08 Si suspension on a 07 Ex ?

[pfbmgd]

I have a 08 Si sedan and I`m looking to install HFP supension on it .Can I install my Si suspension on my wifes 07 Ex sedan with out any major issues ?Will I need to up grade the sway bar or install a rear sway bar ?

[peenoySI]

you can DO IT!!!!

EDIT:
i believe it wil raise the car a lil bit..someone correct me if im wrong

[ryker]

I just put Si springs on my Ex. I didn't measure the tire gap but I think it was raised by a 1/4" or so. But rides soo much better with just the rear springs all other Ex parts.

[20civic07]

your car will be dropped a little bit, the si suspension is a bit shorter than the ex/lx/dx suspensions. nothing will be affected, other than your ex will handle a bit better

[pfbmgd]

Originally Posted by 20civic07

your car will be dropped a little bit, the si suspension is a bit shorter than the ex/lx/dx suspensions. nothing will be affected, other than your ex will handle a bit better

Will I have any other issues ?Is it just a straight swap ?

[iqbbang]

Originally Posted by 20civic07

your car will be dropped a little bit, the si suspension is a bit shorter than the ex/lx/dx suspensions. nothing will be affected, other than your ex will handle a bit better

no, sooo not true. everything will be affected. here is a pic of my family member's EX on my old Si springs. the front end is very loose now. the height was raised. handlingwise, its not much better. Because the stock EX springs makes the front stick better i think stockers will give you more handling than Si. im going back to the stock EX springs soon. Remember, Si is couple hundred pounds heavier than EX. my opinion, Dont do it.

[pfbmgd]

Originally Posted by iqbbang

no, sooo not true. everything will be affected. here is a pic of my family member's EX on my old Si springs. the front end is very loose now. the height was raised. handlingwise, its not much better. Because the stock EX springs makes the front stick better i think stockers will give you more handling than Si. im going back to the stock EX springs soon. Remember, Si is couple hundred pounds heavier than EX. my opinion, Dont do it.

I`m swapping the complete suspension not just the springs .I can`t imagine the Si motor weighting that much more .

[ryker]

Originally Posted by 20civic07

your car will be dropped a little bit, the si suspension is a bit shorter than the ex/lx/dx suspensions. nothing will be affected, other than your ex will handle a bit better

The rear springs from the Si sitting side by side of the EX were the same length, same number of coils, Just a different color code on them.

The Si is a heavier car. The light EX doesn't push down on them as much. So they are higher not lower.

[ryker]

Originally Posted by iqbbang

no, sooo not true. everything will be affected. here is a pic of my family member's EX on my old Si springs. the front end is very loose now. the height was raised. handlingwise, its not much better. Because the stock EX springs makes the front stick better i think stockers will give you more handling than Si. im going back to the stock EX springs soon. Remember, Si is couple hundred pounds heavier than EX. my opinion, Dont do it.

Did you use Si sway bars front and rear?

I only changed out my EX rear springs for Si springs and the car is soo much better. With Si rear sway bar it should be even tighter. If the weather clears up this week I will swap the front springs and we'll see if that makes it worse..????

[iqbbang]

Originally Posted by ryker

Did you use Si sway bars front and rear?

I only changed out my EX rear springs for Si springs and the car is soo much better. With Si rear sway bar it should be even tighter. If the weather clears up this week I will swap the front springs and we'll see if that makes it worse..????

yea i guess if you only do the rear, it will be better since you will have more rotation force(being rear stiffer than front) i just put front and rear springs. Rear sway swap sounds good. do the front spring swap and you'll know what i mean by loose in turns.

and to the OP Si engines do weigh significantly more. that is one of the reasons some autocrossers race with a Lx, not Si. even if you swap the springs and struts, they are still made for a heavier front end. just my opinion...

[OhondaU]

The Si is heavier and the springs will reflect that. At the same time the stock Si suspension is a PACKAGE. The components were designed to work together, especially the spring/damper combo. The EX or LX dampers will not have stiff enough damping to control the extra force created by the stiffer springs of the Si, especially in rebound. This would be felt as a "loose" or severely underdamped condition in almost all suspension modes. Roll is probably the one you will be the most sensitive you when talking about handling in the twisties. The car will feel like it kind of rolls back and forth just a little bit when you first point the car in, its a very unsettling feeling as the car never seems to "plant" in the corner.

Add in the fact that the Si is heavier and you have effectively increased the natural frequency (which can be thought of as how fast something would vibrate if it didn't have any friction) of your EX above that of the Si. Essentially, your car is now "stiffer" than the Si. With a slightly different weight distribution you would probably notice more "pogo-ing" of the suspension over washboards or expansion joints.

Without also swapping over the anti-roll bars of the Si, you will severely alter the roll moment distribution of the vehicle and therefore all aspects of its handling from intitial turn-in, to mid-corner, to exit.

To put it simply you car will probably feel "tight" but the ride will be harsh and bouncy, and handling will be compromised. I wouldn't be surprised if it would end up less balanced than a stock EX.

just my .02

[Xtreme Thunder]

Short answer: Parts will fit.

Long Answer: I would not recommend doing it. You will compromise handling! There is a reason Honda Engineered different HFP suspensions for following: Si Sedan, Si Coupe, EX/LX Coupe AT, EX/X Sedan AT, EX/LX Coupe MT, EX/X Sedan MT.

Chaning only 1/2 of the suspension, especially with one which is not designed for the trim level, is just crazy.

[ryker]

Originally Posted by Xtreme Thunder

Short answer: Parts will fit.

Long Answer: I would not recommend doing it. You will compromise handling! There is a reason Honda Engineered different HFP suspensions for following: Si Sedan, Si Coupe, EX/LX Coupe AT, EX/X Sedan AT, EX/LX Coupe MT, EX/X Sedan MT.
.

We really don't have the tech specs to know what the difference really is. It could be something as simple as the HFP shocks just adjusted different - ie 1/2 turn more soft.

Untill we get a complete chart of the spring weights and lengths along with shock rates - we can only assume the theory of stiffer springs is better.

I know that just rear only Si springs on my Ex auto trans has improved the car greatly. Within a few days we will know if the Si front springs makes it better or worse. trial by fire

[pfbmgd]

I guess we got off topic.I`m changing the complete set up .Not just the springs .

[iqbbang]

^ Thats what everyone has been talking about.
Si shock is designed for a SI
EX shock is designed for an EX

As previously mentioned:
"Long Answer: I would not recommend doing it. You will compromise handling! There is a reason Honda Engineered different HFP suspensions for following: Si Sedan, Si Coupe, EX/LX Coupe AT, EX/X Sedan AT, EX/LX Coupe MT, EX/X Sedan MT."

i think Xtreme Thunder pretty much put it in the right words

[pfbmgd]

Originally Posted by iqbbang

^ Thats what everyone has been talking about.
Si shock is designed for a SI
EX shock is designed for an EX

As previously mentioned:
"Long Answer: I would not recommend doing it. You will compromise handling! There is a reason Honda Engineered different HFP suspensions for following: Si Sedan, Si Coupe, EX/LX Coupe AT, EX/X Sedan AT, EX/LX Coupe MT, EX/X Sedan MT."

i think Xtreme Thunder pretty much put it in the right words

Originally Posted by Xtreme Thunder

Short answer: Parts will fit.

Long Answer: I would not recommend doing it. You will compromise handling! There is a reason Honda Engineered different HFP suspensions for following: Si Sedan, Si Coupe, EX/LX Coupe AT, EX/X Sedan AT, EX/LX Coupe MT, EX/X Sedan MT.

Chaning only 1/2 of the suspension, especially with one which is not designed for the trim level, is just crazy.

I think if you re-read most of the thread people are talking about changing springs only.

[ryker]

Originally Posted by iqbbang

"Long Answer: I would not recommend doing it. You will compromise handling! There is a reason Honda Engineered different HFP suspensions for following: Si Sedan, Si Coupe, EX/LX Coupe AT, EX/X Sedan AT, EX/LX Coupe MT, EX/X Sedan MT."

We really don't know if or how much of a difference there is between the shocks and springs on the HFPs.


So I don't buy into the threory of only honda HFP kits will work correctly. After all isn't Honda that simple stuffed a fatter sway bar on the sedan and kept all other parts the same on the coupe? Then on the Dx verse Ex all they did was stick a sway bar on the car.


To the OP. If you can just install the rear springs and take it for a test drive. I am pleased with my car with only the rear Si springs. Then you can try the Si front springs.

[OhondaU]

I think the real point was to be that the HFP suspension is designed to work together, and the standard EX,LX,DX,Si suspensions were designed to work together.

You say they simply stuffed a fatter antiroll bar and called it a day, which is far from the truth. A lot of testing and tuning went into that decision and you have no idea of knowing what else they tried before deciding on that antiroll bar rate. Could be they trie 100 other options but in the end it was that "simple" change that best met their requirements, which does include some compromise leaning toward safety and ride comfort.

Can you mix and match? You bet your @ss you can, but if you don't understand the complex interactions of springs, dampers, roll bars, weight distribution, tires, and alignment you could very well end up back on here in a couple of weeks complaining about how your car doesn't handle as well as it used to. Or you could get lucky and it makes an improvement.

The most important thing when modifying your suspension is to understand the effect it will have on vehicle balance and road compliance, don't forget that the whole point of the suspension is to keep those little black things in contact with the road at all times.

[Xtreme Thunder]

Originally Posted by ryker

We really don't have the tech specs to know what the difference really is. It could be something as simple as the HFP shocks just adjusted different - ie 1/2 turn more soft.

Untill we get a complete chart of the spring weights and lengths along with shock rates - we can only assume the theory of stiffer springs is better.

I know that just rear only Si springs on my Ex auto trans has improved the car greatly. Within a few days we will know if the Si front springs makes it better or worse. trial by fire

"We don't have technical specs", but Honda does.

Just because the car is stiff does not mean it is handling better. Maybe it is stiffer and skating across the road?

Originally Posted by pfbmgd

I guess we got off topic.I`m changing the complete set up .Not just the springs .

That is why I replied like I did. You asked if it will work. I said yes they will fit. BUT!!! It is not designed to work it's best when going from the two trim levels like you mentioned.

Originally Posted by iqbbang

^ Thats what everyone has been talking about.
Si shock is designed for a SI
EX shock is designed for an EX

As previously mentioned:
"Long Answer: I would not recommend doing it. You will compromise handling! There is a reason Honda Engineered different HFP suspensions for following: Si Sedan, Si Coupe, EX/LX Coupe AT, EX/X Sedan AT, EX/LX Coupe MT, EX/X Sedan MT."

i think Xtreme Thunder pretty much put it in the right words

Thanks.

Originally Posted by pfbmgd

I think if you re-read most of the thread people are talking about changing springs only.

Changing springs only are useless if you are looking for best suspension performance. I would say get the HFP suspension of the LX as well.

Originally Posted by ryker

We really don't know if or how much of a difference there is between the shocks and springs on the HFPs.


So I don't buy into the threory of only honda HFP kits will work correctly. After all isn't Honda that simple stuffed a fatter sway bar on the sedan and kept all other parts the same on the coupe? Then on the Dx verse Ex all they did was stick a sway bar on the car.


To the OP. If you can just install the rear springs and take it for a test drive. I am pleased with my car with only the rear Si springs. Then you can try the Si front springs.

Honda know the difference and that is why there is difference kits for the trim levels I previously listed.

I really hope you don't think they are just slapping stuff on these cars.

Originally Posted by OhondaU

I think the real point was to be that the HFP suspension is designed to work together, and the standard EX,LX,DX,Si suspensions were designed to work together.

You say they simply stuffed a fatter antiroll bar and called it a day, which is far from the truth. A lot of testing and tuning went into that decision and you have no idea of knowing what else they tried before deciding on that antiroll bar rate. Could be they trie 100 other options but in the end it was that "simple" change that best met their requirements, which does include some compromise leaning toward safety and ride comfort.

Can you mix and match? You bet your @ss you can, but if you don't understand the complex interactions of springs, dampers, roll bars, weight distribution, tires, and alignment you could very well end up back on here in a couple of weeks complaining about how your car doesn't handle as well as it used to. Or you could get lucky and it makes an improvement.

The most important thing when modifying your suspension is to understand the effect it will have on vehicle balance and road compliance, don't forget that the whole point of the suspension is to keep those little black things in contact with the road at all times.

Thank you! I totally agree! Someone who understands the way things work and designed.

[ryker]

Originally Posted by OhondaU

I think the real point was to be that the HFP suspension is designed to work together, and the standard EX,LX,DX,Si suspensions were designed to work together.

You say they simply stuffed a fatter antiroll bar and called it a day, which is far from the truth. A lot of testing and tuning went into that decision and you have no idea of knowing what else they tried before deciding on that antiroll bar rate. Could be they trie 100 other options but in the end it was that "simple" change that best met their requirements, which does include some compromise leaning toward safety and ride comfort.

Sure and in the end they found that It didn't really matter that much for the Si Sedan. Or it was cheaper for them to just use a fatter front sway bar. Point is this. Had a person came on this thread and said "I only used a fatter front sway bar" the response would have been - "honda designed -blah blah blah for a reason"

Also the Ex only difference is the addition of a rear sway bar - over the Dx/Lx.