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Discussion Starter #1
Have a 2003 full interior mach1 that I use for track days and that's about it. Right now it has MM R&T springs on the front with HD Bils and a TA/PHB with HD Bils and TA5 springs on the rear. I have just acquired a MM coilover kit for the front that consist of the new black Sport struts with 10" 350 lb springs. My questions are as follow.

1) Should I set the front ride height the same as it is now? (Have the stock K member and CAs)
2) Are the TA5 springs going to work with the front 350 pounders?
 

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I'm no Jack Hidley

But general rule of thumb is to double the coilover rate and that's a conventional rates equivalent.

I've seen and had a few friends run the TA/PHB with a similar front coilover setup and TA5 springs. I would try it out and see what sort of feedback you get from the car. That's usually a good indication of what direction you should go.
 

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Discussion Starter #3
I'm no Jack Hidley

But general rule of thumb is to double the coilover rate and that's a conventional rates equivalent.

I've seen and had a few friends run the TA/PHB with a similar front coilover setup and TA5 springs. I would try it out and see what sort of feedback you get from the car. That's usually a good indication of what direction you should go.
Thanks for your feedback. So I may be close.
 

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From MM's FAQ section:

Q. How do I compare a Mustang front coil-over spring rate to a conventional Mustang spring in the stock location?

A. The spring rates must be converted into wheel rates. The wheel rate is the spring rate measured at the wheel. The conversion is done through the use of what's called the motion ratio. For a stock Fox Mustang front suspension, the wheel rate is 25% of the stock location spring's rate. For example, an 800 lb/in stock location spring has a wheel rate of 200 lb/in. For a coil-over suspension, the wheel rate is approximately 90% of the coil-over spring's rate. For example, a front coil-over spring rated at 350 lb/in would result in a wheel rate of about 315 lbs/in. Note: The exact motion ratio conversion of the wheel rate for a front coil-over suspension is determined by the angle of the strut. That angle is the result of the camber and caster settings, and by the SAI (Steering Axis Inclination).

As per MM, your front springs have a rate slightly higher than Terminator springs which are 600 lb/in. The wheel rate for the rear solid axle stock location springs is about 50% (coil over is 110%). What is the rate of your TA5 rear springs? They come in two different rates.
 

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TA-5s are the lower rate; TA-7s are the higher rate. Given the modest front spring rate of 350# (WR of 315#) the TA-5s appear to be the best conservative match. But springs are cheap. You can also adjust rear roll with a bigger/adjustable bar to compensate if ride quality is important.
 

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Discussion Starter #6
From MM's FAQ section:

Q. How do I compare a Mustang front coil-over spring rate to a conventional Mustang spring in the stock location?

A. The spring rates must be converted into wheel rates. The wheel rate is the spring rate measured at the wheel. The conversion is done through the use of what's called the motion ratio. For a stock Fox Mustang front suspension, the wheel rate is 25% of the stock location spring's rate. For example, an 800 lb/in stock location spring has a wheel rate of 200 lb/in. For a coil-over suspension, the wheel rate is approximately 90% of the coil-over spring's rate. For example, a front coil-over spring rated at 350 lb/in would result in a wheel rate of about 315 lbs/in. Note: The exact motion ratio conversion of the wheel rate for a front coil-over suspension is determined by the angle of the strut. That angle is the result of the camber and caster settings, and by the SAI (Steering Axis Inclination).

As per MM, your front springs have a rate slightly higher than Terminator springs which are 600 lb/in. The wheel rate for the rear solid axle stock location springs is about 50% (coil over is 110%). What is the rate of your TA5 rear springs? They come in two different rates.
Mine are the lower rate 375-440.
 
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