front gt350 springs on PP1 GT

[thornclaw]

i plan on installing the GT350 front springs on my PP1 equipped springset 2015 GT. I expect to get a 0.3 inch drop and an increase in rate from 165 to 194. im leaving rears as is. Should i be concerned about an adverse change in vehicle dynamics if i do this, as im not installing the matching rear springs?

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[James1980]

I have Steeda minimum drop springs on the front of my car and the stock base springs on the rear. I haven't notice any issues but I don't push the car to the absolute limit. I think only then will you notice it and even if so, I doubt it would be that big of a problem.

 

[GregO]

Should i be concerned about an adverse change in vehicle dynamics if i do this,

Yes

 

[Labradog]

Think you'll want to swap the dampers at the same time.

 

[thornclaw]

its on koni sports
the interesting thing is you would think that there would be an optimal ratio between front spring rate and back spring rate but there isn't. the following are from the spring rate spreadsheet:

car , Front rate, rear rate, Front rate/rear rate ratio
base gt, 160, 668 , 0.239
PP, 165, 728, 0.226
BMR H, 250, 980 , 0.255
mach 1, 194, 657, 0.295
mach 1 +, 211, 742, 0.284
GT350R, 240, 914, 0.262

the ratio my combo would yield is 194/728=0.266, which is somewhere between gt350 r and mach 1 ratio.

 

[NightmareMoon]

its on koni sports
the interesting thing is you would think that there would be an optimal ratio between front spring rate and back spring rate but there isn't. the following are from the spring rate spreadsheet:

car , Front rate, rear rate, Front rate/rear rate ratio
base gt, 160, 668 , 0.239
PP, 165, 728, 0.226
BMR H, 250, 980 , 0.255
mach 1, 194, 657, 0.295
mach 1 +, 211, 742, 0.284
GT350R, 240, 914, 0.262

the ratio my combo would yield is 194/728=0.266, which is somewhere between gt350 r and mach 1 ratio.

Give it a try, I don't think it will explode or seek crowds any more than they currently do.

I mean, I'm on 650 front springs, so .. ;)

 

[StangTime]

The sweet spot for the S550 spring rate is 200 front / 800 rear.
That's a ride frequency of 1.47 Front / 1.53 Rear. A ratio of 1.041

A GT350 194lb spring will put you at 1.45 Front / 1.46 Rear. A ratio of 1.007
It would be balanced better with more spring rate in the rear. But certainly drive-able.

FYI: 2017-2018 GT350 front spring has a 194lb rate.
2019 GT350 front has a 211lb rate.

Some useful info here: https://www.mustang6g.com/forums/th...frequency-for-the-mustang.146540/post-2997907

 

[thornclaw]

thanks for above info
ive noted people stating the older gt350 had a different spring than the newer one, however, on any parts website they are the same: FR3Z-5310-k.

 

[NightmareMoon]

Theres more to life than ride frequencies, but it all depends on your goals.

Ride frequencies are great for tuning out expansion joints, but kinda useless if your goal is handling. If bouncy ride and bump compliance is important for you, proper selection of quality shocks matters more than ride frequency IMHO.

 

[Dana Pants]

It will probably handle better, but I’m left asking why. I’m using gt350r springs and all around and they are still pretty floppy.

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