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Discussion Starter #1
In order to maintain consistent ride and handling characteristics under maximum and minimum passenger fuel and luggage loads; to provide a soft ride over minor road irregularities and firm control over major ones, or to achieve a soft ride in straight – line driving without sacrificing roll stiffness in cornering RISING RATE suspension systems are common engineering practise.

Such suspension systems by choice of appropriate geometry and progressive –rate springs ( for the first 100lbs compress the spring one inch but for compressing it 2 inches additional 150 lbs are needed ) become more resistant the more the wheels move farther into jounce.

The suspension system of the Elise has spring- damper- units consisting of a constant rate coil spring surrounding a non adjustable damper = shock absorber made by Koni and nowadays by Bilstein.

But in the aftermarket you can get many other units which are claimed to improve ride and handling enormously and many Elise owners believe that the most expensive most probably will also be the best for their requirements. This units are adjustable in length and damping factor (jounce and also rebound )and they have harder or softer linear and even progressive springs.

Here in Germany you actually can get the cheapest aftermarket unit for ca. 1000 Euro and the most expensive for more than 4000 Euro. and certainly in the US the Tuners will start very soon to offer additional opportunities and also find some enthusiastic customers posting in this forum here that the unit they just bought really is the non plus ultra development in this technology.

Therefore please start discussing this subject before spending lots of money without much value for it.

Perhaps some of the prospective Elise owners in this forum are able to give some criteria for selecting the appropriate damper- spring unit for your rather heavy US-Elise .

Have fun.
 

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Well for one they have to be able to be mounted 'upside down' (damper body at top, piston rod at bottom) to minimize unsprung weight just like the original Bilsteins.

This pretty much means only monotube damper designs to start with as dual tubes don't lie to be run inverted unless specifically designed for this.

Bye, Arno.
 

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Discussion Starter #3
Arno

Saving unsprung weight at the wheels ( rotating mass ) pays nearly 4 times as much as saving some grams at the spring damper units which you cannot add with their complete weight to unsprung mass .

But the question you possibly could help to answer is:

Do you know why your Bilsteins are said to be so much better than the original Konis at the the classic Elise that some S 1 owners exchanged Konis against Bilsteins ? (Brackets have to be adapted for doing so )

Is it because the springs are harder ?( S2 being slightly heavier than the S1 )

Or
The geometry of the S2 is slightly different ? ( If not no other brackets would be needed for the S 1)

Or is it something within the hydraulic dampers that black boxes converting mechanical energy into heat and which only few of us know in detail? ( Mono- or double- tube type ? )

Perhaps you- living in NL- can help to find a drawing showing a cut through a Koni damper as selected by Lotus for the S1,.though the dimensions of the throttling valving and gaps responsible for the damping characteristics certainly will not be given in such drawings.

I only know that the Koni dampers for sport cars normally are double tube whereas Bilsteins are known for their mono tube design but what do we get from Lotus ?-- The cheaper or the better one? --- :D

Somebody more experienced with hydraulic damper technology knows if there are special diagrams figures or other terms expressing damping capacity power or speed of an individual type of damper for comparison?

For checking if a damper installed is still ok. there are special testing devices which produce diagrams.
Can such diagrams also show whether an aftermarket damper was good value for money ? (Similar like a torque curve shows for engine tuning ? )
 

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Ruediger said:
For checking if a damper installed is still ok. there are special testing devices which produce diagrams.
Can such diagrams also show whether an aftermarket damper was good value for money ? (Similar like a torque curve shows for engine tuning ? )
Yes.

One major thing this will tell you how consistent the damping charactierisic is between all 4 (or more) dampers.

Cheap dampers often show that there are big differences between 2 sets and this can give some very strange handling when driving the car.

Also if you use a tester and let it run for longer (so the oil heats up) you can see how the damping is influenced and if the dampers overheat or not (this is the biggest issue with dual tubes.. simply a design issue..).

Longer term testing is different though. There are some very good dampers out there, but these are often race units which do not have good seals and materials to survive for thousands of km's, so are useless for road use.

It would be nice if an independent tester could put a lot of different dampers on such testing machines and draw some conclusions.

Until that time we have to rely on experiences with the same type/manufacturer of dampers on other cars and hope it's the same on the Elise.

Bye, Arno.
 

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Gavin Kershaw cites two reasons: the Bilsteins allowed an increase in medium speed bump valving while largely retaining low speed bump characteristics. The Konis sacrificed low speed bump, negatively impacting ride quality. The other reason was rattling issues with the Konis.

Damper tuning is a core competence of Lotus. I'm not about to mess with the LSS suspension anytime soon, as it is pretty hard to out-tune a well done factory setup designed for a specific tire combination. Once migrating to a different tire (e.g., a Hoosier), all bets are off though. . .
 

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I've heard so many rave reviews about the Elise's handling, that I'm not going to mess with the suspension one bit. I don't have the education and testing time that Lotus did when spec'ing the original components; I doubt I could approve upon the near-perfection that the Elise offers.
 

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frayed said:
Gavin Kershaw cites two reasons: the Bilsteins allowed an increase in medium speed bump valving while largely retaining low speed bump characteristics. The Konis sacrificed low speed bump, negatively impacting ride quality. The other reason was rattling issues with the Konis.

Damper tuning is a core competence of Lotus. I'm not about to mess with the LSS suspension anytime soon, as it is pretty hard to out-tune a well done factory setup designed for a specific tire combination. Once migrating to a different tire (e.g., a Hoosier), all bets are off though. . .


Low speed bump valving affects transitional handling while high speed affects how the car handles road irregularities. Therefore, ride quality is most affected by high speed bump (and rebound) valving.

I have found the high end shocks to have a much broader range of adjustment than less expensive shocks, although a not-so-expensive shock that is valved correctly for a car/spring/bar/tire/driver package can be just as fast around a track. What you get with the expensive shocks is the ability to run different spring rates without revalving, and the comfort of softer damper settings on the street. It often takes a novice quite a while to dial in ideal damper settings on a shock that has alot of adjustment.

Jeff
 

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Tripledigits said:
Low speed bump valving affects transitional handling while high speed affects how the car handles road irregularities. Therefore, ride quality is most affected by high speed bump (and rebound) valving.
From ELISE Rebirth of the True Lotus:

Bilsteins. . . clever one-way valve design with different gate technology to separate compression and rebound low speed damping forces. The damper could be tuned much more accurately with hundreds of miles of testing to give the ideal combination of ride quality and body control. 'You typically run about three times more rebound force than compression,' explained Becker, 'because rebound is trying to contain the spring. With the Koni you were stuck with the same amount of compression and rebound so if you wanted to give the car more body control it would affect the low speed damping and it would give you a very hard ride. That's one of the keys to the way the car feels now, it's got a nice ride because we can increase the rebound to give the body control and keep the compression down to keep the ride comfort as well. It's a unique damper, I don't think anybody else makes a monotube damper that allows you to change compression and rebound separately."

----------------

There are additional comment from Kershaw on the Best of British DVD. When get a chance I'll post them.

edited for spelling
 

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I don't know exactly which "low speed" he's talking about (car or shock piston velocity), but when shock manufacturers refer to low speed compression damping, they're referring to piston speed. Road bumps are high piston velocity events, whereas a car's transitional handling is a low piston velocity event. Any race oriented shock will have separate rebound and bump adjustments. Triple and even quadruple adjustable shocks are readily available as well. Triples allow a separate adjustment for low and high (or medium) speed bump, as well as rebound. You can make a street ride pretty unbearable with just alot of rebound damping, but perhaps it's above the damping range the book is referring to.

Jeff
 

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I run Koni double adjustable c/o's on my M3 (separate bump and jounce). I found that cranking up bump improves transition reflexes and kills ride quality. Markedly so. Perhaps my Koni DA's affect both low and high speed bump. . .much like the Konis referenced by Becker above.
 

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frayed said:
I run Koni double adjustable c/o's on my M3 (separate bump and jounce). I found that cranking up bump improves transition reflexes and kills ride quality. Markedly so. Perhaps my Koni DA's affect both low and high speed bump. . .much like the Konis referenced by Becker above.
Jeff

The DAs compression adjustment would certainly affect both high and low speed, unless they've come up with something new recently. It'd be less useful to have a single adjustment not control a broad range of piston velocities. A single adjustable compression will affect ride quality, just as you have experienced. I run a Moton triple and the high versus medium speed compression adjustments are noticeably different.

Jeff
 

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Jeff and Matt you two have great common sense! Very few people on this forum will be able to do the testing or even understand things enough to improve things. I look at all of the ill handling cars at autocrosses and track days and know that getting into bump and rebound on shocks is a very complex and difficult equation and takes a lot of back to back testing to sort out.
 

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James A said:
Jeff and Matt you two have great common sense! Very few people on this forum will be able to do the testing or even understand things enough to improve things. I look at all of the ill handling cars at autocrosses and track days and know that getting into bump and rebound on shocks is a very complex and difficult equation and takes a lot of back to back testing to sort out.
I'd like to say 'common sense' but it's not. More like, I've dived deep into aftermarket suspension, only to be rewarded with endless tweakign resulting in handling traits from reasonably good to evil. However, no matter what I do, there's a certain feel that the car lost from its stock setup.

It may be faster with Rcomps on the track at 9/10's, but on the street, under less demanding conditions with street rubber, it has lost some feel.

IMHO, aftermarket suspension focuses on the last 2/10's, sacrificing some of the fun at saner speeds on the road.

What folks tend to overlook, is that the LSS Elise comes tuned from the factory with Rcomps already mounted. This is huge, and should not be taken lightly. I do not have the patience or experience to out-tune the factory, so unless there is developed a proven better setup, tuned out of the box, my plan is to hang loose with the LSS setup.

Just my rambling. . .
 

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Jeff, that's some very strange commentary from Lotus. I wonder if it was paraphrased or somehow miscommunicated. First of all, Konis in general do not have the same compression and rebound rates. That may have been true at some point in the past. Modern Konis (the cheapest ones) have a fixed compression rate, and allow independent adjustment of the rebound rate.

Low-speed damping controls body motion, while high-speed damping affects the ride and tracking over bumps. It's preferable to adjust each separately, of course. And Bilstein has a reputation of using very high compression damping rates, so I just don't understand where all of that is coming from. Many years in the past, perhaps?

To answer the original question, the most important objective measure of a shock absorber is the suitability of the selected damping rates to the task. Many shock manufacturers today have the technology to match a desired damping curve using a variety of piston and valve configurations, so you could obtain a proper valving from almost any of them. The real trick is to discover the proper valving, which requires some testing, not just suspension specs.

More money in general buys you higher quality and more consistent components, and more complexity in the valving arrangements. Bilstein has a reputation for using high quality components and materials even on their basic non-adjutable shocks, and I've been told that many people have built shocks for racing based on Bilstein components. In terms of complexity, the simplest adjustable shocks adjust rebound and compression with the same knob, and the adjustment may not be linear. Then you move on to rebound-only adjustment, separate rebound and compression, then separation of high- and low-speed rebound and compression. Unless you know what you're doing or have a guru who can help you with the settings, it's all basically just more rope with which to hang yourself.
 

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frayed said:
What folks tend to overlook, is that the LSS Elise comes tuned from the factory with Rcomps already mounted.
Yes, but tuned for what?

[*]track
[*]autocross
[*]crisp feel in city driving
[*]smooth ride
[*]some compromise of the above

These are all different tunings, just like you can tune your radio to several different stations and get strong signals at each.

While I agree that it's a mistake for the uninitiated to get into upgrading their suspension, especially one that's as well designed as we all expect the LSS to be, I think that "Lotus tuned the suspension" as a blanket statement is equally wrong or even meaningless.
 

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John Stimson said:
Yes, but tuned for what?

[*]track
[*]autocross
[*]crisp feel in city driving
[*]smooth ride
[*]some compromise of the above

These are all different tunings, just like you can tune your radio to several different stations and get strong signals at each.

While I agree that it's a mistake for the uninitiated to get into upgrading their suspension, especially one that's as well designed as we all expect the LSS to be, I think that "Lotus tuned the suspension" as a blanket statement is equally wrong or even meaningless.
Well put, John

I would guess that the Lotus LSS setup is a good all around starting point for a street/track compromise. The fact that it's non-adjustable leads me to believe it's not a track optimized setup. All the pictures I've seen of the Elise on the track shows there is too little camber, especially in front. Obviously, there are compromises involved. Pictures don't lie - if the wheel is not square to the ground in the corner, or very close to it, things can be made better. How many people out there running stock cars in Solo2 can say they don't wear out the outside of their front tires? How many people running prepared cars on the street can say they don't wear out the inside of their front tires?

Jeff
 

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Discussion Starter #18
IMHO it `s only a question of time that you will get adjustable aftermarket shocks also from

Billstein who make them for many sports cars already.
See.
http://www.bilstein.com/html/applications/pss9

and also :
http://www.bilstein.de/de

That one is in German Together with your posts it helped me to understand much better the basics of damping technology. Thank you all.


PS
Somebody can read French? Also this helped me to understand better.

http://www.motorlegend.com/new/technique/amortisseur/index2.htm
 

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Well, camber is just camber. Of course it plays into suspension setup, but few, if any, cars come from the factory with optimal camber for track use.

The brits on SELOC all preach adjusting alignment or 'geo' for track use. Adding 3 degrees of camber up front (or whatever people migrate to) sacrifices tire wear and straight line braking. . . not compromises that you'd expect a factory to make even in a car like the Elise.

In any event, I'd agree. From what I read, development of the car focused on track prowess and spirited street driving, including a focus on predictable dry and wet weather handling. It was also developed on less than Hoosier-sticky Yok A048s.

I haven't proclaimed that the setup cannot be improved upon for narrow, specialized uses like autox. Rather, let's take what we do know:

Lotus is known for its chassis tuning and has been engaged by several car companies for chassis development. The consulting side of the company engaging in this activity has helped keep them alive in rather lean times.

Lotus is widely known for a particular core competence, damper tuning.

The LSS comes from the factory with R comps.

Name another car that is available in the US that comes from the factory with tires as sticky as the A048s, not to mention with a team of engineers and skilled chassis development guys behind the car's tuning around those tires. Can't?

The LSS suspension setup *appears* to be similar, if not functionally the same as the setup on the Exige. We all know how the S2 Exige has been received by the press and what it can do on the track.

I remain reasonably optimistic that I won't have to change anything for my intended uses: weekend track driving and fair weather road use.
 

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Just to add to the geo comment, the factory is allowed only 30 mins per car for geo. It took 3 hours to get my geo exactly right. When the car finally arrives from the factory/dealer, the geo on the car is NOTHING like what it says it should be in the manual. A few hours on a hunter machine and it drives like a different car.
 
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