Cut my SFC's out
10-03-2013, 09:04 PM
#1
Cut my SFC's out I had my tubular SFC's welded on back in 2002-2003, when everyone said it was a must or your car may snap in half. It was the first thing I did to my suspension. I noticed a much firmer ride after and it seemed to handle better with everything 'tightened up'.
When I decided to go further with my suspension in 2008 I installed Bilstein re-valves with Hotchkis springs. After that the ride was very harsh, I felt every single little bump and it was just annoying to drive on anything but a smooth surface. But I figured that was just the price of a well suspended car so I lived with it for 5 years.
I read some threads recently with more info on SFC's and how they were a band-aid fix to get a car to handle well before doing the important parts of the suspension. I was also fed up with the ride quality and looking to do some weight reduction.
So yesterday I took a chance and spent a few hours with my angle grinder....got them out pretty clean too. Took my car for a 15 minute drive and the difference in ride quality was a huge improvement. I can't explain how much more enjoyable the car is to drive now. I'm still on the stock sway bars so those are probably next.
Anyway, I just wanted to share my experience after having them on my car a very long time in case people are wondering about them or on the fence...I also lost ~18lbs.
When I decided to go further with my suspension in 2008 I installed Bilstein re-valves with Hotchkis springs. After that the ride was very harsh, I felt every single little bump and it was just annoying to drive on anything but a smooth surface. But I figured that was just the price of a well suspended car so I lived with it for 5 years.
I read some threads recently with more info on SFC's and how they were a band-aid fix to get a car to handle well before doing the important parts of the suspension. I was also fed up with the ride quality and looking to do some weight reduction.
So yesterday I took a chance and spent a few hours with my angle grinder....got them out pretty clean too. Took my car for a 15 minute drive and the difference in ride quality was a huge improvement. I can't explain how much more enjoyable the car is to drive now. I'm still on the stock sway bars so those are probably next.
Anyway, I just wanted to share my experience after having them on my car a very long time in case people are wondering about them or on the fence...I also lost ~18lbs.
10-04-2013, 12:50 AM
#2
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So chassis flex is real, you've proved it, and out of the two options, you've chosen to have it? I don't get it. Probably never will. Plus wrinkled rear quarters are very real, and I don't want them.
10-04-2013, 04:43 AM
#3
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Also quarter panel torque dents are not prevented by SFC's.
10-04-2013, 07:12 AM
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10-04-2013, 08:23 AM
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While not always true (IE: Shelby Cobra handled really well but was a "wet noodle" of a chassis and flexed like no body's business); typically a stiffer chassis means better handling (harsher ride though) as long as the suspension is designed, setup, and performing properly.
It's a balancing act between flex and stiffness. Super stiff is bad, super flexible is bad.
10-04-2013, 10:45 AM
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Not true... more flex in the chassis (unibody, whatever); means the chassis is bending and moving more; thus the suspension is moving mess; this "typically" means a softer less-harsh ride with some trade-off in performance.
While not always true (IE: Shelby Cobra handled really well but was a "wet noodle" of a chassis and flexed like no body's business); typically a stiffer chassis means better handling (harsher ride though) as long as the suspension is designed, setup, and performing properly.
It's a balancing act between flex and stiffness. Super stiff is bad, super flexible is bad.
While not always true (IE: Shelby Cobra handled really well but was a "wet noodle" of a chassis and flexed like no body's business); typically a stiffer chassis means better handling (harsher ride though) as long as the suspension is designed, setup, and performing properly.
It's a balancing act between flex and stiffness. Super stiff is bad, super flexible is bad.
I understand where a sfc ends and where a 1/4 wrinkles. Cars with sfcs generally do not get the wrinkles. Again, generally speaking. I will tote the extra 25 pounds for the piece of mind. Not trying to knock what you did, I think the whole community is a better place with real world experience threads like this.....doesn't mean we will all understand them. But hey, that's how conversations are started right?
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10-06-2013, 02:15 PM
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im going to have to disagree with super stiff is bad. i have never worked on a race car that wasn't extremely stiff(you can jack it up and put jack stands under 3 corners and it wont even be touching the 4th because it is so stiff it holds it self up off it) the stiffer the better because you don't have chaise flex changing the suspension geometry. now this makes for a back breaking ride but it does wonders in the track
10-07-2013, 10:29 AM
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im going to have to disagree with super stiff is bad. i have never worked on a race car that wasn't extremely stiff(you can jack it up and put jack stands under 3 corners and it wont even be touching the 4th because it is so stiff it holds it self up off it) the stiffer the better because you don't have chaise flex changing the suspension geometry. now this makes for a back breaking ride but it does wonders in the track
Just because it's super stiff doesn't mean it's the best.
The chassis HAS to have some flex, if it didn't it would crack and fail; metal bends and flexes, just the nature of the material. It's controlling the flex and putting the right amount of flex in the right spot for the application that's the "trick" in the engineering of the chassis and suspension.
NOTE - why do you think professional race cars are only used for a certain number of races, and are then retired? Cyclical bending/flexing of the chromoly steel that's used in the chassis using up its fatigue life is one of the reasons.
10-07-2013, 01:12 PM
#11
I'm not here to argue, but there is a ton of misinformation in the previous post. When it comes to performance cars, stiffer is better. The Shelby cobra didn't win races because of supreme handling, it was lighter and more powerful than its competition. Please don't compare a 50 year old car to a modern one. Race car design has changed a lot in 50 years. Also, race cars are retired because they become obsolete, not because they have fatigued and fallen apart. Spend a weekend on any track, and you will see numerous retired race cars, still making laps without issue. If a chassis is properly designed and welded, there should be no issue. Yes, chromoly is more brittle than mild steel, however the only time that should be an issue is during a severe impact.
10-17-2013, 11:56 AM
#15
This has always been, and will always be a hot button issue.
That said, the man stated his findings. And he's not the first. In fact I've seen cars go faster autocrossing without SFC's than with them. And as much as folks always want to say stiffer is better, that's not always the case in reality as much as it is on paper.
First, the notion that these cars will fall apart and twist in half isn't true. In fact the car was designed to be a convertible from the get go. My 2001 Z28 which I won a number of National Championships in on very big, sticky tires, didn't have SFC's, and didn't need them. In fact they guy who bought the car and competes in it bought SFC's, but them on and then took them back off.
The simple fact of the matter is these are not RACE CARS. We cannot do whatever we want to suspension geometry. And chassis stiffness means other changes, every time you see a new stock car get stiffer, you see a myriad of other changes to bushings, dampers, springs, bars, etc.
Here's the dirty secret.... when you make a chassis stiffer you take a bit of a spring out of the system. That generally means you want the car a sprung a bit softer. Another reason I don't run 25mm rear bars, and big rear springs, etc. In fact my front springs are softer than many other street rates.
Looking at it another way: You can never make the car have no flex at all. How much is enough? When do you say when? I'll tell you that a car that gets drag raced a lot and has some power to leave really hard is a great candidate for SFC's to help with the body twist under those hard launches. There are no absolutes.
Why do cars with lousy shocks feel better with SFC's? Simple, because the shocks do a lousy job damping impacts. Impacts that aren't damped get to the body and make it quiver like a big tuning fork. So why do guys with good shocks not see the massive difference? Easy... because better shocks damp impact harshness much more effectively and they don't get into the body to make it quiver and shake.
And as for the quarter panel dimples. Seen them show up on cars with SFC's. Seen them not show up on cars without SFC's. Because the SFC's have nothing to do with it. Look at where SFC's connect, nowhere near the quarter panels. Watch a car wheelhop and you can see the quarters flex like mad, which is where the dimples come from.
That said, the man stated his findings. And he's not the first. In fact I've seen cars go faster autocrossing without SFC's than with them. And as much as folks always want to say stiffer is better, that's not always the case in reality as much as it is on paper.
First, the notion that these cars will fall apart and twist in half isn't true. In fact the car was designed to be a convertible from the get go. My 2001 Z28 which I won a number of National Championships in on very big, sticky tires, didn't have SFC's, and didn't need them. In fact they guy who bought the car and competes in it bought SFC's, but them on and then took them back off.
The simple fact of the matter is these are not RACE CARS. We cannot do whatever we want to suspension geometry. And chassis stiffness means other changes, every time you see a new stock car get stiffer, you see a myriad of other changes to bushings, dampers, springs, bars, etc.
Here's the dirty secret.... when you make a chassis stiffer you take a bit of a spring out of the system. That generally means you want the car a sprung a bit softer. Another reason I don't run 25mm rear bars, and big rear springs, etc. In fact my front springs are softer than many other street rates.
Looking at it another way: You can never make the car have no flex at all. How much is enough? When do you say when? I'll tell you that a car that gets drag raced a lot and has some power to leave really hard is a great candidate for SFC's to help with the body twist under those hard launches. There are no absolutes.
Why do cars with lousy shocks feel better with SFC's? Simple, because the shocks do a lousy job damping impacts. Impacts that aren't damped get to the body and make it quiver like a big tuning fork. So why do guys with good shocks not see the massive difference? Easy... because better shocks damp impact harshness much more effectively and they don't get into the body to make it quiver and shake.
And as for the quarter panel dimples. Seen them show up on cars with SFC's. Seen them not show up on cars without SFC's. Because the SFC's have nothing to do with it. Look at where SFC's connect, nowhere near the quarter panels. Watch a car wheelhop and you can see the quarters flex like mad, which is where the dimples come from.
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2023 UMI King of the Mountain Champion
10-17-2013, 10:57 PM
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The SFCs hook to the LCA mounting point which is what the rear end is pushing on. Obviously upward and twisting thrust come from the TA nose and sway bar body mounts. Makes sense in your head that SFCs would help the problem.......But, why are the rear 1/4s flexing to begin with?
10-18-2013, 06:23 AM
#17
Because they're unit body cars, and react to constant, exxtreme suspension loads applied to them. Back "in the day", when a couple of my friends drag raced 1st gen Camaros ('68 and 69s), you could always tell one that had been dragged. The panel between the trunk lid and back window would be a bit twisted....
10-18-2013, 10:34 AM
#18
Here's the dirty secret.... when you make a chassis stiffer you take a bit of a spring out of the system. That generally means you want the car a sprung a bit softer. Another reason I don't run 25mm rear bars, and big rear springs, etc. In fact my front springs are softer than many other street rates.
This is probably the best way to describe it. It seems now the springs / shocks can do the job I bought them for.
I realize SFC's have their place, but for me all I do is go to car shows and take her out for cruises to relax and possibly find 3 or 4 races a year. Last time I took my car to the track was 2002.
10-18-2013, 06:02 PM
#20
This has always been, and will always be a hot button issue.
That said, the man stated his findings. And he's not the first. In fact I've seen cars go faster autocrossing without SFC's than with them. And as much as folks always want to say stiffer is better, that's not always the case in reality as much as it is on paper.
First, the notion that these cars will fall apart and twist in half isn't true. In fact the car was designed to be a convertible from the get go. My 2001 Z28 which I won a number of National Championships in on very big, sticky tires, didn't have SFC's, and didn't need them. In fact they guy who bought the car and competes in it bought SFC's, but them on and then took them back off.
The simple fact of the matter is these are not RACE CARS. We cannot do whatever we want to suspension geometry. And chassis stiffness means other changes, every time you see a new stock car get stiffer, you see a myriad of other changes to bushings, dampers, springs, bars, etc.
Here's the dirty secret.... when you make a chassis stiffer you take a bit of a spring out of the system. That generally means you want the car a sprung a bit softer. Another reason I don't run 25mm rear bars, and big rear springs, etc. In fact my front springs are softer than many other street rates.
Looking at it another way: You can never make the car have no flex at all. How much is enough? When do you say when? I'll tell you that a car that gets drag raced a lot and has some power to leave really hard is a great candidate for SFC's to help with the body twist under those hard launches. There are no absolutes.
Why do cars with lousy shocks feel better with SFC's? Simple, because the shocks do a lousy job damping impacts. Impacts that aren't damped get to the body and make it quiver like a big tuning fork. So why do guys with good shocks not see the massive difference? Easy... because better shocks damp impact harshness much more effectively and they don't get into the body to make it quiver and shake.
And as for the quarter panel dimples. Seen them show up on cars with SFC's. Seen them not show up on cars without SFC's. Because the SFC's have nothing to do with it. Look at where SFC's connect, nowhere near the quarter panels. Watch a car wheelhop and you can see the quarters flex like mad, which is where the dimples come from.
That said, the man stated his findings. And he's not the first. In fact I've seen cars go faster autocrossing without SFC's than with them. And as much as folks always want to say stiffer is better, that's not always the case in reality as much as it is on paper.
First, the notion that these cars will fall apart and twist in half isn't true. In fact the car was designed to be a convertible from the get go. My 2001 Z28 which I won a number of National Championships in on very big, sticky tires, didn't have SFC's, and didn't need them. In fact they guy who bought the car and competes in it bought SFC's, but them on and then took them back off.
The simple fact of the matter is these are not RACE CARS. We cannot do whatever we want to suspension geometry. And chassis stiffness means other changes, every time you see a new stock car get stiffer, you see a myriad of other changes to bushings, dampers, springs, bars, etc.
Here's the dirty secret.... when you make a chassis stiffer you take a bit of a spring out of the system. That generally means you want the car a sprung a bit softer. Another reason I don't run 25mm rear bars, and big rear springs, etc. In fact my front springs are softer than many other street rates.
Looking at it another way: You can never make the car have no flex at all. How much is enough? When do you say when? I'll tell you that a car that gets drag raced a lot and has some power to leave really hard is a great candidate for SFC's to help with the body twist under those hard launches. There are no absolutes.
Why do cars with lousy shocks feel better with SFC's? Simple, because the shocks do a lousy job damping impacts. Impacts that aren't damped get to the body and make it quiver like a big tuning fork. So why do guys with good shocks not see the massive difference? Easy... because better shocks damp impact harshness much more effectively and they don't get into the body to make it quiver and shake.
And as for the quarter panel dimples. Seen them show up on cars with SFC's. Seen them not show up on cars without SFC's. Because the SFC's have nothing to do with it. Look at where SFC's connect, nowhere near the quarter panels. Watch a car wheelhop and you can see the quarters flex like mad, which is where the dimples come from.
