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Discussion Starter #1
I am replacing the front suspension on my 66 Fastback which has a 75 granada brake conversion. The new springs are 1" longer and thicker than the old springs, does that matter? I am also putting in Roller Spring perches. When I measure the back of the spring perch to the to the top of the fender I have about 10" of clearance but the new spring is 13.5", compressing the new spring 3.5 inches seems like a lot.
Question #1 Should I replace the old spring with a spring that is the same height? The car sits really low and I get way too much tire rub so I don't mind a little more clearance.
Question #2 I purchased a $20 spring compressor from Summit, is it strong enough to compress the newer thicker spring 3.5 inches without breaking and killing my self?
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free height of the spring doesn't tell the whole story, depends on wire diameter, load rating ,ect.
your old coils may have been cut? Most OE coils are a lot taller than replacement "lowering" coils
Not sure what coil spring compressor you have
 

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What 2nd 66 said on the coil springs. The most important question, is the spring applicable to your car/application. If so, that is a 2nd reason not to worry about the height/thickness of the replacement coil.

Do you have a link to the spring compressor that you purchased?
 

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I am personally very cautions when dealing with springs. They freak me out. This is why I bought an expensive tool from OTC. Not sure if it is really better but gives me a piece of mind.

As stated the spring rate is more important than the thickness of the coil. I would install the spring, go for a ride and see how the car drives and how the stance is. It will lower a bit after installation. If it is too high cut the coil.
 

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Discussion Starter #5
What 2nd 66 said on the coil springs. The most important question, is the spring applicable to your car/application. If so, that is a 2nd reason not to worry about the height/thickness of the replacement coil.

Do you have a link to the spring compressor that you purchased?
Here is the link for the spring compressor
Performance Tool Coil Spring Compressors W80554

I also have the info from Kentucky mustang on the springs
Coil spring 67/73 1" drop 620 lg/in
 

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Discussion Starter #6
I am personally very cautions when dealing with springs. They freak me out. This is why I bought an expensive tool from OTC. Not sure if it is really better but gives me a piece of mind.

As stated the spring rate is more important than the thickness of the coil. I would install the spring, go for a ride and see how the car drives and how the stance is. It will lower a bit after installation. If it is too high cut the coil.
Is 620 lb/in normal for the front end? the other springs were a little thinner.
 

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620 is a good spring and a stiffer spring will not be as much of an issue with your roller perches.

Best way is to install the springs in the car and roll it back and forth a few times to let the suspension settle. Measure the height and decide how much lower you want. Remove the springs and take half the height you want to lower off the height of the springs and you will be right where you want. So if you want to lower it 1", take 1/2" off the height of the spring. Just stand the spring on end and measure the highest part, hold the tape next to the spring and rotate the spring until you get to 1/2 lower and cut the coil there. Don't just guess half a coil or whatever, and the springs will probably settle a little after some miles so better to leave a little long. You can always remove more, but you can't put any back.
 

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I just pulled and installed the springs in my 67.

I rented the spring compressor from Advance. Ive also used the one from AZ.

Go to Lowes and get a 5" piece of 1/2 or 3/4 pipe in the plumbing section, get a grade 8 washer for a 1/2" bolt as well. Slide the washer and pipe on the compressor so it is next to the top. (washer then bolt) As you tighten the compressor that 5" of slack will be on top instead of the bottom. Without the pipe the compressor will bottom out on the perch and you will not be able to compress the spring enough to get it off.
 

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Discussion Starter #10
You linked 67+ springs they are too tall if your putting them in a 65/66
I just ordered 65/66 Scott Drake 1" lowering springs from Summit. NOt sure if it was my fault or Kentucky Mustang but it cost me $100.
 

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620 springs refer to the diameter of the spring wire. The stock Mustang front coil springs are about 375 lb/in. There is around 800-900 lbs of downward force on a stock V8 mustang front coil spring with the car stationary. The lever action of the Upper control arm puts more force on the spring than the force being applied at the ball joint.
 

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Discussion Starter #13
620 springs refer to the diameter of the spring wire. The stock Mustang front coil springs are about 375 lb/in. There is around 800-900 lbs of downward force on a stock V8 mustang front coil spring with the car stationary. The lever action of the Upper control arm puts more force on the spring than the force being applied at the ball joint.
My receipt says 620 lb/in, doesn't that mean it takes 620lbs to compress the spring 1 inch? I am concerned this spring is going to change the stance dramatically. i guess i wont know until i put them in. Thanks for the info.
 
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