SI Spring rates vs. Sport Hatch spring rates

[rpetersen]

Anyone know the difference between the SI and sport hatch spring rates?
Looking to stay close to stock height while getting an increase in handling performance

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[ferdinand]

Copied and pasted from the suspension thread above...

Si:
Wheel: 18x8 28lbs. (P235/40ZR18) (91W) Tire 23lbs. for Goodyear Summer Tire
Front Spring Rate: 144.186 lbs/in (+7% stiffer than normal Civic model)
Rear Spring Rate: 208.776 lbs/in (+32% stiffer than normal Civic model)

Sport Hatch:
Wheel: 18X8 32lbs. 5x114.3mm +50mm offset (P235/40R18) (91W) Tire 22lbs.
Front Spring Rate: 126.83 lbs/in ?? Same as LX?? Confusing with part numbers. SPORT 6mt has a different part number than the other Hatchbacks. SPORT CVT has 2 options, one that is the same as all other Hatchbacks and the other is the same as SPORT 6mt. Could be a manufacturer difference though. Tried two different Sport VINs, a CVT and 6mt, and it returned a part number that is only used on those to versions of Hatchbacks. It's possible that the Sport 6mt and Sport CVT use a front spring that is slightly stiffer. Hard to tell.
Rear Spring Rate: 158.53 lbs/in (same as all normal Hatchbacks)

 

[rpetersen]

So the rear spring rate on a sport hatch is that same as a regular hatch?

 

[ferdinand]

So the rear spring rate on a sport hatch is that same as a regular hatch?

..and sedan according to the data above.

 

[Vincent@27WON]

We installed some SI springs on our Sport Hatchback about ~3 months ago. It was a noticeable improvement. A simple and easy upgrade if you want to enhance your driving experience for sure. It's the springs the sport hatchback should have come with from the factory in my opinion.

 

[absolude]

We installed some SI springs on our Sport Hatchback about ~3 months ago. It was a noticeable improvement. A simple and easy upgrade if you want to enhance your driving experience for sure. It's the springs the sport hatchback should have come with from the factory in my opinion.

Does it lower the car a bit? How much are the springs?

 

[Vincent@27WON]

Does it lower the car a bit? How much are the springs?

Very little, it was about 10mm all around. The springs where cheap. Just at $30 a piece. so $120 for a set.

 

[absolude]

Very little, it was about 10mm all around. The springs where cheap. Just at $30 a piece. so $120 for a set.

That's just about right for me. Hate when the wheel gap is huge on the sides and non existent at the top.

 

[Vincent@27WON]

I have had a couple of you guys message me about differences in spring rates and part numbers so I would like to post and share some information for all of you guys.

So if you have a Sport, EX, EL, EXl hatchback (excluding Type-R) you can swap in SI springs as a direct plug and play with no modding required. The SI springs is about a 10mm drop on all models except for the LX where it is closer to 15mm. So either way it's pretty minimal. If you wanted to swap in SI springs the OEM part numbers are.

Front right spring = 51401-TBF-A01
Front left spring = 51406-TBF-A01
Rear springs = 52441-TBF-A01 (need two of these)

*note left and right front springs are not interchangeable as the wingdings are reversed*

Having a Sport Hatchback as one of our R&D cars the switch to SI springs is a nice and simple upgrade and a difference you will absolutely feel. Very good for guys that don't necessarily want to change ride height dramatically.

I hope this helps.

 

[Design]

I also might recommend swapping out the F/R jounce bumper & dust boot while you're at it. It's shorter & stiffer than its base counterpart and (presumably) aids roll stiffness under hard cornering. That said, I can't remember if the Si's strut piston is larger, so it may not be a great fit.

#20 & 21:

 

[absolude]

How about the shocks? Are the shocks identical across the trims?
If not, would there be any benefit for handling and/or reliability in replacing them?
I intend to use the springs in the LX hatch.

 

[Vincent@27WON]

How about the shocks? Are the shocks identical across the trims?
If not, would there be any benefit for handling and/or reliability in replacing them?
I intend to use the springs in the LX hatch.

They are not identical, quite different in fact. Reference the picture from @Design. Lots of differences between the two. The biggest one being that the SI shocks are adaptive and actually have an electronic plug for the feature. A standard non SI/CTR model wouldn't have that. So can't really use it the way it's intended to.

 

[absolude]

Shoot, forgot about the extra features and didn't look a the shocks at all.
Thanks for explaining it.

 

[Design]

Technically it "can" be done. The advantage being stiffer damping rates. But as referenced above, you lose the advantage of Si's ADS. Hence, the actuators would remain inactive.

 

[absolude]

It would be nice to use them but with no ADS they cost too much, just checked the prices.
Wonder how much faster the LX shocks will wear using Si springs.

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