Topic: Rear Spring Shackle Transition 65 to 66

[petersixtfive]

As the topic subject reads
Would anyone have a timeline for the changeover from 65 style 9/16 shackles  to 66 style 1/2 inch shackles
Reason for asking is when I removed the shackles from my late 65 SJ car they were the later marked also with C6 on the loose shackle leaf
I believe they were original to the car but can’t be 100 percent sure
Any advise on possible changeover appreciated
Also is it understood that A GT would have the special staggered shackle

Regards

[jwc66k]

- my late 65 SJ car they were the later marked also with C6 on the loose shackle leaf

Define "late". My May 65 GT Fastback San Jose build has 9/16 inch diameter shafts, my Oct 65 GT Fastback San Jose build has 1/2 inch diameter shafts.

Also is it understood that A GT would have the special staggered shackle

Yes. 65 and 66 use the different diameter shafts there also.
Jim

[J_Speegle]

Also is it understood that A GT would have the special staggered shackle

Not sure if "special" is the appropriate term - Maybe "different" might be better. Its been thought and the common belief that dual exhaust cars received two different (from drivers to passenger side) shackle assys. compared to the single exhaust which used the same version on both sides during 1965-66. 

There has been some discussions recently that question this and we've been discussing the possibilities while looking for documentation.  Once we start getting knee deep in the discussion I expect we will see/discuss/publish it here first

[petersixtfive]

Jim, with your cars we then have a 5 month window for the change in shaft diameter from 9/16 to 1/2
So I was hoping to narrow it down from there so as to determine what a June SJ GT car might have.

Jeff, agree “different” is more appropriate term for the shackle in this case

Cheers

[jwc66k]

Not sure if "special" is the appropriate term - Maybe "different" might be better. Its been thought and the common belief that dual exhaust cars received two different (from drivers to passenger side) shackle assys. compared to the single exhaust which used the same version on both sides during 1965-66. 

The "different/special" shackle using Ford base number 5776, is shown in the 64-65 Mustang Chassis Assembly Manual (AM0005 page 12) with the notation of "For All Production Image Options Models Left Hand Side Only" so it does exist. The PIO as it is known as, included dual exhausts. That "different/special" shackle is not in the 75 Ford Car Parts book so it was not "serviced".

There has been some discussions recently that question this and we've been discussing the possibilities while looking for documentation.  Once we start getting knee deep in the discussion I expect we will see/discuss/publish it here first

The "discussion" was whether that "different/special" was used on 67 and up Mustangs with dual exhaust systems. The original question was for a 65 and 66.
(Note: the 67 Mustang Chassis Manual (AM0020 page 15) has a note: "Direction Of Shackle Optional On All Vehicles Except Dual Exhaust".)
Jim

[Bob Gaines]

The "discussion" was whether that "different/special" was used on 67 and up Mustangs with dual exhaust systems. The original question was for a 65 and 66.
(Note: the 67 Mustang Chassis Manual (AM0020 page 15) has a note: "Direction Of Shackle Optional On All Vehicles Except Dual Exhaust".)
Jim

I have lost count how many of the duel exhaust shackles I have seen on 67 Shelby's so yes they were used in 67 .  67 was apparently the last year.  I inspected a 67 GT500 just last week that still had them also . Of course regular Mustang duel exhaust would be the same .

[J_Speegle]

The "discussion" was whether that "different/special" was used on 67 and up Mustangs with dual exhaust systems. The original question was for a 65 and 66.
(Note: the 67 Mustang Chassis Manual (AM0020 page 15) has a note: "Direction Of Shackle Optional On All Vehicles Except Dual Exhaust".)

The "discussion" I was referring to was not related to 67 and up but a different one related to 65-66. The discussion too place in person with the members and on the phone. That is why I mentioned it here in this new discussion about those 65-66.