New Spring advice front and rear, Height of fenders, Passenger side rear is lower by 5/8" now....or maybe a bit lower.

[Bufus]

New rear leaf springs raised my rear end 1 12/16" on one side and 1 15/16" on the other.  My rear measurements are now 3/8" different.  Neither one looks high enough to me. (The front springs were replaced at the same time.) I'm thinking about air shocks to get the rear end a little higher and leveled out.

 

[midlife]

No on air shocks.  These cars don't have sufficient stiffening in the sheet metal for air shocks.

 

[7173Vert]

New rear leaf springs raised my rear end 1 12/16" on one side and 1 15/16" on the other.  My rear measurements are now 3/8" different.  Neither one looks high enough to me. (The front springs were replaced at the same time.) I'm thinking about air shocks to get the rear end a little higher and leveled out.

I would rethink the use of air shocks long term on these cars. When I bought my 71 Vert, the trunk pan was cracked on both sides as well as the upper shock supports on the underside of the car. Granted, the car was driven hard in its former life and is an original 429 car…

 

[Galucha]

I would rethink the use of air shocks long term on these cars. When I bought my 71 Vert, the trunk pan was cracked on both sides as well as the upper shock supports on the underside of the car. Granted, the car was driven hard in its former life and is an original 429 car…

Ditto on that. The sheet metal where the topside of the shock mounts is not very thick. I supposed you could always weld a plate in to beef it up, but the angle may be tricky since they kind of sit down in a hole behind the seat.

 

[Stanglover]

New rear leaf springs raised my rear end 1 12/16" on one side and 1 15/16" on the other.  My rear measurements are now 3/8" different.  Neither one looks high enough to me. (The front springs were replaced at the same time.) I'm thinking about air shocks to get the rear end a little higher and leveled out.

Sooo, my first question is who's and what springs did you buy??? IF your car is straight and square, i.e. not been crashed, damaged or twisted, it ought to be pretty close side to side. Granted, it is possible I would think, that it could have been built slightly off, but unlikely. I  ONLY use Eaton Detroit Springs springs and even then I have a 1/8" difference center height on the wheel arch left to right. My experience with cheapo junk aftermarket rear springs is well documented on here.

I agree with all others, NO air shocks. Another thought, if you have adjustable rear shocks, are they set the same?

 

[midlife]

It could be that your front suspension is off, throwing the rear height off.  Something to consider.

 

[griffbl]

After 50 years it could be a million things causing the height to be slightly different side to side…..if you get it close, like 1/2” (your number may be different)or so or less no one will know save for yourself Some say that after 50 years the torque that is applied from one side of the car vs another will cause the chassis or other suspension related parts to take “a set” or bend a bit……so it can and could be a myriad of things. Agreed that air shocks are really a last resort as they really throw something of a wrench into the works as to how your springs actually do their job. My rear springs came from EATON. The front springs were on back order for months….so I went with some 600 pound springs from Scott Drake which have worked wonderfully on a bunch of cars for me (springs for this year model but NOT as specific as they would have been via Eaton to be sure) I will post pics when completed. Also my front springs needed new perches which I replaced.

Best,

Brad

 

[Bufus]

Thanks for the info. I don't know alot of detail about what was replaced on my car before I got it but I'm sure that some of the rear body parts were. If air shocks are out, how about using custom length shackles to slightly raise and even up the rear? Any other ideas?

 

[Idaho Chris]

After 48 years, my '73 sat slightly low on the driver's side.  I didn't measure it, but it could certainly be noticed looking straight on from the rear.

I replaced the rear leaf springs with Eaton springs and new stock length Eaton shackles.  Now the car sits even side to side.  Eaton makes three different springs for our cars; Standard, Competition and Boss.  I installed the Competition springs and I am happy with the selection.

As far as the typical rear squat our cars have, I corrected that at the same time by cutting 1/2 coil out of the stock original front springs.  Photos show stance now.

 

[rio1856]

After 48 years, my '73 sat slightly low on the driver's side.  I didn't measure it, but it could certainly be noticed looking straight on from the rear.

I replaced the springs with Eaton springs and new stock length Eaton shackles.  Now the car sits even side to side.  Eaton makes three different springs for our cars; Standard, Competition and Boss.  I installed the Competition springs and I am happy with the selection.

As far as the typical rear squat our cars have, I corrected that at the same time by cutting 1/2 coil out of the front springs.  Photos show stance now.

View attachment 55537

View attachment 55538

View attachment 55539

Your ride looks outstanding!!

 

[Stanglover]

Thanks for the info. I don't know alot of detail about what was replaced on my car before I got it but I'm sure that some of the rear body parts were. If air shocks are out, how about using custom length shackles to slightly raise and even up the rear? Any other ideas?

Eaton make a 1" longer shackle kit sold at NPD, but I guess at a pinch, you could make a set of custom shackles. Still may not be the correct fix. How does the car look from the back? Does it look "off", like it's sagging to one side? 

My guess is the springs are no longer the same arch, i.e. one spring has sagged more than the other. If your car body is not twisted and the rear frame is all good, then it has to be the springs. Nothing else make sense to me. 

 

[Bufus]

Well it has new springs front and rear. Now that I look at the back,  I can see it from there too. Check out the picture. This picture also makes me ask what size tires/wheels are yall using on your mustangs???

 

[Idaho Chris]

....This picture also makes me ask what size tires/wheels are yall using on your mustangs???

My car leaned about the same amount as yours to the driver's side before I installed the new Eaton leaf springs.

As for wheels/tires:

I'm running Wheel Vintiques Magnum 500's; 15x8 rear and 15x7 front.

Tires are BFG 245/60R-15 rear and 225/60R-15 front.

 

[Stanglover]

Well it has new springs front and rear. Now that I look at the back,  I can see it from there too. Check out the picture. This picture also makes me ask what size tires/wheels are yall using on your mustangs??? View attachment 55552

Holy heck batman! Do you have a "fat lady" sitting in the passenger seat?? 

That's some lean to say the least. You say you have "new springs", but what brand? Did you check them side by side before installing them? Is it at all possible you inadvertently have one spring standard eye and the other reversed eye. That's a real long shot but something is very definitely OFF!! As for tire size, I have to assume your rears are the same. I'm fishing for sure now, 

On mine, I have 14" Magnum 500's with 245-60-14 rear and 235-60-14 front on 8" and 7" rims. 

 

[Bufus]

The springs are from CJ Pony Parts. They are both the same. The difference on the back is 5/8".  If I change the shackles, will I have to loosen all of the bolts holding the leaf springs or can I just take the shackles off?

 

[Bufus]

Anybody know if you have to loosen all the leaf spring bolts to change the shackles?

 

[Don C]

Just take the shackles off, after you support the car.

 

[Stanglover]

This is bothering me somewhat as to what is going on. One thought I just had is this. When the car is up on jack stands, wheels off, can you measure vertically from the frame rails down to the springs. Either in front or just behind the axle. My thinking is if one spring has sagged, the dimension ought to be off by the 5/8" you are seeing. 

Going back to my own problems with rear springs and as I have commented on many times, I had bought a set of Grab-a-Track 4 1/2 leaf springs. The extra 1/2 leaf is supposed to help stop spring wrap up on my "one wheeler peeler" (open diff). The problem was they were way too high, lifting the rear by 1 3/4 inches. I had the springs de-arched, but then they started to reverse bend. I started to research and only found Eaton reveal the steel type they used. Even Dayton Springs, another huge US spring maker, did not give the steel type. What I did find is some aftermarket manufacturers use a steel know as 4140, whish is a pre-hardened steel used in tool making. It is not heat treatable beyond that. Eaton use SAE 5160 spring steel. That is why I would ONLY suggest Eaton Detroit Springs to anyone wanting correct rear springs. 

 

[griffbl]

Eaton supplies good kit. Great service and knowledgable staff also.

 

[Stanglover]

Eaton supplies good kit. Great service and knowledgeable staff also.

Yes they do.