bstardchild
Club Retro Rides Member
Posts: 14,948
Club RR Member Number: 71
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Hitting with the stick?bstardchild
@bstardchild
Club Retro Rides Member 71
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OK, let's work with wood. LOL that'll do...... You sound like my dad ;D A standard 'plank' is about 2" thick and it's a bit bendy - cut a bit off the end and it's less bendy - it's stiffer. That's because it's still 2" thick but over a shorter length. It's probably completely wrong from a physics point of view, but you get the idea? Yes (ish) I'm no engineer, and my background in spring chopping is from a looks and not handling point of view, but the theory was explained to me by an engineer and it makes sense to me. Sort off makes sense to me too I'm going to find the old SM article that explains it and gives formulae for working out desired spring rates and lengths to counter-act geometry on different types of suspension. That would be good But back to my issue and my "thoughts" Lowering and uprated springs would have been fine had I had a std Monza GSE but with the weight removed best part of 200 kgs (TBC) So they are stiffer - to me that equals a stringer spring rate and shorter so short that they are hardly compressed by the assembly process....... Trouble is that resulted in a higher ride height at the front - regardless of the handling characteristics of the new springs a rse down and head up doesn't make a happy monza Now if I put the std springs back in it's gonna be just the same if not worse as the springs need to be compressed to get them to fit in so the ride height will be higher or as high due to the lack of weight So I reckoned that if I chopped a coil of the original springs I would get the same rate of compression with a lower ride height as the springs are progressive coils have different distances between them from bottom to top Chop off a coil to compensate for reduced weight and restore ride height
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Mr K
Posted a lot
Posts: 2,993
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got the springs for the kitten from here: www.dfaulknersprings.co.uk/ -- about £50 a pair - any lenth strength or what ever. paul4be: so a 100Ib, 10" long spring.... cut in half is not a 100Ib 5" spring? its a 50Ib 5" spring? surly its not a good idea to heat a spring? as i was taught a springs springy property is made via heat treatment - nad i would have thought heating a spring will destroy this. its all about simple harmonic motion....
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Oh, and if you over do it, your panels will eventually crease, or your 2CV car may snap in half. ;D That was already breaking, the subtle lowering job just emphasised a prior fault. Besides, I didn't even get the grinder near that one! ;D
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paul4be
Part of things
'86 Capri Laser, Frontera 4x4
Posts: 395
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paul4be: so a 100Ib, 10" long spring.... cut in half is not a 100Ib 5" spring? its a 50Ib 5" spring? It's not about spring length, but about the number of active coils in the spring. If you had a spring with 10 active coils and cut it in half, you would actually have a 5 coil spring with double the rate of the original, i.e. 10 coils spring rated at 100lb, cut in half would give you2 springs each 5 coils long and nearly double the rate (about 197lb each). As an example, working with a spring that has 10 active coils, and a rate of 100lb, cutting would give the following rates (roughly): 9 coils left: rate of 108lb 8 coils left: rate of 120lb 7 coils left: rate of 138lb 6 coils left: rate of 160lb 5 coils left: rate of 197lb 4 coils left: rate of 241lb 3 coils left: rate of 321lb There is a proper formula to work out spring rates using wire thickness, spring diameter and number of active coils. Remember, a coil spring is still just a level, only wound into a helix. If you apply a force to the end of a lever of specific length, the lever will deflect a given amount. If you apply the same force to a shorter lever (of the same material and thickness) the deflection will be less. In order to acheive the same amount of deflection with both levers, a greater force is required to be applied to the shorter lever. This is why cutting a linear rate spring increases its effective rate.
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Last Edit: May 7, 2006 22:42:09 GMT by paul4be
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bstardchild
Club Retro Rides Member
Posts: 14,948
Club RR Member Number: 71
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Hitting with the stick?bstardchild
@bstardchild
Club Retro Rides Member 71
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OK now I'm getting it............
So my std springs if I remove a coil will
1. lower the ride height 2. increase the spring rate (ie stiffen the spring rate)
So I get a lower ride height and and a stiffer ride
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Mr K
Posted a lot
Posts: 2,993
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OK now I'm getting it............ seconded
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paul4be
Part of things
'86 Capri Laser, Frontera 4x4
Posts: 395
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Yes if it is a linear rate spring. Are your springs the same overall diameter for their whole length with equal coil spacing and wire thickness?
Depending on your spring seats, you may have a problem seating the cut end.
If so, it is possible to heat part of the end coil once cut and flatten it to create a dead coil for the seat. This won't heat the rest of the spring enough to affect the temper of the spring steel. You need to work out how many active coils you need to end up with.
I am not saying cut springs are the best way to do things, just trying to help with the questions asked.
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Wagoneer, when you cut the fronts on the 240, did you heat and reshape the cut ends, or just grind smooth at the cut? No heating required, we just kept the ends clean as they sit in a recess in the top spring cup.
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Peugeot 307sw - Suzuki SV650S - MX5.
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bstardchild
Club Retro Rides Member
Posts: 14,948
Club RR Member Number: 71
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Hitting with the stick?bstardchild
@bstardchild
Club Retro Rides Member 71
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If the spring is a linear rate spring and not one of the wierd and wonderful rising rate springs, then the spring rate does indead increase with the amount you chop off. 2 coils of a 10 coil linear rate spring (20% length reduction) will see an effective rate increase of 20% over the original rate. Hmmm they are what I can only describe as progressive from memory. Coils at the top of the spring are closer together and then they gradually expand the gaps as they go down I was intending to cut off one of the coils at the big gap ends as I think this will still leave me with a slighty soft ride untill the close coils go coil bound......... Alternatively I suppose I could cut off a couple of close coils....... then I would end up with a spring rate which was more linear?
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paul4be
Part of things
'86 Capri Laser, Frontera 4x4
Posts: 395
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No heating required, we just kept the ends clean as they sit in a recess in the top spring cup. Thanks, had thought that when I looked when everything was in bits to replace the strut top mounts. Was going to buy front springs, but may chop these instead and save the money.
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bstardchild
Club Retro Rides Member
Posts: 14,948
Club RR Member Number: 71
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Hitting with the stick?bstardchild
@bstardchild
Club Retro Rides Member 71
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New Uprated and lowered springs (in Red)Old Std Springs in Black (Well rust)As you can see the new springs are a lot shorter and also thicker wire in the coils (this may what is having a big effect) Now I think i was wrong with what i posted earlier they aren't progressive or variable rate so I guess cutting is an option I think that 1 coil is all I can remove before the sping would be loose in the shock when you jack up teh car and the wheels are off the ground
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Seth
South East
MorrisOxford TriumphMirald HillmanMinx BorgwardIsabellaCombi
Posts: 15,538
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Just a quick comment as I have little to add to what's been said but if you are going to cut coils you don't HAVE to cut a whole coil off. You could try taking half a coil off to start with bstard.
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Follow your dreams or you might as well be a vegetable.
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bstardchild
Club Retro Rides Member
Posts: 14,948
Club RR Member Number: 71
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Hitting with the stick?bstardchild
@bstardchild
Club Retro Rides Member 71
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Just a quick comment as I have little to add to what's been said but if you are going to cut coils you don't HAVE to cut a whole coil off. You could try taking half a coil off to start with bstard. Err maybe thats the case on some cars but on the Monza actually I know I do have to..... The top and bottom spring seats are in a fix orientation - if you turn the top one so the spring sits in the dent with a cut coil and the caster is changed Whole coil or nothing at all But you had a valid point I'm sure for cars without location recesses in the top and bottom spring seats and fixed geometry
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Seth
South East
MorrisOxford TriumphMirald HillmanMinx BorgwardIsabellaCombi
Posts: 15,538
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Ah, OK. Fair enough. I guess all cars have their quirks. I thought the coils looked like they didn't have particularly flat ends. I'm used to simple BMC stuff with flat and ground ends - like a biro just bigger
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Follow your dreams or you might as well be a vegetable.
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bstardchild
Club Retro Rides Member
Posts: 14,948
Club RR Member Number: 71
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Hitting with the stick?bstardchild
@bstardchild
Club Retro Rides Member 71
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Ah, OK. Fair enough. I guess all cars have their quirks. I thought the coils looked like they didn't have particularly flat ends. I'm used to simple BMC stuff with flat and ground ends - like a biro just bigger Yeh they don't have flat ends at all but thy do have shaped seats to take a round coil in a definative position with the correct orientation - but like I said valid point to raise and it might help someone else and thats what it's all about so thanks for that
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Hitting with the stick?BenzBoy
@benzboy
Club Retro Rides Member 7
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OK, here's a question... I've cut the coils on the Merc without a problem, but these had 3 or 4 dead coils (tightly wound) at the bottom. So when I lopped off a couple, the final coil was still more or less at 90 degrees to the spring. This meant it would sit in the wishbone cup nicely, just as before. Now, with springs like bstardchilds, I notice there are no dead coils - if you chopped off a coil or two the final coilwould be at a different angle than the standard spring... wouldn't this mean that the end of the spring would just stick into the spring mount instead of most of the coil? I always thought on those applications the spring had to be heated and bent back to a shallower angle to seat in the cup (which weakens the spring)
Is this the case? Or have I got it all round me neck?!
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Last Edit: May 9, 2006 9:11:09 GMT by BenzBoy
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All very interesting, I'm facing 2.5 Stick hitting jobs, yes i want em all doing! The Sapph yeah its ok cos its still quite new, however it sits summat like 25mm above a Cossie, so ford must think that the Cossie height is better. And the thing really wobbles about when pushed! Next question: how easy is a DIY lowering job do you need spring compressors or summat? And has anyone heard of clamps to keep on the spring to keep it lower? My mechanic mentioned em to hold the 3 door down a bit...
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it doesn't matter if it's a Morris Marina or a Toyota Celica - it's what you do with it that counts
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big job (only example on PB at the mo) 10 cm!
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it doesn't matter if it's a Morris Marina or a Toyota Celica - it's what you do with it that counts
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And has anyone heard of clamps to keep on the spring to keep it lower? My mechanic mentioned em to hold the 3 door down a bit... IMHO a very bad idea, & IIRC, also illegal.
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