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I have this leaf spring sitting around in my shop which was removed from a 66 427/450 (Sept build) car I owned a few years ago. I currently own a different 427/450 (Sept assembly) car and the spring on my current car (original spring) has only 7 leafs. How can this be unless it has something to do with the F-41 suspension package. I assumed all 427/425 high performance cars would have had the heavy (9 leaf) spring.
I'd appreciate help with solving this mystery. Is it possible my current car has the wrong spring?
optional on the L36 but standard on the L71/ L72/ L78 /L88/l89
The F41 option was NOT standard for L72, it was an option for L72 (and only for L72). It was not an available option for L36.
The F41 option was NOT standard for L71, it was an option for L71, L89 and was standard for L88.
This is well documented in the 66 and 67 NCRS Judging Guides
I thought the 66 L72 always came with the 7-Leaf HD Spring and that while it might be listed as an 'option', for the L72 and certain other Bigblocks, it was considered a 'required' option just like the 4-speed trans?
Anyone ever come across a 66 L72 that didn't have the 7-Leaf Spring?
Mike T - Prescott AZ
I thought the 66 L72 always came with the 7-Leaf HD Spring and that while it might be listed as an 'option', for the L72 and certain other Bigblocks, it was considered a 'required' option just like the 4-speed trans?
Mike T - Prescott AZ
Not correct in my opinion. I have had three original L72 cars, none had F41 suspension, all had standard 9-leaf springs. My L71 car also had standard suspension.
To deepen the mystery. My ‘66 has an unrestored suspension (shocks were replaced at some point with KYB’s). I do not have the original order form but the car has a rear sway bar, 7 leaf rear spring and .940” front sway bar. All components have an equal amount of corrosion, dirt and grease. The build date was Dec 17, 1965. Curiously, the car sits slightly lower than a friends unrestored small block convertible of the same year. F40 was available in ‘65 and has the same specs as F41 in ‘66 IRT BB cars. Was F40 designated for early build cars prior to the testing done in Jan ‘66 for the competition suspension that was eventually installed as F41?
sorry guys. I’m now thoroughly confused. But what I DO know is my unmolested (and neglected) September 15 assembled 427/450 (at that time) coupe has a 7 leaf spring. The rear sway bar is 9/16” in diameter. Front sway bar looks much larger but I haven’t measured it. Haven’t a clue as to whether or not I’m F 41. Thanks for the discussion though.
sorry guys. I’m now thoroughly confused. But what I DO know is my unmolested (and neglected) September 15 assembled 427/450 (at that time) coupe has a 7 leaf spring. The rear sway bar is 9/16” in diameter. Front sway bar looks much larger but I haven’t measured it. Haven’t a clue as to whether or not I’m F 41. Thanks for the discussion though.
No need to be confused. Re-read post #6. The NCRS Judging Guide very clearly states the answer. Your L72 could have come with either standard or F41 suspension. Without documentation of the car's history you have no way to know for sure, as the parts can be easily swapped back and forth making one into the other etc. There are no stampings to help figure this out such as the engine block, trans or frame have. If you think your car was really an F41 car and you want judging points, be prepared to spend big bucks getting original/restored F41 shocks
FWIW, I replaced all my F41 springs and bars on our L72 car with new repros but used Bilstein shocks. My car was roughly 1” lower than another L72 that was being restored at the same time. New, U.S. made spring and bar parts are available if you need them. I highly recommend the Bilsteins if you not an Originalist. Love the F41 except when crossing RR tracks. Having F41 is a big plus to me. Cheers
To deepen the mystery. My ‘66 has an unrestored suspension (shocks were replaced at some point with KYB’s). I do not have the original order form but the car has a rear sway bar, 7 leaf rear spring and .940” front sway bar. All components have an equal amount of corrosion, dirt and grease. The build date was Dec 17, 1965. Curiously, the car sits slightly lower than a friends unrestored small block convertible of the same year. F40 was available in ‘65 and has the same specs as F41 in ‘66 IRT BB cars. Was F40 designated for early build cars prior to the testing done in Jan ‘66 for the competition suspension that was eventually installed as F41?
It also had a factory rear sway bar. It was a late July convertible. I read somewhere (years ago) it was due to the added weight of the factory AC.
According to the 66 aim all l72's came standard with f40 suspension from the previous year and a standard rear sway bar. F41 was an option available in Jan of 66. It's a little ambiguous about what suspension was standard for the l36.
I don't have access to a 65 aim, so I don't know exactly what the f40 included.
sorry guys. I’m now thoroughly confused. But what I DO know is my unmolested (and neglected) September 15 assembled 427/450 (at that time) coupe has a 7 leaf spring. The rear sway bar is 9/16” in diameter. Front sway bar looks much larger but I haven’t measured it. Haven’t a clue as to whether or not I’m F 41. Thanks for the discussion though.
No need for confusion - all '66 L-72's and L-36's came stock with a 7/8" front sway bar and a 9/16" rear sway bar and a 9-leaf rear spring; if you also ordered F-41, you got a 15/16" front sway bar, the same 9/16" rear sway bar, a 7-leaf rear spring, stiffer F-41 front springs, and unique F-41 shocks.
01-28-2020, 02:55 PM
66 427/425 9 Leaf Spring Question
