Gear Poet

Been lurking for a few months; first post here. Apologies for the length.

I have a '14 GT with the track pack option. The car is a daily driver, but the route is extreme: 26 miles one-way over a mile-long dirt & gravel driveway, a few miles of broken pavement, good two-lane twisties over a 7500 foot mountain pass, a stretch of highway, and several miles of urban traffic -- and then back.

Obviously I'm interested in suspension and handling upgrades, and to that end, I've already replaced the panhard bar and brace, and the sways. I will also replace the struts and shocks with adjustable units.

My questions involve springs. Knowing that the track pack springs have higher rates, I'd like to go with slightly higher rates even so, and dial in the adjustable shocks and struts. However, for reasons having to do with the road conditions I drive, I need to preserve OEM height -- lowering is not a good option, but lowering springs are basically what the aftermarket is all about. Also, I'm not interested in doing adjustments to pinion angles, etc., at this time.

So --

(a) Are OEM Boss 302 front springs a good option? I believe they have a higher rate than track pack springs; any issues with fit or mounts? I've read they lower height less than a half inch -- true?

(b) Are OEM Boss 302 rear springs an option? I've read they are too stiff for DD Mustangs, but I've also read they do fine. Issues with fit or mounts? I've read that they lower height over an inch, but I've also read they don't lower height any more than about an eighth of an inch. Clarification?

(c) My understanding is that 55D springs are aftermarket track pack springs cut shorter. I'm not concerned with rake, so there's no point in that. Are there any other approx OEM-height spring options available with somewhat higher rates than track pack springs?

Thanks for any answers. GP

todcp

Correct on better shocks. New Koni SR.T will have a very significant impact on your ride and handling. The stock dampers are a very weak link. Koni yellow adjustables for street use only is probably overkill.
There is a market for springs that are firmer without being lower. But none are available. The Boss stock springs will lower the car less than the aftermarket but are not that much firmer. The Boss Springs are cheap from Tasca or Levittown Ford. Sometimes you may find a used set.
A Watts Link would be a big help for bad road performance. I have the Fays2 and the roads here in Northern NH are frost heaved and rough. The Watts Link was a significant improvement. The Steeda Watts may be better for the bad roads you have to deal with.
An aftermarket adjustable panhard bar will not give any improvement on a stock height car and will not improve ride quality or handling. It only allows for relocating the axle center on a lowered car when a significant change in ride height causes the axle to become off center.

Gear Poet

Thank you for answering. Agree that replacing the OEM struts/shocks are a priority.

Would OEM Boss 302 front springs paired with the OEM track pack rear springs already on the car yield any real benefit?

I've seen the Steeda Watts Link, and I suspect I'll probably go that way next summer.

I obtained the panhard bar and brace as a package. The OEM brace is not substantial and flexes badly; I've verified that with a Go-Pro cam -- and that's what I was actually interested in. I've read that the OEM shot-filled bar is thin-walled and not particularly stiff, so the package seemed like a good deal.

silverstate777

I don’t know about the track pack or Boss spring firmness and heights, but here’s a loose comparison for you. I went with the Roush 1/2-inch drop kit:

http://www.roushperformance.com/part...2011-2014.html

This is how it sits with 255/45/18 tires, supercharger and empty trunk. The height measurements ended up as, front: 28.0” and rear: 28.50”

lsxjunkie

This seems relevant to my interests.

OEM Front Springs:
Track Pack - 131lbs
Boss 302 - 148lbs
Boss 302 Laguna Seca - 137lbs

The Boss Springs offer a 3/4 to 1" drop. All are linear. Compare to some aftermarket springs

OEM Rear Springs
Track Pack - 167lbs
Boss 302 - 186lbs
Boss 302 Laguna Seca - 191lbs
Route 66 55D Springs (same height as Boss 302 Springs) - 170lbs

All of these springs are linear, the Boss and Route 66 springs drop the rear about 1/4 to 1/2".

Compare to some aftermarket choices

Steeda Ultra Lites - 195lb front, 175lb rear - Linear
1.2" front / 1.4" rear

Steeda Sport Springs 200lb front, 175lb rear - Linear or Progressive
1.0" front/ 1.25" rear

BMR Springs - 165lbs Front and Rear Progressive
1.5" front and rear


Data out of the way, here are my actual experiences. I bought Laguna Seca shocks and springs as direct takeoffs. The rear was either very stiff or very bouncy, and I couldn't really find a good setting for the shocks for them. I dumped them for 55D springs and the rear settled down significantly. I'm very happy with the 55D rears. However, I still want more rebound stiffness, so Koni Yellows will be replacing the LS Tokico Illuminas when they start to go.

In the front, the 139lbs spring is somewhat stiffer than the OEM track pack, but the real control comes from the shocks, which I currently leave turned all the way stiff. However, I still want more stiffness in the front and will be purchasing OEM Boss springs when I make the switch to Konis, probably in the next few years. The OEM Boss springs are about 40 dollars for the set before shipping from Levittown Ford Supercenter.

Additionally, I will be purchasing sway bars and a Watts Link at some point. I am waiting to see the BMR Clamp Style Watts link to see if it is worth the money over the Fays2.

I will not buy aftermarket springs because they are all too low for where I live and I do not want to mess with the suspension geometry any more. If I drop the front any more, I will need camber/caster plates. If I drop the rear any more, I will need an adjustable upper control arm to set pinion angle. Also, this car is a 20k/yr daily driver, so I am straddling the line between street comfort and body control.

This is my car with LS front springs and 55D rear springs.

Jazzman442

Allot of the suspension tuning is how you drive some like it heavy on the springs medium shock valving and medium sways. Some like it sprung soft heavy sways Larger bars and shocks set to the track. What one person does will almost allways not be what the next wants. Driving style plays allot.

If it is used mostly on the street I like a mediums sprung car with damping that comes on quick then slows. Larger sway bars. That is how all of the vehicles are set up.

Gear Poet

Thanks for answering.

The OEM spring rates given above are backward. OEM track pack rates are 167 front, 131 rear; OEM Boss 302 standard are 186 front, 148 rear; and OEM Boss 302 LS are 191 front, 137 rear. Check the aftermarket spring rates; that's why they're so different.

The OEM Boss 302 standard springs seem to have the best rates for the type of driving conditions I encounter, when paired with Koni Yellows set on medium-to soft. They also don't lower the car very much. Unfortunately, while I've identified the front standard Boss 302 springs, I can't find the right parts numbers for the rear springs -- there are seven choices and all are listed as fitting base, GT, GT t/p, and both Boss 302 suspensions.

2014DIB

In a similiar situation - have Koni Yellows in the closet waiting to install - but - do not want to lower much due to driveway clearance issues.

Can you advise the part number(s) for the front? May go with this and 55D on rear.

TIA

Gear Poet

I managed to track down the OEM standard Boss 302 springs for both front and back:

CR3Z-5310-B front
CR3Z-5560-B back

By the way, if you can get the engineering number from the tag on any Mustang spring, dealers can cross-reference for an ordering P/N.

Can't tell you how it will all work out because I'm in the middle of installation; however I can say that the standard Boss 302 front springs have 4 turns compared to 5 turns for the OEM Mustang GT track pack. Off of the car, mounted and bolted to the strut, both stand at the same height.

lsxjunkie

Trust me, the rates are correct. I know this from my own driving experience AND I've confirmed this with Sam Strano and Kelly Aiken at BMR.

http://mustangforums.com/forum/s197-...ml#post8024475

"In fact that's why aftermarket springs help the balance and handling so much, they all increase the front rate to be at least equal to, and almost always higher than the rear rates. Ford rates, all of them, are stiffer in the back than the front. "

Stevedotmil

You would think it would be opposite because duhhhhh the engine is up front.

Gear Poet

Ford documented the spring rates a few years back, but a mis-edit resulted in the rates being reversed in the public release. People "all over the internet" have been quoting and re-quoting the mistake ever since. It's sad to see vendors do the same.

The mis-documentation was verified to me during a phone call with Ford Tech/Performance Group in Detroit two weeks ago. There have also been a number of posts in various Mustang forums pointing out the problem and referencing independent rate tests that belie the idea that Ford springs are "soft" in front and "hard" in the rear.

I stand on information in my post above.

lsxjunkie

You can go with your information, I'll go with mine. With a 191lbs front spring, I wonder why my car still nosedives like a stock Track Pack car when the shocks are turned all the way down?

You do realize that aftermarket spring manufacturers have to test the stock springs to get a baseline to figure out where to go with their aftermarket springs...

I guess Edmunds got the wrong info too.

http://www.edmunds.com/ford/mustang/...oad-test1.html

And this guy.

http://www.stangtv.com/features/car-...s-302-mustang/

Man, this information has been published everywhere.

http://www.mustangandfords.com/car-r...uspension.html

Gear Poet

*shrugs....

If you say so. I went to the manufacturer, the manufacturer gave me the information I posted. If someone has something beyond "I read this here; I read this there" -- testing, tech used, video, etc. -- I'm happy to be re-educated. Otherwise, the last thing I want to do is get involved in a web draw-down.

I will say one thing, however: Aware of the fact that there is some question over "fronts and backs spring rates", I tested the OEM GT/track pack springs I had, and the OEM standard Boss 302 springs I replaced them with. How?

It's not an especially good test in that it will not give you anything like a numerical value, but you can determine whether one spring's rates are higher or lower than another. You can attach three compressors evenly around the middle three turns on a non-progressive spring, compress until the turns are lightly seated against each other, and measure an analog to "compression force" with a torque wrench. (Three compressors give an additional data point and eliminates offset force.) The value will tell you nothing about the rate, but it will indicate whether one spring has a higher rating than another. In my case, that test tended (notice the word "tended") to confirm what the Ford Performance Group told me.

duff

This backwards spring rate crap annoys the hell out of me. There is nothing wrong with a softer front spring.

If you don't believe the ford spring rates, measure them or calculate them. Measure the wire diameter, mean diameter of the coil, and count the number of coils (I did this btw). If you don't get close to these rates when doing the calc, you are measuring or counting wrong (active coils).

Back to topic, the desire, intended to be the subject of this thread, was to go stiffer without lowering the car, if possible. So it's all relative. You could buy oem gt500 springs for example, but the car will likely push and bounce and ride high up front. Depending on the year, front rates are between 194 and 250 if I recall. But they are relatively cheap, so you could try them at small loss if they don't work out?

In my case, I had a similar desire and tried the boss springs. Love them. My car sits a bit lower sure to undersized tire diameter.

27 5/8" front with boss spring 148 lb/in,
28 3/8" rear with brembo spring less 1 full coil ~175 lb/in (removed top, dead coil).
Measured ground to fender lip, on 275-35 r19. Thus 3/4" forward rake at fender.

To answer the question, the boss (non ls) front springs do, imo, make a noticeable difference if you don't want to lower the car (much)...but it's subtle. Unfortunately, there are not much options for stiffer springs that do not lower the car. Upgrading dampers however, will make the car feel stiffer without ever changing your springs at all.