Are coil-overs worth it?

[ERre23]

Since Joe Blow Racing is having the special on the MM coil-over kits I am considering putting that on my car. Right now I have H&R Super Sports with stock isolators and I have Hans SFC on order. Are coil-overs worth it? I don't ever do track events, I just want my car to handle well on the street, ride well and look good. Also, I am having some trouble with traction and wheel hop right now, Apten, would this help me out? I am running 315/30/18 Michelin Pilot Sports and I still need more traction. I am hoping some better suspension may make it better.

Thanks,
Ryan

 

[03yllwguy]

My last Cobra I did a full GR40 c/o system with koni d/a's. I did not track my car, just wanted the same as you, superb handling and streetability. After the $2000+ for the kit, and all the parts that broke or had to be modified and noises tracked down, I wished I had just stuck with lowering springs. But then again others swear by them.

 

[toofast4u]

Griggs suck and are prone to breaking. MM are great I have had them for almost 2 years on my 03 and haven't had any problems.

 

[sambandit]

If you don't track the car, forget about the coilovers. Lowering springs are just fine.

 

[ERre23]

Thanks sambandit, all I needed to know.

 

[sambandit]

That being said, all the coilover guys will find this thread and scream they are worthy....they are worthy...lol.

 

[jimwood]

Coil-overs are nice because you can adjust your ride height. On the same line, coil-overs suck because you have to adjust your ride height correctly, which is difficult and time consuming. From what I understand corner weighing the car is the best, but measuring ride height works too. Your also going to loose some weight which is real nice.

If your not going to the track no reason for coil-overs, I agree with that. I have also heard that just lowering a mustang (with no other suspension mods) is going to actually make your handling worse.

If your worried about looks and not so much performance, springs are a good way to go.

Tough call.

 

[toofast4u]

Sambandit do you have or have you had coil-overs on your car?

 

[toofast4u]

On the Mustang platform the front suspension is called a hybrid McPherson configuration where the spring is located inboard of the strut location. There are two values to be aware of moving forward one is spring rate and the other is wheel rate. Spring rate is the actual force required to compress the spring. Wheel rate is the actual force from the spring as seen at the wheel location. With the spring in the conventional location has a wheel rate efficiency of ~22%. This means with the stock 600 Ibs/in springs only ~ 132 Ibs/in of force is actually seen at the wheel. The remaining energy is lost in friction primarily at the ball and pivot joints. This energy loss which is primarily in the pivot locations causes substantial resistance to movement which in turn causes ride harshness. On coil-overs the springs located in the true McPherson configuration which is on the strut inline with the direction of movement and thereby have an efficiency of approximately 92%. This means a normal coil-over spring of 350 Ibs/in has a wheel rate of ~329 Ibs/in so in reality you have twice the wheel rate with ~1/22 the energy loss in friction.

Since it was brought up the front suspension on the Mustang due to its configuration does have an optimum balance ride height. The optimum ride height for correct suspension articulation is such that the ball joint pivot point and LCA pivot point are parallel with the ground. When a Mustang has been lowered beyond this point it will compromise steering, braking, and roll stiffness which will also causes rear traction problems. Lowering a vehicle beyond the optimum ride height does lower the center of gravity which can provide some minimum gains, but the benefits of this should be weighed against the more serious compromises mentioned previously. Steeda now has extended ball joints which lowers the ball joint pivot point 1/2" in regards to the spindle. When using conventional springs these ball joints lower the vehicle in respect to the ground a 1/2". Spring spacers are used to increase the spring length 1/2" to maintain the same ride height as before. This means that you can use springs that lower your car 1" and still maintain proper front end geometry.

 

[dgussin1]

Brian how the hell do you know this shit. lol you are the suspension GURU. MM should hire you.

 

[ShelbyGuy]

Even if you track the car, spend your money on coaching/instruction first. Learn to drive what you have with proficiency, THEN start with the modifications.

 

[Twinturbo Ranger]

My thoughts...

I'm in the same boat, so I'll throw my thoughts out there.

If you want looks only then you would be better off with springs. If you are looking for looks plus better handling then you need to seriously give it a thought. So far the advantages to going with the coil overs are as follows. You will be able to adjust your suspension height wise and if needed you can change springs to tailor your handling needs also. You will gain a small but useful weight savings. Your ride quality should improve especially in the front. You should also gain some much needed help in the wheel hop area because of the added spring rate. The last thing is the nice caster camber plates under the hood, which since my car goes to shows I would get the chrome option along with the chrome STB. So that being said there are alot of positives.

The one negative that I see is price. If money were no object then the coil over setup is a definite. The price would normally be greater, but this is the best deal I've seen. You must remember even if you do springs only, you will need a set of caster camber plates, so be sure and add that in. Then ask yourself if the positives are worth the difference?? Thats were I'm at !! The good thing is I have a week to do all my research so I can make a positive decision.

Good luck
Thanks Mike

 

[ERre23]

Wow thats some great info. Thanks.

 

[sambandit]

Sambandit do you have or have you had coil-overs on your car?

No, I never have had coilovers. Been in a couple 03s that do though and have driven a couple too. Let me say, coilovers are the ultimate, without a doubt, but for normal street driving, the coilovers felt absolutely no different than my car does with lowering with springs. Lowering the car in any fashion improves handling quite a bit, not sure why some folks think that springs harm the ride in some way.

 

[iismet]

I just finished the installation of front MM coilovers on my 03. I have been a lurker here for the last year. I used a ton of Brians information to get my car where it is and it is not finished. The car came with HR SS and stock Ford isolators when I purchased it. I was impressed with the power but the suspension was not as tight as I like and the car sat too low for functional driving in the Northwest.

This this is my first Mustang. I did the VW thing for several years ending in a very tight Corrado and then drove an SVT Contour for four years prior to the Cobra.

The conversion to CO's included

MM 375# Springs
MM Aluminum, Center Drilled, steering rack bushings
MM Lower Front Controls Arms with Poly bushings.
MM Front Bump Steer Kit
Steeda X2 Ball joints

I was able to drive the car this weekend for several hunderd miles. All I can say is WOW! Should have come this way from the factory. I was concerned the 375's may be to rigid but it sure doesn't drive like it.

If a person does not like the vague steering I would highly recommend the solid Rack Bushings. I have considered a solid steering shaft for many months but read that Ford had used high durometer rubber in the rag joint so I wanted to give the bushings a try first (NVH is a thing form me). The steering response is beautiful. Not as tight as it could be but very nice for a big, heavy, STREET car. "Turn In" is like night and day. Unfortunately I did alot at once so it's hard to know how much the LCA bushings and corrected Roll Center are adding to the steering response.

Speaking of NVH and the CO's - as of now I could not be happier. I do not notice any more NVH with these mods than before I did them.

The X2 ball joints moved my CA's (visually) back to parallel with the ground. They were tilted up at a very high angle which makes no sense when one considers the limitations of the front geometry and dynamic camber changes as the control arms swing toward the struts. Not to mention the roll center problem. The car now has no roll - very nice. Will it roll? I'm sure it will but I'm not a racer so for me it is great. It definately rolled prior to this upgrade. Not bad, but why should it for no harder than it is pushed.

We have not adjusted the bump steer yet. That will be next. So far I have not experienced it. We shimmed the kit so the Tie Rods are parallel to the LCA.

I am not going to put CO's on the back because of advice William Mathis gave at corner carvers. His opinon is the chassis is just not designed for the loads. I know others have and that is cool, I'm just not going that way because of the time, expense, and the car is a street car.

Brian (or anyone else), if you read this I am interested in your opinion on the following. Mathis stated on one of the threads at CC that the Cobra R had 800 lb rear springs to offset the down force of the wing. He stated he thought a better match would have been a 675 LB rear spring to frequency match the front spring rates. He then stated the differential between the front and rear should be 5%.

1) I assume the 5% is wheel rate not spring rate.

2) If it is wheel rate then

375 * .22 = 337.5 Front MM CO
685 * .31 = 212.4 Rear HR SS

In order to optimize the 5% front to back.

375 - (375*.05) / .31 = 1149# Rear SR in stock location

Obviously I'm not going there.

3) If it is spring rate then

685 * .05 = 34.25 Rear HR SS

So Stock Front = 685 +- 34.25 or 650 to 720

Using 720 in stock location = (720 * .22) = 144 wr

SO CO Spring Rate = 144 / .9 = 160#

Obviously I'm not going there as several have already tried 275# CO and they were too soft for this vehicle.

There was a discussion at CC about LCA bind and the bind adding to the effective wheel rate on the front of the car. If this is true, it is a big variable unaccounted for. So, if you would have gone my path what rear spring would you put in the stock location on your car? Using your 425# springs as a basis what would you have tried and would you still use the Cobra R shock.

Some of my delima is bling as I like the ride height of the car where it is and I like running MM's poly isolators at the rear. This gives me a rear ride height of 26 5/8 at the top of the fender well. I do not think the CO's are matched well to the rear HR SS. I am considering the Race springs but hate to gain more rear height (will cut if needed). What do you think about using the Cobra R shocks with SS rears? The reason I ask, is the rear feels under damped when forcing the thing through a turn on less than stellar road surfaces. I am not opposed to a softer front spring if like a 325# if I can get the thing dialed a little closer.

Also, Brian - Great job on CC. My life is too short to deal with all the psycho- therapy that goes with it, to ever get involved. It is an awsome source of tech but none of my lifes goals include "Mustang Guru" aspirations.

Nice others do aspire to that end!

 

[Bingo13]

That being said, all the coilover guys will find this thread and scream they are worthy....they are worthy...lol.

Your springs may be bigger but ours are stiffer.

Actually, after using several spring combinations before going to coil-overs I found that the '00R spring/strut/shock combination provided the best combination of handling versus ride quality (spring setup) even though the lowering aspects on the car was minimal. However, even though there are significant handling benefits to be realized with the right coil-over setup I found the biggest improvement was in overall ride quality on this car (375/575 setup).

 

[toofast4u]

If a person does not like the vague steering I would highly recommend the solid Rack Bushings. I have considered a solid steering shaft for many months but read that Ford had used high durometer rubber in the rag joint so I wanted to give the bushings a try first (NVH is a thing form me). The steering response is beautiful. Not as tight as it could be but very nice for a big, heavy, STREET car. "Turn In" is like night and day. Unfortunately I did alot at once so it's hard to know how much the LCA bushings and corrected Roll Center are adding to the steering response.

I would highly recommend you strongly consider the solid steering shaft. The rag joint really sucks and causes a lot of play, isolation, and resistance in steering effort. I was very apprehensive on doing them my primary concern was I couldn't believe the price was worth it, but after I was amazed at the difference. I haven't noticed any adverse increase in NVH after doing it.

The X2 ball joints moved my CA's (visually) back to parallel with the ground. They were tilted up at a very high angle which makes no sense when one considers the limitations of the front geometry and dynamic camber changes as the control arms swing toward the struts. Not to mention the roll center problem. The car now has no roll - very nice. Will it roll? I'm sure it will but I'm not a racer so for me it is great. It definately rolled prior to this upgrade. Not bad, but why should it for no harder than it is pushed.

Great job. That is the hardest thing to get people to understand that slamming a car does not make it necessarily handling better. Yes you are lowering the CG, but it does have adverse affects especially on the Mustang platform.

We have not adjusted the bump steer yet. That will be next. So far I have not experienced it. We shimmed the kit so the Tie Rods are parallel to the LCA.

If you have the LCA and tie-rods parallel that is probably as close as you really need it. If you are up for a frustrating adventure you can go through the fun of using a bump steer gauge. I would highly suggest staying away from the bumpsteer gauge that MM sells and use the Long acre one instead. Yes it is about twice as much, but after screwing with the MM for a couple hours you will wish you had bought it.

I am not going to put CO's on the back because of advice William Mathis gave at corner carvers. His opinon is the chassis is just not designed for the loads. I know others have and that is cool, I'm just not going that way because of the time, expense, and the car is a street car.

Brian (or anyone else), if you read this I am interested in your opinion on the following. Mathis stated on one of the threads at CC that the Cobra R had 800 lb rear springs to offset the down force of the wing. He stated he thought a better match would have been a 675 LB rear spring to frequency match the front spring rates. He then stated the differential between the front and rear should be 5%.

1) I assume the 5% is wheel rate not spring rate.

2) If it is wheel rate then

375 * .22 = 337.5 Front MM CO
685 * .31 = 212.4 Rear HR SS

In order to optimize the 5% front to back.

375 - (375*.05) / .31 = 1149# Rear SR in stock location

Obviously I'm not going there.

3) If it is spring rate then

685 * .05 = 34.25 Rear HR SS

So Stock Front = 685 +- 34.25 or 650 to 720

Using 720 in stock location = (720 * .22) = 144 wr

SO CO Spring Rate = 144 / .9 = 160#

Obviously I'm not going there as several have already tried 275# CO and they were too soft for this vehicle.

I am fairly certain he is referring to wheel rate as spring rate is worthless in any discussion other then comparing two springs for the same application.

Using my car as an example with coil-overs
Front 425*.92=391
Rear 650*.61=396.5
Difference ~2.1%

Using your current set-up.
Front 375*.92=345
Rear 685*.31=212
Difference ~38%

In order to bring it into spec
375*1.05=393.75
Coil-overs 375/.61=614.75 393.75/.61=645.50
Conventional 375/.31=1209.67 393.75/.31=1270

So using conventional springs then would need to be between 1209-1270 and coil-overs between 614-645. This is in line with conversations with MM and information I have found other places. btw, do you want to guess what Griggs would usually recommend in this solution hint your number is close.

Just for fun the 00R
Front 800*.22=176
Rear 750*.31=232.5
Difference ~24%

There was a discussion at CC about LCA bind and the bind adding to the effective wheel rate on the front of the car. If this is true, it is a big variable unaccounted for. So, if you would have gone my path what rear spring would you put in the stock location on your car? Using your 425# springs as a basis what would you have tried and would you still use the Cobra R shock.

Some of my delima is bling as I like the ride height of the car where it is and I like running MM's poly isolators at the rear. This gives me a rear ride height of 26 5/8 at the top of the fender well. I do not think the CO's are matched well to the rear HR SS. I am considering the Race springs but hate to gain more rear height (will cut if needed). What do you think about using the Cobra R shocks with SS rears? The reason I ask, is the rear feels under damped when forcing the thing through a turn on less than stellar road surfaces. I am not opposed to a softer front spring if like a 325# if I can get the thing dialed a little closer.

You shouldn't have bind in your front suspension especially with the MM tubular LCAs. Stock you might and with Griggs most definitely from the arms I have seen I don't know if it is the jig or on purpose. You can easily check and correct the holes so they are in alignment and not causing a binding situation using a rod and drill bit. Now as far as the rear goes it is very possible you do have a binding situation with the Passenger side LCA. I found out when I put in the Delrin bushings and had to modify the mounting hole closest to the muffler.

Something else to be aware of is using higher durometer bushings has a dramatic affect on spring efficiency. I noticed this dramatically with the Delrin rear LCA and UCA bushings. The spring efficiency changed to such a dramatic degree that I could feel the 00R shocks were under dampened afterwards and I know of 00R owners who reported they also felt the 00R shocks were under dampened with there “stock” springs. This makes me believe that it has a greater affect on conventional spring location which decreases the efficiency delta between the two. The under dampening is not to a degree that I feel it is a performance hindrance and it actually gives me some entertainment now. It only really noticeable at slow speed over rough road at full out it is solid even over rough surfaces. I would recommend the 00R shocks for most set-ups without Delrin bushings. If you are doing Delrin bushings with higher rate springs coil-overs 675+ or conventional 800+ then you most likely will want them revalved by Bilstein.

Also, Brian - Great job on CC. My life is too short to deal with all the psycho- therapy that goes with it, to ever get involved. It is an awsome source of tech but none of my lifes goals include "Mustang Guru" aspirations.

Nice others do aspire to that end!

The most amusing thing about them is a couple weeks after the blow out I had with them over coil-overs. One of the F-body guys who was giving me a hard time about doing coil-overs showed he didn't know anything about Mustang suspension and what we were talking about. Somebody asked how to remove springs on a Mustang and his response was to pull out the strut and bring it to a shop to remove the spring. That would be fine if we had a McPherson set-up, but would kill you with our stock set-up.

 

[iismet]

Actually, after using several spring combinations before going to coil-overs I found that the '00R spring/strut/shock combination provided the best combination of handling versus ride quality (spring setup) even though the lowering aspects on the car was minimal. However, even though there are significant handling benefits to be realized with the right coil-over setup I found the biggest improvement was in overall ride quality on this car (375/575 setup)..

Ah - I was hoping you would chime in. Absolutely - the ride quality is fantastic. After listening to you guys for the last year I was still leary about the investment (NVH). Your advise has been right on the money and I could not be happier. Thanks.

Just for fun the 00R
Front 800*.22=176
Rear 750*.31=232.5
Difference ~24%
.

Using your 00R 800# Rear example as a basline to drive the front spring rate I get the following

00R Rear = 800*.31=248 rwr

375# FCO = 375*.92 = 345# fwr => 345-248/345 = 28%
350# FCO = 350*.92 = 322# fwr => 322-248/322 = 23%
325# FCO = 325*.92 = 299# fwr => 299-248/299 = 17%
300# FCO = 300*.92 = 276# fwr => 276-248/276 = 10%
275# FCO = 275*.92 = 275# fwr => 253-248/253 = 2%

HR Race Rear = 770*.31=239 rwr

375# FCO = 375*.92 = 345# fwr => 345-239/345 = 31%
350# FCO = 350*.92 = 322# fwr => 322-239/322 = 26%
325# FCO = 325*.92 = 299# fwr => 299-239/299 = 20%
300# FCO = 300*.92 = 276# fwr => 276-239/276 = 13%
275# FCO = 275*.92 = 275# fwr => 253-239/253 = 6%

HR SS Rear = 685*.31=212 rwr

375# FCO = 375*.92 = 345# fwr => 345-212/345 = 38%
350# FCO = 350*.92 = 322# fwr => 322-212/322 = 34%
325# FCO = 325*.92 = 299# fwr => 299-212/299 = 29%
300# FCO = 300*.92 = 276# fwr => 276-212/276 = 23%
275# FCO = 275*.92 = 275# fwr => 253-212/253 = 16%

So now I know where the 275 came from to begin with - duh! Also I can see why the 350# is appealing when coupled with the 00R rear as it's closer to the struts ability to dampen and right on the 00R setup (comparing indices only). The HR SS do not make since to me in this application.

I am thinking the 325# CO with HR Race Rear might make since for me. I like the looks of the 300 but am concerned they me be to soft. If any one has run the 300# - please advise. I assume I will need the 00R shocks.

You shouldn't have bind in your front suspension especially with the MM tubular LCAs. Stock you might and with Griggs most definitely from the arms I have seen I don't know if it is the jig or on purpose. You can easily check and correct the holes so they are in alignment and not causing a binding situation using a rod and drill bit. Now as far as the rear goes it is very possible you do have a binding situation with the Passenger side LCA. I found out when I put in the Delrin bushings and had to modify the mounting hole closest to the muffler.

I was referring to the bind before I pulled the stock CA's. I thought maybe somehow Ford accounted for this in the wheel rates but after working thru the math above I can see this isn't so. I was surprised they were bound from the factory and would not fall to the floor. The MM Arms swung under their own weight with the bolts torqued.

Something else to be aware of is using higher durometer bushings has a dramatic affect on spring efficiency. I noticed this dramatically with the Delrin rear LCA and UCA bushings. The spring efficiency changed to such a dramatic degree that I could feel the 00R shocks were under dampened afterwards and I know of 00R owners who reported they also felt the 00R shocks were under dampened with there “stock” springs. This makes me believe that it has a greater affect on conventional spring location which decreases the efficiency delta between the two. The under dampening is not to a degree that I feel it is a performance hindrance and it actually gives me some entertainment now. It only really noticeable at slow speed over rough road at full out it is solid even over rough surfaces. I would recommend the 00R shocks for most set-ups without Delrin bushings. If you are doing Delrin bushings with higher rate springs coil-overs 675+ or conventional 800+ then you most likely will want them revalved by Bilstein.

Interesting - I am headed for the rear Delrin solution later this winter but as stated above plan on using the HR Race. Would you still be concerned with the valving as they are only marginally softer (30lb) ?

If you would revalve, do you see any potential balancing problems with respect to the stock strut valving?

Also I thought I read in a thread of yours somewhere you were not sure the UCA needed the Delrin. Is this true or am I confused?

The most amusing thing about them is a couple weeks after the blow out I had with them over coil-overs. One of the F-body guys who was giving me a hard time about doing coil-overs showed he didn't know anything about Mustang suspension and what we were talking about. Somebody asked how to remove springs on a Mustang and his response was to pull out the strut and bring it to a shop to remove the spring. That would be fine if we had a McPherson set-up, but would kill you with our stock set-up.

My point exactly - too much psycho therapy needed for effecive communication. Somehow you keep it together and get the answer - very cool.

 

[toofast4u]

Using your 00R 800# Rear example as a basline to drive the front spring rate I get the following

Just for the record the 00R rear springs are Eibach 750 Ibs/in not 800. The fronts are Eibach 800 Ibs/in.

So now I know where the 275 came from to begin with - duh! Also I can see why the 350# is appealing when coupled with the 00R rear as it's closer to the struts ability to dampen and right on the 00R setup (comparing indices only). The HR SS do not make since to me in this application.

I am thinking the 325# CO with HR Race Rear might make since for me. I like the looks of the 300 but am concerned they me be to soft. If any one has run the 300# - please advise. I assume I will need the 00R shocks.

There are a few drag racers running 12" 200 Ibs/in coil-over springs on the road. I don't know how the car would actually handle when pushed especially with the heavy engine in the 03-04.

Interesting - I am headed for the rear Delrin solution later this winter but as stated above plan on using the HR Race. Would you still be concerned with the valving as they are only marginally softer (30lb) ?

If you would revalve, do you see any potential balancing problems with respect to the stock strut valving?

I would use the 00R shocks with the HR Race springs since they are only 20 Ibs/in stronger then the 00R springs. The 00R strut valving is very weak and according to MM they said it is the weakest shock they car for the SN95 platform. Which is interesting as the 00R shock is the strongest they have. They had not finished the dyno testing when I talked to them about it, but they did expect the 03 valving to be stronger.

Also I thought I read in a thread of yours somewhere you were not sure the UCA needed the Delrin. Is this true or am I confused?

The discussion was about which affect the rear bushing would have on handling and NVH. It was my opinion that since the majority of all transitional loads are controlled by the LCA that using a higher durometer bushing in this location would have the greatest affect in handling with the least NVH increase. Since the load on the UCA is substantially less I didn't believe the higher durometer bushings were necessary and would most likely cause an unnecessary increase in NVH due to this. Since I have had the Delrin bushings in my car for some time I have not experienced any significant increase in NVH over stock. I believe this at least in part is due to the fact the IRS assembly itself is isolated from the chassis using lower durometer urethane bushings.

 

[iismet]

Just for the record the 00R rear springs are Eibach 750 Ibs/in not 800. The fronts are Eibach 800 Ibs/in.

For the record I have edited below and added 750# to Matrix.

Reminder - this info is for matching spring rates for front CO's to stock springs at rear, not front CO's to rear CO's. It also assumes stock 03 struts which is why it only goes to 375# FCO.

800# Rear = 800*.31=248 rwr

375# FCO = 375*.92 = 345# fwr => 345-248/345 = 28%
350# FCO = 350*.92 = 322# fwr => 322-248/322 = 23%
325# FCO = 325*.92 = 299# fwr => 299-248/299 = 17%
300# FCO = 300*.92 = 276# fwr => 276-248/276 = 10%
275# FCO = 275*.92 = 275# fwr => 253-248/253 = 2%

HR Race Rear = 770*.31=239 rwr

375# FCO = 375*.92 = 345# fwr => 345-239/345 = 31%
350# FCO = 350*.92 = 322# fwr => 322-239/322 = 26%
325# FCO = 325*.92 = 299# fwr => 299-239/299 = 20%
300# FCO = 300*.92 = 276# fwr => 276-239/276 = 13%
275# FCO = 275*.92 = 275# fwr => 253-239/253 = 6%

Eibach (00R) Rear = 750*.31=233

375# FCO = 375*.92 = 345# fwr => 345-233/345 = 32%
350# FCO = 350*.92 = 322# fwr => 322-233/322 = 27%
325# FCO = 325*.92 = 299# fwr => 299-233/299 = 22%
300# FCO = 300*.92 = 276# fwr => 276-233/276 = 15%
275# FCO = 275*.92 = 275# fwr => 253-233/253 = 8%

HR SS Rear = 685*.31=212 rwr

375# FCO = 375*.92 = 345# fwr => 345-212/345 = 38%
350# FCO = 350*.92 = 322# fwr => 322-212/322 = 34%
325# FCO = 325*.92 = 299# fwr => 299-212/299 = 29%
300# FCO = 300*.92 = 276# fwr => 276-212/276 = 23%
275# FCO = 275*.92 = 275# fwr => 253-212/253 = 16%

The Eibach hurts my bling i.e. rear ride height of stock 00R. Someone at CC spoke of removing one of the rear spring isolators to comp the ride height. Do you remember which one .i.e. top or bottom? It seems it would be bottom.

The discussion was about which affect the rear bushing would have on handling and NVH. It was my opinion that since the majority of all transitional loads are controlled by the LCA that using a higher durometer bushing in this location would have the greatest affect in handling with the least NVH increase. Since the load on the UCA is substantially less I didn't believe the higher durometer bushings were necessary and would most likely cause an unnecessary increase in NVH due to this. Since I have had the Delrin bushings in my car for some time I have not experienced any significant increase in NVH over stock. I believe this at least in part is due to the fact the IRS assembly itself is isolated from the chassis using lower durometer urethane bushings.

NVH aside, is the money and effort on the UCA worth it? Do you think it adequate to only replace the lowers?

Did you also switch out the Poly in the front CA's for Delrin at some point in your build? Is so, to what affect?