SN95 Mustang Spring Rates?

[G_Lemke]

What are the best spring rates for a SN95 Mustang?

 

I am building up my HPDE/TT car to eventually become a CMC car.

 

It is a 1994 Mustang Cobra. This car is still sees some street time, but mostly to and from the track.

 

So far it has sub-frame connectors, a panhard bar, MM lower control arms, and urathane bushings and camber/castor plates.

 

What have you tried and what works and what does not?

 

Thanks

 

Gary

A few pics to show why they are needed -

 

left turn:

http://vanhap.com/imgs/2009/June/06-27-BW-NASA/HPDE%203/am920/slides/VP__0147.html

 

right turn:

http://vanhap.com/imgs/2009/June/06-27-BW-NASA/HPDE%203/am920/slides/VP__0226.html

 

http://vanhap.com/imgs/2009/June/06-27-BW-NASA/HPDE%203/pm155/slides/VP__3506.html

[Adam Ginsberg]

Gary - I saw your car in the pits, and regret not stopping by. If you attend the Nov BW event, we need to talk.

 

Because your car is performing double duty (street and track), it's a compromise at best. If you still plan to run it on the street, high spring rates won't provide a nice ride in LA.

 

Regarding spring rates - many CMC'ers use H&R Super Race springs all the way around, depending on their config and driving style. You really can't go wrong with the H&R's, especially at the early stages of your CMC build up.

 

Hope to see you @ BW in November.

[KiMifan]

1100 F, 250 R. Take the panhard off or go higher in the rear.

[Tony G]

Take off the panhard and keep it for later when you call me so I can tell you what to do with it..

900 front 250 rear is a great start.

[SNAKBITN]

I installed what Tony G. said and the car handle's great.I also thought about trying 1000's in the front but have not tried it yet.

 

Robert

[Tony G]

Thanks , the more you put out front the more it will push.

A super fast car is a car that actually oversteers just a bit, but with driver control its really fast, and the good thing with Mustangs is that you can get out of slight oversteers really easy.

Also make sure your not higher in the rear than the front as far as actual car height is concerned.

Best combo so far was 800 front/250 rear..but 900 works well also and all cars a little different.

DON'T run a rear panhard..you will hate it...but call me and I'll tell you what to do with it if you want.

[liebbe1548534713]

H&R Super Race front and rear(rear cut down for ride height), Maximum Motorsport Panhard, Koni Double adjustable shocks, Poor Man's 3-link (you'll never regret this easy mod). This combo makes Camaro drivers nervous - but not in the "Watch out - here comes Spinny McGinsberg" way.

[SNAKBITN]

Agree,after I removed the panhard bar it was faster but did feel strange at first.

 

P.S. kind of scared to ask what to do with the bar though.

 

Robert

[G_Lemke]

The biggest remaining problem is the car pitching in the breaking zones and rolling in the turns. The attached pictures show some of this.

 

As Adam may have seen, the rear of my car seems VERY high compared to the front. The best picture I can find is this:

 

http://vanhap.com/imgs/2009/October/10-10-BW-NASA/HPDE%203/920%20am/slides/VP__0410.html

 

I assume you have a list of officials that the bar could be better used on?

 

I added the Panhard bar to keep the back half of the car from moving so much in high speed sweepers like riverside/taladega at BW. The car felt MUCH more stable, which increased my confidence and made ME faster. I can see your point on how this may not have actually made the car faster.

 

I should have added the first things I did were a roll bar, seat and harness. The other change I made since June was the solid steering shaft and aluminum bushings - which made together with the list above made the car much more controlable.

 

Thanks for the help.

 

Hope to meet more of you in November.

 

Gary

[CMC#11]

H&R Super Race front and rear(rear cut down for ride height), Maximum Motorsport Panhard, Koni Double adjustable shocks, Poor Man's 3-link (you'll never regret this easy mod). This combo makes Camaro drivers nervous - but not in the "Watch out - here comes Spinny McGinsberg" way.

I agree with what Rob says across the board except I am running 1000/300 linear springs. We have some pretty bumpy tracks in TX which can suck, but on smooth pavements it feels amazing!!

[Adam Ginsberg]

The car felt MUCH more stable, which increased my confidence and made ME faster. I can see your point on how this may not have actually made the car faster.

 

This is the key....you being comfortable in the car. It's why we preach "seat time, seat time, seat time"....the more comfortable you are in the car, the better you're able to push the car harder.

 

If you move to the PM3L as many of the Ford drivers have done, you'll need the PHB, so don't remove it just yet.

 

In November, we'll be pitted on the far end of the track - where the showers are located. Come pit by us - it'll be one hell of a party, like it was last weekend.

[Trevor571548534737]

What is the gain from running cut springs in the back?

[bsim]

Lower ride height in the back, better balance. Also, slight increase in spring rate.

[G_Lemke]

Springs:

 

Stock ~400 Front ~170 Rear

H&R Race = 750-850 Front, 260-280 Rear

H&R Super Race = 950-1050 Front, 260-300 Rear

 

Shocks/Struts

KYB GR-2 (What is on the car now)

Koni SA

Brillstein HD

Koni DA

 

 

From all of this, I am leaning towards The H&R Race springs with the Koni SA shocks. This seems to be the closest to Tony's recommended best, and I have heard that the race springs aren't that bad on the street.

 

Any additional input for the shocks/struts before I decide?

 

Where can I find more details on the Poor Man's 3-link?

 

Gary

[Trevor571548534737]

I have the h&r "race" springs on my 95, and the car has a ton of dive, although it is under damped. Other than that they have been good for me. I was likely going to try a new pair of springs in front. Those gr-2 dampers are basically a stock replacement.

[Adam Ginsberg]

Gary - FWIW, a few years ago, I picked up a set of MM race valve Bil's, and haven't looked back. In the early stages of racing, there was no way I could figure out shock adjustments, so I took that out of the equation. And I don't regret it.

 

A nice benefit of using the Bil's is they can be rebuilt for about ~$75 each, and turn around time is about ~2 weeks. They are located in San Diego.

 

My suggestion at this point is find a set of used H&R Super Race springs, install, and get more track time. When money/time permits, change to a better set of shocks/struts (unless you can do both at the same time...which I would recommend), and get more track time. Then focus on the safety gear, and work on your comp license.

 

I'm sure you've heard it many times before, but there is no substitute for track time.

[CMC#11]

I completely agree with what Adam said about the Bil's. I ran them on my CMC Fox for 3 years when I started and this year I switched to Koni DA's.

 

If your are looking for a complete set of Bilstein Race Valve shocks/struts let me know.

[DrC]

Gary thanks for the post. I am currently HPDE2 and building my someday CMC car. I have been keeping notes from what I read here and other forms and this is what I plan to do which may change.

I currently have Koni Sport adj shocks and plan to add some new spring.

Based on what I read linear springs sounds like the key. For my 95 GT I will go for 900-800 front and 200-250 rear. Looking for a good place to buy if anyone know of a Co.

I also hear a lot being said about not using a rear panhard bar. Not sure about the Panhard bar at this time, will know more after I talk to others as to why, For now at my level it is easy to do without.

[CMC#11]

Gary thanks for the post. I am currently HPDE2 and building my someday CMC car. I have been keeping notes from what I read here and other forms and this is what I plan to do which may change.

I currently have Koni Sport adj shocks and plan to add some new spring.

Based on what I read linear springs sounds like the key. For my 95 GT I will go for 900-800 front and 200-250 rear. Looking for a good place to buy if anyone know of a Co.

I also hear a lot being said about not using a rear panhard bar. Not sure about the Panhard bar at this time, will know more after I talk to others as to why, For now at my level it is easy to do without.

IMO, I would stick with a "drop in" type spring like the H&R's. There is not a linear spring out there that doesn't require some type of adjuster to get the correct ride height. The only alternative is to start cutting taller springs to get the desired ride height and then spring rate calculations come into play and things get interesting. A linear spring is great to get that last 2% our of the car but for HPDE and your first few years of racing the normal H&R springs work great!!

Stick with a standard spring install for now and then re-visit this discussion in a few years. It will be much easier in the long run.

[bsim]

700#+ springs will overwhelm your Konis. Either get them valved for the higher spring rates or wait until you can do both.

 

Why are you changing rates anyway? What's the car doing? Just throwing bigger springs on for the sake of throwing begger springs on will just magnify issues unless you're trying to fix something specific the rates will address.

[Al F.]

Maybe not Brad. This is a mustang after all, which runs much higher spring rate for an equivalent wheel rate than a 4th gen.

[bsim]

Agreed, the wheel rates are different. However, the Konis are application specific, and representative of a standard range of springs for the specific application. Once you get towards the higher range and beyond, the shocks can't dampen enough. I'll stand by my questions:

Why are you changing rates anyway? What's the car doing? Just throwing bigger springs on for the sake of throwing bigger springs on will just magnify issues unless you're trying to fix something specific the rates will address.

The driver should determine the spring rate. Not the interwebs collective consensus.

[Lady in Nomex]

Agreed, the wheel rates are different. However, the Konis are application specific, and representative of a standard range of springs for the specific application. Once you get towards the higher range and beyond, the shocks can't dampen enough. I'll stand by my questions:

Why are you changing rates anyway? What's the car doing? Just throwing bigger springs on for the sake of throwing bigger springs on will just magnify issues unless you're trying to fix something specific the rates will address.

The driver should determine the spring rate. Not the interwebs collective consensus.

 

Absolutely. It is a matter of seat time to see what one's preference is.

[DrC]

That is what I like about this site. You are so free with you success and failure. I think I will wait and put my money and time in other areas for now. Spring are easy to change and can be done between weekends. I need to keep striping the car so I can get the roll cage in and all the other safety items required for CMC in 2010. That way I can spend more time on the driver once the season starts in April.

[G_Lemke]

MM Race valved Bilsteins and H&R Super Race Springs are now installed.

 

Some quick testing on the freeway on-ramps and a mountain road says it was the correct choice. They greatly minimized brake dive and all the extra motion the car had. It was lowered somewhat, but most importantly the car now seems level front to back

 

Can't wait to try them out for real on Nov 7/8 at Buttonwillow.

 

Thanks to all who gave their input - See my new post on alignment!

 

Hopefully I will see some of you at Buttonwillow.

 

Gary