Spring rates and damper bump/rebound.

[Kozy]

Kozy I have been reading your threads; doing some math and mostly beating my head against the wall trying to get my car to ride better. I feel the same way about the ride on my hatch. It doesn't ride like **** but I believe it should be able to ride better as it did before.

Good stuff, it's good to see someone have a proper think about what is going on underneath their car instead of just asking what the best coilover is!

Current set up is Neuspeed Sport springs on a set of brand new KYB AGX. Previous shocks were some worn out Tokico Illuminas. Car handles much better now but I seem to notice every imperfection in the road.

I spoke to some one at Ground Control and he told me the AGX have a lot of compression damping. I have been thinking that increasing the spring rate will help as it appears the AGX are overdamped for the spring rates I am using.

Can you tell me if simply increasing the spring rate with the current shocks seems to be going in the correction direction?

I am going to pull the trigger in the next 24 hours as I am getting tired to going back and forth. I am hoping I am going in the correct direction.

It may do, it may not. Ride quality is a tricky thing, a stiffer spring will make the car harder no doubt, but if you are currently overdamped then while it might get slightly stiffer, it may react to bumps better. Thats how it felt when I ditched the Koni/Tanabe setup for the Spoons. It didn't really get softer, but having the damping properly matched made a huge difference to the road holding at speed on bumpy roads.

It's hard to say whether stiffer springs is the answer without seeing a typical FV shock dyno plot for the KYBs and knowing the spring rate. If you can get those I could figure it out for you. What's probably happened is the high speed damping is very high (probably a linear FV curve) and that is what you are feeling through the road imperfections. A stiffer spring won't help that necessarily, it's more a shortcoming of the damper than the setup.

I could be wrong, but that's my gut feeling on this one. Can you find a dyno curve for those dampers?

Another thing I have been wondering about is how ride height has factored into the equation. I don't know anything about the Spoon springs but does your car ride higher know than with the GF210's?

Yes, about 20mm higher. Made everything better apart from it doesn't look quite as good!

 

[Salami]

I could be wrong, but that's my gut feeling on this one. Can you find a dyno curve for those dampers?

This is all I could find. The dyno was done by Koni, I don't know if this is good or bad. http://www.koni-na.com/civicdyno.pdf

Current springs are Neuspeed Sport for an Integra. Progressive rate. The rates I found on this site show 250lb/in front 185lb/in rear. Drop is about 1.75" fr/ 1.5" rr.

Springs I am entertaining are also progressive:
4.9 front 3.6 rear (~274lbs fr/ 201lbs rr)
5.4 front 4.2 rear (~301lbs fr/ 235lbs rr)
Lowering would be a bit less at ~1.0-1.25 inches.

 

[Kozy]

That's actually a much better curve than I anticipated!

Car is an EK4?

 

[Salami]

US Civic hatchback. Has a B18C1 drive train and Civic SI four wheel disc brakes and suspension. Manual everything. Stripped down base hatch except for what I have added.

US curb weight stock is 2350lbs for my model. I am guessing I am about 2450lbs, maybe 2500lbs tops with the changes.

 

[Kozy]

Ok I'll have a look into it. On a quick glance, it doesn't look a million miles off but I'll need to have a twiddle around with the spreadsheet and overlay the result on that Koni dyno plot and see how it stacks up!

Might not be until later this evening that I get to reply.

 

[Salami]

Thanks.

Out of curiosity, where are you? I am thinking you are on the other side of the pond, England maybe? Probably a few hours ahead of me.

 

[Kozy]

Yep, England, currently coming up to 2pm.

 

[Kozy]

Sorry I didn't get round to this last night, took the lady out for the evening, and had spent most of the afternoon puzzling over a problem with the maths running the curve digression on my model as it only worked for one fixed digression ratio. All fixed now!

Here's a crude overlay of the basic calulated 'ideal' curve for the Neuspeed springs with those dampers and a 2475lb weight, 62% front weight dsitribution. Ignore the rear curves.

It's actually not a bad match, the low speed damping seems pretty good and the high speed damping is actually less than one might expect.

For comparison, overlays of the other proposed springs:

4.9/3.6

5.4/4.2

Of course, this is only theory and ideals, so real life results may differ wildly, but you do not appear to suffer from overdamping, so I do not think going to stiffer springs in this case will give the change you seek.

You might find that the ride height is actually a little too low for the rate of springs, causing it to hit the bump stops. I would suggest trying the zip tie on the damper piston trick, to see how much bump travel you are using.

 

[Salami]

You might find that the ride height is actually a little too low for the rate of springs, causing it to hit the bump stops. I would suggest trying the zip tie on the damper piston trick, to see how much bump travel you are using.

I was thinking the same thing last night. I have been paying close attention the last two days to what bugs me. It is sudden dips in the road I notice most. When the shock would use more travel is when it seems to get unsettled. Not too bad with the minor imperfections where less travel would be used. When I was talking to the tech at Ground Control the other night he mentioned altering the length the bump stops. He mentioned for the amount the car has been lowered that most likely it was hitting the bump stops too soon and he recommended that I trim them. Seems to make sense as spring rate would suddenly go through roof when the bump stops where contacted.



Right now I am leaning towards the 4.9/3.6 simply because it should raise the car 1/2-3/4 of an inch. I am thinking with the added ride height/shock travel along with trimming the bump stops will go long way to improving the ride, even though the spring rate will be increased a bit.

Does this sound logical to you?

 

[Kozy]

Right now I am leaning towards the 4.9/3.6 simply because it should raise the car 1/2-3/4 of an inch. I am thinking with the added ride height/shock travel along with trimming the bump stops will go long way to improving the ride, even though the spring rate will be increased a bit.

Does this sound logical to you?

Sounds spot on. I know it's extra work, but I would perhaps trim the bump stops first and see if that improves things enough, if not then go ahead and change the springs.

 

[Salami]

Sounds spot on. I know it's extra work, but I would perhaps trim the bump stops first and see if that improves things enough, if not then go ahead and change the springs.

I have thought of doing that but it is very unlikely that I will. My gut is telling me it will solve much of the issue. However with the age of the springs and amount of drop there is at the moment I still plan on changing them. I want the car to ride a bit higher than it does now. Another thing which is completely stupid but is bugging the **** out of me is the green springs sitting on red shocks. Looks like complete **** and needs to go.

I am going to order the springs today and will cut the bumpstops next week when I install the new springs.


Before I forget, Thanks for all of the help!!!

 

[Kozy]

No problem, check back in once it's done and let us know if the changes worked!

 

[Salami]

Will do.


Unrelated: I came across your build thread last night. Started to get sad as I was reading it thinking you got rid of the car. Glad to see you decided to keep it.

Mine is also a 1996. I have had mine for 12 years now and have thought about getting rid of it quite a few times. It even sat on jackstands for two years during a long stretch of frustration. Currently it is my daily driver and I am making changes to make it fun to drive but enjoyable enough to drive that I don't park it again. At one point all I cared about was drag racing. Maybe at another point in life the car will be reborn morphed into something fun to road race.

At this point I though I am pretty sure I will own it for life, it has become part of the family.



Semi-related: Did you start a thread on Honda Tech like the start of this one a while back? While searching there I came across a thread that looked like it had your car in it. Seemed like there was a bunch of egg heads in the thread that just kept saying just buy this or that rather than answering the questions asked.

 

[Kozy]

Yup. Didn't get the response I was looking for particularly, but it probably came across as me bashing Koni, and they are all big Koni bummers over there.

They are skeptical of n00bs asking questions like that. Then they are also fed up of retards asking if they can slam their car so low they need a periscope to go kerb crawling. Can't win sometimes!

As for my car, it's a bastard. Very much a love/hate thing going on, depending on the drive/fix ratio at the time. At the moment, it is not so good. Replacing the entire engine looks like a bit of a financial win though. Repairing the old one looked daunting...

 

[Salami]

My car is a bastard too, there is VERY little that is original on my car. Most of the shell(minus the entire front end) and 3/4 of the interior are original but EVERYTHING else has been changed. But I love my bastard child.

The love/hate thing will get better.
Hear you about the drive/fix ratio. Back in April I tore my motor down for a major rebuild, took me about a week straight but I got it back together. Would have been a whole lot quicker to just drop in a new bullet but I wanted to see if I could do it. I am sure it will not be the last time.

 

[Kozy]

Good to hear, much like my own car! Mine has been broken since the beginning of April, sat on axle stands since early June! Finally got it back on its wheels with an engine fitted this weekend. But now my hubs are seized on so I can't fit the driveshafts, and I still have to plumb the new motor in before I know if it works or not.

I'd have liked to have built my own engine for it, but it wasn't going to happen this time. The old bottom end is in the garage though, just crying out for a set of Darton sleeves... maybe next year.

 

[Salami]

Right now I am leaning towards the 4.9/3.6 simply because it should raise the car 1/2-3/4 of an inch.

The 4.9/3.6 springs are on back order with no ETA. Freaking pissed I waited so long.

The 5.4/4.2 is in stock and will also raise the car 1/2-3/4". How well do you think this choice will work?

 

[Kozy]

Hard to say really. It's only a slight increase over the 4.9/3.6, it should be aboslutely fine, the rise in ride height will make a difference though!

Did you get round to trimming the bump stops?

 

[Salami]

Haven't trimmed the bump stops yet. I had ordered the 4.9/3.6 and they were supposed to be here today. I wanted to install the springs and trim the bump stops at the same time to save myself the extra work. According to the seller UPS picked up the package and then proceeded to loose it. Not sure I believe the story though. It was the only set I could find anywhere.

Maybe I will trim them tomorrow if I have some extra time.

 

[Salami]

Gave up trying to locate the before mentioned springs. Wound up ordering a Eibach Pro-kit. If nothing else the ride height should be higher and hopefully it will ride the same if not better than it does now.