Coil over rear shocks
Race Director
Joined: Dec 1999
Posts: 16,945
Likes: 9
That cantilver setup won't work on 80-82 because of the batwing. Either way, if they build it like that the shock and spring will be very inefficient, just eyeballing it it looks to be a 3:1 or greater ratio on the cam and the suspension is on the long arm of the cam, that means for every 3" of suspension movement the spring/shock deflect less than 1" (since the angular change over cam motion also detracts from the efficiency). This will require very stiff springs and a very stuff shock and all the play in the shock mounting and rod ends will be amplified, the suspension won't be very reactive at all. It should have been done the othre way around, connecting the live suspension to the short arm of the cam and the shock/spring to the long arm, that increases the efficiency.
Also, looks like they used flexusmark's solidworks models..they are identical. Wonder where they came up with the cantilever idea (I posted about a cantilever setup I wanted to do sometime earlier this year)
Also, looks like they used flexusmark's solidworks models..they are identical. Wonder where they came up with the cantilever idea (I posted about a cantilever setup I wanted to do sometime earlier this year)
Race Director
Joined: Nov 2000
Posts: 11,872
Likes: 12
From: Waterloo ontario Canada
Originally Posted by Twin_Turbo
That cantilver setup won't work on 80-82 because of the batwing. Either way, if they build it like that the shock and spring will be very inefficient, just eyeballing it it looks to be a 3:1 or greater ratio on the cam and the suspension is on the long arm of the cam, that means for every 3" of suspension movement the spring/shock deflect less than 1" (since the angular change over cam motion also detracts from the efficiency). This will require very stiff springs and a very stuff shock and all the play in the shock mounting and rod ends will be amplified, the suspension won't be very reactive at all. It should have been done the othre way around, connecting the live suspension to the short arm of the cam and the shock/spring to the long arm, that increases the efficiency.
Also, looks like they used flexusmark's solidworks models..they are identical. Wonder where they came up with the cantilever idea (I posted about a cantilever setup I wanted to do sometime earlier this year)
Also, looks like they used flexusmark's solidworks models..they are identical. Wonder where they came up with the cantilever idea (I posted about a cantilever setup I wanted to do sometime earlier this year)
Each year an engineering team right next to my lab gets $100,000 plus free engines to put together a indy style of car and race it against other schools where they are judged on performs , design, handling etc etc and all of them have this design. No weight on the suspension other then a thin rod.
Burning Brakes
Joined: Dec 2004
Posts: 1,020
Likes: 1
From: Nederland Texas
Originally Posted by Twin_Turbo
That cantilver setup won't work on 80-82 because of the batwing. Either way, if they build it like that the shock and spring will be very inefficient, just eyeballing it it looks to be a 3:1 or greater ratio on the cam and the suspension is on the long arm of the cam, that means for every 3" of suspension movement the spring/shock deflect less than 1" (since the angular change over cam motion also detracts from the efficiency). This will require very stiff springs and a very stuff shock and all the play in the shock mounting and rod ends will be amplified, the suspension won't be very reactive at all. It should have been done the othre way around, connecting the live suspension to the short arm of the cam and the shock/spring to the long arm, that increases the efficiency.
Also, looks like they used flexusmark's solidworks models..they are identical. Wonder where they came up with the cantilever idea (I posted about a cantilever setup I wanted to do sometime earlier this year)
Also, looks like they used flexusmark's solidworks models..they are identical. Wonder where they came up with the cantilever idea (I posted about a cantilever setup I wanted to do sometime earlier this year)
I am considering a Fab 9 with coilovers and a 4-link. Do any of you have pics of a similar setup on a Vette without gutting the body?
-P
Race Director
Joined: Dec 1999
Posts: 16,945
Likes: 9
I'm not saying cantilever is a bad thing, in fact it's brilliant..if done right. You guys are not reading my post right..it's about the actual design there, not the concept. Having only a rod as a partly unsprung component vs. the sprin & shock is great, if you use cams with multiple holes you can also adjust the cam ratio and thus the resulting spring/shock rate vs. wheel rate, spring & shock efficiency, even ride height by adjusting the coil over ot even the pushrod....and so on.
I originally wanted to do a cantilever but figured it would be too much work.
What I'm gettig at is the actual cams, take a look at the cad drawings and you'll see what i mean about the cam ratio, they are making the shock/spring travel SMALLER than the suspension travel, meaning that the wheel rate is increased (making it easier to push the spring/shock in) and the amplitude is decreased. It should be done the other way around.
Here's a good pic:
See that the spring/shock is attached to the long leg of the cam????
I originally wanted to do a cantilever but figured it would be too much work.
What I'm gettig at is the actual cams, take a look at the cad drawings and you'll see what i mean about the cam ratio, they are making the shock/spring travel SMALLER than the suspension travel, meaning that the wheel rate is increased (making it easier to push the spring/shock in) and the amplitude is decreased. It should be done the other way around.
Here's a good pic:
See that the spring/shock is attached to the long leg of the cam????
Last edited by Twin_Turbo; Sep 15, 2006 at 11:47 AM.
Burning Brakes
Joined: Dec 2004
Posts: 1,020
Likes: 1
From: Nederland Texas
TT,
You do an amazing job. I can tell it takes a lot of careful planning and some trial and error to arrive at a creation like yours. However, this would cut into my "Loose Women and Beer Drinking" time. I will watch you and Norval invent the wheel, and then hopefully learn something creative to apply to my hoopty.
-P
You do an amazing job. I can tell it takes a lot of careful planning and some trial and error to arrive at a creation like yours. However, this would cut into my "Loose Women and Beer Drinking" time. I will watch you and Norval invent the wheel, and then hopefully learn something creative to apply to my hoopty.
-P
Premium Supporting Vendor
Joined: Nov 2002
Posts: 1,485
Likes: 81
From: Santo TX
Originally Posted by Twin_Turbo
I'm not saying cantilever is a bad thing, in fact it's brilliant..if done right. You guys are not reading my post right..it's about the actual design there, not the concept. Having only a rod as a partly unsprung component vs. the sprin & shock is great, if you use cams with multiple holes you can also adjust the cam ratio and thus the resulting spring/shock rate vs. wheel rate, spring & shock efficiency, even ride height by adjusting the coil over ot even the pushrod....and so on.
I originally wanted to do a cantilever but figured it would be too much work.
What I'm gettig at is the actual cams, take a look at the cad drawings and you'll see what i mean about the cam ratio, they are making the shock/spring travel SMALLER than the suspension travel, meaning that the wheel rate is increased (making it easier to push the spring/shock in) and the amplitude is decreased. It should be done the other way around.
Here's a good pic:
See that the spring/shock is attached to the long leg of the cam????
I originally wanted to do a cantilever but figured it would be too much work.
What I'm gettig at is the actual cams, take a look at the cad drawings and you'll see what i mean about the cam ratio, they are making the shock/spring travel SMALLER than the suspension travel, meaning that the wheel rate is increased (making it easier to push the spring/shock in) and the amplitude is decreased. It should be done the other way around.
Here's a good pic:
See that the spring/shock is attached to the long leg of the cam????
Our design is for a street car with 5" or more of wheel travel. The ratio we are currently using is designed to keep the shock and rocker at the greatest mechanical efficiency at our designed ride height.
Race Director
Joined: Dec 1999
Posts: 16,945
Likes: 9
Originally Posted by Speed Direct
I disagree that the cam should be the other way. You are correct in stating that the spring rate must be greater in this configuration. The thing you are missing is the intent of our suspension verses a race car. The above photo is a very typical race car design. The reason they run the rocker ratio that way is to increase the shock travel because the suspension travel is so small. Many times race car suspension travel is about .5" (Formula cars and Prototypes) and certainly not more than 2" (GT cars). Because the wheel travel is so small the shock cannot be effective in the job it is required to do. So the ratio is changed to give the shock enough movement to actually work.
Our design is for a street car with 5" or more of wheel travel. The ratio we are currently using is designed to keep the shock and rocker at the greatest mechanical efficiency at our designed ride height.
Our design is for a street car with 5" or more of wheel travel. The ratio we are currently using is designed to keep the shock and rocker at the greatest mechanical efficiency at our designed ride height.
I like the system you have designed there, I like it alot...I just feel it would be better if you had a cam that had less ratio in it, all to get as much shock stroke out of it as possible.
Marck
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Premium Supporting Vendor
Joined: Nov 2002
Posts: 1,485
Likes: 81
From: Santo TX
Currently we have a 2:1 ratio so it's not really that extreme. I agree that something closer to 1:1 would be ideal for travel and spring rate but packaging wise I don't see that a rocker of that size would fit. The other issue is that the more travel there is on the shock side the greater the arc distance it is moving thru thus making it less efficient geometry wise. With the current ratio we have a rising spring rate situation and that's good.
I'm not saying everything is set in stone right now. We are going to be testing this design within a couple months and we will change the ratio as needed. Testing always provides interesting new information.
I'm not saying everything is set in stone right now. We are going to be testing this design within a couple months and we will change the ratio as needed. Testing always provides interesting new information.
Team Owner
Joined: Nov 2004
Posts: 20,715
Likes: 25
From: Sorrento Italy
Originally Posted by Durango_boy
Is that a better ride than a mono-leaf? Seems you took it out, added a stab bar, and the coil overs. Anything else?
it's faaar much better the coil over set up, if it's well done, you'll avoid that kind of swinging that all corvette have, even the tougher set up with the best hardware and tuning...
i think my car drives through bends nearly as good as an euro sportcar BUT when you go into sharp and short bends and go right and left very quick, it's there where the monospring sistem shows it's limits.
if i could and had the knowledge i'd go streight to coil overs but unfortunately i dont have it and can't find kits to convert...
durango, i've been thinking to change my avatar to one showing my left hand written...what could i write on it? give me an advice
Pro
Joined: Sep 2002
Posts: 546
Likes: 0
From: Pinellas Park FL
One thing to note is that many forum members have an investment in mono spring and shock setups already. The kit will need to be direct bolt on, perform much better that adjustable mono setups on a lot of our cars today and above all have an attractive price. To often someone comes out with a kit but the price is way over where it should be.
Melting Slicks
Joined: Feb 2003
Posts: 3,053
Likes: 4
St. Jude Donor '03,'11
Originally Posted by Durango_boy
'Get Laid!' 
I agree with Marck. The reverse ratio is gonna make the rear really soft. And its going to put some extreme lateral forces on the bottom of that diff. I don't know that the rear cross member is strong enough not to twist a little, creating some slop in the system.
I guess he knows how i feel about steeroids but i'm willing to try and keep an open mind on this one. I do tend to criticise the hell out of everyone including Marck.
It do look cool though.
Team Owner
Joined: Aug 2006
Posts: 24,125
Likes: 15
From: Columbia Missouri
Originally Posted by conway62
One thing to note is that many forum members have an investment in mono spring and shock setups already. The kit will need to be direct bolt on, perform much better that adjustable mono setups on a lot of our cars today and above all have an attractive price. To often someone comes out with a kit but the price is way over where it should be.
I wonder how hard it would be. The coil overs would go where the stock shocks reside right? Then all you have to do is link the two sides in a similar location as the leaf. Somene's got to have made one by now.
Melting Slicks
Joined: Dec 1999
Posts: 2,116
Likes: 156
From: Mid West
Cruise-In III Veteran
Originally Posted by Speed Direct
Currently we have a 2:1 ratio so it's not really that extreme. I agree that something closer to 1:1 would be ideal for travel and spring rate but packaging wise I don't see that a rocker of that size would fit. The other issue is that the more travel there is on the shock side the greater the arc distance it is moving thru thus making it less efficient geometry wise. With the current ratio we have a rising spring rate situation and that's good.
I'm not saying everything is set in stone right now. We are going to be testing this design within a couple months and we will change the ratio as needed. Testing always provides interesting new information.
I'm not saying everything is set in stone right now. We are going to be testing this design within a couple months and we will change the ratio as needed. Testing always provides interesting new information.
Team Owner
Joined: Aug 2006
Posts: 24,125
Likes: 15
From: Columbia Missouri
How does tire width affect the performance of that new system? It would seem that a narrow tire would have more toe in out movement where as a wider tire would tend to stay zero'ed just because of the wide footprint.
Team Owner
Joined: Aug 2006
Posts: 24,125
Likes: 15
From: Columbia Missouri
Originally Posted by Durango_boy
How does tire width affect the performance of that new system? It would seem that a narrow tire would have more toe in out movement where as a wider tire would tend to stay zero'ed just because of the wide footprint.
No one know this?