Rear suspension spring popped

[Musicman]

Evening all, a little technical advice from you knowledgeable people if I may?

The leaf spring has collapsed on the way home today, managed to limp to a local garage where I have utilised the lift (carefully!) and noted that it will need replacing.

What is your advice on composite springs, from what I can tell they affect the ride making it much stiffer and are more suited for race cars so I am very much leaning towards a 7 or 9 leaf replacement but thought I should check in first.

With thanks!

 

[Chuffer]

What year is your C3 and what is fitted already and what shox are fitted ? A 9 steal leaf is standard fitting and a 7 leaf is a heavier duty and will give a harsher ride .

 

[antijam]

Composite springs are essentially maintenance free, so that's a plus and they will give a more consistent spring rate since there's no inter-leaf friction. However, they don't like high temperatures ( how near is your exhaust?) and they can be damaged by road debris. If you fit one you will really need to change your shocks too. I fitted a 9 leaf replacement to my '71.

 

[Musicman]

Sorry Chuffer, it is an '81 and looks as though shox are standard, can't see that they have been upgraded from the original.
So stick with 9 leaf and don't go for a composite?

 

[Baron von Del Boy]

Sorry Chuffer, it is an '81 and looks as though shox are standard, can't see that they have been upgraded from the original.
So stick with 9 leaf and don't go for a composite?

1981 Vettes with the standard suspension and automatic trans came with the composite spring as standard from the factory.

 

[Forrest Gump]

The factory composite spring option for 81 and 82 was actually to provide a softer ride than the steel spring.
But aftermarket composites are available in a range of spring rates from “comfort“ ~200lb to racing stiffness ~400lb.
Composites have been in short supply from the US, I’ve been waiting for a specific one from VanSteel since January, so you’re probably better of sticking with a steel replacement that I reckon are more readily available.

 

[Forrest Gump]

1981 Vettes with the standard suspension and automatic trans came with the composite spring as standard from the factory.

Correct! Composite standard, Steel was the option for a stiffer ride.

 

[Baron von Del Boy]

The factory composite spring option for 81 and 82 was actually to provide a softer ride than the steel spring.

And it weighed 33 lb less.

 

[Chuffer]

And it weighed 33 lb less.

I believe the factory OEM composites were 192 lb rated for a softer ride

 

[Chuffer]

Sorry Chuffer, it is an '81 and looks as though shox are standard, can't see that they have been upgraded from the original.
So stick with 9 leaf and don't go for a composite?

Your car should already have a composite spring unless a steel spring was selected as an option or has been replaced with a steel one during its life . As Antijam said , compo springs are affected by heat . Does your car have heat shields fitted on the exhaust under the spring ? ( assuming it`s compo of course ) .

 

[Chuffer]

Musicman , as an after thought what actually happened to your spring when you say " popped" ? Has a leaf cracked or become displaced ?

 

[kentvette]

I swapped the metal spring on our '78 for a composite item in 1997 and it's one of the best things we ever did! Greatly improved ride (I'm not interested in "stiffening it up" for racing around), and lighter weight. I did need better shocks and I went with Koni adjustables all round. There is a lot of talk about the risk of exhaust heat and I was a tad concerned as our exhausts follow a slightly different route down the car than stock, but so far, 24 years later, its all OK and, it still looks like new.

 

[Baron von Del Boy]

Your car should already have a composite spring unless a steel spring was selected as an option..

The 81 manual gearbox option also came with a steel spring presumably because the manual gearbox equipped car would be lighter anyway so they were not so 'desperate' to shave weight off as they were with the auto gearbox equipped car.

The stiffer sporty steel option being known of as the Gymkhana suspension.

 

[Forrest Gump]

I have a brand new composite with all fittings in stock 460lbs if I remember correctly..........

I do hope it's not that stiff - that would be like having an RSJ under your backside
"Musicman" ideally needs to stick to the same rating of spring as is on the car already or it could upset the balance of the car unless front springs are changed too.

 

[Forrest Gump]

And it weighed 33 lb less.

Thats about 1% of the cars total weight....a lot for just one component.

 

[Chuffer]

Thats about 1% of the cars total weight....a lot for just one component.

The 1980 model year shed 250lbs from the preceeding model to improve power to weight ratio . That`s an even bigger saving unless you had a fat driver .

 

[Chuffer]

I do hope it's not that stiff - that would be like having an RSJ under your backside
"Musicman" ideally needs to stick to the same rating of spring as is on the car already or it could upset the balance of the car unless front springs are changed too.

To quote the Moody Blues , it`s all " A Question Of Balance " .

 

[Chuffer]

I have fitted many they are the perfect answer for a smooth but perfect handling ride

460 lb rating seems immense to me . Nearly two and a half times more than stock ! Do you provide BUPA spinal surgery vouchers with each one ?

 

[Forrest Gump]

460 lb rating seems immense to me . Nearly two and a half times more than stock ! Do you provide BUPA spinal surgery vouchers with each one ?

A Gymkhana steel leaf spring is in the region of 300lbs I believe. A composite of the same rate will feel more compliant. Corvette suspension specialist Vansteels stiffest composite is 400lb and recommended only for racing or very high powered cars.

 

[Roscobbc]

Someone further back in the chain is perhaps confusing front rates for rear?