Lotus Europa Community
Lotus Europa Forums => Garage => Topic started by: Nukski on Monday,April 13, 2020, 05:20:09 AM
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Hello, mar car ride height is almost 1" Lower on the passenger side but the coil over shock spring is already raised more than that amoint apposed to the drivers side. This causes a slightly softer feel to right hand turns vs left. The lenght of my spring on the passenger side is also 3/4" shorter on the passenger side. Is this a worn spring problem? Thanks to those in the know.
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:Welcome: Nukski!!
Springs don't wear but they can collapse but that is rare. Regardless what happened, you need new springs. Do you know anything about your springs such as the rate, where they came from? I would be tempted to change them all so that I was sure I knew what I had.
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Hi Nukski!
:Welcome:
Mark
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Thanks BDA,
The PO had installed Spax adjustables all around. They now have 15k miles on them. Springs were changed at the same time. The fact that I have to adjust the Spax very differently to get any semblance of equal ride height is what led me to the question of springs condition. May make a good Summer project.
Is there data on correct Springs for S2 ?
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How long have you had the car? Was it like this from the beginning? Is it the front or rear springs that are unequal?
I just wonder if the PO assembled something incorrectly when the new shocks were installed. Perhaps if you could post a few photos of the relevant suspension bits and coil-overs then that might reveal something.
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I'll second gideon's request for pictures. We really like pictures here! :)
I can't speak to the S2 but I imagine they would respond to springs similarly to the TC. There is a wide variation in spring rates used by owners. A lot depends on what kind of driving you intend to do. I would give a call to Dave Bean or Ray at r.d. enterprises for advice. I might lean toward Dave Bean because of their history of past development but I wouldn't be surprised if they both had similar advice. They will likely advise stiffer springs than stock in which case you should be prepared to adjust the shock stiffness to accommodate them. Again, their advice will be useful.
Basic rules for shocks:
1) before you monkey with the shocks, make sure your alignment is correct
2) general instability or vagueness in feel, even on the highway indicates the shocks are not stiff enough
3) stiffening the shocks increases the roll resistance which affects over/understeer
4) stiffening the front shocks will tend to increase understeer, stiffening the rear will tend to increase oversteer
5) shocks that are too stiff will not allow the tires to remain in contact with a bumpy road.
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A couple of questions....
Where are you measuring your ride height; the wheel arch, bumper height or underneath the chassis ? Bodywork measurements can be deceiving although they are good for comparing changes on the same car when you're modifying. Chassis datum points are probably your best bet ?
Secondly, is the 1" difference the same at the front & rear or just one end ? to have a 1" lower ride height coupled with an extra 3/4" compression (hence pre-load) on the spring at that side is odd.
15k is no mileage for a spring, I'd be very surprised if they're anything other than their full strength and unladen lengths at that age. I would look at the rubber bushes though, one of mine collapsed at an early age.
As the others have said, photos of what's concerning you would be good....
Brian
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Thanks All, for your quick responses.
I have had the car for along time and always wondered why the Spax were adjusted at different heights on the front.
I am measuring at the bottom of the body wheel arch to the ground.
The rear springs are also adjusted lower on the passenger side by about 3/4" at the wheel arch. The rear springs seem soft only because I can see they rub the Spax paint off in certain places, and I creak a little when slowly going over bumps(i.e.- turning into the driveway at an angle).
I'll try to post some photos.
Possibly time to re-bush and remove the Spings to see if they have equal strength.
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If the PO installed them then it may be worth loosening the suspension bolts and retightening them as per the workshop manual - could be that one side has been tightened up at something like full droop whilst the other side has been tightened with some load on the suspension.
It’s a bit of a long shot admittedly but if everything else looks to be correct then it’s worth checking before you start disassembling and swapping parts out.
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Ok, pulled the first Spring Spax coil over. It measures 10.5" in free length so it seems this was a height lowering installation years ago. Will try to pull the other side so I can measure the springs side by side.
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It looks like the PO cut your springs. That's not optimum... It shortens the springs and raises the rate. So if he did cut it, did he cut both the same so they would be the same rate? It's not an uncommon practice and whoever did it may have known what he was doing but I wouldn't assume that.
I can't say for sure but the little I can tell from your picture, you probably should get some new springs. Compression springs for coil-over suspensions are commonly squared and ground meaning the last turn is "closer" than the others and the ends are ground flat. Your spring just stops in mid coil. That's why I suspect it was cut.
I would check into new springs from r.d. enterprises or Dave Bean. They may have different ideas of the proper spring rate so it would be worth a call to each of them. There are some good places in England for springs (and shocks) as well (eg. SJ Sportscars, Europa Engineering) so you can check with them too if you want.
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Agree with BDA.
The spring seems to have been cut. It also appears to be distorted on the left hand side unless that an optical illusion.
Luckily, new springs are inexpensive.
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Yep, that spring has been shortened, and not very well either because that's not going to sit evenly on the platform. It looks to me as if someone's just taken a grinder and lopped off a coil or two.
The good news is that, as has already been quoted, new springs are cheap. That would be my preferred option although if you want to play around first, it's certainly possible to recover the spring.
First off, unless you've got a method to test the spring rate of your shortened spring, you can always calculate it instead. Very simple to do but you must be accurate on the coil & wire diameters, plus number of coils. The formula is in the first attachment. This is worth doing because it will give you some idea of what you've been riding on and let you decide if you want to go harder or softer with a new spring.
If you decide to experiment with what you've got (you might as well) then I'd try to get them looking right first. The second image shows my springs as received and after shortening. It's not very clear on the lower image but basically you need to bend & grind the wire where you've made the cut and flatten it so it's like the original spring, which is clear on the top image.
You can't do this without heat and the danger is that you'll heat up too much and lose the temper in the first active coil. I don't think it makes much difference on half coil you're flattening, but if you get heat further down then I'd reckon that's not good. It's easier than it sounds but you need a directional heat source and I usually wedge wet rags & a bit of stainless to deflect the heat away from where you don't want it. It goes easily if you grind both sides of the last 1/3rd of the coil in a gradual taper so that when you bend it to the first active coil, it sits neatly in place. You can see this on the "as received" image.
It's definitely the Brian School of Bodging, but if you want to experiment with a slightly higher coil rate then it's fine for learning. And you can always buy a new spring at the rate/length you decide is best after you've played about. That's exactly what I was doing there, I bought a slightly softer spring (still higher than OEM), drove it and then modified it one coil at a time, adjusting the platform to get the ride height the same. It was cheaper than buying 3 sets of springs and throwing 2 away !
Brian
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Thanks Gents, for your input.
The picture I sent was not very clear but the PO did grind the end of the spring cleanly. Also when I first compressed the spring to remove from the shock it appeared to be slightly distorted, then as if by magic, it was perfectly straight again this morning.
I am working with the formula that EuropaTC sent because I would like to estimate what the PO had installed before I order new. The car was very firm on the road so I suspect something more than the original 100 lbs.
Regards,
Bruce in NJ
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If the spring is still squared and ground on the other end and you really want to know the rate, I would work up a rig with a bathroom scale and a ruler. Brian's equation will get you close to the rate but I didn't see where it accounted for the squared and ground end. One of my engineering books says to take off two coils for ground and squared springs but I tried to calculate the rate of one of my springs and wasn't satisfied with the results (sorry I can't provide details, it was some time ago).
To test the rate with a bathroom scale, you need two pieces of metal or wood that won't bend under the pressure of your spring, two pieces of threaded rod long enough to go through both pieces of wood or steel, the scale, plus a bit longer than your spring. Basically, you are building a clamp around the scale and the spring. Tighten the clamp evenly to generate some pressure on the spring and note the reading on the scale. Then tighten the clamp, evenly again, compressing the spring one inch further and note the scale reading. Your spring rate in pounds per inch is the second reading minus the first.
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Brian's equation will get you close to the rate but I didn't see where it accounted for the squared and ground end. One of my engineering books says to take off two coils for ground and squared springs but I tried to calculate the rate of one of my springs and wasn't satisfied with the results (sorry I can't provide details, it was some time ago).
I'd love to take credit for those sums, but I just copied it from a book....
As I understand it you only consider active coils so you ignore the first loop at either end which contains roughly half a coil of flattened steel. I generally count up the lot and take off 2.
It is critical to get the number of coils even down to part coils - for example you could have 10.5 active coils, don't round it up to 11 or down to 10. The more coils you have the lower the error you have because it's the bending over the whole length of the wire - think of it as unravelling the coils into a straight rod. If you've only 10 coils then you've a short rod so 0.5 would mean 5% but on 20 coils it's obviously a lower error.
Taking ito account the part coils, the equation has been fairly accurate when I've checked against new, known springs where it's easy to get an accurate measurement of wire and coil diameters. Not perfect, but good enough within a few %.
Brian
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Brian, I in no way meant to be dismissive of your equation or post. (I think you know that.) I was only relaying my experience. If the spring does not have squared or ground ends, the calculation is very straightforward.
I won't quibble with your assertion that your calculation is close. I only remember that I was disappointed with the calculation I did and I really don't remember much beyond that such as how far off I was or how I counted the coils.
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Brian, I in no way meant to be dismissive of your equation or post. (I think you know that.)
No BDA, I didn't consider your comment as negative, I actually thought you were giving me credit for the maths equations.... which may have been possible many, many years ago but is sadly so far beyond me now that I'd consider such an equation as "magic" :)
The problem I found with cross checking calculations vs measurements was being very critical on measuring the wire/coil diameters. I played about with a spreadsheet going slightly up or down with the numbers and it can make a heck of a difference, much more than I thought at first. In the end, like all the other sums I've done on suspension & brakes I treat them as comparative rather than absolute and just to give an idea of where I'll end up. (and if it's likely to be a disaster !)
Brian
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I'm glad you didn't consider it negative!
I know what you mean about equations! When I go to refresh my mind on simple engineering equations, I get lost very quickly! I think to myself, this used to be so simple! :headbanger:
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Thanks BDA,
For the additional test method. I used Brian's formula and got 103 lbs which makes sense because 100 was the factory spec. It would be logical that these springs were likely cut down from factory 16 coils to the current 11 coils.
But now that I got the second shock off I see that the one with the perch adjusted all the way to the bottom(drivers side) has a free length 1/2 inch longer(see pic).
I'm going to take advice of most on this thread and order 2 new front springs of known quantity. Ray from RD Ent. was very helpful on the phone so I'll go with his recommendation, 10 inch @ 115 lbs. Just hope it does't lower the front too much since the current ones are over 11".
Will let you know how it works out.
Bruce
70' Europa 0318R
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If the PO cut 5 coils from the original springs the new rate would be significantly higher than the stock rate (possibly in the neighborhood of 30% higher). Of course, that's somewhat academic now since you're going to order new springs. 10 inch springs shouldn't lower the front too much and if it does, you can raise it by adjusting the spring perches higher.
Do you know if the shocks have been adjusted (likely stiffened)? I think I mentioned earlier that with stiffer springs, it might require an increase in shock stiffness. It would be helpful to know the "click" adjustment. But driving and what you are comfortable with is what will determine how to adjust the stiffness of your shocks (see my earlier post concerning basic rules for shocks.
While you're waiting for your new springs, you might take a look at your rear springs. Then when you get the front shocks and springs back on your car, you can think about what you might need to balance the car. Softer rear springs will tend to decrease oversteer (and increase understeer), harder rear springs will tend to increase oversteer (and decrease understeer). This is relative to the springs in the front so, for example, if your rear springs are stock, you would likely have more understeer. You'll have to take some corners pretty hard to get a feel for how the balance is. You may decide that you want new rear springs, too. You should also see how it handles on the highway. If it feels like it wants to wander on the highway, stiffer shocks would likely help that condition.
Good luck and let us know how things go!
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Hi again Bruce,
Well, you've got to the bottom of that little problem, there's certainly something adrift with those springs !
I think BDA is right though, you'd expect more than 3lbs from a 5 coil reduction so either the previous owner didn't start off with original springs or there's something else wrong. For reference I ended up taking 2 coils off mine and they went from 140 to roughly 160lbs. (the calcs were 141lbs as received, 159lbs modified)
10" will be fine for ride height with adjustable platforms, mine are 9" albeit with a much higher spring rate.
From the manual the standard S2 is 100lbs so 115lbs is closer to the TC spec, but the extra poundage won't make a dramatic difference because it's working at an angle which reduces the leverage. Looking at the manual the standard S2 rear is 72lbs against 75lbs for the TC with it's slightly different weight distribution so I reckon it's good advice from Ray, it should work fine with adjustable dampers.
But while you're going to the trouble of sorting out the front I would think seriously about BDA's suggestion of rear springs.
Again they aren't expensive and you will have the peace of mind in having a matched set. If the DPO cut those front springs I wouldn't have any confidence that the rears were standard. And there's nothing worse than a Lotus with duff suspension !
Brian
(you'll note how quickly we on this forum are to spend your pocket money on cars ;) )
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Brian: You say "From the manual the standard S2 is 100lbs so 115lbs is closer to the TC spec, but the extra poundage won't make a dramatic difference because it's working at an angle which reduces the leverage. Looking at the manual the standard S2 rear is 72lbs against 75lbs for the TC with it's slightly different weight distribution so I reckon it's good advice from Ray, it should work fine with adjustable dampers."
I'm a little confused. You're mentioning two numbers that are associated with the TC, 115 lbs and 75 lbs. What are those? Front and rear, respectively? (I admit I haven't tried to look; I'm just responding to your post).
And while you're discussing springs, how do you all remove them from the dampers? Brian?, Bruce? Others?
I'm anticipating getting into this down the road, and I don't want to buy tools that won't work. Might as well benefit from your experience and knowledge.
Vince
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Yes the TC spring rates are 115#/in in the front and 75#/in in the rear.
The front springs require some creative methods to compress them to take them off. Some have used ratcheting straps to squeeze the interior coils so you can take the spring off (didn't you show pictures of the springs off your front shocks?) There is a keeper or collar at the top with a cut through it so you can take it off the shock. When the springs are compressed enough, you'll be able to take the keeper off.
I've posted pictures of my spring compressor. A long time ago, I had steel plates cut for a compressor design based on the stock shocks and springs (which you are unlikely to encounter now). I just adapted it for using the smaller diameter springs we use now. I use threaded rod with a threaded union. It's been a long time since I built it so I don't remember how I made the hooked parts. They are obviously not completely threaded. The red stuff is the stuff you can buy to dip your pliers handles in to cushion them. I used this so as not to scuff up the paint on the spring. You could file or grind the threads off a section of threaded rod to replicate that part. It's pretty obvious how it works. The bottom of the stock goes in the hole in the plate, the hooks hook to the coils near the top of the spring. I think I used the threaded unions because my threaded rod wasn't long enough. Other than the plate, you should be able to find everything at a hardware store and you could probably replace the plate with something else from a hardware store too.
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+1 on BDA's suggestion to disassemble and check the rear springs as well. One lister had uneven front ride height and the problem was traced to the rear springs.
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I'm a bit late responding and I see Jim's already sorted out the confusion on spring numbers.
As for fitting them, I said mine are 9" free length at the front and I didn't need a compressor. I just wound the platforms as low as they'd go and the springs fell in place. You might be equally lucky with a 10" free length.
Otherwise we all seem to have our own, custom built compressors because the original springs have loads of coils and quite a bit of pre-load so not all conventional spring compressors will work. I have a set that's very chunky and robust but useless for standard Lotus springs because the clamps are too thick.
Brian
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(didn't you show pictures of the springs off your front shocks?)
That wasn't me. But thanks, fellows. Especially the pictures, but the descriptions are invaluable too.
Vince
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Oops! Sorry! I hope you get your springs off without drama!