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Clives Suspension/Handling Thread

67K views 301 replies 79 participants last post by  4g638 
#1 · (Edited)
Ok, I'll start with the basics.

You've probably heard of 1way, 2way, 3 way suspension.

This denotes the amount of external adjustments that the user can change, each with so many 'clicks'

1 way means the shock absorber has one external adjustment which changes the damping rate internally. Depending on the manufacturer and design, this can alter the bump (compression) and rebound together with a preset ratio, or with some, rebound only, with preset bump valving.

Ok, this is a good time to explain what what bump/compression and rebound is.

Bump or Compression is when the shock absorber compresses ie the strut moves down into the body of the suspension unit. This happens when hitting bumps or rising undulations on the road, or when entering a corner and the weight of the car causes roll which again compresses the outboard shock absorbers. It also happens when braking and accelerating when inertia forces of the car cause the suspension to compress.

Rebound is when the shock absorber extends, ie the strut moves out of the body of the suspension unit, and happens on the downward slope of an undulation (normally after a compression has happened) Again this also happens under cornering and braking/accelerating.

The cars stationary weight is always trying to compress the suspension and the suspension springs are always trying to extent (rebound) the suspension.

Back to the number of adjustments.

2 way means the shock absorber has two external adjustments, one for compression and one for rebound, which can be adjusted completely separately from each other. (in theory, I'll explain later!)

Next is 3 way.

These have separate external bump and rebound adjustments and an added adjustment which is high speed bump (compression)

Normal bump adjustment is 'slow' speed bump. This affects the damping rate, or in simple terms the restriction to movement of the strut, when it is moving slowly, up to a predetermined/preset speed/force. When hitting normal small bumps or undulations, or when turning into a corner and the car slowly rolls until supported by the springs and anti-roll bars, normal 'low speed' bump damping is controlling things.

High speed bump starts controlling things when hitting big bumps or undulations (such as big kerbs on track) which try to move the strut at a faster rate (a bigger force over a shorter time)

Think of it as a sort of pressure relief valve which opens when pressure inside the shock exceeds a certain amount, but still with controlled damping, which can be adjusted with this third external setting.

There are 4,5 and 6 way suspensions, but let's not over complicate things at this stage.
 
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#2 · (Edited)
Ok, next up Springs.

Very simple really, sprung steel wire, wound into a coil!
There are two main types, progressive and linear. (also helper springs which are flat wire)
Each spring is rated in a unit which is force over distance such as lbs/in, N/mm, KG/mm.
Take the imperial rating, lbs/in. If the spring has a rating of say 500lbs/in, it would take a force of 500 pounds to compress the spring 1 inch.
With a linear spring, this rating is linear, so using the 500lb/in spring, if you add a force of 1000 pounds to the spring it will compress 2 inches, and so on.
Kg/mm is how many kilograms per millimetre and N/mm is how many Newtons per millimetre of compression.

A progressive spring (such as the aftermarket Eibachs for the standard shocks) has a progressive rating, which means as the spring compresses, the force required progressively increases.
The Eibach aftermarket rear springs for example, require 143 pounds of force to compress them 1 inch, when they are fully extended, to 312 pounds of force when they are fully compressed.

Progressive springs allow a better initial ride quality, and as they compress they get firmer, so when cornering, they in effect act like a stiffer spring. Most original equipment springs are progressive for this reason.
The downside is the damping of the shock absorber is only optimised at one point of the springs compression.

A parallel linear springs rating is defined by the thickness of the sprung wire used for the spring. The thicker the wire, the higher the rating. (if the material spec is the same)
This also means there is less available travel before the spring is fully compressed as a springs rating increases.
Due to this, higher spec race springs are available which use a higher tensile steel to allow a thinner wire for the same rating spring, which allows more travel before they're fully compressed.

Aftermarket springs for coilovers suspension units are also graded in length and diameter, metric in millimeters, imperial in inches.

Most coilovers have linear springs, but not all.

The springs basically support the car, allowing compression of the suspension when cornering or hitting a bump, and a force to extend it again. (in very simple terms)

They give resistance to roll when cornering, and resistance to pitching when accelerating and braking.

Springs of a certain rating are chosen for the front and rear suspension depending on vehicle weight and distribution, vehicle usage, tyre choice, anti-roll bar diameters, suspension design and geometry. On non adjustable shock absorbers, the spring rates are also finely tuned to match the internal valving and damping characteristics.

The spring rates can be changed/selected to help 'tune' the suspension to obtain certain handling characteristics and balance of the vehicle to suit the drivers preference.

To take the Evo 6 as an example, the standard spring rates are 5kg/mm front and 5.5kg/mm rear. There are a couple of reasons why the rears are harder. Firstly the position of the shock absorber to the lower suspension arm means in effect, the spring has a lower effective rating due to the larger mechanical advantage of the wheel/knuckle assy on it.

This means a rear 5.5kg spring would only act like a 4.5kg spring in reality.

The second reason for the higher rear spring rate is the fact the Evo is a 5 seater car with a big boot and as such can have a fair amount of weight in the rear of the car.

Most after market suspension kits come with a lower rear spring rate such as 9kg front, 7kg rear. With the rear suspension designed how it is, this is more like 9kg/5kg effective.

The standard weight distribution is 60/40% so even taking this into account, most kits still have a soft rear spring.

This is because most kits are set-up to give an understeer balance to the car. The majority of people can cope with understeer on the limit, as it's not going to throw you off the road in a big tank slapper!

The reason soft rear spring rates encourage understeer is because they gives more grip in relation to the front stiffer spring rates.

So, one way to adjust the balance of the car, ie which end of the car starts to slide first, or both ends together, when at the edge of available grip, is to change the rate of the springs, front or rear.

The higher the rear spring rate, the more the balance will move towards oversteer at the edge of grip. The lower the rear spring rate, the more the balance will move towards understeer. The opposite is true for the front springs.

Again, this is simplified, and many other things also adjust balance such as anti-roll bars, geometry, differentials. Etc.
 
#3 · (Edited)
A bit more info in laymans terms about set-up;

Suspension set-ups are a bit like wine, individuals have their preference on what they like!

What I will say is, depending on tyres used and roads driven, adjust the compression setting to obtain the preferred compliance, if too soft the car may hit the bumpstops too often or feel too vague in turn-in and left/right/left transitions (anti-roll bars also affect these last two points) If too hard, the car will feel too bumpy for you and hitting bumps will push the car upwards and tend to loose grip/thow off line in a corner.

Spring rates used also have a big effect on roll/dive/squat, but hopefully these will be in the ball park for the type of usage of the kit/car.

With rebound adjustments, you want to adjust to the soft side and feel how it makes the car feel. Too soft and it will feel floaty and have and unstable feel at higher speeds, due to the car rising (rebounding) too quickly after a compression. Keep hardening the rebound by one click at a time L/R, but one end of the car at a time. As the rebound becomes too hard, the car will again start to loose grip/traction and feel harsh.

You can also adjust balance a small amount, the end that is too hard, loosing grip first.

Try and imagine in your head what the suspension is doing, in basic terms the springs are supporting the car, the compression damping in controlling how quickly the suspension will compress when hitting a bump, and the rebound how quickly the shock extends, against spring pressure. If set right, when a bump is hit, the wheel/tyre should follow the up-ramp of the bump (compression) and the down-ramp of the bump (rebound) with the car/chassis staying in the same plane, ie, not moving up or down.

If the compression is too hard, the up-ramp of the bump will try to 'launch' the car upwards, and at the peak of the bump the wheel may leave the ground (exaggerated!) and if the rebound is too hard, the wheel will take off at the peak as it cannot extend quick enough and follow the down-ramp of the bump. This looses grip and feeling harsh when the wheel lands!

Also try to 'feel' and seperate what the front and rear of the car is doing, to help you understand what is happening.
 
#5 ·
Absolutely spot on, Corky :smthumbup

That's what I'm trying to get across, you're better off with standard suspension than budget coilovers.

People keep mentioning budget, but why spend £650 when it's a backward step?

Three things that will allow you to go faster everywhere, quality tyres, brakes and suspension.

And those that don't see the point in buying 'expensive' suspension I gauarentee have spent more money on tuning the engine to higher power or bought a higher power edition car.

:crackup:

It makes me laugh.

Look at the results from Teesside, and see how many cars were behind my lardy 10 that has standard shocks with lowering springs and standard brakes with XP8 pads.

At our level of motorsport, I just don't think it is worth doing unless you are extremely experienced in car setup or you have a company that is at the events fine tuning it all for you.

£3k race spec suspension and £2k brakes are awesome, but is it worth £5k for a fraction of a second at a club sprint? Yes if you can afford it. Cheap imitations aren't worth it IMO.

Anyway, sorry for the off topic Chaz.

Best of luck with 2012 and enjoy your testing.

I did the same for AVO and I liked them if I'm honest. (but I didn'y have anything to compare to :crackup:)
 
#6 ·
And why do you prefer harder suspension?

And when you say harder, do mean in compression, rebound or high speed damping?

And if the rebound is too hard, how will you know?

Ok, onto spring rates, what balance do you prefer, and how would you achieve this balance by changing the spring rates?

Will you adjust geometry to suit the differences in the different suspensions, camber changes for differing roll resistance/low speed bump, and what tyre temp differences inner to outer will you be aiming for?

we have a few spring rates and will have a play around. Thing is, your driving style obviously suits softer suspension whereas mine may suit harder. We'll play about to see what works and what i find most comfortable with :) Trial and error as they say which is why im looking to offer a bit of feedback on my findings with the 2 different brands :)
 
#7 ·
Clive, if the cheaper suspension is pointless, why you still here?! In answer to your question above, I will run the car, offer some feedback and let the lads make the relevant adjustments :) The quote you raised was a hypothetical one. I was trying to make the point that what works for one, may not work for another :)

Never seen you get so bitchy before, somethings got your goat obviously....You seem to be a professional on suspension so how about I forward them to you so you can try them and make an unbiased opinion...?!
Firstly, I'm still here because I actually want people to realise that spending £650 on suspension is a waste of money. Even if one person sees the light, I'll be happy.

Secondly, bitchy?, You haven't been around this forum long enough to have any clue to what my posts are like concerning these matters.

My questions to you are to prove a point.

If you have no idea of the answers to the basics of suspension set-up, then how on earth can you assess how a suspension unit is performing. You have to know his to enable adjustments to be made, to 1. See if they improve the set-up 2. Relay this info to the guys making the adjustments.

And what about the non adjustable high speed bump setting, which is preset? The only person who can assess this, is the driver. If you don't know what it is, or how it affects the car, the whole thing is pointless.

There are traders on this forum (who see the MLR as a club, not just a sales outlet) who sell high quality suspension at a great price, they are also not just interested in profit at the expense of the buyer, but want to sell the right product to the buyer with decent support.

You are a pawn Chaz, and obviously don't know it.
 
#8 ·
those making the negative comments wont be the ones interested in purchasing a set anyway so not sure how their thoughts are important
Are you serious, so unless I'm interested in, or buying a product, I can have no views or 'thoughts' on it, even though I can give factual info and ask relevant questions regarding 'the test/review'

Perhaps I'm doing it on behalf of others, to help fellow members, to give a balanced discussion?
 
#10 ·
Do you consider bc coilovers flagship suspension the er 2 way coilovers a waste if money also?
Not being bitchy just interested
The rm suspension is priced at £650 ish while the er is £1200-1300
I'm sure there is some sort of improvement, but more likely a higher profit margin.

If spending that sort of money I would buy a European made product that conforms to European standards such as TUV/UKAS meaning it's had to pass certain tests/certification and is a guaranteed standard.
 
#11 ·
Mat all chav is trying to do is help a few people out.
And how exactly is he going to help people?

It,s a tinpot set of coilovers for a armature sprint series anyone would think it;s F1.
So you're happy to fit 'tin pot' components to your £30k car?
With that logic, why did you buy an Evo, and pay extra for a higher spec?
Why did you buy an Evo at all, unless you want to drive faster, and you obviously do, otherwise you wouldn't have bought the higher power model, unless it's just for bragging rights in your case?

And if you genuinely want to drive faster and were willing to pay thousands more for higher power, then why fit budget suspension that will slow you down?

Baffle them with bull**** then sell them the product less suited for the average bloke, that's all i see in this thread.
Oh, how ironic!

I'm not selling anything, just trying stop people wasting their hard earned by buying rubbish that will slow them down, give an awful harsh ride and need replacing in a couple of years.

You say it's for sprinting, so these cars aren't going to be used predominantly on the road?

If not, you can afford a custom sprint car, for the sole reason of going fast on track, but want to buy the cheapest suspension going?

Hilarious.
 
#12 ·
Seems like you have a complex none of that was aimed at you directly.
My money i spend it were and when i like
The funny thing is i read a lot of your posts and appreciate your a very knowledgeable bloke.
I take part in the sprints knowing i'm not going to win but enjoy myself anyway.
Like i said it seems if your not throwing a 100k at a car on here your opinion ain't worth Jack****.
And yes i would be happy to fit budget coilovers to my car, as high spec ones wouldn't really benefit me as i seem not to have the talent to go much faster anyway.
Keep up your hard work to benefit others you seem to do a good job, I'll just spend my money in other areas of my life. Yes unlike many on here i don't live for a piece of Japanese tin.
Have a nice day.
If you actually read and understand what I write and take the blinkers off, you may 'get' where I'm coming from, but I doubt that will happen.

I've driven cars with budget and midrange £1k-£2k coilovers, on road and track. We're not talking about £4k suspension.

If you haven't tried decent stuff, how on earth can you say they won't benefit you? Quite simply you can't.

You don't need 'talent' to appreciate a set of suspension that won't try to bounce you into a field when pushing on down a bumpy country lane, or cause the car to skip across the road when cornering and hitting multiple ripples mid bend.

And then after a year or two you need to replace it again because it's worn out, or has had knocking problems which requires it to be removed again at your expense.

You then end up spending more than a good set of quality mid price stuff, with all the extra hassle that goes with it.

It's got nothing to do with massive budgets, it's simple common sense financing, buy once buy right, or end up paying more down the line, lowering the ability of your road car and causing yourself hassle.

And if a thread is ruined by facts (that some don't like) and pertinent questions, so be it.
 
#13 ·
Better handling car i have driven was a spec c with kw variant 3's
Fantastic ride and handling
They just don't seem to be the thing on evo's
I might give these a try next yr , was very impressed with them
I have the bc on ,,Only got them because the stock shockers were knackered
Exactly Northy, someone who understands from his own experience! :smthumbup

KW V3 and similar won't break the bank either.

Spend a little bit more but gain a lot more in quality and performance of the suspension.
 
#14 ·
North top mounts are an option on all dampers from kw.
Yeah, and the KW top mounts are quite expensive.

This is where you can save some money as you can use the standard top mounts as the camber is adjusted at the knuckle.

Or buy some decent spherical top mounts for less money, such as Cusco or HKS.

Or make your own ;)

 
#15 ·
Clive could you do a thread when you have some time explaining bump rebound etc... Works, And how the settings actually effect the cars handling as I for 1 would like to understand it better as I'm sure other would :smthumbup

Like if you have understeer what adjustments to make to fail it out.

Cheers
Ok Peeler, good idea, I'll write a technical thread in laymans terms on the basics of suspension set up and adjustment. :)
 
#21 ·
Lee, it's all to do with balance, the standard evo is set up to have an inherent understeer balance, which is much safer for joe blogs on the road.

Saying that, the standard spring rates are actually stiffer on the back compared to the front.

The reason for this, is to do with the geometry of the rear suspension mechanism. The shock absorber mounts to the lower camber arm around 3" inboard of the knuckle attachment.

This means the knuckle/hub/wheel assy has a high mechanical advantage (moment arm) than if the shock connected straight to the knuckle (as on the front suspension)

Due to this greater leverage, the spring had in effect has a lower rate than the actual spring rate. Eg a 10kg spring will act like an 8kg spring, where as on the front suspension, a 10kg spring will act like a 10kg one.

So, to offset this lower effective rate, a high spring rated can be used to equal thing out. Also, to help reduce understeer, a stiffer rear can help lower grip and give a more oversteer or neutral balance depending on preference.

There are lots of other factors such as anti-roll bars, geometry, ride height, damping adjustments, diff settings, tyre pressures which all have an effect aswell.
 
#18 ·
Your valid opinion on this .

Money isn't flowing out of peoples pockets like it was a few years ago, So someone with a budget of say £700 needed to replace is suspension which one would you recomend. Use would be say a few trackdays a year and road use.
 
#22 ·
If budget was tight and I didn't have more than £700 to spend, I would look at getting some second hand KW V3's or Bilstein PSS10's without top mounts, or some second hand original equipment Bilsteins with decent springs.

I would look at why I wanted to change the suspension, because for a car mostly used on the road, OEM units are excellent, depending on Evo model and age/mileage of the car.

As you know from the previous thread I would not pay this money for new units in this price range because in my experience and opinion the quality is just not good enough for a car like the Evo (with it's excellent chassis) to give a forward step in regards to handling and ride quality (it is a road car)
 
#25 ·
Going back about 4 years ago I was in the situation where my car needed new suspension. Tein mono flex were bought and at the time I thought they were 'ok'. That was until I was taken out in several of marks customers cars fitted with either ohlins or exe tc suspension. I was blown away with the difference, and promptly put the teins up for sale.

The point to me writing this is I'm not a suspension guru, and it took first hand experience to see what all the fuss was about with high end suspension. So whilst I can understand some of the comments made on the deleted thread sticking up for 'budget suspension', I would urge any of you guys to hitch a ride out in a car with high end suspension. If you can't afford it now, it will just make you think 'hey i'll just save a little bit longer and skip the budget stuff' :mhihi::handsup::D
 
#26 ·
Going back about 4 years ago I was in the situation where my car needed new suspension. Tein mono flex were bought and at the time I thought they were 'ok'. That was until I was taken out in several of marks customers cars fitted with either ohlins or exe tc suspension. I was blown away with the difference, and promptly put the teins up for sale.

The point to me writing this is I'm not a suspension guru, and it took first hand experience to see what all the fuss was about with high end suspension. So whilst I can understand some of the comments made on the deleted thread sticking up for 'budget suspension', I would urge any of you guys to hitch a ride out in a car with high end suspension. If you can't afford it now, it will just make you think 'hey i'll just save a little bit longer and skip the budget stuff' :mhihi::handsup::D
That pretty well sums it up wozzy, you don't need to be a guru to benefit and 'feel' the difference with higher end suspension.

It amazes me the amount of people who spend thousands on the engine and then fit cheapo suspension, same with brakes.
 
#33 ·
Looking forward to the rest of the write up, so far i understand :D

I have proflex 2 way & i've set them up through basic advive from the guys at Proflex when i collected them after a service. They quickly lost me when they got technical. :handsup: I think it handles pretty good & they seem to take b roads & air no problem, but don't feel i understand enough about what i'm adjusting to be worth messing with it. It's pretty neutral, don't rub/bottom out or roll too much & thats were i've left it. But i'm sure if someone like yourself was to drive it you could list the changes that need making!

Hopefully this thread will give me a much better idea how to get the best out of them.

Dan :thumbup:
 
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