Spring rates for coilovers - how much before chassis stiffness becomes weak link

[twistedneck]

I'm buying a set of coilovers this week and i need to know what spring rate is considered too stiff. I don't want to put 550lb/in front 275lb/in rears on and only flex the body. Yes, my goal is to put a 5 pt. cage with door guards in for stiffness but that's not the case right now. Goal - drive weekends only on the road and as many track days as possible - probably 3-4 / year.

Choice is between the following suppliers:

Vorshlag MCS 1-way setup with either the 550/250 or the 450/175 rate.
Cortex Jri 2way front 1 way rear - TBD on springs but i think he specs. 550/250?
T&A custom inverted struts from Alex - if he decides to get back in touch with me before Friday! Customer service is very important. He responded instantly before.. nothing now for two weeks.

Any feedback appreciated.

I know Modernbeat knows how to valve these things right same with Filip.

 

[VoodooBoss]

Many vendors were at SEMA last week and I know that was the case with CorteX. CorteX posted updates on the FB page all week. I'm a fan of the CorteX product because I've seen their stuff in action many times here in NorCal. Give them a call and ask about what setup they recommend. I think their street setup, the one I'm looking at, has lighter springs than what you mentioned.

 

[twistedneck]

Many vendors were at SEMA last week and I know that was the case with CorteX. CorteX posted updates on the FB page all week. I'm a fan of the CorteX product because I've seen their stuff in action many times here in NorCal. Give them a call and ask about what setup they recommend. I think their street setup, the one I'm looking at, has lighter springs than what you mentioned.

I also like the Cortex stuff.. its nice having several vendors with quality parts!

My goal is not a street car, its a race car that drives OK on the street.. if i have kidney stone creating springs / dampers its not bad for me at all.. so i'd be more focused on what works at the track.

At what point does the spring rate overtake the stock S197 body stiffness?

 

[steveespo]

Without a cage I read 20,000 Nm/Deg, with a cage (Watson/302S) it goes up to 30,000. That is pretty stiff for a road car. I would guess that those spring rates which are close to what the race teams run won't cause odd alignment changes due to flex or twist.
Steve

 

[JScheier]

Vorshlag MCS 1-way setup with either the 550/250 or the 450/175 rate.
Cortex Jri 2way front 1 way rear - TBD on springs but i think he specs. 550/250?
T&A custom inverted struts from Alex - if he decides to get back in touch with me before Friday! Customer service is very important. He responded instantly before.. nothing now for two weeks.

I'm running AST 4200RRs with 450/200 on a square setup with Strano adjustable bars front and rear. The 175 in the rear was way to soft, and honestly, the 450 in the front is pretty damn soft as well.

I'm not sure if I'm going to be running the Boss much next year, but if I do, the plan was to go 600 front / 275-300 rear. The car really is just too damn heavy for the lighter spring rates, and better dampers (AST, JRi, MCS) can handle these loads and still give a pretty damn good street ride (if needed).

I'd definitely discuss your total setup with your vendor. Are you going with a square setup? Are you going to run a rear bar? Will you be running R-compounds, slicks or 200TW tires? All of this comes into play with selecting a good starting point for your spring rates. Then, drop them in, hit the track and see how they fit your driving style. Be prepared to buy more rear springs (25-50 lb increments) to get it just where you want it to be.

And yes... ModernBeat (Jason) also knows his stuff. I think he's on some back roads in the SW right now

 

[twistedneck]

I'm running AST 4200RRs with 450/200 on a square setup with Strano adjustable bars front and rear. The 175 in the rear was way to soft, and honestly, the 450 in the front is pretty damn soft as well.

I'm not sure if I'm going to be running the Boss much next year, but if I do, the plan was to go 600 front / 275-300 rear. The car really is just too damn heavy for the lighter spring rates, and better dampers (AST, JRi, MCS) can handle these loads and still give a pretty damn good street ride (if needed).

I'd definitely discuss your total setup with your vendor. Are you going with a square setup? Are you going to run a rear bar? Will you be running R-compounds, slicks or 200TW tires? All of this comes into play with selecting a good starting point for your spring rates. Then, drop them in, hit the track and see how they fit your driving style. Be prepared to buy more rear springs (25-50 lb increments) to get it just where you want it to be.

And yes... ModernBeat (Jason) also knows his stuff. I think he's on some back roads in the SW right now

Thanks JScheier, that's a lot of what info i was looking for. I know Vorshlag had to increase rates on their car last year - and 550/250 sounds a lot like what Fillip had recommended also. Curious to see if / how T&A would like to setup the shocks / springs.

 

[JScheier]

Thanks JScheier, that's a lot of what info i was looking for. I know Vorshlag had to increase rates on their car last year - and 550/250 sounds a lot like what Fillip had recommended also. Curious to see if / how T&A would like to setup the shocks / springs.

If I remember my fox body / Grigg's days, the TA allowed for slightly softer rear springs, but resulted in some pretty unfavorable side effects (axle tramp under hard braking was the big one). I know on the fox (fully caged) I kept going up in front rates trying to get that under control (which was never a bad thing in fox bodies because they work way better when you don't let the front suspension do ANYTHING). Never quite got it where I wanted it. Then I moved to a lateral 4-link with a watt's link. That was far superior to the TA setup in my opinion (track data confirmed it). Wasn't too much different than what is found in the S197 chassis, just R&R the panhard with a good watts.

More food for thought

Terry (vorshlag) has had TA experience as well... I'm sure he'd LOVE to talk to you about it

 

[ArizonaBOSS]

I know the Vorshlag guys said they have their front spring rate set up at 800#/in on the Red car due to all the front aero they have. So that's one reference point.

600/250 or 600/275 is what I am looking at for my new setup next year, much like JScheier is thinking. Maybe 600/325 with no RSB. Maybe I'll just get all 3 rear sets. Rear springs are easy to change.

 

[JScheier]

Yeah, with that huge splitter and giant wing, they had to go way high with spring rates. Aero is another consideration in spring selection...and if you go to 800#, you need to make sure your dampers can handle it.

 

[Swiss Boss]

Rear springs are easy to change.

Only if you keep the stock location. If you go with coilover, it might be a little more involved.
Also coilover need more rate as they sit more outside, compare to the stock location, to achieve the same stiffness.

I'm running with MCS 550/250 from Vorshlag with a 18mm rear bar and middle hole Strano front bar and 295 Rival all around and the car is pretty neutral.

Another thing to consider with the Cortex offering, I think you have to remove the rear wheel in order to make adjustment

 

[VoodooBoss]

Another thing to consider with the Cortex offering, I think you have to remove the rear wheel in order to make adjustment

That's not with all of them. The JRi's I'm looking at can be adjusted with the wheel on. I believe the Koni's are not east to adjust and I believe you need to remove the damper to adjust them.

 

[Swiss Boss]

Ok I didn't know that but that's also another point to look for when buying damper, ease of adjustability.

 

[ArizonaBOSS]

Only if you keep the stock location. If you go with coilover, it might be a little more involved.
Also coilover need more rate as they sit more outside, compare to the stock location, to achieve the same stiffness.

I'm running with MCS 550/250 from Vorshlag with a 18mm rear bar and middle hole Strano front bar and 295 Rival all around and the car is pretty neutral.

Another thing to consider with the Cortex offering, I think you have to remove the rear wheel in order to make adjustment

I'm planning on using the stock mounting locations for that reason.
Can you PM me some feedback on the MCS dampers? I'm looking to get the 2WNR setup in 2015.

 

[VTBoss302]

Another interesting option (at least to me) are the double adjustable JRi's that Maximum Motorsports is offering:

http://www.maximummotorsports.com/MM-JRi-Shocks-Suspension-Kit-2005-2014-Mustang-P1474.aspx

I like that both compression and rebound are adjustable at the top (I'm lazy)

 

[ArizonaBOSS]

Another interesting option (at least to me) are the double adjustable JRi's that Maximum Motorsports is offering:

http://www.maximummotorsports.com/MM-JRi-Shocks-Suspension-Kit-2005-2014-Mustang-P1474.aspx

I like that both compression and rebound are adjustable at the top (I'm lazy)

Yes, three great kits to choose from, Vorshlag MCS, Cortex JRi, Maximum JRi. Great time to be an enthusiast/racer!

 

[twistedneck]

Yes, three great kits to choose from, Vorshlag MCS, Cortex JRi, Maximum JRi. Great time to be an enthusiast/racer!

Hopefully four to choose from if Alex from T&A decides to get back in touch with me. Those are the custom made inverted Penske dampers.

One thing with the maximum motorsports kit, looks like everything is bolted on to create a strut out of a shock body - not sure if that's good or bad. also, that Maximum motorsport kit is the most expensive by far but it does have two way front and rear.

 

[ArizonaBOSS]

Cortex is clearly proven on-track, but I have never known Maximum to put out a bad product.

 

[JScheier]

Cortex is clearly proven on-track, but I have never known Maximum to put out a bad product.

Ditto. MM is proven on track as well. I've run them in the past, know a couple of their engineers personally. If anyone puts the time, effort, math and engineering into a product, it's MM.

 

[wwilde001]

With a full race suspension with AST 4150 coil overs, front splitter, and G-Stream Wing, I am running 600# front and 400# rear. Very neutral setup on the faster road courses. I would consider maybe going down a little in the rear spring rate to 350 or 375 with an 18mm sway bar, but haven't tried it yet. A little rough on the street, but still bearable. Good luck.

 

[steveespo]

Just pulled the trigger on the Maximum Motorspots JRi 2 way adjustable set up. MM Deal of the day $4608 shipped. Thanks to 2012-Boss for the phone call heads up 8)

Went with 600 front and 375 rear spring rate, springs are cheap (relatively) so if fine tuning is needed or if I get big aero we can swap easy. Now the question becomes, do I get them in time to install prior to leaving for VIR on the 21st? Probably not but I am a sicko.
Steve