Boss front springs + 55D rear springs?

[corruptor]

Anybody running the front Boss springs and rear "55D" rear springs from Brembo50.com? Seems like it would be a good way of keeping near stock GT Brembo spring rate levels while lowering slightly (front Boss springs and the 55D are both about 1/2" lower than stock).

I have a set of Steeda Sports and Koni Yellows sitting in my garage but am contemplating ditching the Steeda Sports and running the above spring setup.

Pros/cons of the above setup vs. Steeda Sports?

 

[JAJ]

It's hard to say - pro's and con's will depend on what you're trying to achieve. If all you want is a lower stance, then order up a set of Boss springs for all four corners.

The biggest effect on ride and handling is the struts and shocks, not the springs. The factory ones have weird damping curves that tend to make the car wallow from end to end, or at least mine did. That won't get better until you pick up some shocks with a better damping curve like Koni STR.T's or the equivalent. A good alternative is actually the GT500 dampers if you can find a take-off set, otherwise they're too expensive to bother with.

My point is that if you're going to mess with the suspension, then swap out both the springs and shocks. You'll be happier than if you just swap springs.

 

[Grant808]

That's my plan for my GT. Already have the 55D springs.

I want to add the whole Boss front end suspension, if possible. Depends on what comes out from FRPP, and I might go that way.

 

[MikeLTDLX]

The problem is, the 55D springs barely level out the front and rear air gaps with stock Brembo springs in the front. If you lower the front end, you will wind up with rake again. I am about to say fook it and just put the standard Cobra Jet springs in there, rake be damned..I just want to hook.

Mike

 

[300AGT]

I have a 2011 brembo GT with Koni STR.T struts & shocks and the 55D springs in the back .In changing over to Koni strut with GT500 mount on the front i think you find this change alone with drop the front of the car about a 1/2 inch .From the ground up to the bottom of the fender lip on the front is 28 1/2 high same as on a stock Boss 302 .

 

[Grant808]

The problem is, the 55D springs barely level out the front and rear air gaps with stock Brembo springs in the front. If you lower the front end, you will wind up with rake again. I am about to say fook it and just put the standard Cobra Jet springs in there, rake be damned..I just want to hook.

Mike

Rake aside, even the 1/2" drop will lower the Instant Center and increase the 'squat' at launch. I've noticed that my car hooks better and hops less, but I also changed the rears to 275/40 at the same time.

 

[MikeLTDLX]

Rake aside, even the 1/2" drop will lower the Instant Center and increase the 'squat' at launch. I've noticed that my car hooks better and hops less, but I also changed the rears to 275/40 at the same time.

I have the 55Ds and LCAs and brackets. My car is still not what I would consider a hooking beast, even on slicks.

Mike

 

[Grant808]

I have the 55Ds and LCAs and brackets. My car is still not what I would consider a hooking beast, even on slicks.

Mike

Personally, I wouldn't use brackets on these cars, unless you're lowered. They are 'anti-squat' and raise the IC. Better for a car with more low-end torque or clutch dumping, IMO.

 

[MikeLTDLX]

Personally, I wouldn't use brackets on these cars, unless you're lowered. They are 'anti-squat' and raise the IC. Better for a car with more low-end torque or clutch dumping, IMO.

Well, I do dump the clutch....at 5 grand.

Mike

 

[twistedneck]

The Boss coils a much lower rate than the steeda sport front coils. They are also designed to work at a rake angle, with the rear ride height at least 3/4" higher in the boss.

Then there is the variable rate aspect, the your steeda coils linear or variable rate sports? The old ones are linear, yo ucan tell the linear have evenly spaced coils vs. the variable that have the first few coils very close to each other.

 

[corruptor]

The Boss coils a much lower rate than the steeda sport front coils. They are also designed to work at a rake angle, with the rear ride height at least 3/4" higher in the boss.

Then there is the variable rate aspect, the your steeda coils linear or variable rate sports? The old ones are linear, yo ucan tell the linear have evenly spaced coils vs. the variable that have the first few coils very close to each other.

Good point about the boss springs. The Steeda ones I gave are from Strano, so they're the linear version. I'm going to just stick with my original plan and install the Steeda. If the ride sucks or I start scraping over bumps, I'll swap the stock springs back in.

 

[cdog1157]

When I install the 55D rear springs then is there any other parts I will need? I remember seeing something about parts being 'one time use only' but can't remember what parts that was referring to.

 

[corruptor]

Thought I'd post an update to this thread:

I installed Koni Yellows, GT500 Strut Mounts, and Boss front and rear springs (non-Laguna version) yesterday. I bought the springs from Tousley Ford and when I compared to my stock springs, they were a bit shorter than what I was anticipating. Most of the auto reviews indicated the Boss setup was 10mm lower in front, and 1mm lower in rear compared to a standard GT. I did not make any exact measurements, but the front and rear springs were closer to 15mm and 10mm shorter than stock, respectively. Needless to say, I was sort of worried that Tousley sent me the wrong springs, but the part numbers match...

With the Konis near full soft, the setup is better than stock in every imaginable way. Impacts from bumps are less harsh, and the car gets settled more quickly. I have not yet adjusted the Konis to a firmer setting as I wanted to shake down the car and make sure there were no squeaks, creaks, or rattles before stiffening up the shocks. Weight transfer - both under acceleration and hard braking - seems slightly improved with the Boss springs, though there is still rear weight transfer and nose dive in both situations. Some of it would probably be reduced if the Konis were adjusted to a firmer setting.

Here's a tip for you guys doing aftermarket strut installs in your driveway - when removing the stock front strut covers, you may want to first spray the top strut nut with some WD40, otherwise they won't be coming off. I spent a good 45 min trying to loosen the top nut before the WD40 worked its magic. Other than that, install was easy.

Overall, quite happy with the Koni and Boss setup. Don't think I'll be doing the 55D rear springs since the rear suspension travel is quite limited and I used to hit the bump stops when I was lowered on Roush/KW coilovers at around 1.5"-1.75".

 

[Grant808]

I'm surprised that the Boss rear springs had any drop compared to stock. You have a Brembo GT, right?

Do you have any before/after pics? Could you post or PM the spring part# and price?

 

[twistedneck]

I'm surprised that the Boss rear springs had any drop compared to stock. You have a Brembo GT, right?

Do you have any before/after pics? Could you post or PM the spring part# and price?

Depends if he was measuring coil spring free height or vehicle ride height. The check loads are higher on the boss...

 

[Highway Star]

You know, i would not go with the 55d rear springs. Ford did a lot of testing to get that combination right. If you like the look then so be it. But a stock Boss setup with yellows on a brembo car is a real good setup. But I do know the lure of the lowered look. Ford says the car performs better with the back end slightly jacked up. I believe them. But I am so much happier with my Boss Springs over the Steeda that I will never go back. Steedas were not bad but the roads where I live are horrible.

 

[Fun4me]

Thats funny that you dug up this old thread, I was just reading this.

 

[corruptor]

I ran the stock boss 302 spring setup for a while but made the change to the Ford Racing P springs recently. I should have installed the P springs to begin with. I don't bottom out, ride is excellent, and overall stability/steering feel is slightly improved over the stock boss springs.

 

[Fun4me]

I ran the stock boss 302 spring setup for a while but made the change to the Ford Racing P springs recently. I should have installed the P springs to begin with. I don't bottom out, ride is excellent, and overall stability/steering feel is slightly improved over the stock boss springs.

What kind of damper do you have?

 

[corruptor]

Koni Sports