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Dec 30, 2004 15:25:00 GMT
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Okay you can lower your car by cutting your springs, you can lower your car by getting shorter/higher rated springs.
Can you lower you car by fitting springs from another car. What are the issues you need to overcome to get this to work nicely. I'm guessing spring radius/length/rating will need to be taken into account. So how do you go about finding out this info and evaluating it?
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Dec 30, 2004 20:00:52 GMT
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the spring and shocks on the back of the viva are caravan springs so yeah but: i would say if you still wanted a 'nice' ride get some aftermarket lowering springs which are designed for that car. a spring isn't just a spring, they have loads of different specs for example you could match a spring from say a panda to a punto with the same OD and say 1" shorter which would fit but one may be much much stiffer or vise versa which would give a terrible ride. and don't just think that the number of twists in a spring determins the springeness, theres different materials used which have different properties.
I'm only saying all that because I'm an engineer and i have been taught all that. I'm sure a few of us have cut springs/swapped them with different cars and its worked fine.
as for finding the rating of springs out i cant tell you until i go back to work and can get my engineers bible out but i think retro cars had a section on it a few months ago
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Assumption is the mother of all f**k ups
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Dec 30, 2004 20:05:02 GMT
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december 03 issue
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Assumption is the mother of all f**k ups
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Dec 30, 2004 20:39:16 GMT
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I'd have thought that if you swapped springs with a car of similar weight you'd be halfway there really. As long as the spring diameter is the same, and also you have to consider the spring seat on the damper / wishbone - some are shaped to accommodate a "pigtail" whilst others are flatter. Then like Oldskool said you have the spring rate to consider, and then some springs are progressive rate coils and some are not.... I think it has been done in the past, and I have some Sierra rear springs which are intended to go on the back of my Merc should I ever wish to lower the back end - not sure if it'll work but I'd give it a go!
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Dec 30, 2004 20:42:18 GMT
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Don't even think about cutting the springs!
You need to know the inside diameter of your standard springs, the unloaded length, the compressed length at rest and the rate. The latter three figures are important if you need to work out what your finished ride height will be. Given those three specifications you can work out how much the spring is preloaded when fitted. Lets say you have 100lb/in springs that are three inches longer free than when fitted to the car. There is therefore a load of 300lb on the spring with the car at rest. Lets say you want the fitted length of the spring to be one inch less and you've decided that you want to upgrade to 120lb/inch. In this case you would need your springs free length to be 1.5 inches shorter than your old spring. That is to say take the 300lb compression, divide it through by the spring rate to get the distance the spring will be compressed. Now add this to the desired compressed length and hey presto.
Remember when lowering the car that you are reducing the amount of available travel. If you don't want your car to bottom out pretty catastrophically then you need to make sure your new spring rate is high enough. How long would the spring be with the shock on the stops? Based on it's standard rate you can work out how much force it will take to get it there. Make sure that with your new spring at the same length it will take the same or more force to get it there. When a car hits the bump stops it can cause the handling to become dangerously unpredictable, it can even damage the shocks or other parts of the car. A friend had a mini that regularly bottomed out at the rear, until the arches parted company with the boot floor.
As you can see from the above finding a spring that fits the bill on another car would be fairly difficult. Buying a spring to your specifications from somewhere like DemonTweeks would be a much better bet.
But it's not even that simple. On some cars the rate of wheel movement to spring compression can change with travel so things may not work out in quite the simple linear way I've described. And then there are those cars that don't have linear rate springs, that is to say the spring rate changes with compression.
Of course uprated springs are going to mean your damping needs have changed. If you're lucky your standard shocks or inserts can be revalved. However ideally you want adjustable shocks/inserts so you can tailor the damping, in which case you really need seperate compression and rebound adjusters. Also shocks/inserts are available with different length rods in order to alleviate the bottoming out problem.
As you can see from the above doing a lowering job yourself is pretty complicated and potentially expensive. Buying a lowering kit comprising shocks/inserts and springs from a good manufacturer or supplier can save you one hell of a lot of grief.
If you really favour a DIY approach bear in mind that a car on new springs will tend to settle a bit over time. So if your car looks dead right the day you do the job you may find it's too low after a couple of weeks.
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Dec 30, 2004 20:45:38 GMT
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The front springs on the Sceptre are from a Superminx, which were longer than the Sceptre ones, they've been cut down to the same length, but being softer have lowered the car.... only did it like that because I wanted to use some 'spare' springs in case it went tit$ up..... got the complete Superminx front clip for free ;D The Sceptre, Minx, Superminx, Alpine Ect all used different length springs, unfortunatly the Sceptre has the shortest ones anyway...... It would be VERY useful to find details of spring lengths/dimensions for different cars..... I seem to remember that 'Custom Car' used Mercedes springs on their project PB Cresta.....
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... the only injury I sustained was a bumped head when I let the seatbelt of without realizing the car was upside down and that's not really the car's fault.
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Dec 30, 2004 20:45:43 GMT
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Don't even think about cutting the springs! does this count if you're going for maximum droppage pimp cruiser style, rather than as a performance mod?
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Dec 30, 2004 20:53:36 GMT
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I've cut the spring on my Merc - I wouldn't really recommend doing it if you want to use the car aggressively as it is a bit of a hit-and-miss affair as regards the changes to the cars handling characteristics / spring rate/ ride height etc... (although mine seems to handle better). But to look good, it's a cheap route to go down! If there were lowering springs for my car I'd have bought them but nobody makes any
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Dec 30, 2004 20:53:48 GMT
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Sorry, I don't understand this bit........ ;D ;D ;D
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... the only injury I sustained was a bumped head when I let the seatbelt of without realizing the car was upside down and that's not really the car's fault.
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Dec 30, 2004 21:58:15 GMT
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what devilsadvocate said!!!!! ;D at some point a previous owner of my 411 has messed about with the springs to lower it.the result-a nice low looking car. ive had some dodgy handling cars in my time but this takes the biscuit. the only time the wheels don't foul the arches is when its empty.if youve got two adults in it you can only go in a straight line.it bottoms out if you drive over an empty crisp packet.the drivers side wing has un-bolted its self and now flaps about and it wobbles along like a half set jelly. ive sourced some springs in the states.when they come I'm going to send one off to a place called race engineering to see if they can make a lowered version suitable for the car. I'm sure not all cars would be the same, and you might find you end up with good results. I'm going to do to my merc what benzboy has done to his.cos you cant get lowered ones of the shelf.
benzboy....don't worry mate i wont try to sue if it all goes breasts aloft ;D
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SkoCan
Posted a lot
Quando omni flunkus, mortati
Posts: 1,916
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Dec 30, 2004 22:22:42 GMT
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I think devilsadvocate just gave me a headache
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Dec 31, 2004 11:39:25 GMT
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When it comes to cutting springs there are all sorts of problems, the greatest of which is the legallity. Plod don't like it, MOT men don't like it and insurance companies don't like it. With the latter you have two options; firstly tell them you have lowered the car by cutting the springs, you may be OK or they may hit the roof; secondly don't tell them and hope you never have an accident. Trouble with undeclared modifications being that the insurers will often use them as a reason for not paying out, not something you want to happen when you have put a lot of time and money into your P&J.
One technical reason not to cut springs is to do with the way the spring meets the seat. If you are lucky you have a seat which is shaped to the spring, in which case if you cut the spring directly below it's original end it won't cause a problem. If however your springs are flattened at the end in order to put the load 360 degrees around a flat seat then you will not be able to cut the spring to get the same end result. You would end up with a point load on the spring seat/platform which could break the platform with very nasty consequences. I have heard of people using a welding torch to bend the spring so they end up with a flat end similar to the original. This is potentially worse, in heating the spring you are altering the properties of the metal itself and introducing problems with stress concentration which could lead to a broken spring. Of course you could stress relieve the whole spring, if you had the necessary equipement like a big oven that could heat the whole spring intil it was cherry red.
If you have flat spring platforms then you can buy lowering springs. All you need is the specifications mentioned in my original post and a good supplier such as Demon Tweeks. If you don't have flat platforms then try making some up, it's a lot better than using cut springs. For some cars you can even buy a kit to convert to flat platforms.
If we are dealing with a car with suspension other than macpherson strut or coil overs then you can often buy kits to convert to coil overs. Even if you can't get such a kit you can often do a good DIY job. A nice set of coil overs with adjustable spring seats will allow you to adjust your ride height to your hearts content.
I know you can buy coil over conversion kits for a Mini, but they always seem a bit expensive. When a friend wanted to convert his mini we shopped around for the necessary shocks (2 different suppliers front and rear), springs (another supplier) and made our own bracketry. The end result was a 1/3 saving on the cost of a full kit.
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Dec 31, 2004 14:22:15 GMT
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I looked into doing a coilover conversion on my Merc. The problem I have is that the spring sits between the lower wishbone and an upper crossmember. The damper is separate and attaches to the inner wing. I did look into adapting it to a coilover setup but I wasn't really too happy with placing the coilover assemblybetween the wishbone and the inner wing, as I'm not too sure how much load they are designed to take . I could weld in turrets and strengthening but it's a helluva job to get it right - I'd have nightmares of the dampers ramming their way through the bonnet! ;D My other option was to find some very small coilover dampers that would fit between the wishbone and the crossmember in direct replacement of the original spring, but I couldn't find any small enough. I dare say a Mini conversion kit would be about the right dimensions but of course they're designed for a Mini and not my heavy old beast! The dampers wouldn't cope even if I used the correct rate coilover springs. Fortunately my spring seat is shaped to fit, and the lower three or four coils are tight together (unlike some which are shaped at the bottom). My cut springs just seated as they did originally. I've heard of people heating the springs whilst they're on the car (!) to lower them, but that could get really messy, and how you'd get both sides to compress by the same amount I don't know! Plus as devilsadvocate said, you then have a weakened spring. tonycocacola - thanks for not suing me! ;D At least if it doesn't work you can get off-the-shelf lowered springs .
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Dec 31, 2004 15:59:05 GMT
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benzboy...where do you get lowered springs for my 123?ive phoned a couple of places and heard the whole office laughing in the background. lowering the back is no problem cos its self levelling and ive come up with a nifty idea to make it fully manually controlable ;D,rather than working off the anti roll bar.until i get the front end in the weeds theres no point messing with the back. when its low its gonna look amazing with the 16 inch pentas on.especially once they're blinged up. ;D
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Dec 31, 2004 16:01:21 GMT
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When it comes to short coilovers you could do a lot worse than look at a bike breakers. Some bike rear shocks are very short, and because of the very high ratios involved deal with some pretty heavy loads. Whereas the springs used on cars tend to work at closer to 1:1.
Actually the Mini kit wouldn't suit as they are pretty long shocks.
The Mini conversion I favour uses much shorter shocks that fit into the front turrets vacted by the rubber cones.
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Dec 31, 2004 18:23:36 GMT
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tonycocacola - the W123 springs I found were by P.I. (I think!). I had to brace myself and go into one of those barry boy "tuning shops" - you know the sort... carbon-fibre look junk in the window, the odd poster of a bird draped over a tragic looking Paxo. My brain has gone dead at the minute... but I think there's a downloadable catalogue from Spax which do a whole load of lowering springs for classics including Mercedes. The chumps that were laughing were probably only trying to hide their limited knowledge beyond Paxos, Corsas and other tin-box junk they flog bits for! Can't wait to see pics of your Merc... with it having self-levelling rear suspension, I assume it's an estate? That'll look excellent! Devilsadvocate - great thinking on the bike shocks! I'm gonna need some beefier suspension when I shove the V8 in there so that's definitely something I'll look at. I really want to use the existing mount points as I know they're strong enough, and I don't have to give myself headaches regarding geometry!
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Dec 31, 2004 20:05:40 GMT
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thanks il look into that ;D ;D yep shes an estate.i specifically picked it cos theres plenty of room in the back for stereo .its big enough to camp in .successfully had many camping missions with my ex(but thats another story) ;D.and we'll have no witty comments off mrsigma and mantamad as to how the rear of it collapsed. ;D thats all sorted now.had a bit of a mare trying to find info on how to sort the self levelling.all anyone could say,even the haynes was take it to a dealer. bit the bullet and took it to bits anyway to find its the simplest thing in the world to work with . the only bother I'm having at the moment is that one of the pipes has corroded and its leaking fluid . so theres another job to add to the list. i was thinking about selling her to buy a 230 coupe but ive changed my mind,again. man,I'm so indecisive
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Dec 31, 2004 20:33:17 GMT
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MOT men don't like it and insurance companies don't like it. With all respect, if an MOT man is doing his job properly he is not concerned if a spring is modified..... his job is to test a car within the framework of the MOT regulations, not enforce the construction and use regulations...... True story.... guy gets pulled by the plod in his fenderless rod and given a producer and told to take it for another MOT, which he does.... and of course it passes without fenders because nowhere does it say in the MOT regs 'thou shall have fenders'....... if it had had fenders and they'd had sharp edges or were flaping about, different story..... As far as insurance goes, companies either insure you or they don't.... if you declare the mods you've done there shouldn't be a problem. If they 'don't like' a particular mod they won't insure you.....
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... the only injury I sustained was a bumped head when I let the seatbelt of without realizing the car was upside down and that's not really the car's fault.
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True story?
Plod don't tell people to take cars for MOTs because, as plod are very fond of telling us, an MOT certificate does not prove or imply legality it only shows that a car is road worthy. Plod have vehicle inspection specialists, if you get stopped for a possible breach of C&U there are two ways it will usually go. If the breach is obvious then you will have to present the car with the breach corrected within seven days. If the breach is not obvious then you will get an appointment with the force's own vehicle inspectors. If you're really curse word them off they might even call in mobile vehicle inspection unit.
Also broken, damaged or poorly mounted/secured springs are definitely an MOT failure. A spring that doesn't interface with the seat correctly would count as inproperly mounted or secured and would get you a fail.
A friend of mine lowered his mini so far that the top arms were contacting the bump stops at rest. It failed the MOT on the grounds that suspension operation was impaired.
It's surprising what things are ignored by the MOT test and what things are picked up.
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........Also broken, damaged or poorly mounted/secured springs are definitely an MOT failure. A spring that doesn't interface with the seat correctly would count as inproperly mounted or secured and would get you a fail.
In total agreement with you there..... however, modifying a spring does not make it "broken, damaged or poorly mounted/secured" ....... if it has been shortened and not had the end re-shaped then yes, it could fail for the reason you give, however a shortened spring is not IN ITSELF a reason for failiure. In fact the MOT tester could not be expected to decide if a spring has been shortened.
The point I was trying to make is that there is a world of diference between the MOT regs and the construction and use regs.... my Sceptre quite rightly passed it's MOT without a working speedo, because it's not a testable item, but I was still breaking the law.....
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Last Edit: Jan 1, 2005 15:36:24 GMT by mattblack
... the only injury I sustained was a bumped head when I let the seatbelt of without realizing the car was upside down and that's not really the car's fault.
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