Kozy.

Hello all from an autocrosser over the pond in the UK!

I have been doing a bit of research into my suspension and have come to the conclusion that my Tanabe GF210 springs (320F/156R) are too soft for my Konis and as a result are overdamped, leading to a bad ride a comprimised handling response.

I calculated (based on a few assumptions and some formulae from OptimumG) the ideal damper curve based on spring rate, corner weight, wheel rate, natural frequency etc, and assumed a 65% critical damping ratio. I then overlayed the resulting graph onto a koni dyno plot I found:



Some of you will no doubt the underlying Koni dyno plot, but I am wondering if I should be looking at a seperate plot for the rear dampers as I cannot imagine they use the same valving front and rear!

I know a few people here have dyno'd various dampers, was wondering if perhaps anyone had plots for front and rear OTS Yellows on a 96 EK Hatch application?

Thanks and I look forward to your replies.

RR98ITR

Hmmmmmmmm...while it looks like you've come to the forum well prepared, a post count as low as yours doesn't encourage the HT forum heros to engage you in discussion. Consequently you'll probably only get response from idiots and weirdos. And what are you doing here anyway? Were you run out of your own English forums? This is all very suspicious and therefore I'm going to take a very cautious approach and just sit back and see what happens.

Scott, who wonders if you've seen this thread https://honda-tech.com/forums/suspension-brakes-54/%5Bfaq%5D-shock-dynos-1104049/ and if what you're looking for is in there somewhere...

beanbag

Well, I've got good news for you - the formulae on OptimumG are wrong because they forgot to take the shock motion ratio into account. You need shock motion ratio ^2 worth more damping.
One factor more due to lever action and another factor due to shock moving slower.
In fact, RR98ITR has a post about that...

STN_Pat

I humbly fit into this category I believe.

You should always choose a spring rate, and then use shocks to handle it. Not the other way around.

And Tanabe springs are show springs, not performance springs. How is this track oriented ?

Kozy.

Scott, I see where you are coming from, perhaps I should have introduced myself better so I'll do a brief one now.

My name is Dan, I live on the Isle of Wight off the south coast of England and I run my daily driven Ek4 hatch in the Isle of Wight Car Club 'sealed surface' championship. You can check out our club sebsite here: http://www.iowcc.co.uk/
Our events probably run a bit different to yours, the classes, regulations etc are a bit more relaxed as the sport is not as big over here as it is in the US but the format is basically the same.


A few shots of me and the car in action:




Major parts of the spec are a Quaife ATB differential and 9lb lightened flywheel, ASR 24mm rear roll bar and subframe brace, Koni yellows and the crappy Tanabe springs. As it is my DD it is still in full road trim, all interior minus the parcel shelf is present and I sit in EP3 CTR seats with custom rails as I am too cheap to buy Recaros. Usual wheels, brakes, intake and exhaust mods are present too.

I was currently running 5th in class up until last weekend, where a business trip over to Pennsylvania (still here until next weekend) made me miss the last event and dropped me to 20th. Next season I am looking to improve the car and my ablilities to take a top 3 finish in class, the main competition being a stripped EF9, a Lotus Elise, Group 4 Mk1 Escort Mexico rally car and an Impreza.

I know the usual route is to pick springs then choose the dampers to suit, however I am happy with the dampers and wanted to change the springs anyway. I am set on going the GC route and am currently attempting to find what rates will best match the valving in the Konis. I could probably find this out by asking around, but much like yourself Scott, I like to figure these things out as much as possible for myself, I love numbers and stuff.

The reason I am here instead of on some UK board? You've clearly never visted a UK Honda site have you? It's all about kids running EJ9s with cut springs, 17" chrome wheels and massive sound systems. They don't have the kind of techincal expertise shared by the members on this board, let alone a dedicate autocross forum! I've been lurking here for a while, and have read many of your threads on suspension as it is a subject that is of great interest to me.

Please, if you have comments on the way I may have calculated things from the OptimumG website I am willing to listen, I can only learn as well as the stuff I read so any input is greatly appreciated! The motion ratio ^2 thing is familiar, however I am not sure how it fits into the equations.

I'll be sticking around for a bit, and will get more involved in the discussions in future!

Kozy.

Sorry that should be dropped to 11th in class, it was 20th overall.

chrisdavis6

Cool thread!
Komodo that ek is looking mean as hell in the gunmetal grey. good Stuff!

RR98ITR

Hi Dan,

I should tell you that my post was tongue in cheek. I'm under the influence today of some funny video I saw on another board I lurk on:
http://www.youtube.com/watch?v=iB-_l2r4pvE

Welcome to Honda-Tech.

Scott, who did try to be helpful with that link to the Suspension shock dyno thread...so that much was completely serious...oh, and for the record - I consider myself a weirdo and not an idiot.

civichb20

LOL you guys are a trip

Kozy.

I don't know what settings you've got you monitor on, but my car is actually Dark Amethyst Pearl! Although as some kind of weird mind reading trick, I do actually seriously want to respray it in gunmetal grey, I think it would look awesome. Now, get out of my head you weirdo!

Haha OK I didn't get that! I will have a read through that thread you linked and see if I can find some answers!

When I get back from the US I shall be getting the car up on ramps, all the suspension off, dimensions measured and parts weighed so I can make start knocking up some accurate CAD models and calculating everything properly.

I'll post my findings up here as I'm sure someone will find it useful!

I also found that video amusing, I used to own an Oak Green Mk2 16v about 5 years ago, so it makes a lot of sense.

beanbag

Don't bother, this info is already out there.

In any case you are not overdamped, and you'll end up turning the ***** until it feels right anyway.

chrisdavis6

LOL! Purple is cool too!
Chris who just bought some dunks in Purple & Anthracite!

Kozy.

I've searched, I can't find it. Must be something people keep close to their chests I guess, any threads I've seen here requesting such info have zero replies. Maybe I need to search back before 2003 but I really cannot be bothered, I would rather be out working on the car and measuring it myself than trawling through years worth of forum posts!

As for the *****, I've already tried playing with the rebound settings and found they don't make any much difference to ride quality.

As has already been said, Tanabe springs are show springs, not performance springs, I just want to figure out what is going to be better theoretically, I don't have a massive budget to go out testing spring rates in 50lb increments like some of you guys appear to.

My logic is that for a given weight and rate, you have a frequency, for that frequency you have an ideal damping force. Now I agree you should select a damper based on the springs in question, but since I have what is pretty well regarded as a good damper and what is also generally regarded as a crap spring, I don't see the harm in trying to work it backwards to select a spring that will work well with my existing setup.

Then again maybe I should just scrap it and go by the RX8 I've been lusting over...

beanbag

The only info you need is the car total weight, weight distribution, and front and rear motion ratios. I'm pretty sure this exists out on the interweb somewhere. And why do you need to weigh the suspension components? What are you going to do with this info?

What does "ride quality" mean? The shocks are only rebound adjustable so certain aspects of "ride quality" are unaffected.

You haven't provided any metrics to determine which spring rate is "theoretically" the best. The short answer is "it depends".

Go ahead and play around with the spring rate, then. Koni yellows are supposedly good up to 500 lbs/in, so I've heard.

This seems like a no-brainer to me. You can either try to get an econo-box to work ok, or get a real sports car.

PS if u want to know more about critical damping or unsprung weight, go here:
https://honda-tech.com/forums/road-racing-autocross-time-attack-19/diy-bilstein-revalve-project-part-2-a-2437593/

Skip the first few posts and start at post #5 where JMac starts blabbing about stuff. Armed with the new vast knowledge, you can try to track down a full sweep dyno plot of your shocks. You might find out that you'd have to set the ***** at 1/4-1/2 from full soft in the rear and 3/4 in the front. Even then, that would be a starting point, and you still have to "adjust them until it feels right".

PPS You might find out that you can adjust the shocks all you want and they will still never feel "right". This is a sign that you need to step up to better shocks.

Kozy.

Learn mostly. The weighing was to get accurate unsprung weight data, and the measuring was to build some models with which I can do some analysis such as bump steer characteristics, camber gain curves etc. The info isn't really going to be of interest to anyone other than myself, but as I said, it interests me, I like to know how things work. Eventually I want to transfer my skills into a career in motorsport from my current career in rotating machinery, I think of it as studying for a degree without going back to uni.

As my daily driver, I want something that will drive over the columbian goat tracks my local council tries to pass of as roads without rattling my teeth out. My current setup, despite the soft spring rates, fails miserably at this, it is far far worse than any other car I have been in, and when I get the car on an autox or circuit the whole thing becomes too soft and wallowy.

I know different people go for different approaches, and there are both fans and haters of setting up by natural frequency, but so far this is best way I have seen in which to guage the performance of a setup. The rates some people here run work out as 4hz which to me seems utterly ridiculous on anything that is driven on surfaces that are anything other than glass smooth. Can people even provide inputs at 4hz to require that kind of response?

Going on what I have read in various suspension papers and books, I am aiming for ~2.2F 2.5~ rear, seems to be a good reccomended ballpark for the kind of use I make of the car, although I am always willing to listen to different opinions. As I said, I do not have the budget to constantly test and change setups, so calculating things this way appears to be the best way to go at present.


I have heard this also, and by my reckoning, a damper that can handle 500lbs/in is going to be overkill on a 230/156 setup surely?



Yes, I would love one having borrowed one for a week last month, but fuel costs the equivalent of $7 gallon here so sub 15mpg mileage is a serious ballache.

I have checked out that thread breifly but will give it another read. Your reccomended settings on the dampers happen to be exactly what I run now after fiddling for the past 6 months.

beanbag

These two goals are incompatible

If you calculate what that spring rate comes out to, then
a) you need new front shocks
b) you are going to be in a world of hurt on the bumpy roads

PS: If you are in PA, then maybe you can pick up a bunch of used springs from the local circle track folk

Kozy.

Yes I agree, it would seem so, but surely by fitting springs better suited to the dampers I can have the suspension working the way it is supposed to, with the springs taking care of shock absorbtion and the the dampers controlling the oscillations.

A friend who previously owned an EK9 (250lb front and rear) said his ride was a serious amount better than mine, surely proving the point that you can improve the ride even with harder springs if the whole lot is working together?

If you are seriously telling me that the ride from these soft Tanabes cannot be improved on I will consider walking away from Hondas altogether, but I simply do not believe that is the case. As I said there I simply cannot see how a damper rated to 500lb is going to be good on 200lb springs. The whole system will be slow to respond as a result force from road bumps will be transfered to the chassis rather than being absorbed and dissipated.

Then again maybe I have indeed got the whole thing wrong and I do seriously need to go back to school and learn basic physics.

Kozy.

FWIW, (I don't know if I mentioned it before) I am currently looking at ~290F/190R. By my rough guesstimations, this should put the ideal damping force somewhere in the ballpark of that provided by the Konis, however having learned that I've calculated the MR wrong I am going to have to go back and re-do it, so this could change considerably.

It still doesn't answer my original question with relation to front/rear dyno plots...

beanbag

I think you are confused about something. The adjustment on Koni yellow's means that they can work for any spring from stock up to about 500 lbs. Again, you are not overdamped. You don't need to get different springs to somehow try to match the shocks.

PS: your ride quality might also suck because u have no suspension travel left and are riding on the bump stops.

spcrxracer

iTrader: (1)

Tell that to Claude Rouelle. I would love to see that conversation take place.