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Strut replacement question

Hello everyone new guy here. I was turned onto this forum by a guy at work ever since then I have been reading a lot and I must say there is a wealth of knowledge here and I have already learned a lot.

Now to the question. After reading about several members suspension setups and I may have made a mistake. I initially went for the Ford Racing K springs instead of the P springs, not knowing that the springs rates were similar and k springs would just be harsher without any increase in performance. I have been driving it around for several months now. While it is not unbearable I feel like the suspension needs a little more play in it. Based on everything I have read I am going to replace the k springs with the P springs. Should I replace the struts when I replace the springs? I would hate to throw away money buying new struts but as they have been riding on k springs for several months I would hate to put new springs on worn out struts. Any thoughts?
 

TMSBOSS

Spending my pension on car parts and track fees.
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Welcome!!

There are several of us running the P springs with the stock boss struts and shocks. Others have up graded to the FRPP 18000c struts. All have had good luck with both set ups.

What struts/shocks are you currently running? Doubtful that a few months wear would trash your struts.

If you could post a few more details regarding you current set up, there are several smart guys on this site who always jump in to help, year, mods, other info. Not to mention a few Ford/boss engineers who jump in when they can contribute.

Again, welcome
 
TMSBOSS said:
What struts/shocks are you currently running? Doubtful that a few months wear would trash your struts.

+1

If anything, especially if you are on stock Boss struts, I would say the P springs will bring the struts closer to their proper operating range and just changing the springs will make everything feel much better. Others on this forum have BTDT. And welcome aboard!
 
SS welcome to BMO. Do you have a Boss LS?

FWIW I swapped out my stock dampers for the 18000's. My strategy was they are an improvement and I didn't have to pay much additional labor to have them installed with the new springs. I then sold the stock dampers and springs for almost as much as the new dampers cost so it wasn't much out of pocket. I'd also consider the Koni Yellow sport dampers. The P springs are not the end all for track work but are an improvement over stock and a nice compromise between street and track. While a bit stiffer on the street they still maintain a nice ride and frankly this is how I expected my car to ride from the factory.
 

Grant 302

basic and well known psychic
My GT is on Boss shocks (^from Rick) and P springs. Only additional suggestion is to get the FRPP jounce stops too, or cut the existing ones down.
 
745
352
I do not think you will be happy with just replacing the K springs with P springs. They are similar rates and you may simply be out of the effective range of the Boss struts and shocks (Tokico Illuminas), but it is also just as likely you are more sensitive to the spring / damper mismatch than some. If you are going to stick with Ford springs, I would keep the K springs and get new dampers.

The Ford 18000-C is a Tokico D-spec. Its pretty good. However, if you compare feedback of the D-Spec to the Koni Sports, the Sports win basically hands down. Maximum Motorsports also seems to prefer the Koni over the Tokicos, especially as spring rates rise.

If you like the ride height of your car with the K springs and still want to make a spring change, I would go with the Steeda Ultralights with the Koni Sports. You will have a linear spring (about 230 lbs/in according to Sam Strano) with a very good damper.

I know this goes against the board's proscribed recipe of P's and 18000-C dampers, but I think there are other combinations that are probably better for the money. But, the Ford path is proven to work well together.

I personnaly run the Steeda Boss specific springs (225 lbs/in) with the Koni Sports. The car responded to the change with much flatter cornering, greatly reduced brake dive, near elimination of rear end "wiggle" under heavy braking, and ride qualities that are as good as the stock setup. The Boss spring ride heights are comparable to the P springs.

No matter what spring you choose, I think you will only be happy with a damper upgrade.

Hope this helps.

Steve
 
745
352
This thread has a good discussion: http://www.svtperformance.com/forums/2012-2013-boss-302-mustang-373/910499-best-lowering-spring-suggestions.html

It has a first hand comparinson of the P springs and Steeda offerings plus dampers.

I should have added above that I do not think the Steeda Boss springs and Koni dampers on a softer setting ride worse than the stock setup with the dampers on 5 front and rear.

Steve
 
Our Ford Racing member posted that the P springs are fine with the stock Boss dampers. I'm not sure what the rates of the K and P springs but they are probably similar. I've read others were not happy with the K springs and it may be the limited travel they allow on the street.

The 18000 dampers are D Spec but made for FR using Multimatic valving specs. I know from my MX experience that changing valving can have a big impact on damping charactistics. I'd like to see a direct comparison between the 18000 and the Koni Yellows.
 
745
352
NFSBOSS said:
Our Ford Racing member posted that the P springs are fine with the stock Boss dampers. I'm not sure what the rates of the K and P springs but they are probably similar. I've read others were not happy with the K springs and it may be the limited travel they allow on the street.

The 18000 dampers are D Spec but made for FR using Multimatic valving specs. I know from my MX experience that changing valving can have a big impact on damping charactistics. I'd like to see a direct comparison between the 18000 and the Koni Yellows.

All true. My understanding is the Ford parts are matched to work together out of the box.

I would also like to see more comparison's and first hand feedback. Unfortunately, when it comes to ride quality, opinions become really subjective. What I consider ok or not ok could be completely different from someone else.

For example, I know others think my setup rides firmer than the P springs. However, if I ever make another spring change, I am probably going to H&R race springs at 325 lb/in front and 285 lb/in rear. That means my rears woudl be stiffer than the top end of the P's front spring rate.

If the OP is changing springs himself, then he could go straight to the P's and figure out if he likes them without spending money on dampers. If he does buy the P's and decides on dampers, I would probably go the proven route of P's and 18000-C's. If he wants to try non-Ford springs, I would go with the Koni's.

Sorry If I confused anyone.

Steve
 

Grant 302

basic and well known psychic
There's some truth to what you're saying, Steve, but the P spring rates as tested by Vorshlag (below) are significantly lower that the Steeda Boss specific springs. They are much closer to stock in the working range. I believe this also makes them much softer than the K springs, despite some of the internet info that Ps and Ks are similar. P springs are a tad under-damped on the stock Boss shocks, but not by much IMO. If there was one or two more clicks up, I think they'd be well matched. I have a set of LS takeoffs that I will swap in later with the P springs to compare. If the LS fronts on (1) are similar to the base Boss (5), I'll be happy with that combo.

spring-rates-shelbygt.jpg

I too would like the comparison between Sports and the 18000-C.
 

Sesshomurai

I just got the 18000-c's as a stop-gap solution until I can understand my exact needs and move on to a race coilover system.
I'll have them installed before my next track day so will provide some feedback after that.
 
First thanks for all the replies. I have a 2012 GT with the K springs and M-18000-A's and BMR adjustable panhard bar and Gt500 upper strut mounts. I came across the 18000-C's right after I got the 18000-A's on my car. When I was looking at parts initially I looked at many different springs and a couple of different dampers. For some reason I was drawn to the Ford Racing parts.
 

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