69 L71 rear leaf springs

[Richard M.]

Re: 69 L71 rear leaf springs

Joseph, Since that mono leaf rear spring is thinner than stock, for the new spring....

Carefully pre-measure the assembled spring/plate/hardware thickness for proper length of the required 4 spring attachment bolts to prevent diff case damage and ensure final torque is with the suspension fully loaded(i.e. completed car weight and normal camber) on flat ground.

Rich

[Joe L.]

Re: 69 L71 rear leaf springs

More follow up on this….
So I texted the PO and he said that yes, he remembers removing the rear 7 leaf spring and the lower shock mounts to use on his other corvette he was working on. At the time he had no idea they were different.
He said 30 years ago, he didn’t care that much about originality so he tossed it.
He confirmed it as having an F41 rear suspension.

So I made the drive into LA and visited the mythical warehouse full of corvette parts.
I picked up F41 NOS front coils, NOS F41 rear shocks that aren’t the correct date (date correct were too expensive) a rear 7 leaf spring and what appears to be NOS lower shock arms with hardware.
so all I’m missing are front shocks to be able to complete the F41 package. I would have purchased the front shocks, but I ran out of money.

Joseph-------


I'd check the currently installed front springs to see if they are F-41 as I doubt that they have been changed. If they are stock OEM, non-F-41 springs I'd be virtually certain of it as I HIGHLY doubt such springs would have been installed on the car post-factory. Also, check front sway bar OD as that's another clue as to original suspension.

By the way, I would NEVER want F-41 springs, front or rear, on any Corvette I owned and drove.

[Mark F.]

Re: 69 L71 rear leaf springs

Ive counted numerous times the number of leaf springs in these pictures and I keep counting only 7. I would love to have some consensus on what some of you are seeing. are any of you able to determine if their are 7 or 9 leaf springs from these pictures? Do any of you also see any signs indicating F41 suspension? thanks in advance

Joseph,

Comparing yours to mine ('67), I count 7

Comparing yours to mine 7 leaf spring_001.jpg

[Joseph W.]

Re: 69 L71 rear leaf springs

Joseph-------


I'd check the currently installed front springs to see if they are F-41 as I doubt that they have been changed. If they are stock OEM, non-F-41 springs I'd be virtually certain of it as I HIGHLY doubt such springs would have been installed on the car post-factory. Also, check front sway bar OD as that's another clue as to original suspension.

By the way, I would NEVER want F-41 springs, front or rear, on any Corvette I owned and drove.

[Joseph W.]

078C2290-D096-40B5-B3EF-98C61F88EC92.jpeg
What is the purpose of it? To stiffen the ride or give the proper stance?

[Gary B.]

[Mark F.]

Re: 69 L71 rear leaf springs

Joseph,

My recollection is (and that shot is from before I tore that spring apart ~20 years ago ) that plate has a hole dead center in it which aligns with the head of the thru-bolt that holds all the leaves together until the spring assembly is mounted and tightened up with the 4 larger thru bolts and bottom plate. If the hole were not in that plate (spacer, as Gary correctly points out), the head of the bolt would not mate flush with the diff (IOW, the bolt head would interfere with a perfectly flush, flat mount to the bottom of the diff).

It also seems to me that spacer would help spread the loads placed on the bottom of the diff and diff cover - particulalrly where those two components are bolted together (cover casting to diff housing casting) - dunno for sure, though.

My guess is that's the same for all '67 springs, but I have never owned, nor seen the top of a SB 9-leaf spring (removed from the car).

[Richard M.]

Re: 69 L71 rear leaf springs

Original 1967 F41 spring I restored several years ago. Note no top flat bar.
P5020002.jpgP5260035.jpgP5260036.jpg

Here is a Eaton reproduction F41 spring I got about 10 years ago. Note flat top bar.
PB090016.jpgPB090017.jpg

Note the leaf end curls on the repro compared to the original. There is a slightly noticeable difference.

Repro
PB110037.jpg

Original
P6010014.jpg

P5260028 - Copy.jpg

Joseph, one other item to look at when time. See if your rear hubs(if originals) have any unusual casting "features" on the outer facing lip.
Like this cast "O", sometimes "X".
PC100003.jpg

[Patrick B.]

[Joseph W.]

Re: 69 L71 rear leaf springs

Original 1967 F41 spring I restored several years ago. Note no top flat bar.
[ATTACH=CONFIG]112207[/ATTACH][ATTACH=CONFIG]112208[/ATTACH][ATTACH=CONFIG]112209[/ATTACH]

Here is a Eaton reproduction F41 spring I got about 10 years ago. Note flat top bar.
[ATTACH=CONFIG]112210[/ATTACH][ATTACH=CONFIG]112211[/ATTACH]

Note the leaf end curls on the repro compared to the original. There is a slightly noticeable difference.

Repro
[ATTACH=CONFIG]112212[/ATTACH]

Original
[ATTACH=CONFIG]112214[/ATTACH]

[ATTACH=CONFIG]112213[/ATTACH]

Joseph, one other item to look at when time. See if your rear hubs(if originals) have any unusual casting "features" on the outer facing lip.
Like this cast "O", sometimes "X".
[ATTACH=CONFIG]112215[/ATTACH]

[Terry M.]

Re: 69 L71 rear leaf springs

Patrick
I believe you and I know a bunch of people on the 1970-72 judging Manual revision team who also believe you.

Keep the faith.

[Patrick B.]

Re: 69 L71 rear leaf springs

Patrick
I believe you and I know a bunch of people on the 1970-72 judging Manual revision team who also believe you.

Keep the faith.

Thanks Terry

[Gary B.]

Re: 69 L71 rear leaf springs

Joseph,

My recollection is (and that shot is from before I tore that spring apart ~20 years ago ) that plate has a hole dead center in it which aligns with the head of the thru-bolt that holds all the leaves together until the spring assembly is mounted and tightened up with the 4 larger thru bolts and bottom plate. If the hole were not in that plate (spacer, as Gary correctly points out), the head of the bolt would not mate flush with the diff (IOW, the bolt head would interfere with a perfectly flush, flat mount to the bottom of the diff).

It also seems to me that spacer would help spread the loads placed on the bottom of the diff and diff cover - particulalrly where those two components are bolted together (cover casting to diff housing casting) - dunno for sure, though.

My guess is that's the same for all '67 springs, but I have never owned, nor seen the top of a SB 9-leaf spring (removed from the car).

[Mark F.]

Re: 69 L71 rear leaf springs

So why did just those five years use a spacer plate? Gary

Gary,

I cannot answer that question.

And, based on Rich's photos in post #23, perhaps mine was an Eaton replacement spring? (my car was 31 years old when I bought it)

I guess I'm also mis-remembering how the "knob top" of the bolt that holds the leaves together (as shown in Rich's shot of his original F41 spring) can clear the bottom of the diff case and/or cover when bolted in place with the 4-bolt bottom plate?

If that clears and mounts correctly w/o a spacer, then my logic for why a spacer was used is balderdash!

[Richard M.]

Re: 69 L71 rear leaf springs

Gary,

I cannot answer that question.

And, based on Rich's photos in post #23, perhaps mine was an Eaton replacement spring? (my car was 31 years old when I bought it)

I guess I'm also mis-remembering how the "knob top" of the bolt that holds the leaves together (as shown in Rich's shot of his original F41 spring) can clear the bottom of the diff case and/or cover when bolted in place with the 4-bolt bottom plate?

If that clears and mounts correctly w/o a spacer, then my logic for why a spacer was used is balderdash!

Mark, Correct. The center bolt passes through that flat plate so the head still needs to be low enough to fit in the diiferential center locator hole.

In rebuilding that original F41 spring, I acquired a repro center bolt. It's head was significantly taller than the original I removed.

Repro left, Original right.
P5260019.jpg

The original head depth was apx 0.248".
P5260020.jpg

Repro bolt apx 0.373".
P5260021.jpg

Checking it for clearance, it could have been disastrous if I used it.
P5260025.jpg

I ground the head to fit the space properly before reassembling the spring and attaching to the differential.
P5260026.jpg
P5260027.jpg

Rich