What to do about coilovers?

[WireMesh]

I am wanting to get coilovers on my 03 Cobra and am not 100% sure of the route I should go.
My car is mostly street with some autocross and a little dragstrip time. I really am not concerned about ride quality on the street and like the ride to be firm. My current thoughts are to go with the Maximum Motorsports front and rear coilover kits with springs that would match the specs of either their MM2 Race dampeners or MM3 Race dampeners then get my stock Bilsteins revalved and buy some MM CC plates.

Thoughts on spring rates when wanting cornering performance - what is too stiff for the street?
Thoughts on getting the stock Bilsteins (with 78k miles) revalved to match the springs?
Other coilover options that are better?

 

[snakeraper11b]

MM sport dampers with 375 front 600 rear springs. That's all that you'll want on the street. Race valved on the street and strip is a waste and will be uncomfortable

 

[SlowSVT]

"11B" has the basic spring rates correct. The problem is the shock towers were never designed to carry the weight of the car. Lots of people complained of popping and creaking sounds from the factory shock towers "oil canning" with coilovers. The stock coil springs place the weight of the engine and tranny on the K-member by-passing the chassis. Unless you beef-up the chassis structure I would think hard before installing coilovers on an SN95.

 

[mvk13]

It was noisy and you an feel a significant amount of flex when you go coil over. I'm using a MM strut tower brace and a modified convertible brace and that helped quite a bit. 325 front /HD TA rear springs here with stock 04 Bilstein front and MM HD Bilstein out back. Fairly comfy and glass smooth on the freeway.

 

[WireMesh]

MM sport dampers with 375 front 600 rear springs. That's all that you'll want on the street. Race valved on the street and strip is a waste and will be uncomfortable

The guy from MM said he liked the MM2. Would I be able to get the same result from having my stock bilsteins revalved?

"11B" has the basic spring rates correct. The problem is the shock towers were never designed to carry the weight of the car. Lots of people complained of popping and creaking sounds from the factory shock towers "oil canning" with coilovers. The stock coil springs place the weight of the engine and tranny on the K-member by-passing the chassis. Unless you beef-up the chassis structure I would think hard before installing coilovers on an SN95.

It was noisy and you an feel a significant amount of flex when you go coil over. I'm using a MM strut tower brace and a modified convertible brace and that helped quite a bit. 325 front /HD TA rear springs here with stock 04 Bilstein front and MM HD Bilstein out back. Fairly comfy and glass smooth on the freeway.

I have a 3 point strut tower brace in the front already and full length subframe connectors. I could also get a brace for the back if needed?

 

[sonic cobra]

I've been running MM coil-overs on my '03 since 2006. Billstein sports frt and '00 Cobra R bilsteins rear w/hyper coil springs. 375 frt 600 rear. Work well on the road course but will kill weight transfer at the drag strip.Thats about as stiff as I would go on the street.
Also have MM strut tower brace and 4 pt K-member brace.Highly recommended. Over 100k on the clock and 3000 miles on track and no problems with the strut towers or the rear shock mounts that many cite as reasons against coil-overs. Nonsense.
Go with MM recommendation based on your intended use and don't look back.

 

[RDJ]

Back in the day there was some real concern with coilovers. Griggs had a bunch of people who had their shocks bust through the shock towers because of the Griggs C/C plates not being beefy enough. IIRC most of the makers of C/C plates beefed theirs up when that started hitting the net.
That being said I have Coilovers on my 04 and am not concerned about it at all. I love'em

I've been running MM coil-overs on my '03 since 2006. Billstein sports frt and '00 Cobra R bilsteins rear w/hyper coil springs. 375 frt 600 rear. Work well on the road course but will kill weight transfer at the drag strip.Thats about as stiff as I would go on the street.
Also have MM strut tower brace and 4 pt K-member brace.Highly recommended. Over 100k on the clock and 3000 miles on track and no problems with the strut towers or the rear shock mounts that many cite as reasons against coil-overs. Nonsense.
Go with MM recommendation based on your intended use and don't look back.

 

[SlowSVT]

I have a 3 point strut tower brace in the front already and full length subframe connectors. I could also get a brace for the back if needed?

A strut tower brace won't do much to reinforce the shock towers. That static and dynamic load is mostly in the vertical. Strut tower brace works better in the horizontal. Still worth having though. I welded in a doubler (.060 thk chromoly sheet) on the top of the shock tower to prevent "oil canning" and added some bracing.

 

[WireMesh]

A strut tower brace won't do much to reinforce the shock towers. That static and dynamic load is mostly in the vertical. Strut tower brace works better in the horizontal. Still worth having though. I welded in a doubler (.060 thk chromoly sheet) on the top of the shock tower to prevent "oil canning" and added some bracing.

Thanks! Now I'm just wondering if I should get my stock Bilsteins revalved or if it worth paying for the MM2 race dampeners.

 

[SlowSVT]

Thanks! Now I'm just wondering if I should get my stock Bilsteins revalved or if it worth paying for the MM2 race dampeners.

IMO the stock Bilsteins are one of the few things on that car that don't need an upgrade

 

[LargeOrangeFont]

Save yourself the money and just have your Bilsteins revalved. They do a very good job. 375# front springs are about the limit on the stock valved struts.

 

[WireMesh]

Save yourself the money and just have your Bilsteins revalved. They do a very good job. 375# front springs are about the limit on the stock valved struts.

I ended up going with 375 front and 600 rear. Having Bilsteins revalved too. Should be awesome! The guy at maximum motorsports was very helpful with it all.

 

[snakeraper11b]

IMO the stock Bilsteins are one of the few things on that car that don't need an upgrade

I'm sure you know this, but the stock dampers can't handle the upgraded spring rates. Maybe the info will help others who are questioning that move though.

 

[WireMesh]

I'm sure you know this, but the stock dampers can't handle the upgraded spring rates. Maybe the info will help others who are questioning that move though.

It is easy and pretty cheap to just send them to Bilstein to be revalved to match whatever spring rate you are getting.

 

[SlowSVT]

I'm sure you know this, but the stock dampers can't handle the upgraded spring rates. Maybe the info will help others who are questioning that move though.

Not sure what do you mean by the stock shocks not being able to handle the spring rate? Those are completely different aspects of the suspension. The factory springs are 600 lbs per inch of compression compared to the bone jarring 750 for the Cobra R which is not a big spread compared to the GT which is about 1/2 that. Shock valving is governed more by road conditions then spring rate.

The factory Terminator suspension is by no means "spongy"

 

[snakeraper11b]

Not sure what do you mean by the stock shocks not being able to handle the spring rate? Those are completely different aspects of the suspension. The factory springs are 600 lbs per inch of compression compared to the bone jarring 750 for the Cobra R which is not a big spread compared to the GT which is about 1/2 that. Shock valving is governed more by road conditions then spring rate.

The factory Terminator suspension is by no means "spongy"

That is true, but those aren't coilovers. The linkage ratio of where the spring is on the arm cuts the front rates in half, and the rear by 60%. So in essence, your wheel rates are more around 300 front and 360 rear for an 03-04 coupe. Cobra R valving is the same as Bilstein B8 sports, or MM sport valved. They dId that to match the increase in spring rate.
A damper is only on a car to slow the spring and return it back to its rest height without excessive cycling. If the valving of the damper isn't optimal for a high spring rate, you are in essence, overworking the damper. You can fade the fluid by overheating which will lead to aeration and possibly kill your dampers. My point is, higher spring rates call for specific valving to control them.

 

[SlowSVT]

That is true, but those aren't coilovers. The linkage ratio of where the spring is on the arm cuts the front rates in half, and the rear by 60%. So in essence, your wheel rates are more around 300 front and 360 rear for an 03-04 coupe. Cobra R valving is the same as Bilstein B8 sports, or MM sport valved. They dId that to match the increase in spring rate.
A damper is only on a car to slow the spring and return it back to its rest height without excessive cycling. If the valving of the damper isn't optimal for a high spring rate, you are in essence, overworking the damper. You can fade the fluid by overheating which will lead to aeration and possibly kill your dampers. My point is, higher spring rates call for specific valving to control them.

That makes sense. I would imagine there maybe some valving differences on the shocks between both set-ups but the shocks are damping the wheel travel and unsprung mass as well as cancelling out the spring reasonance. The spring rate the spindle sees depending on the spring selection could be very close to one another so I don't imagine the optimal damping for either would be drastically different.

I'm sure MM knows more about this than anybody but when you order revalved shocks and struts what you going to get are shock rates are going to be somewhat "generic" and not tailored to your car. Wheel weight alone have a huge effect. Trying to optimize compression and rebound for a variety of road surfaces is like trying to catch a moving bus :nonono:

 

[LargeOrangeFont]

When switching to coilovers you have to take into consideration the wheel rate.. which is the amount of force it takes to move the wheel. By moving the spring outboard (as you do with coilovers) The wheel rate goes up, so a softer spring is needed. With coilovers 375# springs up front are about the limit, and then you need a revalve or to go to Bilstein Sports. I overworked the front struts on my Cobra, even with 375# springs.

When you send your struts to Bilstein you give them a description of what you are doing with the car, the weight, spring rate, etc. They do not give you the MM valving, as that is the IP of MM, but they do give you a very similar setup. They do a very good job, and is pretty painless to do aside from the shipping lead times. A friend runs 425# front springs on his SN95 track car with Bilstein revalved struts and it handles great with the full MM package on the car.

You will not get the reinforced strut housings that come with the MM2 and MM3 struts when you get your OEM struts revalves.

 

[snakeraper11b]

When switching to coilovers you have to take into consideration the wheel rate.. which is the amount of force it takes to move the wheel. By moving the spring outboard (as you do with coilovers) The wheel rate goes up, so a softer spring is needed. With coilovers 375# springs up front are about the limit, and then you need a revalve or to go to Bilstein Sports. I overworked the front struts on my Cobra, even with 375# springs.


When you send your struts to Bilstein you give them a description of what you are doing with the car, the weight, spring rate, etc. They do not give you the MM valving, as that is the IP of MM, but they do give you a very similar setup. They do a very good job, and is pretty painless to do aside from the shipping lead times. A friend runs 425# front springs on his SN95 track car with Bilstein revalved struts and it handles great with the full MM package on the car.

You will not get the reinforced strut housings that come with the MM2 and MM3 struts when you get your OEM struts revalves.

In the front the ratio goes from .5:1 to .9 to one, which I explained above. That's why you run a 375 up front instead of 600 and it still feels stiffer. But the rear is somewhere between .5..:1 and that goes to .6:1 with an IRS. Just to clarify what LargeOrange was saying.
To expand on another topic Orange brought up, mounting ears are a big deal. Maybe not so much on the sport dampers (reinforced to resist bending), but the MM2 and MM3 actually relocate the ears higher on the body of the shock as well as reinforcing them. This means more bump travel, and that's a good thing.

 

[Bingo13]

Wheel Rates for the '03~'04 Cobra with IRS -
Front:
The front wheel rate is 25% of the stock location spring's rate. For example, the 600lb/in stock location spring has a wheel rate of 150 lb/in. For a coil-over suspension, the wheel rate is approximately 90% of the coil-over spring's rate. Therefore, a front coil-over spring rated at 375 lb/in would result in a wheel rate of about 337.5 lb/in. Your wheel rate will increase by 225%.

Rear:
The wheel rate for the rear of our Cobra with IRS is approximately 33% of the spring rate in the stock location. For example, the 600 lb/in stock location spring has a wheel rate of 198 lb/in. For a coil-over suspension, the wheel rate is approximately 50% of the coil-over spring rate so a matching 575 lb/in would result in a wheel rate of about 287.5 lb/in. Your wheel rate will increase by 145%.

As for the OP question about rates and what to do. I have been using coilovers on this platform since 2002. The archives have a significant amount of information on what a lot of us went through after the car came out and we started open tracking or autocrossing the car. Just a recap based on what I have discovered over the years.

Street Setup - Firm yet very good for daily driving, light to medium HPDE/AutoX events and hooks well for spirited starts. Items 1 to 6 are required, the balance are highly recommended (pick and choose based on component age) to get this platform corrected.
1. Full Length Subframe connectors - MM XL, Global West, KB, Griggs, Stifflers. I would actually do the Global West COMP, KB Extreme Matrix or Stifflers FIT system if you do not have FLSC installed already.
2. MM 4-point K-Member Brace (much more important than the upper strut tower brace)
3. MM CC Plates
4. MM Sport Dampers (do not re-valve to be honest, start with a set designed for coilovers)
5. MM 375/575 Coilover spring kit (this is a perfect compromise for what you want)
6. FTBR FT5001 IRS Kit (this will transform the handling of your car more than you can believe)
7. FTBR FT1350M Differential Housing (do it now if you plan on any racing activities)
8. FTBR M4204T31H Torsen T2-R Differential Unit (do it now if you plan on any racing activities)
9. FTBR FT1860 Toe Link Kit
10. FTBR FT1900 Rear Sway Bar End Link Kit
11. MM non-offset front control arms with Urethane - MMFCA-7
12. MM front tapered bumpsteer kit - MMTR-4
13. MM steering shaft assembly mmst-14
14. MM solid steering rack bushings -MMST-7
15. Upgraded front sway bar endlinks
16. Upgraded urethane front and rear swaybar bushings
17. Check and replace front inner tie rods, hub assemblies, bearings, etc while the front end is apart.
18. Check and replace the rear hub assemblies, halfshafts, boots, etc. Based on mileage I found it much easier and cheaper to replace the entire rear knuckle assembly (FTBR FT6800P) with the IRS out. The halfshafts were fine but needed new boots and do not forget new IRS halfshaft retaining nuts, front hub nuts, and IRS camber adjusting bolt plus low profile IRS subframe bolts.
19. While everything is out I would install front/rear SS brake lines.
20. Mathis Bracket, KB Rear Shock Tower brace with additional seam welding on the shock towers, and a MM or KB front strut tower brace would round it out.
21. Upgrade the braking system, FTBR FT9490HD and FT7000A kits plus appropriate pads, front duct cooling and fluids. At the minimum I would do the M-2300-X Cobra R front system and FT7000A rear. But if you get serious do not waste your money on the Cobra R and just go straight to the FTBR FT9490HD fronts.



Balanced HPDE/AutoX Setup - Very firm yet streetable for the most part, but beware potholes. Also, this setup for serious track work but not all out track capabilities.
1. Subframe connector kit - Global West COMP, KB Extreme Matrix or Stifflers FIT system
2. MM K-Member with oil filter relocation kit (OC-7, required with K-Member)
3. MM CC Plates
4. MM Race Spec MM2 Dampers
5. MM 425/650 Coilover spring kit (this is a perfect compromise for serious track/street)
6. FTBR FT5001 IRS Kit (this will transform the handling of your car more than you can believe)
7. FTBR FT1350M Differential Housing (do it now if you plan on any racing activities)
8. FTBR M4204T31H Torsen T2-R Differential Unit (do it now if you plan on any racing activities)
9. FTBR FT1860 Toe Link Kit
10. FTBR FT1900 Rear Sway Bar End Link Kit
11. MM K-Member non-offset front control arms with Delrin - MMFCA-8, still need the MMFSB-51 kit also
12. MM front bolt through bumpsteer kit - MMTR-3, required for MM K-Member
13. MM steering shaft assembly- mmst-14
14. MM solid steering rack bushings - MMST-6, required for MM K-member
15. Upgraded front sway bar endlinks
16. Upgraded urethane front and rear swaybar bushings
17. Check and replace front inner tie rods, hub assemblies, bearings, etc while the front end is apart.
18. Check and replace the rear hub assemblies, halfshafts, boots, etc. Based on mileage I found it much easier and cheaper to replace the entire rear knuckle assembly (FTBR FT6800P) with the IRS out. The halfshafts were fine but needed new boots and do not forget new IRS halfshaft retaining nuts, front hub nuts, and IRS camber adjusting bolt plus low profile IRS subframe bolts.
19. Mathis Bracket, KB Rear Shock Tower brace with additional seam welding on the shock towers, and a MM or KB front strut tower brace.
20. While everything is out I would install front/rear SS brake lines.
21. Need to upgrade the braking system, FTBR FT9490HD and FT7000A kits plus appropriate pads, front duct cooling and fluids.
22. Some serious cooling mods will be required, especially for open tracking.

Obviously there are other options regarding suspension choices, tires/wheels, cooling and braking but if you are serious enough to switch to coilovers to improve handling I would go as far as you can based on your budget. Believe me, half assing it in some areas will just lead to frustration. :-D