Original 427 street cobra spring rates

[blue sky]

Anyone having an original 427 AC Cobra street version that would know the front and rear coil spring rates I would be deeply in gratitude for having that information passed on. I have to make new springs for a set of Koni shocks and cannot use the springs I have to determine the rates. Thanks so much. AJ

[Cobra #3170]

I have 4 spring sets in the garage that are of the original diameter but three of the sets were made for me by Hypercoil and I am not sure about the stock ones but this is my best guess. 3.25 ID 11.68 O/l length 7 active coils with a .566 wire diameter F and the same dimensions with a .59 wire diameter rear. I think the rates were about 275 front and 320 rear but don't know for sure and did not calculate the rates based on the wire diameter I just listed. I can tell you these rates are no good for anything but the very small original blue dot tires. The wheel rates are in the 100 pound range and certainly not sufficient for any modern tire unless you like scary roll angles with bad geometry. Hope this helps

[blue sky]

Thanks so much for the input. I had talked to David Kirkham awhile back about the springs on his original car. He had most of the design specs but wasn't sure about the ratings. Thought they were 325/390# front/rear. Even though AC Cars spares list indicate that the same springs were used on comp cars as well as street versions, I would think the rating were boosted for the track. Will start stronger than what you had listed and hopefully will not have something that has no rough pavement absorption. Thanks again.

[Tom Kirkham]

Originally Posted by blue sky

... I had talked to David Kirkham awhile back about the springs on his original car... Thought they were 325/390# front/rear...

That is the spring rate that Dralle Engineering used to update a 427 street car. Defiantly firmer than original. The original Armstrong shocks were also pretty soft.

[blue sky]

Tom, Thanks so much. I will work with those rates. Both you and your brother have done great work over the years. All the best. AJ