lighter spring.
One final note, the article linked above (copied below)
http://tech.corvettecentral.com/2012...vers-vs-leafs/
sadly contains some serious BS engineering claims by the aftermarket vendor.
... continued by giving us this great example; “Imagine that you have a beam, pivoting upon a single point like a see-saw. For our purposes, imagine it is actually clamped down to the pivot point. When you pull down on one side, the other side naturally wants to move upwards with about the same amount of force.”
05-10-2016, 01:32 PM
#22
Le Mans Master
I think if some would also look at the core chassis design, and how it manages it's torsional stiffness, the leafs have an advantage on how they act upon the chassis. The mounting points have the springs acting very low on the subframe, and in a narrow configuration that works in unison with the tunnel structure and reinforced center structure designed into Corvette. For a street car, used in the fashion that the majority use it, I do feel it's hard to beat. This design logic goes to the inception of C5 and really took full advantage of the leafspring idea. Furthermore, GM has really led the mass production pack in using dampening technology to really supplement spring rate. This give great road compliance with a myriad of different "attitudes" controlled by the mag ride.
Coilovers have their place, in that spring rates are easily changed, the technology is readily available to the aftermarket to produce, etc. Making a composite leaf spring isn't really a known game and GM has been doing it for decades. As with the T1 stuff, molds were required, specialized manufacturing required, etc. With coilovers you're talking cnc, off the shelf springs, etc....anyone with reasonable equipment can build a coilover, especially when utilizing china manufacturers.
Those that are "anti" leafspring are typically bandwagoners listening to media mainstream thinking and don't like the term "leafspring". If you look at the design and overall benefits, for a street based platform, it's what makes Corvette unique and I don't think Corvette has been having trouble in the handling game.
Coilovers have their place, in that spring rates are easily changed, the technology is readily available to the aftermarket to produce, etc. Making a composite leaf spring isn't really a known game and GM has been doing it for decades. As with the T1 stuff, molds were required, specialized manufacturing required, etc. With coilovers you're talking cnc, off the shelf springs, etc....anyone with reasonable equipment can build a coilover, especially when utilizing china manufacturers.
Those that are "anti" leafspring are typically bandwagoners listening to media mainstream thinking and don't like the term "leafspring". If you look at the design and overall benefits, for a street based platform, it's what makes Corvette unique and I don't think Corvette has been having trouble in the handling game.
Last edited by RC000E; 05-10-2016 at 01:35 PM.
03-01-2018, 06:56 PM
#23
Intermediate
yea but what about the aftermarket mono springs?
Hello-
I get it that Chevrolet knows the benefits of the transverse front spring and rear mono, since they have been doing it since 1984.. What i am trying to find out is on a C-2 upgrade that has a big block and C-5 disc brakes, all 4 wheels and the offset trailing arms, does the Vette Brake Products setup, transverse front, rear mono, stand up in quality to the factory? Engineering wise I wonder how good the aftermarket coilover setups are like Sharkbite and ridetech, since they are bolt on how robust are they??? I want to improve handling and will NOT be racing on a track except drags a few times in the summer. Looking for the BEST solution. The coil over guys all love coilovers & the transverse guys that have upgraded C-2's & C-3's tell me they like their setup. Does VBP have the best or are there any other vendor solutions? They (transverse vs coilover)seem to be almost the same price but I like the idea of reducing weight, where the transverse setup seems to have an advantage over coilovers. Unbiased Chime ins welcome.
I get it that Chevrolet knows the benefits of the transverse front spring and rear mono, since they have been doing it since 1984.. What i am trying to find out is on a C-2 upgrade that has a big block and C-5 disc brakes, all 4 wheels and the offset trailing arms, does the Vette Brake Products setup, transverse front, rear mono, stand up in quality to the factory? Engineering wise I wonder how good the aftermarket coilover setups are like Sharkbite and ridetech, since they are bolt on how robust are they??? I want to improve handling and will NOT be racing on a track except drags a few times in the summer. Looking for the BEST solution. The coil over guys all love coilovers & the transverse guys that have upgraded C-2's & C-3's tell me they like their setup. Does VBP have the best or are there any other vendor solutions? They (transverse vs coilover)seem to be almost the same price but I like the idea of reducing weight, where the transverse setup seems to have an advantage over coilovers. Unbiased Chime ins welcome.