The Strut thread - Koni / Illumina / Tokico / Carrera / Bilstein / Ground Control

[johnc]

ITS A 2 INCH SHORT STROKE

 

Is that the total stroke of the shock?

 

And your shock graph shows a steep progessive curve which is different from the trend in the industry towards digressive shocks. In general, high shaft speeds require a much lower rate of increase in damping, with compression damping the main concern. Think of it this way:

 

Your wheel hits a sharp bump at speed. The shaft is accelerated to about .5mps. The shock can do one of two things 1) transfer most of the load through the shock shaft into the chassis (progressive damping) or 2) let the spring take the load and not upset the chassis (digressive damping).

 

Now let's say you're exiting the corner and applying throttle. Progressive rebound damping will tend to lift the inside rear wheel as weight transfers back to the out rear wheel. Digressive damping will let the inside wheel drop as the spring unloads and keep the inside tire on the ground helping accelerate the car.

 

Maybe the shock requirements for drifting are different then for grip, but the dyno graph above shows a 1980s technology shock.

[driftz240]

so how do they stack up against other off the shelf adjustables commonly used by the masses on the 240z....and what spring rates would be good on them in your opinion....you can read they have been around since the 80s,

i think the kyb agx would be an awesome choice also, not sure of a dyno graph but like to see your opinion

off the sheld out of the box how do you feel they compare

[driftz240]

those are all out drift shocks by the way the hts 102, so your correct road racing might be a different story but ive autoxed cars with them and cant complain...

[johnc]

so how do they stack up against other off the shelf adjustables commonly used by the masses on the 240z

 

Look on page 3 of this thread. I posted dyno graphs for the recently revalved Koni 8610s and 8611s. Look at the knee points and you'll see they digress.

 

and what spring rates would be good on them in your opinion....

 

Ideally you don't chose spring rates based on your shocks. Spring rate is chosen to establish a basic suspension "Platform" that achieves a neutral steady state cornering balance. To chose the ideal rate a lot of factors come into play:

 

Gross vehicle weight

Unsprung weight

Balance

Power to weight ratio

Tire width and diameter

Track characteristics

Aerodynamic downforce or lift

Driver preference

 

Carroll Smith has a rule of thumb that is a good, basic place to start:

 

My basic system is to run the softest rear springs that will keep the car off the track - and maintain some semblence of camber control - at the ride height I want to run. I then balance the understeer/oversteer with the front springs - and use equal rate front and rear anti-roll bars.

[driftz240]

what if i dont like neutral...lol

i know about corner balancing and yata yata, i mean do you feel they would explode under the higher rate springs that drifters seem to favor...

or as the paper states 4kgfmm "200" to 10kgfmm "550" and tune them into somthing that could make the car work for just about anyones taste..

everyone says the illuminas explode over 250lb spring rate...

i will agree you seem to know much more about the physics and workings of shocks than I. i never claimed to be an engineer, im just looking off the shelve alternatives to the illumina and koni and others people seem to use commonly, i infact am having somthing made up custom valved, but i do plan on using higher spring rates, makeing the car slide and do it smoothly requires a different approch than road racing... but bang for the buck i think the mr2 agx or the tokico hts would be a good alternative...not everyone revalves shocks in there basement or has axcess to shock dynos, not everyone owns scales, and if i set up a drift car using scales to determin my ideal spring rates it might not work like i expect it too...

autox or road race are quite different..

[katman]

Dude, you'll get more replies on this forum if you learn how to spell and use punctuation. Jeez.

[johnc]

I don't know enough about drifting to make a shock recommendation. Also, shocks don't explode, the shim stack usially fatigues and stops doing its job. Rebound damping goes away and the car just kind of wobbles down the track.

 

Also, what Keith said - one of the rules we have on this site is proper punctuation, capitalization, etc.

[driftz240]

Well indent your sentances then.

[74_5.0L_Z]

The comment about your grammar and spelling is not meant as a personal attack. You will be taken more seriously if you take the time to compose your thoughts. If you fill up the page with run-on sentences and misspelled words, then you come across as someone who doesn't think before he speaks. People like that tend to be ignored in life and on this site.

 

If you have an idea or an opinion, take the time to express it clearly. We will do our best to return the favor.

[driftz240]

thanks for the info

I do like in the forum rules how you say not to take things personally, sounds like you guys may have p-ed some folks off in the past..

id have to say this is the harshest website i have ever been on..

on the other hand back to the subject.

I did more testing and the 95 mr2 front kyb-agx fit in the front 240z struts, the cases would be cut 30.8mm, the dampeners are 4 way adjustable.the upper mounts would have to be drilled to a circle hole from the stock "D" shaped hole. the rears from the 95 mr2 will work in the 240z rear with a cut from 2 inches or space to what you choose, rears would be 8 way adjustable.

I am also looking into the trd race struts for the same 95 mr2 application, I wouldent know what I was looking at on a shock dyno graph,but im sure there out there if you planned on buying a set and wanted to see one.

The ae86 tokico hts "if your into drifting", would be a 2 inch cut in front "hts 102" and a 1.5 in the rear with hts112. Basicly anything you can find for the sw20 mr2 "carterage strut, there was a sealed strut on a few versions".

Another thing i wanted to look into was the rear control arm angle when you lower the car, since it has the spindle pin design how would you correct control arm geometry after the car is lowered, the front suspension can use bump steer spacers, the rear is a mystery to me...any ideas? i have yet to install my rear suspension on the car ,the struts have been cut 40mm, and i am estimating about a 1/2 inch more drop in the springs with weight on wheels..

 

Was my grammar and punctuation better on this one? im not an english major, but am a college grad, and can type somewhat when i slow down and use only 2 fingers...

[tube80z]

id have to say this is the harshest website i have ever been on..

 

If you think this is harsh you should see corner carvers

 

Another thing i wanted to look into was the rear control arm angle when you lower the car, since it has the spindle pin design how would you correct control arm geometry after the car is lowered, the front suspension can use bump steer spacers, the rear is a mystery to me...any ideas?

 

In the back nothing is usually done. You can only change the angle of the control arms by moving the inner pickup points or the outers. Both require a lot of fabrication that most aren't willing to do. That aside as long as you don't get them past flat you usually won't see any issues. You can adjust the front to make it work with the new rear.

 

Was my grammar and punctuation better on this one? im not an english major, but am a college grad, and can type somewhat when i slow down and use only 2 fingers...

 

It was a definite improvement.

 

As far as setup goes I don't think you'd have anything that different than an autox or track car. I think you really want something that is close to neutral and easy to drive and it will be adjustable anyway. Watching the D1 guys in Fontana a couple of years ago it seemed like they needed to be able to get under their competition and then control the angle as they were very close.

 

Steering may be the area where you'd diverge from the normal thinking. I'm thinking at high slip angles parallel steering would be better than any ackerman. I'm also wondering if fiddle brakes might be something worth looking at as those would likely have more control when you are really sideways.

 

Cary

[v8dream]

If you think this is harsh you should see corner carvers

Cary

 

No kidding. For some real entertainment (ours, not yours), go over to corner-carvers.com and tell them about your crazy good shocks. One of the moderators is currently building a car and would no doubt be glad to consider your insights. Just be sure to start your post out with "Hey, Lewis!".

 

But right before you do that, let us know, okay? I'll need time to make some popcorn.

[johnc]

From the CC Wiki:

 

Corner-Carvers Guide For Newbies

 

by Nick Mollison

 

The staff of CC.com has become aware that you, oh timid newbie, may be wary of posting your musings on our little corner of the Internet. You may fear having to wear the title “*** Clown “ like a scarlet letter for the duration of your stay, or facing one of our Parliament style shout downs. But, young fragile newbie, we want to make you feel welcome and answer your questions. To ease the process we suggest you heed the following advice:

 

First, research our topics to see if your question has already been answered. The site is equipped with a search function that allows you to browse past discussions. Not only might you find an answer to your question, you will also find a great archive of accumulated knowledge that you may wish to read at any time.

 

Be patient. The simplest questions are often answered last. Many people here have been on Internet discussion boards for quite some time and are reluctant to draft answers to questions that they may have posted several times before. We try to make sure all questions receive at least some sort of response at the end of each day.

 

Most importantly, be clear and objective. State the specifics of your situation, as each situation demands a different answer. List your modifications, your intended purpose for the car, and specifically what characteristics you would like to change. The more information you can give us, the better answer you will receive.

 

If you have a question, make sure it’s a question. Most victims of our JackAssery! post answers in the forms of questions. They have their mind made up, they are not impartial, and all too often they have not done their own research.

 

Discussions are sometimes better than answers. If you don’t feel as though you are 100% sure of your answer, let your uncertainty be known or don’t answer at all. You will not be flamed for posting your thoughts, theories, opinions, or even wild guesses as long as you don’t represent them as fact. You’ll have done no wrong by making an incorrect assumption as long as you remain open to its discussion and dissection. Keep in mind there is probably someone else out there that can provide a 100% answer.

 

You will notice the absence of a "Kill Stories" section. Please refrain from posting your illegal or poorly rationalized exploits unless it is intended to teach a lesson. If you do, we will quickly make you an example of what not to do. We do not condone any behavior that places yourself, or others at risk. We encourage everyone to keep their racing at an appropriate and safe venue.

 

Try not to piss off the big meany-head administrators.

 

The best way to draw attacks and flames for being a newbie is to begin a post with "Hi, I'm a newbie, so please don't flame me". Once the smell of fresh blood is in the water a feeding frenzy will almost always ensue. Thrashing around will only make it worse.

 

Vendors: We will allow you to break the laws of physics and the second law of thermodynamics so long as you provide us with a working model.

 

Enjoy yourself

[driftz240]

ahhh i have found enuff a-holes on the internet lately...thanks lol

anyone have an illumina dyno graph john could traslate? i just want to see what would be better the illuminas commonly used or tokico hts, whats so bad about the crazy good struts comment, i feel they are good, and on other cars i have used them on i have gotten excellent results..but driver preference goes along way.

[johnc]

I printed out the HTS and the Koni 8611 dyno graphs and had to do a bunch of coversions from Newtons to Pounds (I'm assuming the HTS dyno graph vertical axis is Pounds). Ignoring anthying beyond .3mps, which is a meaningless velocity (unless you're off road and just hit a 3' berm), I think the Tokico HTS compares very well with the Koni 8611 1259RACE. The scale on the Tokico dyno graph threw me because its so steep and logarithmic.

 

The range of adjustment is greater on the Koni so its can be used on more applications but the HTS should work fine on a 240Z. I think the spring rates should be in the 250 to 400 lb. in. range.

 

Now, back to previous concern, what is the total stroke length of the Tokico HTS? It can't be 2" as posted above.

 

EDIT: Oh crap, I missed that the HTS is a single adjustable shock. I don't like it as much because the compressing damping gets too high for a light car like the 240Z when the rebound is getting good. Its the same problem with the Tokico Illumina. What's nice about the Koni 8610-1437RACE is that the compression damping stays the same while rebound is adjustable. With the 8611-1259RACE you can idependently adjust compresion and rebound.

[katman]

..but driver preference goes along way.

 

I have worked with some top notch 240Z pilots and frankly all of them thought the shocks they had were great. Most of them could do a lap with crap shocks as fast as they could with the double adjustables properly designed and damped for the app. One lap out of 20. The difference is on the stopwatch after 20 laps, and in the tire temps and tire wear. JohnC raises an interesting point that I too have noticed. For some reason shock manufacturers that come from the street end of things seem to think performance comes with raising bump and rebound in proportion to go from "street to track". It's like they're afraid of "jacking down" the shock. I prefer much more rebound than bump in my race shocks than whats usually available in a single adjustable.

[driftz240]

the hts is 2 inches shorter in the main body, and 2 inches shorter in the rod length. im not exactly sure how to determin internal travel, how do i mesure that, im guessing bottom the strut out and mesure how much is sticking out the top, is that correct? is that what you are looking for?

[johnc]

how do i mesure that, im guessing bottom the strut out and mesure how much is sticking out the top, is that correct? is that what you are looking for?

 

That's one way or check with Tokico and see what they say. 6" of shock travel is good for a 240Z.

 

One lap out of 20. The difference is on the stopwatch after 20 laps, and in the tire temps and tire wear.

 

Exactly! A well setup racecar is easier to drive at 10/10ths lap after lap. A poorly setup racecar in the hands of a great driver may be able to lay down a lap or two equal to the well setup racecar (I've seen some amazing qualifying runs in what I thought was complete junk) but over the duration of a race the poorly setup racecar will lose time and positions.

[tube80z]

One lap out of 20. The difference is on the stopwatch after 20 laps, and in the tire temps and tire wear.

 

Keith, when you are developing shocks how are you doing it? Do you use linear pots and damper velocity histograms or some other method.

 

Cary

[katman]

Keith' date=' when you are developing shocks how are you doing it? Do you use linear pots and damper velocity histograms or some other method.

 

Cary[/quote']

 

That would be one way. On the Atlantic team and the Formula Mazda team I did a wee bit of consulting on we had the pots and capability of plotting the velocity histograms, but frankly I can look at the raw data (pot displacement versus time) and tell if we're close to critically damped and if we're jacking down with too much rebound (which in a winged car you want to do sometimes). For the ITS 240Z I hadn't been through Claude Rouelle's course yet (we had data acquisition but no shock pots), so I developed the ShockTek the old fashioned way- I paid a Phd in Vibrations with a ton of shock experience to get me close. Then it was a lot of testing and long term trend analysis (tire wear, for instance is a long term trend). The ITS E36 Bimmers I did most recently were the same way. Team didn't have the funds nor the data acquisition expertise anymore (it moved to Formula Atlantic and Mazda), and my favorite Phd was incognito. So I called somebody smarter than me- Bilstein. They knew a little about racing BMW's. The BMW story is interesting (well, in that anal retentitive engineering way). Everybody in the class is running the Ground Control setup. I knew from using their AD shocks on the Z after SCCA banned the ShockTek's that they didn't have enough adjustment or fluid volume on the rebound side. Both of the Sunbelt BMW's were originally built with the GC package and neither car had any feel whatsoever. They were winning, but the driver's said they knew it was understeering when they ran out of steering lock, and knew it was oversteer when they were looking out the side window. Otherwise, they had no idea how close to the traction circle they were. I did and off the shelf adjustable Bilstein package on the first car and totally transformed it, but it was single adjustable and isn't quite where I think it needs to be. Regardless, the driver loves it and won't let me change it. The second car was a totally different spring and bar setup using revalved non adjustable Bilsteins. I don't want to say where they came from, but it involved another person smarter than me. It too has great feel but is a little harder to drive as it is about twice+ the spring rate, but should ultimately be faster than car 1. That car ran one race since the conversion and lapped the field in the rain and hasn't raced since. I'd like one more iteration on springs and one more revalve with Bilstein but alas, the team has the cars up for sale to move on.

 

So, long winded way of saying I develop shocks by using other peoples money (OPM), try to find the experts for the application, and then do my own testing.