vince vette 2

I'm sure this has been answered, but I haven't found it by searching. For an 80 vette the shop manual says that you use a jack and C-clamp to relieve the tension on the trailing arm leaf spring mounting bolt before taking the nut of the bolt. It refers to Fig. whatever. But Fig. whatever doesn't show a clamp. So exactly what is the clamp supposed to clamp. Feel free to direct me to a thread on this as it seems a likely topic to have been covered.

And, while I'm here, pros and cons of steel vs. plastic (OK - carbon fiber).

Thanks,

Alan 71

Hi vv,
Here's a photo showing the spring being put back on the car.
Taking it off is just the opposite.
Removing the spring:
The jack is jacked up under the spring just far enough to release the pressure on the bolt between the t-arm and spring end.
Once the cotter pin, nut, washer, and bushing are removed the jack is slowly lowered.
The c-clamp prevents the block of wood from sliding along the bottom leaf rather than raising or lowering the spring.
There's a LOT of energy stored in the spring.... so be very carful.
Regards,
Alan

How long the block of wood need to be depends on how high the car is raised and the upper limit of the jack you're using.

vince vette 2

Excellent image and explanation. Thank-you

drwet

Installed the fiberglass rear spring in my '79 about 20 years ago and its still probably the best upgrade I've ever made to the car. Ride and handling both improve, and it shaves off a bunch of weight. If steel was better, GM would still be using it.

vince vette 2

When you did that I assume lots of bushings were replaced. Did you stick with rubber or go to poly?

drwet

I went poly but I'm not sure I would do it again. They have stood up well and performance is good, but they squeak. I know this was a problem when I bought them and I did some research and bought them from a supplier who assured me that his bushings wouldn't squeak. Well, they do. No amount of lubrication solves the problem for long. Its not so bad that I have changed them out, but it is annoying.

Bills17n72

Around 80 or 81 all the corvettes went to the composite spring,you need to put that one on your car,i have one on my 72 ,and it is really a comfortable ride , but then i am a old fart!!!

vince vette 2

Well I bought the '80 vette in .....'80 - fresh out of college. Now it's time to restore (improve) it. So you can do the math on my age. All the neat goodies went into the next two model years - composite spring, 4 speed overdrive tranny, and the first round of fuel injection via throttle body type. But then they never came with an L82 engine option. No one disagrees about the ride from the composite spring. But for GM there was really just one reason it went it - 32 lb weight reduction which was a 1% reduction. It doesn't sound like much, but it's not easy to take 1% off the weight of a car. Of course, they grabbed another 1 to 1.5% by switching to the aluminum Dana 44 differential that year also - don't even get me started. And all that was really done to eek out a little more mpg, same as the reason the set the idle mixture to starve the engine and then plugged the ports to mixture screws so Joe Public couldn't fix the problem. One good thing about the steel spring was it was mass right on the axle and down low. It had to help handling in that respect. I guess i could always bolt a piece of steel back there.

vince vette 2

I'm pretty certain I'll swap over to composite now. I'd appreciate hearing recommendations on what's working well and what's not as far as spring maker, spring rates, shocks, and any gotcha's that might come up.

Big2Bird

I would look at what Vette Brakes and Products has to offer.

Stoge

I replaced the factory spring on my '79 with a VBP composite and went with KYB shocks valved for the composite spring. I chose the 320lb spring rate and would pick that one again. It rides great, and is not harsh or anywhere near harsh.


I used that block of wood and c-clamp method when removing my spring. It worked. I didn't trust it from a safety standpoint. My spring bolts were shot, nuts stripped & rusted. I had to cut the bolts. I didn't like being near that spring with the lifting method engaged, but it didn't fail. So to make a long story short, when you release & lower the jack, its a good idea to stand back - don't be right up under the spring or really close to it.


One more thing, my spring project turned into sending halfshafts, diff, and trailing arms off to VanSteel and I also replaced u-joints, brake calipers, master cylinder, strut rods, and exhaust. The while-you-are-at-its are very strong with your project, so beware of what you're getting yourself into.

vince vette 2

Thanks for the recommendation on the VBP spring. I think I'm going in the same direction. To avoid an attack by the spring I just hog tied it to the bat wing and wrangled to the floor.

I was really stunned in my case on the all the bolts so far. Some were stubborn but all gave it up with a couple hammer smacks on the wrench. This includes the the strut bracket which I removed tonight. Of course, I move pretty slow - jacked it up over a week ago and every time I passed by it I would squirt pb blaster on everything. Sot that probably helped, along with the fact that the diff has been lubricating all the rear suspension. We'll see if there might be an issue there - perhaps i won't have a rebuildable core.

I agree with the "as long as I'm in there" philosophy as long as it doesn't turn into mission creep. So all bushings will be replaced and I'll clean up whatever I find along with the swap diff rebuild and gear swap. On the issue of brakes, that's where I started the whole shibang. I figured after it sat for 10+ years I should be sure it would stop before I started it. Of course, now with the rear spring and other stuff removed I can see it would have been a lot easier functioning back there if I had gotten the spring out.

caskiguy

Here's some information regarding Leaf Springs.This from a post by Eaton Detroit Spring on this forum/09-24-2009

Learn something everyday :-)

Default 3 diferent springs were used
The most popular rear leaf springs used were 2 different versions of a 9 leaf springs and a 7 leaf spring. A 10 leaf spring was used very sparingly. But we will not talk about it.

The diferences between the springs were thier rates. The down and dirty description of rate is it is the amount of weight required to deflect a spring one inch. The higher the rate, the stiffer the spring.

The 7 leaf spring has a rate of 305lbs.

The 9 leaf spring which all 9 leaves are curved has a rate of 196lbs.

The 9 leaf spring which the 1st 6 leaves are curved and the shortest 3 leaves are straight is a 2 stage or variable rate spring. It's rate starts at 140lbs and increases to 196lbs when all the leaves are touching.

The loads they were designed to carry are all pretty much the same.

The 7 leaf has a design load of 1,325 lbs. Both 9 leaf springs have a design load of 1,360 lbs.

All 3 springs are designed to have a 3/8 reverse arch when at their design load.

In order to accomplish the same spring height when under load with the spring having different spring rates, the free arch of each spring is different.

The free arch of the 7 leaf spring is 5-7/8 inches. The 9 leaf spring is 7-1/2 inches and the 6/3 spring is 8-11/16 inches.

The correct way to measure the free arch is for the spring to be off the vehicle. Place a straight edge across the ends of the spring and measure down to the main plate next to the centerbolt.

Whle we use the correct type of steel, SAE 5160 High Alloy Spring Steel, the thickness's have been adjusted to sizes the steel mills now produce. Way back when the mills would produce quantities as low as 5 tons of a size. Today 22 tons is the bare minimum of one size they will produce. And that is a lot of Corvette springs.

While the overall thickness of the springs have slightly increased, the fit, feel and performance of the springs are unchanged. However the free arches have been lowered form the original factory specs in order to maintain stock ride height.

I hope this helps at least some in understanding leaf springs.

vince vette 2

Thanks for the information on this. The spring is 9 leaf. The suspension is gymkhana. Always was a rough ride.

gg521

The 7 leaf spring is the gymkhana. There is also a 5 leaf spring but that guy is really stiff.

caskiguy

Didn't know there was a 5 leaf spring........brand ?
I just was made aware by Alan on a 70' I was disassembling that unbeknownst to me was wrong. It has a # making a F41 7 leaf but mine has a smaller plate on the top, making it an 8. I completely missed it on my leaf count.
Now I have no idea what or where it came from as the PO is long gone of course. So I'm left with buying a new leaf spring, hadn't figured on that. From what I understand the original 7 leaf was used for racing and the 9 is more than enough for most builds. Also making it of original design.




8 spring leafs. Go figure.



Mistake ? Or fraud ? God knows I don't.

vince vette 2

I bought the car new and paid the extra $55 for the gymkhana suspension. So unless someone sneaked off with my spring and was kind enough to put in another, it is the gymkhana for that year. Also, see this link - https://www.corvsport.com/the-c3-cor...actory_Options

Gymkhana Suspension (FE7)

• An optional, heavier-duty suspension system for higher levels of performance.
• The Gymkhana rear leaf springs contained 9 leafs, though the top leaf is very small. GM identifies the rear leaf springs as an 8-leaf spring.
• Included a stiffer front sway bar and stiffer springs.
• There were no restrictions on ordering this option – it could be ordered with any engine/transmission combination.

caskiguy

Sorry I missed that your car was a 1980. I thought you had a 68-72 C3.
Have fun.

revitup

My understanding is that the short plate incorporated on top side of the 7-leaf spring is not a 'leaf', it's a spacer. Its purpose was to keep the ride height similar to those cars with the standard 9-leaf spring.

vince vette 2

I wish. I could have picked up one of those for half half what I paid for mine new and would have something worth 3 to 5 times what mine is now.