RE: REAR COIL-OVER SUSPENSION
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RE: REAR COIL-OVER SUSPENSION - 3/14/2008 4:45:39 AM
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aldous
Posts: 128
Joined: 1/5/2008
Status: offline
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Oopss, I have made a check on my car and I have realized only now that I have the gymkhana suspensions (FE7 option)
the front sway bar is 1 1/8" , rear sway bar 7/16" , rear leaf spring is the 7 leaves type ( not 9). If I have the stiff 550 lb/in front coils, as I suppose, how is it possible that the driver's side coil is sagged so much to be lower about 1" in respect to the other?
I have ordered the replacement front springs already, but supposing that my car had the standard set up , I bought the 280 lb/inch. Ok anyway?
Actually my car rides quite harsh on bad roads...
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Aldo from south Italy
1979 L82 ,4 speed, edelbrock performer rpm intake, edelbrock 600cfm carb,double hump 64cc heads 2.02/1.6 valves, Hedman Hedders dual headers, Flowmaster 40 series, Goodyear Eagle GT+4 255/60/15 , 4 Bilstein HD shocks
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RE: REAR COIL-OVER SUSPENSION - 3/14/2008 1:28:31 PM
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DeeVeeEight
Posts: 494
Joined: 10/24/2007
From: South Jersey
Status: offline
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Aldo,
I replaced my steel leaf spring when it fell apart. I originally went with a 330 lb. spring rate when I got my composite monospring but I found that the car bottomed out in dips at highway speeds. I contacted VB&P where I had purchased the spring and they sent me out a 400 lb. monospring. I am very happy with the 400 lb. rear spring. I added Bilstein sport shocks and it made the whole thing come together very nicely.
The big surprise with the 400 lb. spring in the rear was the way the front of the car responded. I was also very pleased with the results. In the past if I went over a big dip or a small rise in the road at speed the front of the car would have a floating sensation to it. When I changed the rear suspension it somehow balanced out the front and totally eliminated the float. The steering is quite responsive and has a much more confidence inspiring feel to it. The only thing I can figure is that the center of gravity was shifted towards the rear with the old soft suspension and it seems to be properly balanced now.
_____________________________
If you don't ask, you get the same answer as no.
1979 L-82, 383 Stroker, Edelbrock RPM Air Gap intake, Holley 750, Headers, Flowmasters, VB&P 400# rear monospring, Richmond 5 speed. American Racing Vector Wheels, Firestone Indy 500's
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RE: REAR COIL-OVER SUSPENSION - 3/14/2008 1:38:18 PM
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DeeVeeEight
Posts: 494
Joined: 10/24/2007
From: South Jersey
Status: offline
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quote:
ORIGINAL: aldous
Oopss, I have made a check on my car and I have realized only now that I have the gymkhana suspensions (FE7 option)
the front sway bar is 1 1/8" , rear sway bar 7/16" , rear leaf spring is the 7 leaves type ( not 9). If I have the stiff 550 lb/in front coils, as I suppose, how is it possible that the driver's side coil is sagged so much to be lower about 1" in respect to the other?
I have ordered the replacement front springs already, but supposing that my car had the standard set up , I bought the 280 lb/inch. Ok anyway?
Actually my car rides quite harsh on bad roads...
The new springs should be OK. As far as the front of the car sagging - the car may have had a LARGE previous owner. If the P.O. rode alone often and was of Large proprtions then the car would tend to sag a bit on that side due to spring fatigue.
Another possibility is the frame to body mount cushions - there are 8, 4 on each frame rail, the originals are made of rubber and are probably rotted and badly compressed. Replacing them can restore a cars ride height. It is a fairly straightforward job, except for the drivers side frame to body mount at the door hinges (there you gotta disconnect the steering coupling and some other stuff). Beware of the rusted body mount bolts, they may need to be cut off from time to time.
_____________________________
If you don't ask, you get the same answer as no.
1979 L-82, 383 Stroker, Edelbrock RPM Air Gap intake, Holley 750, Headers, Flowmasters, VB&P 400# rear monospring, Richmond 5 speed. American Racing Vector Wheels, Firestone Indy 500's
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RE: REAR COIL-OVER SUSPENSION - 3/14/2008 3:26:21 PM
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73shark
Posts: 1089
Joined: 4/18/2006
Status: offline
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From the people that I've talked with and those on this forum (C3 in particular) have indicated that the composite rear spring is an improvement over the steel leaf spring.  Part of this is due to the elimination of the friction between the leaves. Also there is a weight reduction.
I talked with a guy that drove the test Shark at SpeedDirect with the steel spring, a composite spring, and finally their coilover setup. He stated that the composite was an improvement but the coilover was a big step up improvement over the composite. Of course there's a big step up in the cost.  Just another example of you get what you pay for. 
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So many toys, so little time
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RE: REAR COIL-OVER SUSPENSION - 3/15/2008 10:10:25 AM
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aldous
Posts: 128
Joined: 1/5/2008
Status: offline
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DV8
which front coils do you have?
I must admit that my car is quite stable when going straight on roads with dips and small rises. But I have Bilsteins on front too. I think you should place a pair of Bilsteins on front of your car. I have seen that they are more effective than any other suspension job.
The idea to keep my original Gymkhana rear suspension is not too bad at the end. I think it's somewhat a pity to remove it . let's see. Anyway I don't totally agree that it's better to reduce the weight on the back of the C3 with a composite spring . It seems that the main problem of the c3 is exhactly the too low weight on the back in respect to mid-rear engine cars.
with the c3 , until the car is in acceleration , the back press the tires to the ground. but when you release the gas, for bracking before a bend, there's too much weight moving toward the front, the back becoming too light, the car becomes unstable and doesn't give a good feeling. mid engine cars behaves better in this.
For the reasons above, It seems to me that the secret of driving the Corvette is to drive it smoothly , avoiding excessive movement of weight back to front.
I'll do a test asap . I'll remove the spare tire and possibly the lid and see if the handling improves ( their weight should be approx the same of difference between an iron and a composite spring)
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Aldo from south Italy
1979 L82 ,4 speed, edelbrock performer rpm intake, edelbrock 600cfm carb,double hump 64cc heads 2.02/1.6 valves, Hedman Hedders dual headers, Flowmaster 40 series, Goodyear Eagle GT+4 255/60/15 , 4 Bilstein HD shocks
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RE: REAR COIL-OVER SUSPENSION - 3/16/2008 12:56:23 PM
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73shark
Posts: 1089
Joined: 4/18/2006
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If you are getting a lot of weight transfer when changing from acceleration to braking, then it might be shock related. I agree that smooth, consistent driving is the way to go.
I suspect that the spare tire and carrier weigh more than the difference in weight of the composite and leaf spring. Don't forget when you're doing the comparison that gas weighs about 7.5 lbs/gallon, so you'll want to do your testing with the same load of gas. Good luck with your tweaking.
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So many toys, so little time
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RE: REAR COIL-OVER SUSPENSION - 3/17/2008 5:01:39 PM
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DeeVeeEight
Posts: 494
Joined: 10/24/2007
From: South Jersey
Status: offline
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I am not sure which front springs are in my '79, the car was lightened by a P.O. for performance purposes so I am not sure if I have stock springs or not. Once my cash flow improves again I will be installing Bilstein's up front as well. Changing over to a stiffer rear spring made a big difference in the handling characteristics of the car, it is much more stable and predictable now.
_____________________________
If you don't ask, you get the same answer as no.
1979 L-82, 383 Stroker, Edelbrock RPM Air Gap intake, Holley 750, Headers, Flowmasters, VB&P 400# rear monospring, Richmond 5 speed. American Racing Vector Wheels, Firestone Indy 500's
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RE: REAR COIL-OVER SUSPENSION - 3/18/2008 12:40:01 AM
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aldous
Posts: 128
Joined: 1/5/2008
Status: offline
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In these days I have made the subscription to 2 italian forums ( one on vintage USA cars , one on Corvettes only).
On the US cars forum I've found persons that prefers to keep the car somewhat original, also on Corvettes, but without the NCRS excesses
On the italian Corvette forum, I've seen tons of modifications and race minded Corvette owners.As mad for mods as you there in the US
Now I'm a bit fighted inside on what to do.
I would like to improve the handling of my Vette , but the idea to place a ton of aftermarket things on my car, makes me not totally happy or convinced.
Ok , my Vette is "just " a 79 , not a 69 , but it's still an historic car and it would be more historic in 10 years ( a 40 years old car...). Don't forget that Chevy made just about 40.000 per year , not 400.000. And many Vettes are lost , destroyed, too heavily modified...If you check ebay , there are just 7-9 vette per each prod year.
For example, I have on my Vette the original Gymkhana suspensions. Is it wise to replace the original Gymkhana leaf spring with a composite? and replace all the other original parts?I l already have the larger original sway bars too...
I start to think that I should keep my car more original and don't exceed...
yesterday I have received a package from ecklers with many parts I needed. but I was a bit disappointed by the quality of certain parts. They look not as nicely made as OEM and definitively they look too new.some things made in China...
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Aldo from south Italy
1979 L82 ,4 speed, edelbrock performer rpm intake, edelbrock 600cfm carb,double hump 64cc heads 2.02/1.6 valves, Hedman Hedders dual headers, Flowmaster 40 series, Goodyear Eagle GT+4 255/60/15 , 4 Bilstein HD shocks
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RE: REAR COIL-OVER SUSPENSION - 3/18/2008 9:03:15 AM
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73shark
Posts: 1089
Joined: 4/18/2006
Status: offline
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Aldo, first you need to decide if you want to enjoy the car now for yourself or keep it pristine for some future owner to enjoy. What I would recommend is to make the mods you want but keep the original parts so that if a future owner so desires, they can put it back to stock if that's their thing.
I kept all of the stuff I took off mine when I added A/C, power windows, etc even though I never plan to put it back the way it was when I ordered it. When my estate (I'll never sell it) disposes of it, they can put all of that in a box and give it to the new owner.
Just my $.02 worth.
_____________________________
So many toys, so little time
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RE: REAR COIL-OVER SUSPENSION - 3/19/2008 8:17:23 AM
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aldous
Posts: 128
Joined: 1/5/2008
Status: offline
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73shark,
yes I'm keeping apart everything I remove-replace from my car. that's the way to go. Anyway , if my former idea was to largely improve-modify my car , now i start to think that I like it also straight as it is , and so the idea to keep her substatially original , is not too bad at the end. I'll go slowly in these things and think...
I have removed the spare tire (related lid still in place and will remain there, it's quite light and I like the back of my Vette with that lid in place) and made an 1/2 hour ride. I think the car behaves better. It may be just an impression but I feel better like this.
I haven't weighted it , but the spare tire is at least 30-35lbs
I think that If I'll be able to drop 200lbs on my Vette removing stuff here and there, the car would ride better...
_____________________________
Aldo from south Italy
1979 L82 ,4 speed, edelbrock performer rpm intake, edelbrock 600cfm carb,double hump 64cc heads 2.02/1.6 valves, Hedman Hedders dual headers, Flowmaster 40 series, Goodyear Eagle GT+4 255/60/15 , 4 Bilstein HD shocks
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