A bit of boingy ponder minge t00t rar.

27th May 2008, 22:17

I've been thinking about springz n shit y0

I did make an excel sheet with everyones custom faulkners, aftermarket springs on etc, with a graph to show the correlation between length, rate and ride height. This was many yonks ago. I then thought hmm why not use a bit of theory.

For this theory to work the springs need to be under no tension with the dampers fully extended, so say a 240mm spring with grpN billies/pugsport tarmacs.

Take a few examples to work from.

A saxo weighs 920kg or thereabouts.
Front end weighs 540 or something
Rear weighs 380 etc.

So one side at the front weighs about 270kg. 270kg = 595lb, call it 600lb.

Take spring A. This is 200lb/in and 240mm, this lowers the car(A standard vts) by 20-30mm, a known quantity.
The maximum extended length of the damper piston to the bottom of the top mount thread is approximately 190mm on both damper designs. So this is your amount of travel(ignoring the bump stops because they won't affect ride height, if you are low enough to be sitting on the bump stops at ride height you need to modify them so you don't). So anyway yeah. You drop the car onto the ground, your 200lb/in spring will compress by an inch for every 200lb of weight you put on it.

So you drop the car down. The damper travel moves approximately 75mm from extended, leaving 105mm travel. It has moved by 3" which is 75mm, 600lb compresses a 200lb/in spring by 3 inches. voila, magic.

So if you were to make some(poofdahs) 160lb/in springs, they would compress by(600lb/160) = 3.75 = 93mm. Take 90mm from your 180 and you end with 90mm travel remaining, this is 15mm lower than your 20-30mm springs, so 35-45mm below standard ride height.

Or you are one hardcore motherlover, you made some 250lb springs, and they would lower la voiture par(600/250) = 2.4" = 60mm. This leaves 120mm of travel, this is 15mm more than our 20-30mm springs, leaving 5-15mm lowering from standard ride height.

And here endeth the lesson for today

27th May 2008, 22:18

makes me remeber why im dreading my exam on kinesiology next week.

27th May 2008, 22:21

That's just some basic calculations n shiz y0. off the top of my head. a fair bit is presumption. gimme my damn suspension book back unless you're gonna read it homolord

What the hell is kinesiology?

27th May 2008, 22:22

kinesiology is about inertia, and planes and motions of movement of the human body etc... and lots of fucking triganometry

Book ive read some of but due to being away alot not recently.

27th May 2008, 22:26

you guys have toooo much fucking time spare.

27th May 2008, 22:27

apply4life.com

just kidding... Just so i know? is there a question to this thread? or is this an open discussion?

27th May 2008, 22:30

what the next lesson?

explain free lengths and shit

27th May 2008, 22:30

I can't see any question marks?

Feel free to query anything.

Saxo springs work directly on the hub, which works at the end of the wishbone so there is no leverage. As for changing spring length, it's pretty much directly related to ride height, make the spring 20mm shorter, you lower the car 20mm more. On some cars the springs & dampers are linked like halfway along the wishbones, in which case, the 200lb/in spring would effectively be 100lb at wheel rate, it's the action of leverage, and again obviously the lengths etc would all differ because of it. you get more accurate damping having 100% mechanical advantage, every milimeter the wheel moves the damper moves.

27th May 2008, 22:32

so if i wanted a harder spring than my eibachs and still be 50mm down i would do what exactly...

27th May 2008, 22:32

What about free length? The 240mm is the free length, it's the length of the spring before any weight is placed on it. Obviously as above the free length can vary depending on what you want from it. For the original calculation, if you used a free length that required spring compressors to fit, or any effort at all, some weight would technically have been placed on it before the weight of the car(compressed already init) so you can't work out ride heights that way, you can use the 240mm example spring then the direct addition or subtraction of length to change the ride height

27th May 2008, 22:33

Quote:

Originally Posted by jaybiss

so if i wanted a harder spring than my eibachs and still be 50mm down i would do what exactly...

Decide what rate you want, then calculate the required length using the basic formula in the top post. i swapped my 50mm eibachs for 160lb 245mm, reckon 240mm, maybe 155lb would be an identical height, i did get 10mm raise from the customs.

27th May 2008, 22:35

so you can run the same lb rate on diff lengths giving different heights?

27th May 2008, 22:35

Quote:

Originally Posted by AlexR

I can't see any question marks?

Feel free to query anything.

Saxo springs work directly on the hub, which works at the end of the wishbone so there is no leverage. As for changing spring length, it's pretty much directly related to ride height, make the spring 20mm shorter, you lower the car 20mm more. On some cars the springs & dampers are linked like halfway along the wishbones, in which case, the 200lb/in spring would effectively be 100lb at wheel rate, it's the action of leverage, and again obviously the lengths etc would all differ because of it. you get more accurate damping having 100% mechanical advantage, every milimeter the wheel moves the damper moves.

what about unsprung weight,how do we determine the springs poundage to control unsprung weight,plus how can we lower it on saxo's?
what did citroen/pug sport have different hubs/wishbones etc?

27th May 2008, 22:35

deiced on damper/spring combo for el shed??

27th May 2008, 22:39

Quote:

Originally Posted by bullit

so you can run the same lb rate on diff lengths giving different heights?

Yeah of course, the real 200lb 240mm spring that gives 20-30mm lowering, if this was 220mm long it would give 40-50mm lowering, but then it wouldn't be long enough to stay seated if you got airbourne, jacked the car up etc(would fail mot). again 200lb 260mm(which i had) were a maximum of 10mm lower than standard.

The spring doesn't affect unsprung weight, apart from 50% of the spring being unsprung weight, a lighter spring might reduce it lol. Full rally cars use alloy hubs, struts, wishbones, light calipers, 2 piece discs, light wheels etc.

No Ryanal, that's why i'm messing about working this stuff out.

27th May 2008, 22:40

kk let me know when payment is needed again LOL!

27th May 2008, 22:41

I will, mincer said he'll go pick them up, saves postage costs init.

27th May 2008, 22:42

Cooliarse

27th May 2008, 22:44

whats the maximum lengths you can use? and shortest. or does the rate come into this aswell

27th May 2008, 22:45

Quote:

Originally Posted by AlexR

Yeah of course, the real 200lb 240mm spring that gives 20-30mm lowering, if this was 220mm long it would give 40-50mm lowering, but then it wouldn't be long enough to stay seated if you got airbourne, jacked the car up etc(would fail mot). again 200lb 260mm(which i had) were a maximum of 10mm lower than standard.

The spring doesn't affect unsprung weight, apart from 50% of the spring being unsprung weight, a lighter spring might reduce it lol. Full rally cars use alloy hubs, struts, wishbones, light calipers, 2 piece discs, light wheels etc.

No Ryanal, that's why i'm messing about working this stuff out.

the kit cars also didnt have bushes on the wishbones right?

how much would a full pug sport kit car suspesnion cost?

rear beam if any different
front wishbones,hubs?
also if there metal bushes them aswell.

fitted me group N engine mounts,they made a massive difference.

so if you want to go above 200lb and 35mm drop youd have to look at coilovers?

27th May 2008, 22:45

you could use any length you wanted, as long as when the suspension bottoms out the spring coils don't all touch, limiting travel, and of course you don't have to compress the springs so much to get the top mount on that it snaps the top off the damper.

Standard springs are around 330mm.

27th May 2008, 22:47

you defo want to get a little guide going on what everyones got mr R

27th May 2008, 22:48

Quote:

Originally Posted by littleracer

the kit cars also didnt have bushes on the wishbones right?

how much would a full pug sport kit car suspesnion cost?

rear beam if any different
front wishbones,hubs?
also if there metal bushes them aswell.

fitted me group N engine mounts,they made a massive difference.

so if you want to go above 200lb and 35mm drop youd have to look at coilovers?

There's far too much to list to do with kit car parts, needless to say, some of the parts were so expensive that even bic took a cheaper option...

yeah that's it, coilovers just allow adjustable height. it's helper/tender springs that allow uber short main springs to be used, and then you have dual spring rates, which brings me to progressive springs, i spoke to faulkner about them in depth, might be a good option for us 250lb guys without helpers?

27th May 2008, 22:52

Quote:

Originally Posted by AlexR

There's far too much to list to do with kit car parts, needless to say, some of the parts were so expensive that even bic took a cheaper option...

yeah that's it, coilovers just allow adjustable height. it's helper/tender springs that allow uber short main springs to be used, and then you have dual spring rates, which brings me to progressive springs, i spoke to faulkner about them in depth, might be a good option for us 250lb guys without helpers?

250lb in 35mm drop on billie group n's?

if that can be done

.

so a progressive spring of 2 stage stiffness?

softest then when the soft spring hits its limit then the stiffer spring kicks in?

27th May 2008, 22:56

still wish there was a non cack coilover set up for the saxo.

one that does include platform and doesnt break like comprake

27th May 2008, 22:59

Quote:

Originally Posted by littleracer

250lb in 35mm drop on billie group n's?

if that can be done

.

so a progressive spring of 2 stage stiffness?

softest then when the soft spring hits its limit then the stiffer spring kicks in?

200lb is really the limit for grpNs i reckon. I'm going for pugsport grpA dampers now.

And sort of, it's twin wound so you get a smooth transition between rates, what i'd do is have a short bit of 150lb to allow the car to drop down, then it hits the 250lb well before it gets to ride height so i can be 40mm down but with a 250lb(@ ride height) 230-240mm spring init.

Edit: williams said he'd make up some helper platforms of our desired size for the cost of postage, just gotta knock up a design. and of course we need flat spring seated platforms(pugsports cos they'll fit std top mount arrangement if needed) and faulkner make custom helpers. could be the first to have pugsport coilovers with helpers?

27th May 2008, 23:01

Quote:

Originally Posted by Ryan

still wish there was a non cack coilover set up for the saxo.

one that does include platform and doesnt break like comprake

thought there was a few coilover set-ups for the saxo.

i dont see the idea of coilovers on a saxo unless your good/quick/dont mind adjusting torsion bars.

probs the only reason id get them is that you can adjust the rebound/damping effect on them to suit your style of driving,wish billie group n's came with that.

27th May 2008, 23:02

im using coilovers and using 6" 225lb springs and 4" 40lb helper springs. ive got around 4 different sets of springs of different height and lb. this makes everything a little bit easier to change around as i dont have to order cutom springs i just phone my spring man and get a set for £25 any lb.

if you keep the sme lb when you go shorter spring it will adjust the ride height according to the amount shorter the spring is. if you start changing lb then its harder to predict ride height unless you have corner weighted the car.

27th May 2008, 23:02

Quote:

Originally Posted by AlexR

200lb is really the limit for grpNs i reckon. I'm going for pugsport grpA dampers now.

And sort of, it's twin wound so you get a smooth transition between rates, what i'd do is have a short bit of 150lb to allow the car to drop down, then it hits the 250lb well before it gets to ride height so i can be 40mm down but with a 250lb(@ ride height) 230-240mm spring init.

yeah thats what i had in me head.

who are the group A shocks made by?

27th May 2008, 23:04

Quote:

Originally Posted by littleracer

thought there was a few coilover set-ups for the saxo.

most are as i say cack.

pugsport ones id have if they came with scope to do a helper spring set up.

27th May 2008, 23:06

Quote:

Originally Posted by Ryan

most are as i say cack.

pugsport ones id have if they came with scope to do a helper spring set up.

why can the pugsport items have helper springs?

27th May 2008, 23:08

danny i'm probably getting some platforms made up to go between the main springs and some helpers on pugsport coilovers, they are 3.5" so not normal...

27th May 2008, 23:10

Quote:

Originally Posted by Ryan

most are as i say cack.

pugsport ones id have if they came with scope to do a helper spring set up.

they too short to have helpers then?

27th May 2008, 23:11

Quote:

Originally Posted by AlexR

danny i'm probably getting some platforms made up to go between the main springs and some helpers on pugsport coilovers, they are 3.5" so not normal...

ahh that makes sense now, im tempted to buy some 2.5" platforms and springs so i can fit the billie cover over the shocks (blue plastic casing.)
but im tempted to get psf tarmac dampers front and rear and go a bit more "hardcore" what do you think?

27th May 2008, 23:12

Quote:

Originally Posted by littleracer

they too short to have helpers then?

no just an odd diameter.

normally springs come in 1.9" 2.25" and 2.5"

27th May 2008, 23:15

Quote:

Originally Posted by dannygti

no just an odd diameter.

normally springs come in 1.9" 2.25" and 2.5"

ahh so do the pusport ones use a oversized or undersized spring?
iam guessing oversized

27th May 2008, 23:16

Danny, i say tarmac her up!

And i'm going to stop thinking as my bed time was over an hour ago, brain overload

27th May 2008, 23:17

Quote:

Originally Posted by AlexR

yes you fecking have havent YOU alex lol

27th May 2008, 23:26

i think i will end up tarmac'ing it up lol

Quote:

Originally Posted by littleracer

ahh so do the pusport ones use a oversized or undersized spring?
iam guessing oversized

they are bigger diameter than regular coilover sizes but smaller than o.e. springs.

the pugsport is trick stuff and extremely hard, definatley NOT for consistant road use. i think billie group n's and custom faulkner 160lb spring would be untouchable on the road.

27th May 2008, 23:31

I did really like my 160lb, i reckon i would have gone 140 lb for the shite around here, doing 20k+ a year can get jarring. But 160 was a good compromise. I don't remember 200lb being that bad, but then i was young, a daily driver with a roll cage and badass suspension, 4 pots, no power steering

I'm guessing 250lb will be very hardcore, we'll see

27th May 2008, 23:32

go 300lb and tarmacs