Broken rear spring ?

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Higgins56

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Jan 2, 2012
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Location
Finland
My Car
1971 Mach 1 Fastback now with 503 CID 4 bolt block with AFR Bullit heads , Edelbrock Performer RPM AirGap intake and ProSystems carburettor 1050.
4 sp Toploader with 9" Wavetrac rear.
Caltracs and shocks at the rear.
Hi,

I have been running my 71 mach 1 and recently noted something new...

When looking from the back the car is slightly ( 10-15 mm) leaning on the left.

I have not yet studied the case but does anyone have sivilized guesses whats the problem.

The rear springs are apparently original. The 9" rear axle with Detroit locker is eventually from 69 Fairline.

Gearbox is 4 sp Toploader and the engine is a 429 with ca. 450 hp.

I added a year ago self made shelby bars to the rear axle as the previous owner had made "ears " for them in the back axle and under the rear seat foot wells.

I do not use any rubber or poly-u bushings with them.

In case the left rear spring is broken and I need new springs for both sides does anyone have a good proposal what components to use ?

I might reconsider changing the shelby bars to Cal Tracs or similar and have mono leafs and new Cal schoks as well - perhaps in the front, too.

I would appreciate to get some advise of the components that work well with a Mach 1 with this specification.

Perä vinossa.jpg

 
Broken leaf in the spring pack most likely. Is the car rusty? Sometimes the rear spring shackle mount in the frame rail rusts and it changes the ride height. Your car looks too nice for that though!

 
Broken leaf in the spring pack most likely. Is the car rusty? Sometimes the rear spring shackle mount in the frame rail rusts and it changes the ride height. Your car looks too nice for that though!
Thanks for your comment.

The car chassis was completely done by the previous owner = zero rust- like you were guessing.

As it seems that I have to buy new springs - would stock springs / KYB shocks do or would I gain something when choosing something else.

The car is used mainly for street and sometimes for strips ( 1/4 mile) in local Ford / classic performance car happenings.

 
Eaton Detroit spring company has the exact replacement ratings for all years and drivetrains. will do 3 different eye locations if you want to adjust from stock height. Dedelum bushings/shackles work nicely also. Makes yer springs actually move rather than bind.

 
I'd check the opposite corner (right front) before buying rear springs to ensure that something there isn't amiss that is causing the car to tilt down on the driver's side.

 
I'd check the opposite corner (right front) before buying rear springs to ensure that something there isn't amiss that is causing the car to tilt down on the driver's side.
Thank you guys !

When dismantling the rear springs - is there any tension to be aware of not to get the springs to your face ?

 
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