Ford Racing Boss 302 Springs...

[VoodooBoss]

I ordered and received mine as well. They appear to be K springs in the rear (same part number). Fronts are in fact unique.

Thanks for the photos and welcome to BMO.

 

[colticus]

I ordered and received mine as well. They appear to be K springs in the rear (same part number). Fronts are in fact unique.

Rear:



Front:

Well that's a little disappointing.

 

[bluemax]

I have been holding off on doing the suspension mods until the "T" springs came out, now I am curious if the "P" springs isn't the way to go...

I thought the "K" spring lowered the car too much. I know this is just the rear that the new kit is using, but now I wonder why they selected the "K" rear over the "P" rear.

So, I guess I will now wait on some of you to get them installed and checked out.

 

[VoodooBoss]

I have been holding off on doing the suspension mods until the "T" springs came out, now I am curious if the "P" springs isn't the way to go...

I thought the "K" spring lowered the car too much. I know this is just the rear that the new kit is using, but now I wonder why they selected the "K" rear over the "P" rear.

So, I guess I will now wait on some of you to get them installed and checked out.

I think the problem with the K is they lower the car too much in the front which throws off the geometry. In the rear there's an easy solution using relocation brackets so it's not as big of a deal. I suspect the T springs split the difference between the P and K relative to lowering the car and might be closer to stock relative to spring rate. With that said the P springs work fine for a nice compromise between the street and track and don't slam the car.

 

[further]

I think the problem with the K is they lower the car too much in the front which throws off the geometry. In the rear there's an easy solution using relocation brackets so it's not as big of a deal. I suspect the T springs split the difference between the P and K relative to lowering the car and might be closer to stock relative to spring rate. With that said the P springs work fine for a nice compromise between the street and track and don't slam the car.

This really makes good sense of the facts given without the true word from FRPP. As soon as I opened the box and saw the letters "KR", I suspected something along these lines.

The boss is "lowered 11 mm in the front and 1 mm in the back" per Ford. The P and K springs drop the "GT" 1 and 1.5" respectively (25mm and 37.5 mm). Although the FRPP catalog is a bit confusing because the heading for the P spring item says"1 inch" and in the specs it says "1.5 inches". Probably just an error.

http://www.caranddriver.com/news/ford-mustang-news-2012-ford-mustang-boss-302

http://www.fordracingpartsdirect.com/Ford_Racing_Mustang_GT_1_Inch_Lowering_Springs_p/m-5300-p.htm

http://www.fordracingpartsdirect.com/Ford_Racing_Mustang_GT_1_5_Inch_Lowering_Springs_p/m-5300-k.htm


The T spring kit drops the "Boss" 15 mm and 35 mm for the front and back. Already you can see the greater drop on the back. If you add up the numbers, the relative drop for the T kit to the standard GT is 26 mm for the front and 36mm for the back. Kind of adds up to a P/K spring hybrid. I didn't mention it because I didn't want to create a ruckus before FRPP could clear things up a bit, but it looks like the word is out and I guess you guys are just too darn sharp.

I do have a few issues.

If the rake was the issue, why the heck did Ford drop the Boss so much in the front to begin with, and now "level things out" with a hybrid spring setup?

Is the T spring unique, or is it a P spring? Probably different in its spring rate but with a similar drop. If it is unique, then the rates must but different. Are they stiffer or looser, and why? I'm going to abuse this setup on the track, and I just want to know what I'm getting into out there on the relative edge.

The FRPP catalog states that these springs must be used with upgraded FRPP dampers and sway bars (for optimal performance) but they also state that the Boss lowering springs were specifically for the Boss. The catalog also states that the K and P springs are standard on the Shelby GT and GT-H.

http://www.fordracingpartsdirect.com/Ford_Racing_Mustang_Coupe_Damper_Kit_p/m-18000-a.htm

Regardless, I'm going with these springs on the the stock Boss dampers based on FRPP's recommendations (with the relo/panhard). I imagine I'll bottom out the springs on the track and wear out the Tokicos. We'll see.

If any of these statement are off, please correct them. If FRPP can comment, it would be greatly appreciated.

 

[VoodooBoss]

A few of us early buyers were concerned about upsetting the balance of the car by messing with the suspension since Ford had spent a lot of time dialing it in. So we took our time making any changes. While the T springs were in development it was recommended to us to use the P springs for the track and not the K springs so that's the route many of us took. For me the P springs do not upset the balance of the car and are a noticeable improvement at the track with less body roll and brake dive. I'm a beginner at this so take what you will from my comments. My understanding is the P and K springs were developed for the GT500 which has a heavier nose. So it would make sense the T springs are a bit softer than either the K or P. For what it's worth the P springs do ride stiffer than stock but they do not ruin the ride. Where I notice it mostly is when hitting a sharp bump at speed with the rear wheels. You will know you have stiffer springs out back.

Last Spring, while the T springs were under development, I called Eibach and talked to one of the tech's what was working on the project. While he wouldn't give me the secret sauce he did confirm they were working on the project and weren't happy with the development so far and were going to try some additional springs. I wouldn't be surprised if the initial testing was the P spring on the front and K on the rear as you suggested.

My understanding was the goal was to lower the car and keep the ride close to the stock. Again that leads me to believe the T springs are softer than K or P but slightly stiffer than stock. If I was looking to lower my car and retain a similar ride I'd go with this kit. TBD for the track.

 

[Grant 302]

I did make the guess that the kit could have comprised of P fronts and K rears, and that should work great for a square setup. I've been considering doing that on the GT. But with the smaller front tires, I'm pretty sure that the T springs will be a little softer than P springs for use on an otherwise stock Boss. It would be nice to know the actual rates though...

What I think I'm going to do is buy a 'T' kit and put the K's on the rear of the GT and put P rears and the T fronts on the Boss.

 

[VoodooBoss]

I did make the guess that the kit could have comprised of P fronts and K rears, and that should work great for a square setup. I've been considering doing that on the GT. But with the smaller front tires, I'm pretty sure that the T springs will be a little softer than P springs for use on an otherwise stock Boss. It would be nice to know the actual rates though...

What I think I'm going to do is buy a 'T' kit and put the K's on the rear of the GT and put P rears and the T fronts on the Boss.

That looks like a good plan. I'd put the P front springs on the car you're going to track the most.

 

[Grant 302]

That looks like a good plan. I'd put the P front springs on the car you're going to track the most.

And the nice thing is that once I have it all set-up I would be able to swap parts between cars as needed...without the need to even use the spring compressors. With the similar drop, alignments should be really quick little adjustments.

I do want the GT to sit level, and for the Boss to maintain a little rake.

Forgot that my guess was on page 1 of this thread! :

Maybe it's just a front set of Ps with a rear set of Ks...

I hope somebody gets a set of these to Vorshlag for testing. I'm sure FR isn't releasing specs on the rates...

I'll probably get a set as soon as they're available from other vendors for a more reasonable price like $240-250.

The price of the kit does sound a bit more reasonable since they're adding the bumpstops too.

 

[fun4me]

What are the spring rates for the P and K springs?

 

[further]

Thanks for the interesting insight. Seems like its a K spring setup but the front is a bit higher and softer. I do have a coupe of concerns. The softer front will add more grip. Does the higher stance also increase grip in the front? I'm running square so I'm pretty grippy up front. My front sway is set on medium (still pretty stiff c/w stock). This gives me a bit of pause too in changing springs. A softer front may give all the more reason to go with stiffer shocks. Not really sure what I'm doing yet. Guess I'll probably leave it be for the next track Sesh, until I hear more from you guys.

 

[VoodooBoss]

Just by chance I met a guy with a 2012 Boss that installed the T springs on his car. I have the P springs on mine and the front looked about the same, possibly lower, and the rear looked a lot lower. It looked very good but no comments on how it rides since he just installed them. Maybe he'll join the forum and share his opinion.

 

[colticus]

Just by change I met a guy with a 2012 Boss that installed the T springs on his car. I have the P springs on mine and the front looked about the same, possibly lower, and the rear looked a lot lower. I looked very good but no comments on how it rides since he just installed them. Maybe he'll join the forum and share his opinion.

No pics? WTF, youre slacking.

 

[VoodooBoss]

No pics? WTF, youre slacking.

LOL It's looks just like my car but about a 1/2" lower in the rear.

 

[The Rip]

My "T" springs showed up today. Should have them on by Monday.
Steve

 

[BadPony]

I am having the T springs installed tomorrow, along with the Ford racing adjustable panhard bar and LCA relocation brackets. I will post pictures and my driving impresssions as soon as I can.

 

[likeaboss302]

I am having the T springs installed tomorrow, along with the Ford racing adjustable panhard bar and LCA relocation brackets. I will post pictures and my driving impresssions as soon as I can.

Looking forward to your results. I was getting ready to pull the trigger on the same setup.

 

[vista6019]

Those that guessed TSW's are correct. I went with the stock sizes...19 X 9.5 for the rear and 19 X 9.0 for the front.

I re-mounted the stock Pirelli's for now.

Excellent Choice on the TSW's Way lighter than Stock. Had them on my 13' Track Pack GT and they were great....

 

[max5ive0]

Okay, so when you do these mods do you replace all fasteners? I guess the services manual states these fasteners should not be reused. How do you all feel about that?

 

[Justin]

Okay, so when you do these mods do you replace all fasteners? I guess the services manual states these fasteners should not be reused. How do you all feel about that?

I reuse them....just use blue locktite.