60 replies to this topic

[meb58]

Why on earth would anyone cut suspension springs? I assume the spring rate will increase - by some unknown factor unless one has a machine to measure rate??? The market place is full of so many choices...I'm just a wee bit perplexed by this short cut. Or is this common place?

[tristancliffe]

It's common on poorly modified road cars because it's cheap - it costs nothing!

Yes, it will increase the rate of the spring, although the amount is fairly straightforward to deduce. And it will almost certainly stop the spring from sitting nicely on the pressed spring platforms top and bottom, which won't help matters...

In short, it's a convenient way to tell who knows what they're doing, and who is a fool.

[meb58]

Can assume that the new rate can be determined only after cutting? Lets say we know the rate of a given spring. We cut 2" from the spring. Place the spring on a scale and place a load on the spring. Divide the load by the distance the spring compressed? Accurate this method may be, I don't see how one can determine a new rate before cutting...unless one has performed the same operation to the same type of spring several times.

A fool yes...I should just let this one go.

It's common on poorly modified road cars because it's cheap - it costs nothing!

Yes, it will increase the rate of the spring, although the amount is fairly straightforward to deduce. And it will almost certainly stop the spring from sitting nicely on the pressed spring platforms top and bottom, which won't help matters...

In short, it's a convenient way to tell who knows what they're doing, and who is a fool.

[zac510]

I suppose if the new rate and length was suitable for your car then if would be fine, aside from the shape of the spring that usually makes a flat edge to rest against the strut/spring support?

[cheapracer]

In short, it's a convenient way to tell who knows what they're doing, and who is a fool.

As with the locked diffs there is people who will comment on things continually and daily on the internet of things they have most obviously never done themselves.

You can get near an inch out of many springs by cutting about half of the end coils without any real noticeable rate change at all. Most ends have a flat coil which gradually starts to 'unwind' so to speak and carefully choosing where to cut can reduce the springs length without upsetting the seating on it's platform. If there is a platform problem you merely weld some safety dams to keep the spring in place.

The greatest risk in cutting springs is in going too short and the springs jumping off their platforms, I have seen people use multiple zip ties to keep springs on platforms and you be surprised how strong 20 of the good ones are (its good to have Mates in Telecom).

This fool managed to go racing and rallying and have a great time over many years thanks to many free tricks learnt along the way while successfully feeding and clothing 3 children all on one income. If you ever go to a club day pits or rallying at club level, I wouldn't go mouthing off because theres a hell of lot of 'fools' there.

[meb58]

I know there are short-cuts thru life...some just seem to be a waste of time...funny, I know. My son and a few of his buddies are embarking along this road...perhaps I should let them go without harassment...perhaps they will learn something I didn't...life doesn't have to be perfect, it just has to work.

But springs are so cheap! ...the effort...not worth it to my brain.

Edited by meb58, 26 January 2010 - 20:41.

[Greg Locock]

Depends on the car and what you are trying to do. I'd say we shorten a pair of springs every couple of weeks.

Yes, the rate does change, the old adage measure twice cut once 'springs' to mind. You can usually get a reasonable end on the the thing with an angle grinder, which tends to detemper the spring so it flattens a bit. Most of our production springs are moving towards the square cut ending, because spring rotation/orientation is a big deal on struts. So fancy ends matter less than they did.

[gruntguru]

Can assume that the new rate can be determined only after cutting? Lets say we know the rate of a given spring. We cut 2" from the spring. Place the spring on a scale and place a load on the spring. Divide the load by the distance the spring compressed? Accurate this method may be, I don't see how one can determine a new rate before cutting...unless one has performed the same operation to the same type of spring several times.

Predicting the new rate is actually easier than calculating the rate of an unidentified spring using the formula (the one which includes wire dia, coil dia and # of active coils). Siince the only variable you are changing is # of active coils (n), the rate change will be inversely proportional to the change in n.

So reduce n from 10 to 9, the spring stiffness will increase by 10%.

[SteveCanyon]

It's a good combination, cutting the spring and having the rate increase as with a lower car you'd want a higher rate anyway.
But yes, it's not a good way to do it.

[Lee Nicolle]

Depends on the car and what you are trying to do. I'd say we shorten a pair of springs every couple of weeks.

Yes, the rate does change, the old adage measure twice cut once 'springs' to mind. You can usually get a reasonable end on the the thing with an angle grinder, which tends to detemper the spring so it flattens a bit. Most of our production springs are moving towards the square cut ending, because spring rotation/orientation is a big deal on struts. So fancy ends matter less than they did.

I too have done it but most springs never seat properly when cut.And break the ends off. Though most are useable though. It does give a baseline though for a stiffer or softer spring without buying new ones.

[Greg Locock]

I too have done it but most springs never seat properly when cut.And break the ends off. Though most are useable though. It does give a baseline though for a stiffer or softer spring without buying new ones.

If you cut them off square spend 20 minutes milling up a nice aluminium seat for them. If you bolt that into the spring seat the spring won't rotate any more and you'll get a more consistent setup, if you have coil overs.

[cheapracer]

I know there are short-cuts thru life...some just seem to be a waste of time...funny, I know. My son and a few of his buddies are embarking along this road...perhaps I should let them go without harassment...perhaps they will learn something I didn't...life doesn't have to be perfect, it just has to work.

But springs are so cheap! ...the effort...not worth it to my brain.

Cheap or expensive is irrelevant when you have no money at all, simply unobtainium.

Follow my advice and they won't have problems (you won't get more than an inch though) but as Lee mentions if you go to far and the angle where the spring leaves the platform is too great it may give a stress load at that point and break.

There are plenty of spring rate calculators on the net, Google is your buddy.

[cheapracer]

So reduce n from 10 to 9, the spring stiffness will increase by 10%.

In difference to what I am advocating you are quoting cutting a consistent wind of which most springs are not. Most have 1 to 2 winds at each end that have from less to zero spacing (often typical for the last wind at each end, flat in other words).

I am saying you can cut around a half coil from each end to lower the car without any noticeable change to the rate.

Edited by cheapracer, 27 January 2010 - 06:43.

[gruntguru]

In difference to what I am advocating you are quoting cutting a consistent wind of which most springs are not. Most have 1 to 2 winds at each end that have from less to zero spacing (often typical for the last wind at each end, flat in other words).

I am saying you can cut around a half coil from each end to lower the car without any noticeable change to the rate.

Notice I used the word "active" in my post. Any section of spring which is touching either the seat or the next turn when installed is "inactive".

[imaginesix]

I would have cut the springs at the back of my old Nissan if I could have found something equivalently shortened to put on the front. The rear springs were open-wound so it would have been no big deal to just shorten them. I fact, removing exactly 1 winding of the spring would have given me just the drop I wanted while allowing it to sit properly back in the spring perches.

The fronts were closed-wound so they couldn't be cut down as well, and everything that I could find as an aftermarket option was too short.

This wasn't for racing, this was for looks/handling.

[McGuire]

In short, it's a convenient way to tell who knows what they're doing, and who is a fool.

Then I'm a fool as I have cut some springs. When they make springs they cut them, don't they.

Rambling off-topic now but some might find this interesting.... you know the cars you see on the floor at the big International auto shows, etc? These are not production cars. Soon as they come off the line they are totally blown apart and rebuilt. Show paint, show chrome, tig-welded 3mm panel gaps, perfect-fitting trim and upholstery, etc. Might take $30-40K USD to cherry out a brand new car in this fashion (so it's nice work if you can get it, especially with the Japanese OEs as they are really fussy). Anyway, one of the tricks: sometimes the springs are cut down so the car sits around an inch lower. Makes most any car look better, especially when photographed.

[meb58]

So this begs a question - and I honestly have not read this chapter in Milliken...keep in mind, I'm a Landscape Architect, not an automotive engineer...damn it jim, i'm a doctor not a scientist...

What criteria do we use to mate a shock to a spring? I understand spring rate in lb/in...I think I understand that a spring's energy is both mechanical and kinetic - mechanical in compression and kinetic in rebound - and that the shock/damper must be able to control the spring's frequency (ies). How a shock does this may depend upon not only damping force but damping characteristics - damping curve???

Is there a rule of thumb - I know you don't like that phrase Greg but perhaps you'll humor me for a moment - to mating say a 350lb/in linear rate spring to a shock?

Or should I just go read the appropriate chapter in Milliken?

Edited by meb58, 27 January 2010 - 14:41.

[cheapracer]

So this begs a question - and I honestly have not read this chapter in Milliken...keep in mind, I'm a Landscape Architect, not an automotive engineer...damn it jim, i'm a doctor not a scientist...

well said Bones.

[DaveW]

In difference to what I am advocating you are quoting cutting a consistent wind of which most springs are not. Most have 1 to 2 winds at each end that have from less to zero spacing (often typical for the last wind at each end, flat in other words).

I am saying you can cut around a half coil from each end to lower the car without any noticeable change to the rate.

Cheapracer, have you ever wondered why spring manufacturers bother to "finish off" the ends of the springs you illustrated? If the springs are used "coil over" then you might find that what you save by butchering the springs is offset by the cost of replacing leaking dampers on a regular basis - unless, that is, you added bespoke (& expensive, perhaps) spring seats. Personally, If I wanted to lower the static ride height of a vehicle for any reason other than making it look pretty, I would think seriously about increasing spring rate & adding damping (particularly in compression). I would also think about stiffening up "top mounts" & power train mounts (assuming that to be relevant)....

Edited by DaveW, 27 January 2010 - 23:02.

[gruntguru]

Is there a rule of thumb - I know you don't like that phrase Greg but perhaps you'll humor me for a moment - to mating say a 350lb/in linear rate spring to a shock?

While you're waiting for Greg to tell you to read Milliken, here's my two bob's worth. The damping rate required will depend not only on the spring rate but also a whole list of other variables including
- paralell springs (ARB's etc)
- series springs (tyres, bushes . . )
- sprung mass
- friction
- degree of damping required for the application (underdamped, overdamped or critical)
- ratio of bump:rebound damping

[Lee Nicolle]

While you're waiting for Greg to tell you to read Milliken, here's my two bob's worth. The damping rate required will depend not only on the spring rate but also a whole list of other variables including
- paralell springs (ARB's etc)
- series springs (tyres, bushes . . )
- sprung mass
- friction
- degree of damping required for the application (underdamped, overdamped or critical)
- ratio of bump:rebound damping

And after that the drivers preference! Or go to [in speedway shock terms] to about a straight 5 rate as a starter and drive around it. If you can!

[Greg Locock]

Cheapies photo is handy.

The upper ends are what I called square cut, they work well IF you can be bothered to make a spring seat for them. If you don't then the spring will break after 1 turn where it has to bend over the cut off end

The lower ends are ground off flat, and that is dead easy to do with an angle grinder, and a modicum of skill will lead to a nice end that doesn't cause the spring to break due to bending.

Matching shocks to springs is a black art, at least for road cars. Ferrari claim to be able to calculate it for their F1 car.

Milliken has some rules of thumb, roughly speaking if your car feels OK as is, and you bump the spring rates up by 20%, you can probably uprate the shocks by 20%. But that is very crude. On a road car you'd probably back off on the low velocity setting a bt more, and perhaps reduce the low velocity window. I don't do much detailed work with shock valving, that is a job for the GAs. Roughly speaking a shock has 3 ranges, a low velocity bit around centre, a rebound rate, and a jounce rate. You can decide on the window for the low velocity slope in each direction, and then everything else i haven't mentioned is voodoo. Basically you have 4 points on a graph, and the middle straight line must pass through 0,0.

[DaveW]

Cheapies photo is handy.

The upper ends are what I called square cut, they work well IF you can be bothered to make a spring seat for them. If you don't then the spring will break after 1 turn where it has to bend over the cut off end

Good point, Greg.

Matching shocks to springs is a black art, at least for road cars.

Perhaps not quite a black art, just not simple. I like gruntguru's contribution....

...and you bump the spring rates up by 20%, you can probably uprate the shocks by 20%. But that is very crude.

Actually, & equally crudely, spring rate is proportional to natural frequency squared whilst damping coefficient is proportional to natural frequency - hence a spring rate increase of 20% is likely to require a damping coefficient increase of no more than 10%. Increasing spring rates of a tightly sprung race vehicle often requires either no increase, or may even require a reduction, in damping coefficients (for reasons buried in gruntguru's list).

[NeilR]

While you're waiting for Greg to tell you to read Milliken, here's my two bob's worth. The damping rate required will depend not only on the spring rate but also a whole list of other variables including
- paralell springs (ARB's etc)
- series springs (tyres, bushes . . )
- sprung mass
- friction
- degree of damping required for the application (underdamped, overdamped or critical)
- ratio of bump:rebound damping

could I add motion ratio to this one?

[gruntguru]

could I add motion ratio to this one?

Definitely - motion ratio of spring/wheel (and damper/wheel if different)

[NeilR]

Might also add the angle of the damper relative to the arc of the suspension arm.

[mariner]

A safety question, if you cut 10% off a spring ( and so make it a shorter torsion bar) does that put the energy absorbtion margin at any serious risk?

I PRESUME that OEM's put in a big safety margin but springs are very highly stressed and get hit by endless little rocks etc. over life so what is safe - <10% cut or <20% or what?


On a lighter note, re McGuires Auto show comment, there used to be stories in the UK of mfrs hiring big temporary staff people and making them endlessly sit in rival's cars at the Motor Show to make the interiors look smaller - probably not true but funny.

[cheapracer]

Cheapracer, have you ever wondered why spring manufacturers bother to "finish off" the ends of the springs you illustrated? If the springs are used "coil over" then you might find that what you save by butchering the springs is offset by the cost of replacing leaking dampers on a regular basis - unless, that is, you added bespoke (& expensive, perhaps) spring seats.

So you're saying also that you haven't done it?

You Guys keep spinning all the theories and I'll just continue to do it as I have been for the last 30+ years.

Ok heres how to set up a '74 Corolla KE30 for general street and fun work...

Cut the springs as I said above to get about an 1" out of them with little other effect, dont worry about the **** some are spinning because the bulk of Japanese cars have formed spring platforms and not ground springs (refer to the top of the springs pictured above).
While the struts are off remove the strut seals and replace the oil with 15 weight - (measure how much oil comes out of the strut and replace equal amount).
Go to the wreckers and buy another standard front anti roll bar for about $5.
Remove the front anti roll bar and throw the front U clamp rubbers in the bin.
Replace the front roll bar along with the new old rollbar (2 roll bars) which fit snuggly into the U clamps without the rubber and the end struts have more than enough thread to the now 2 ends (make sure you get the end mount rubbers and cup washers from the wrecker.
remove the front caster rod inner spacing tubes and cut 10 mm off to crush/stiffen up the rubbers a bit more and replace adding a bit of caster while you're there.
Remove the rear springs and shocks.
Get some scrap bar to size and replace the front leaf spring eye bushes with the steel bushes (this also increases the anti roll effect of the leaves).
Drill some 5 mm holes in the shocks and drain the oil then weld 8mm nuts on somewhere in the middle and refill with 15 weight using a bolt and copper washer to cap it.
Put everything back but leave out the leaf springs rubber insulator pads lowering the car a half inch - shorten the shackles if you need more.
Lock the diff.

Go out and have a lot of fun for over 5 years driving to work daily and doing many various club events with a huge smile on your face for $10 worth of mods. Do the same mods to a number of your friends cars and even see one go out and win the 0-1600cc State rally champs with them (older RWD Mitsubishi Lancer and ok, I admit, we bought some expensive motorcycle fork oil for the struts and shocks for that car).

This is but a small example (not specifically the mods to the car but the thought process) of what thousands of club racers on a budget around the world do every weekend.

[cheapracer]

Might also add the angle of the damper relative to the arc of the suspension arm.

I'm tring to think of a car that has seperate spring shock location on the front and I can't??

[Greg Locock]

I'm tring to think of a car that has seperate spring shock location on the front and I can't??

Rover P6?

The reason that a more or less vertical coilover is ubiquitous in front suspensions is that the steering of the wheel leaves a vertical hole inboard of the wheel centre. Even if you use torsion springs you still end up with the shock there.

[DaveW]

So you're saying also that you haven't done it?

You are correct.

Ok heres how to set up a '74 Corolla KE30 for general street and fun work...

I'm not familiar with the KE30, so I was unable to piece together a view of your detailed description in its entirety. A couple of comments, however.

Your shock modifications might well have filled the device with swarf & burrs, with unknown consequences. Increasing fluid viscosity (assuming that is what you did) would have increased damping in laminar flow ports, but not otherwise. Hence, provided the contaminants didn't stop shims sealing, you might have made the dampers more digressive, but would probably not have changed the overall damping significantly (although subjective impressions might have suggested otherwise). I'm not sure if the units were pressurized originally. If they were, then their dynamic performance would probably be affected unless you managed to re-pressurize them. Any air you failed to purge might also affect dynamic performance, at least for some architectures.

Probably the saving grace of your modifications was doubling the front bar.... That would at least increase understeer (push) & help to protect punters from possible consequences of the other modifications.

Greg implied that Ferrari F1 claim to be able to predict the effect of suspension changes. They probably can. Without wishing to be rude, are you able to do that? Did you carry out the modifications in one iteration, or were they a series of "fixes on fixes"? Personally, and again without wishing to be rude, I would hesitate to encourage others (perhaps with insufficient knowledge) to undertake the kind of modifications you have described.

[meb58]

I always hesitate to begin a thread that feels, well, like a stupid question. But here again, the information is wide spread and very interesting.

The term 'black art' was used once before but I thought I would ask a more learned group. I think I understand the frequency balance and or range for a porting ride rate...2 - 2.5 hz...I garnered this from Milliken. That information gives me a basic range of linear spring rates for a car of given weight and weight distribution. But boy oh boy, damping characterisitcs are so important!

My most aggressive set of coilovers to date: Eibach springs mated to koni sports...the koni's where shortened, re-valved for rates higher than 400lb/in and adjustable for bound and rebound. The final rates ended up around 400lb/in front and between 10% and 20% higher in the rear - track car...okay, a honda. Each front corner weighed about 850 lb and each rear corner about 450 lbs.

I basically stuck my finger in the air while adjusting the dampers...I always tried to strike a good balance between control and grip...which seemed to go in opposite directions at some point. Black art at my level, indeed!

[Greg Locock]

Another way of shortening springs is to scrag them. This involves overcompressing them. it only works with some designs, many springs go coilbound before taking on a permanent set.

This has the advanatge that the rate is unchanged and if anything the fatigue life is improved, and of course the ends still fit the old spring seats.

[meb58]

Is there a machine designed for this purpose?

Another way of shortening springs is to scrag them. This involves overcompressing them. it only works with some designs, many springs go coilbound before taking on a permanent set.

This has the advanatge that the rate is unchanged and if anything the fatigue life is improved, and of course the ends still fit the old spring seats.

[Fat Boy]

Is there a machine designed for this purpose?

You can do it with some spring raters depending on the rate of spring and design of the rater. We called it 'Bulldozing' the spring, not that technical term 'scrag'.

[Lee Nicolle]

So you're saying also that you haven't done it?

You Guys keep spinning all the theories and I'll just continue to do it as I have been for the last 30+ years.

Ok heres how to set up a '74 Corolla KE30 for general street and fun work...

Cut the springs as I said above to get about an 1" out of them with little other effect, dont worry about the **** some are spinning because the bulk of Japanese cars have formed spring platforms and not ground springs (refer to the top of the springs pictured above).
While the struts are off remove the strut seals and replace the oil with 15 weight - (measure how much oil comes out of the strut and replace equal amount).
Go to the wreckers and buy another standard front anti roll bar for about $5.
Remove the front anti roll bar and throw the front U clamp rubbers in the bin.
Replace the front roll bar along with the new old rollbar (2 roll bars) which fit snuggly into the U clamps without the rubber and the end struts have more than enough thread to the now 2 ends (make sure you get the end mount rubbers and cup washers from the wrecker.
remove the front caster rod inner spacing tubes and cut 10 mm off to crush/stiffen up the rubbers a bit more and replace adding a bit of caster while you're there.
Remove the rear springs and shocks.
Get some scrap bar to size and replace the front leaf spring eye bushes with the steel bushes (this also increases the anti roll effect of the leaves).
Drill some 5 mm holes in the shocks and drain the oil then weld 8mm nuts on somewhere in the middle and refill with 15 weight using a bolt and copper washer to cap it.
Put everything back but leave out the leaf springs rubber insulator pads lowering the car a half inch - shorten the shackles if you need more.
Lock the diff.

Go out and have a lot of fun for over 5 years driving to work daily and doing many various club events with a huge smile on your face for $10 worth of mods. Do the same mods to a number of your friends cars and even see one go out and win the 0-1600cc State rally champs with them (older RWD Mitsubishi Lancer and ok, I admit, we bought some expensive motorcycle fork oil for the struts and shocks for that car).

This is but a small example (not specifically the mods to the car but the thought process) of what thousands of club racers on a budget around the world do every weekend.

Cheapy, that is a little too basic even for me who has done similar sorts of lo buck mods in my youth.
Two sway bars is a proven method, there is still lots of cars using that now inc some very quick Gp N Cortinas. But spring eye bushes need some sort of bearing and damper. I have seen leafs break and the end result is not pretty. Nylon is ok, though very hard urethane bar machined to size is better.When you solid mount the spring at the centre it can cause them to break too, and having both solid binds the spring too. Though stiffer harder material is usually good. Rear shackle bushes need to be harder too but the spring has too move not be bound up.
As for shocks, these days there is fairly cheap sports gas advailable, or in the old days Pedders red which were proffesionally rebuilt [with heavier oil] consistent shocks.
Cutting 10mm off the crush tubes is too much, about 4 mm unless the bushes are stuffed in which case go buy some urethane ones.
You can do things cheap but you have to spend some money otherwise things break.
I won a SA Rallycross championship using mostly parts scrounged from the dump, wreckers etc. And on occasion it was wrong, I found spending a little money is far cheaper in the long run. And ran Sports Sedans competitivly and reliably spending about a third of what my main competitors were spending.
Though these days i do spend more money on important things but still far less than most.

[carlt]

Is there a machine designed for this purpose?

'Big Fat Bastard'

[gruntguru]

Easy spring rate uprate - jam in some bits of plastic to bind some active coils!

Link

[scooperman]

my friend Kenny is from the school of hard knocks, not book learning. Every couple years he would trade in his old truck and get a new truck, which he would immediately lower. He liked that lowrider look, a couple inches lower than stock but not slammed. One day I asked him about lowering, I knew about lowering a rear with leafs but I didn't know how he lowered the front, I asked if he bought a lowered spring kit, or a raised spindle kit. He looked at me like I was crazy, told me he just crawls under the truck and heats up the spring with a torch, he knows by the color when to quit and the weight of the truck makes the spring sag as it cools. Yikes.

[McGuire]

Once again the tiresome taxicab reference... spring rubbers similar to those pictured above are common in NASCAR as they allow spring rates to be adjusted during the race -- the tire changer can reach in and add or remove a rubber during a pit stop. The spring rubbers (actually they're polyurethane) are made in a variety of rates (much like bump stops) and in various section lengths (quarter, half, etc) with a lanyard attached for easy yanking. A typical spring rubber might have 15 - 25 lb effect on spring rate as measured on the bench with some progressivity. One common way to employ spring rubbers: start the race with a rubber in the right rear, planning on removing it later as the track tightens up -- it being quicker to remove a spring rubber than to install one.

Between the spring rubbers and the bump rubbers, you have to wonder how close they are at times to polyurethane suspension.

[McGuire]

my friend Kenny is from the school of hard knocks, not book learning. Every couple years he would trade in his old truck and get a new truck, which he would immediately lower. He liked that lowrider look, a couple inches lower than stock but not slammed. One day I asked him about lowering, I knew about lowering a rear with leafs but I didn't know how he lowered the front, I asked if he bought a lowered spring kit, or a raised spindle kit. He looked at me like I was crazy, told me he just crawls under the truck and heats up the spring with a torch, he knows by the color when to quit and the weight of the truck makes the spring sag as it cools. Yikes.

Apparently the knocks have not been hard enough so far to impart the required lesson. Perhaps he drives slowly and avoids potholes. A torched coil on a spring will eventually collapse completely onto the coil below it -- Mother Nature guarantees it. Sure, I've done it, but only on cars I knew were never going to be driven.

[cheapracer]

1 You are correct.

2 Probably the saving grace of your modifications was doubling the front bar.... That would at least increase understeer (push) & help to protect punters from possible consequences of the other modifications.

1 Yes I knew that before you posted, the have done's and haven't done's are often easy to spot.

2 Did you not understand that solid bushing the main leaf eyes increases the anti roll at the rear of the car helping to balance the extra at the front?

Lee - I have seen a number of 'reset' leafs break or the eyes unwind but not originals, not to say you haven't. Of course I greased the bushes occasionally and they were fine for the 5 years I ran it. Standard shackle bushes. Spacer tube length is independent to the car I have found. Pedders you say? The front struts in this famous Pedders car here have my finger prints all over them and a little more complicated than 15 weight oil ;)



If you reread your post you will notice a couple of references to spending money, money I simply didn't have for my own selfish interests during that period of time.

[OfficeLinebacker]

Between the spring rubbers and the bump rubbers, you have to wonder how close they are at times to polyurethane suspension.

Indeed. I often wonder if polymer science is where the great teams excel.

[DaveW]

1 Yes I knew that before you posted, the have done's and haven't done's are often easy to spot.

I'm impressed!

2 Did you not understand that solid bushing the main leaf eyes increases the anti roll at the rear of the car helping to balance the extra at the front

I'm pleased we agree on something...

[Fat Boy]

I'm tring to think of a car that has seperate spring shock location on the front and I can't??

All of the 80's and 90's Ford Fox bodies (i.e. Mustangs, etc) had the spring inboard of the strut.

[gruntguru]

Between the spring rubbers and the bump rubbers, you have to wonder how close they are at times to polyurethane suspension.

In the case of the spring stiffeners, whatever resilience remains after they are added to a spring, is supplied mostly by the steel coils that remain unbound, so the suspension is probably still more steel than poly. Can't comment on the type used in Nascar - they may be different.

[DaveW]

In the case of the spring stiffeners, whatever resilience remains after they are added to a spring, is supplied mostly by the steel coils that remain unbound, so the suspension is probably still more steel than poly. Can't comment on the type used in Nascar - they may be different.

NASCAR: The result of giving an unlimited budget to graduates of the Cheapie School of Engineering (with apologies all round).

My understanding of the use of spring keepers in NASCAR, & an example of clever regulating, is that they are/were not permitted at the start of a race. I added the optional past tense because I suspect that they have become largely redundant (at some tracks, at least) after it was discovered how the make the vehicles work through turns with coil-bound front springs. I believe that one objective of the COT was to discourage that solution, but I think it has failed to deliver, in that respect anyway.

[Kimi on nopein]

I didn't want to lower my e46 but wanted to have stiffer rear springs. So , I bought heavyduty rear springs (same length , .5 mm thicker , 70€) and cut them so that the car's rear end is now in stock height. After 3 trackdays and (very hard) 10k miles everything's still in place and in one piece. They don't fall off when I lift the car . - And the old thing understeers less now

Edited by Kimi on nopein, 31 January 2010 - 09:25.

[McGuire]

NASCAR: The result of giving an unlimited budget to graduates of the Cheapie School of Engineering (with apologies all round).

My understanding of the use of spring keepers in NASCAR, & an example of clever regulating, is that they are/were not permitted at the start of a race. I added the optional past tense because I suspect that they have become largely redundant (at some tracks, at least) after it was discovered how the make the vehicles work through turns with coil-bound front springs. I believe that one objective of the COT was to discourage that solution, but I think it has failed to deliver, in that respect anyway.

At the moment, it's coilbind in Nationwide and bump stops in Cup. As I see it, spring rates are more critical with coil bind and bump stop packages rather than less.

[OfficeLinebacker]

At the moment, it's coilbind in Nationwide and bump stops in Cup. As I see it, spring rates are more critical with coil bind and bump stop packages rather than less.

How so? Or do you mean the spring rates of the polyurethane used in the stops?