1981 Rear Spring Replacement

[Charlie P.]

I need to replace the rear fiberglass spring. I have two questions:
I see different spring rates offered. What is the factory spring rate?
What vendor is best source for correct OEM or OEM copy spring?

Thanks,
Charlie

[Richard C.]

Re: 1981 Rear Spring Replacement

is it a stick or auto?

[Charlie P.]

Re: 1981 Rear Spring Replacement

Richard- It's an automatic, hence the fiberglass spring.
Thanks,
Charlie

[Tom R.]

Re: 1981 Rear Spring Replacement

I need to replace the rear fiberglass spring. I have two questions:
I see different spring rates offered. What is the factory spring rate?
What vendor is best source for correct OEM or OEM copy spring?

As much as I've looked at the original springs, both front and rear, I've not come across a rating for the rear spring. You have a base suspension so you may wish to avoid heavy-duty spring rated springs. Rear springs are rated anywhere from 250 lb/in up at 550 lb/in but than that is the rating for steel rear leaf springs. I do see, after a look at Ecklers, they are rated from 300 up to 360 lbs. A 330 lb states its great for big blocks...I would not think you would want that stiff of a spring. A 355 is a heavy-duty replacement rated spring. A 300 lb rated spring seems more appropriate for your base 1981.

I would talk to vendors and state you want a service replacement monoleaf rear spring for an 1981 Corvette. Your vette weighed less than the late model C3s that preceded by hundreds of pounds. A 1978 weighed about 3500 pounds while your 81 was reduced to around 3200.

Came across this discussion on another forum that discusses the various ratings. Apparently, VB&P states the original 1981 spring was rated at 290 lb. Suggest some followup with posters and ask about results.

http://forums.corvetteforum.com/c3-tech-performance/2389601-81-re-use-stock-monoleaf-or-replace.html

[Patrick H.]

Re: 1981 Rear Spring Replacement

If originals are not still available, I'd check with a place like Contemporary Corvette or similar to see if they have one. It would be a shame to put a replacement part on a car as nice as yours, Charlie.

Patrick

[Charlie P.]

Re: 1981 Rear Spring Replacement

In the thread Tom referenced, one poster states that the stock spring is 315 lb. rating, which I have seen with at least one vendor.
Patrick- I definitely want to use a direct, correct replacement or find an NOS spring if I can. I just took the original out, but I need to get it back together for the Carlisle Gallery display.

Thanks,
Charlie

[David H.]

Re: 1981 Rear Spring Replacement

The rear spring rate for your 1981 is listed as 121 lbs/in at the wheel in the Manufacturers Motor Vehicle Association document for 1981 available at GM Archives. Link below

Scroll down and select "Corvette", select the year, select "YES" on the usage agreement. Once the pdf finishes downloading go to page 60 of 75 for suspension information. The spring rate shows a little different rate on the 1982 archive (different page in the pdf) so you might want to compare them. The MVMA document appears to have been submitted prior to production beginning, so it is useful to compare info on relevant years around the year in question.

Link:

http://www.gmheritagecenter.com/gm-heritage-archive/vehicle-information-kits.html

[Patrick H.]

Re: 1981 Rear Spring Replacement

Charlie,

Van Steel lists one as a "direct replacement":

http://www.vansteel.com/index.cfm?fuseaction=shop.ProductList&SubGroup=1955

Another site lists the TRW as a direct replacement.

From what I can tell you need what are listed as the 300 lb springs, if not less. However, that is a bit difficult to find. Do you happen to have an AIM to check for the original part number?

Patrick