7 Leaf Spring on 1970 454??

[Mark E.]

When I rebuilt the rear suspension of my 1970 454 ten years ago, I installed a composite spring and stored the original in the attic. The new spring has always been too harsh, so I recently decided to rebuild the original and install it. When I retrieved it from storage, I was surprised it has 7 leaves; see photos.

According to the JG 6th edition, "...in 1970 and 1972 F41 suspension was only available with the ZR1 and 1972 ZR2 options." I believe this is a typo... wasn't ZR2 only 1971 (LS6 based)? The Corvette Black Book doesn't list a HD suspension option (F41 or otherwise) for 1970. Is this an error too? Or was there actually no separate suspension RPO in 1970?

The Black Book says ZR1 has "special springs". So it sounds like the JG and Black Book agree that a heavy duty ("F41" or "special" or whatever it's called) suspension is only available in 1970 with ZR1. Is this correct?

What does this mean for this 454 car... that most likely the original spring was swapped for a 7 leaf during its past? Have any non-ZR1 1970 cars been documented with a 7 leaf spring?

Does the spring in the photos look OEM? Note the orange tag near its center.

Sorry for all the questions, but I'm trying to figure this out.


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[Joe L.]

Re: 7 Leaf Spring on 1970 454??

When I rebuilt the rear suspension of my 1970 454 ten years ago, I installed a composite spring and stored the original in the attic. The new spring has always been too harsh, so I recently decided to rebuild the original and install it. When I retrieved it from storage, I was surprised it has 7 leaves; see photos.

According to the JG 6th edition, "...in 1970 and 1972 F41 suspension was only available with the ZR1 and 1972 ZR2 options." I believe this is a typo... wasn't ZR2 only 1971 (LS6 based)? The Corvette Black Book doesn't list a HD suspension option (F41 or otherwise) for 1970. Is this an error too? Or was there actually no separate suspension RPO in 1970?

The Black Book says ZR1 has "special springs". So it sounds like the JG and Black Book agree that a heavy duty ("F41" or "special" or whatever it's called) suspension is only available in 1970 with ZR1. Is this correct?

What does this mean for this 454 car... that most likely the original spring was swapped for a 7 leaf during its past? Have any non-ZR1 1970 cars been documented with a 7 leaf spring?

Does the spring in the photos look OEM? Note the orange tag near its center.

Sorry for all the questions, but I'm trying to figure this out.


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Mark-------


Only 3 possibilities I can think of:

1) It was a factory mistake

2) It was an engineering-approved substitute installed at St. Louis due to a shortage of the 9 leaf spring;

3) It's a later SERVICE spring (in later SERVICE the 9 leaf spring was replaced by a 7 leaf spring)

[Mark E.]

Re: 7 Leaf Spring on 1970 454??

Thanks Joe.

Does this spring look like it's a GM piece or could it be aftermarket?

[Mark F.]

Re: 7 Leaf Spring on 1970 454??

Thanks Joe. Does this spring look like it's a GM piece or could it be aftermarket?

Mark,

Other than it's distinctive green color , it looks just like mine when I restored it 19 years ago...

[Joe L.]

Re: 7 Leaf Spring on 1970 454??

Thanks Joe.

Does this spring look like it's a GM piece or could it be aftermarket?

Mark------


I'd say, apparent color aside, it's virtually certain it's a GM spring.

[Mark E.]

Re: 7 Leaf Spring on 1970 454??

It's not really green. Funky camera color enhancement effect.

[Terry M.]

Re: 7 Leaf Spring on 1970 454??

Mark

Joe L has given you the possibilities.

In spite of our best efforts when writing the TIM&JG we sometimes are not as clear as later readings reveal. If one re-reads the sentence in the JM certainly the year 1971 falls within the bounds of 1970 to 1972. In 1971 There was supposed to be no F41 available in 1970 to 1972 except for ZR1 and in 1971 for ZR2. Even the sentence I just wrote can be misconstrued. However, at this point we have beat this horse to death and I think we will take a look at this and see what we can do to clarify the matter. In spite of my tangent above I have an idea that might work.

To my knowledge we have not seen a 1970 to 1972 Corvette in the hands of the original owner with the anomaly you present. Joe L offers some possible exceptions and of course we have not seen all the Corvettes produced in those three years.

[Mark E.]

Re: 7 Leaf Spring on 1970 454??

Mark

Joe L has given you the possibilities.

In spite of our best efforts when writing the TIM&JG we sometimes are not as clear as later readings reveal. If one re-reads the sentence in the JM certainly the year 1971 falls within the bounds of 1970 to 1972. In 1971 There was supposed to be no F41 available in 1970 to 1972 except for ZR1 and in 1971 for ZR2. Even the sentence I just wrote can be misconstrued. However, at this point we have beat this horse to death and I think we will take a look at this and see what we can do to clarify the matter. In spite of my tangent above I have an idea that might work.

To my knowledge we have not seen a 1970 to 1972 Corvette in the hands of the original owner with the anomaly you present. Joe L offers some possible exceptions and of course we have not seen all the Corvettes produced in those three years.

Thanks Terry.

I believe you're referring to the JG 6th edition phrase: "...in 1970 and 1972 F41 suspension was only available with the ZR1 and 1972 ZR2 options."

For accuracy and clarity, this could be rewritten to say: "...for 1970 through 1972, F41 suspension was only available with the ZR1 and ZR2 options."

Would this be correct?

The Black Book does not list F41 (or any suspension RPO) for 1970-72. So although heavy duty springs and shocks were part of ZR1 and ZR2, it looks like RPO F41 did not exist. It may be more accurate to say: "...for 1970 through 1972, no separate suspension options were available. However, LT1, LS5 and LS6 include rear sway bars, and ZR1 and ZR2 include special springs, shocks and sway bars." (I don't know if the front sway bars varied in size for LT1 and big blocks. If they did, state that also.)

[Duke W.]

Re: 7 Leaf Spring on 1970 454??

The NCRS Specifications Guide does NOT show a standalone suspension option for 1970. The ZR-1 and ZR-2 Special Performance Equipment packages included HD suspension components that were available previously as F-40/41 and included in the 1963 Z-06 Special Performance Equipment package.

Total 1970 ZR-2 production which included the LS-6 454/425 HP engine was 12, and ZR-1 that included the LT-1 engine was 8. The other HD parts included in these Special Performance Equipment Packages were J-56, HD brakes, and M-22 HD four-speed transmission.

The LT-1 engine used with the ZR-1 package has a different engine code than the LT-1 standalone engine option. The difference is that the former was equipped with a L-88 flywheel and 10.4" clutch. The Spec Guide does not show a different code for the LS-6 included with ZR-2, but I wonder if that is correct, as I expect it had the L-88 flywheel and clutch, too.

Draw your own conclusions, but I'll make an even odds bet that the answer, based on available evidence, is Joe's number 3 in post #2.

Duke

[Mark E.]

Re: 7 Leaf Spring on 1970 454??

The NCRS Specifications Guide does NOT show a standalone suspension option for 1970. The ZR-1 and ZR-2 Special Performance Equipment packages included previous HD suspension components that were available previously as F-40/41 and included in the 1963 Z-06 Special Performance Equipment package.

Total 1970 ZR-2 production which included the LS-6 454/425 HP engine was 12, and ZR-1 that included the LT-1 engine was 8.

Draw your own conclusions, but I'll make and even odds bet that the answer, based on available evidence, is Joe's number 3 in post #2.

Duke

Thanks Duke. The JG verbiage needs an update so it's consistent with the Specs Guide.