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I purchased a 1973 Cobra Jet Mustang convertible, and the rear end seems to be riding too low. It's been "restored", but I've found a few things that weren't done right, and I'm thinking that the rear springs are original and sagging. I don't want to waste money buying "original height" springs if the rear height is correct but just too low for my liking. I'm an old school guy who likes my muscle cars up a little in the back. Can anyone tell me the correct rear bumper height on a 73 Mustang ragtop? Also, what are the thoughts about replacing the springs versus just adding a leaf to boost the back end? Thanks in advance for any help and advice!
 

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New springs = stock ride and (theoretically) height if all else is correct
add a leafs = stiff ride. You'll have it all disassembled to add, so why not remove 2 more bolts to replace it all? My vote's for new complete springs..
 

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All springs will sag eventually. If yours are original you can bet after all these years that is what has occurred. Adding a leaf will not "boost" doodley squat, but will increase the spring rate, make them stiffer. Get new ones. If you want the original look/ride height restored get original spec springs. Eaton Detroit would be 1st choice, made from the factory specs with SAE 5160 steel. NPD sells them and the code you would want is 5560-30.

Welcome to VMF! :smile2:
 

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I purchased a 1973 Cobra Jet Mustang convertible, and the rear end seems to be riding too low. It's been "restored", but I've found a few things that weren't done right, and I'm thinking that the rear springs are original and sagging. I don't want to waste money buying "original height" springs if the rear height is correct but just too low for my liking. I'm an old school guy who likes my muscle cars up a little in the back. Can anyone tell me the correct rear bumper height on a 73 Mustang ragtop? Also, what are the thoughts about replacing the springs versus just adding a leaf to boost the back end? Thanks in advance for any help and advice!
Rear ride height for '71-73 is 11.74" from the ground (level floor/ground) to the centerline of the bolt that holds the rear spring shackle to the rear subframe.:yoho:
 

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buzzojoe, like you I'm also from the old school also, you recall the old air shocks back then but a draw back then was needing an air pump when they got low or the airline would get damaged. I feel the best way to go is to add an extra flat leaf spring going from 4 leafs to 5 leafs, the cost was less than a 100 bucks and was done by local truck spring shop. That's what I did with Bitching n Blue, now dips in the road or pulling to driveways I no longer cringe for hearing the tire rub that with the rear wheel well being rolled. Just an old fool from the old school opinion. jrichs.
 

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Rear ride height for '71-73 is 11.74" from the ground (level floor/ground) to the centerline of the bolt that holds the rear spring shackle to the rear subframe.:yoho:
There's got to be something more to that measurement (or something wrong), because 11.74" doesn't get you from the floor to the rear eye of the spring, let alone the upper shackle bolt.

Of course, any measurement is dependent upon tire size and tire inflation. I've got an M-code 1971 convertible here with 32K original miles, all original springs, and I've attached some photos below... I think she sits absolutely perfect for my tastes. Using bartl's method, I measure 17 15/16" from the centerline of the rear shackle to subframe bolt to the ground, and I measure 26" from the top of the rear wheel arch to the ground. Those are reproductions of the original O.E. spec tires.

I haven't cracked the books to determine if Cougar ride heights were different, but for ships and wiggles, I've got a 500-original-mile '73 Cougar with the same Q-code as the OP, sitting on original tires, and it measures 18 1/8" shackle bolt to ground. Which seems pretty much in-line with my '71, given the higher mileage of the '71. I'd wager the '71 sat very very close to the '73 Cougar's height when it was new.

Admittedly, this is all about as scientific as predicting weather with a wet finger. ;)
 

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