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Looking for spring reviews and recommendations? K vs P vs T?

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I know this subject has been covered quite a bit, but looking to collect everyone's opinion that has had a chance to get some miles/track time on their respective set ups. The overall suspension thread has been a little slow as of late.

My car is still nearly stock, but have a few things to do over the winter and was contemplating lowering the car as well. My car is a weekend warrior and im trying to get to the point that i am doing 3-5 track days a year. My initial reaction was to go with T springs (which are K rears anyway, right) because everyone seems generally happy with them. Those that have P springs also seem happy and have found improved performance on the track. K is the most track based, but start to have noticeable harshness on the road (depends on strut set up, etc).

I dont mind sacrificing ride quality a touch so long as there is improved performance!

From the suspension forum it appears that T springs are .5in foward and 1.5 in rear drop, P springs are about 1in all the way around, and K are about 1.5in all the way around.

So, has anyone tried multiple set ups, what makes you the happiest? Those that have any of the above provide your feedback, please! I am going to stick with ford parts i think and want to make everything easily reversible for resale down the road. Anyone with T springs used them on track and have feedback compared to stock?

Any input greatly appreciated and look forward to what everyone has to say.
 
I think you have it fully analyzed. ;) The T springs use the K rear spring and a new spring up front. the T front spring is softer than the K. I have the P springs and have always thought that's how the car should have come from the factory. All three have a similar ride height in the front but the K and T's are lower in the rear than the P's. IMO the following applies:

T mostly for street use
P for both track and street
K for track and some street and the lowest look.
 
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NFSBOSS said:
I think you have it fully analyzed. ;) The T springs use the K rear spring and a new spring up front. the T front spring is softer than the K. I have the P springs and have always thought that's how the car should have come from the factory. All three have a similar ride height in the front but the K and T's are lower in the rear than the P's. IMO the following applies:

T mostly for street use
P for both track and street
K for track and some street and the lowest look.

you did struts at time of adding the Ps right? I can just put in Ps without changing the struts, right? what else did you do when you added the Ps?
 
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Just for the record, the P springs will only drop the front of a Boss about 1/4-1/2" and the rear about 1". I had Ps for a while and really liked them, stiffer than stock but not ridiculous and the ride height was still easily manageable around town. The stock dampers run out of rebound with stiffer springs, though.

The Ts don't seem to get great reviews for guys who track (or even just push their) cars, in large part because the fronts have a pretty soft rate.
 
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I tried the P's once. Ran them one track event. (Button willow) Not to bad. Remove some of the issues that the stock springs have. Had to drop the rear sway bar to 22mm. Rear bite had been a issue. Switched to the MM R&T spring, drop the rear sway bar to 18mm, Front on full stiff (Eibach). with Koni's and have never looked back. Just my 2 cents.
 

steveespo

Lord knows I'm a Voodoo Child
Moderator
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Cookeville TN
NFSBOSS said:
Rob what spring rates were the Phoenix cars running at LS this year?
Rick
Go 650/325 with an 18mm or 1/2" rear bar. Go 1/4 stiff compression on the rear shocks 3/4 rebound and 3/4-3/4 up front. Car will squat back and go on corner exit, you will have to enter a little slower, but you'll be full throttle before the apex.
 
I had the T springs for a while and really liked them, both on the street and track. As long as your shocks ar decent (like Koni's) and you're running a stiff front sway, it'll perform great. I've got the HR race now and it seems tighter but it's not a world of difference. I've read so much about T's for the street and P's for the track, but you're splitting hairs with the spring rates compared with the rates of decent coilover setups. The P spring drop was not enough for me to bother, especially running 295 18 35 tires, leaving a huge gap.
 

steveespo

Lord knows I'm a Voodoo Child
Moderator
4,008
1,924
Exp. Type
W2W Racing
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Cookeville TN
NFSBOSS said:
I'm driving to and from the track so I doubt I'll go that stiff.
OK, you asked what the GS guys were running, that is close. If you drive the car a lot then yeah that is too stiff, for a track rat with occasional Sunday drive you could live with it.
One of the reasons I like the rear spring on the axle vs over the shock is I can play with rates easily at the track if I want, spring change in literally 10 minutes with a jack, 2 stands, and the perch adjusting tool. My plan is to get the front locked into a rate the tune with rear springs and shock settings.
Steve
 

Grant 302

basic and well known psychic
Steve,

Could you post pics of your adjusters? I'm a little confused about the differences between the MM and CorteX JRi DA units.

Quick changing is definitely an advantage of the axle perches.


But to the OP regarding the T,K and P springs: I've only tried the P springs, but any of them would be suitable for mixed use on street tires.
 

Grant 302

basic and well known psychic
Hey Steve, Thanks for the pics, but that's the part that I understand! I was wondering about just the adjusters... Cortex has low speed compression (30 clicks) and rebound plus a high speed rebound (14 flat sweeps). From the MM site, it look like separate compression and rebound each with 17 clicks A to Q.

My apologies for not being clear. :(
 

Grant 302

basic and well known psychic
steveespo said:
Sorry Grant I thought you meant spring adjusters. The shock adjustment is A to Q on rebound and 3 full turns on compression. Compression clicks, rebound doesn't.

JRiMMTemp-15_zpse7baf229.jpg
Steve

Thanks for clarifying Steve! Now I'm only confused about why the two systems are so different! ;)
 
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Exp. Type
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Waco, TX
I was comparing spring rates of all these springs. I did notice that the K springs are the same as SR springs which i have. Don't shoot me i had the springs on before i was on this site and began reading and researching suspension. According to Brembo50 my GT came with specifically tuned struts and shocks for the spring rates which was entirely different between GT's and the Boss. I was going to get the 180000-C but it seems that is a older strut version than what i currently have which requires GT500 mounts. I've only tracked this car once so far and it felt strong in the corners even for only being on stock Pirellis. Since then i added the adj PHB and CAI which works with my Trackcal ( Red Key).

Sorry for the long winded post but research is key to me. So many questions have been answered already. Any who so the springs rates i have found are as follows.

FSB RSB Front Rear

GT 34.6 mm 24 mm 123 lbs. 156 lbs.
Brembo 34.6 mm 24 mm 131 lbs. 167 lbs.
Boss 302 34.6 mm 25 mm 148 lbs. 186 lbs.
Laguna Seca
34.6 mm 26 mm 137 lbs. 191 lbs.

The SR spring rates are advertised as:
Front: 230 lb/in.
Rear: 200 lb/in.

The FRPP K spring rates are:
Front: 228 lb/in.
Rear: 199.5 lb/in.


Since my car only has 3000 miles on it. I'm taking the advice of some friends on here and going to learn how to drive the current setup to the limit first. Then add the R6's.

Now wouldn't higher spring rates be stiffer? decreasing body roll and increasing corner stability?
 

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