Springs, could use some advice...

[aspares]

First thanks for all the advice so far, the Europa is doing great.
I would like to lower the front and rear of the car. I think the fronts are original as it has the Motorboat look, the front spring are about 3.25 OD. The rears look like it has adjustable shocks, I can post some pictures if needed. The springs in the rear are just big enough for the shocks to fit inside of.
Any advice is appreciated. I have the standard steel wheels with 175 X13 tires.

[BDA]

It sounds like you do have the original front shocks. I don't think they're still available any more and now all the suppliers use shocks (usually adjustable) with I believe 2" springs. There is a lot of variation in rates. Richard suggested to me 250# fronts and 140# rears which is about double the stock spring rates. I am finding out this requires a bit of development. Richard also sells shock/spring combinations. I'm not sure if he carries the 250/140 rates with them. r.d. also sells shocks and springs as does SJ Sports Cars. I've heard good things about all of them but I don't know the particulars.

I might call around to the usual suspects (which have expanded to a couple of UK suppliers):
Dave Bean (209) 754-5802
r.d. enterprises 215-538-9323 
JAE  (805) 967-5767
Lotus Supplies Ltd +44 (0) 1926 835296
SJ Sports Cars   +44(0)1363 777790

[jlmullen2]

You might have an easier time sourcing springs from local circle track shops/suppliers. My TCS isn't finished yet but I did the suspension first with new shocks(Spax) and springs. I went through two different lengths before I was initially satisfied with the ride height. The springs I found ere cheap enough that I may change them again once the car is on the road and I do a final tune/setup.

[JR73]

Are your rear shocks relatively new/in decent condition? If so then probably worth buying the equivalent front shocks to match - more likely that any adjustment on the damping rate will be similar etc....

Rear springs are likely to be 1.9" diameter from your brief description.
 
250lb fronts are what Richard (Banks) used to class as a fast road/track day orientated spring rate (depends really on what your preference is like most things related to suspension set ups?) and typically on most of the front shocks I have seen with adjustable spring platforms the ideal length is around 8" (for 250lbs) if you want the car to sit 'level' front to back rather than with the federal stance of 'nose up'? This should allow adjustment on height either way.

If you wish to adjust the height at the rear too then first of all is there any adjustment available with the current spring length? Is the adjustable spring platform currently about midway up/down the threaded section? - obviously if the rear springs are long and the platform is near the bottom of the shock you don't have much to work with if you want to lower it.

I'd assume that springs cost about the same to buy where you are, they are pretty cheap here so experimenting with spring rates and lengths doesn't cost too much but the rates that BDA has fitted (250 front, 140 rear) could be considered fast road/track and I think Certified mentioned his more standard rates in his build thread not too long ago (can't remember what they are?!).

As I've already said, the rates you end up with and the damper settings you chose are very much down to your own personal preference.

Jon

[Certified Lotus]

I bought AVO shocks from Dave Bean with 12” x 115# springs for the rear and 10” x 150# for the front. These are the “stock” set up according to bean. I’m not happy with the front springs as they need to be compressed too much in order to set the ride height lower so I’m going to move to an 8” spring in the front. I happen to a set of 8” springs but they are 140# (left over from one of my Elan rebuilds. These springs were too short for my S1).

So the question is, do I go to 250# front?

[BDA]

Certified, I am certainly not the expert and I have a lot of work to do on my car with regards to springs, shocks and alignment but here's what I think I know about the situation with springs:

First, I would not increase the front spring rate without a similar increase in the rear (but not increasing the rear might be an interesting experiment. see below).

If I wanted the simplest route to a lower front end, I think I would go with 8" springs closer to the original rate, but maybe up to the 140# you got from Dave Bean. This may work but then you'll have less pre-load in your springs and that may require other changes.

Increasing the spring rates to my 250#/140# and leaving the shocks soft has no effect on driving around town, say up to 60 mph. By that I mean, the ride is not harsh nor bouncy. After 60 mph, it gets nervous.

From what I've read from others, that is cured by increasing the stiffness of the shocks and likely more stiffness in the front than the rear and it may require different shock settings for the highway and city driving where you're more likely to find bumps. I think Lou might have more experience in that area.

It may be that the best situation is marginally increase the spring rates (a la Dave Bean and maybe others) rather than double them like I have on mine.

That's probably all I know, which obviously is not much. I hope it helps, but I won't be offended if it doesn't!

Edit:
I forgot to get to the "see below" part! What I've found on my car is that the rear feels like it wants to swap ends going into a turn especially. From what I've read, stiffer front shocks will help cure this. Softer springs on the rear might as well but I'm not sure about changing the balance of spring rates. A stiffer front bar should also help but that's a bit beyond the scope of this discussion. At the same time, I've heard of people who have added a rear bar (that should increase over steer) and claimed it improved the handling. In fact, Addco sells a kit for one.

I THINK that what ever spring rate changes you do, it might be best to keep the same relative increase front and rear and tune with shock settings. At least, that's the tact I'm planning.

[GavinT]

Certified,
I reckon try the 8” x 140 lb front springs because they’ll be a better match for the 12” x 115 lb rears . . particularly given you already have them. See how you like it.

The 250 lb fronts would tend towards increasing understeer all else being equal.
I'm assuming the "correct" rear spring for a 250 lb front is 140 lb, of course.

[BDA]

I think you make a good point about trying the 8" 140# front spring, Gavin. You reminded me to address the oversteer I've been experiencing (see my edit above if you're curious about what I have to say about it).

[GavinT]

G'day BDA,

A skittish rear end sounds odd.
Usually, most of that stuff ends up being insufficient toe-in or failing trailing arm bushes etc.

I’ve not found rear end skittishnes but also haven’t played with these new fangled stiffer springs either. In fact, I think the original balance fore & aft is excellent.
I’d expect stiffer springs to demand more attention to setup because essentially they transfer weight more quickly, but that’s the way to go, I reckon.

Since you have the luxury of adjustable dampers, I’d definitely be inclined to experiment.
If you’re at full soft, it may be that there’s really insufficient damping for the stiffer springs but it only displays that behaviour at speed. That being the case, I’d start by increasing the damping two clicks on both front and rear. Ya gotta start somewhere.

The general principal is that if you harden up (say) just the front, it’ll technically lose grip (increase understeer) - and vice versa.

[BDA]

Hey Gavin,

I think the stiffer springs are what's driving this. I've owned the car since new so I have some memory of how it handled when new and you're right. It handled pretty well. My radius arms are essentially new so I don't think that's my problem and I've done most of my own alignment but I've set up an appointment to put my car on a rack to get a better baseline. I think the shock settings are probably more determinant than any misalignment on my part, but that's yet to be determined. I've stiffened both front and rear shocks by three clicks out of an expected 14 clicks (I have Spax and the tech guy I emailed wasn't sure how many clicks there were because at some point in the past, the design changed a bit and he wasn't sure which side of the change mine are). After I get what I hope is a better alignment baseline, I'll experiment more with shocks adjustments and I'm thinking of stiffening the front a click or two more than the rear.

Anyway, that's the immediate plan. I'm not discounting the possibility that I might lower the spring rates all the way around.

[dakazman]

Asperes,
FWIW,
Dave Bean specs, I cannot give an opinion only passing on info I’ve come across.
See pic.

[JR73]

I bought AVO shocks from Dave Bean with 12” x 115# springs for the rear and 10” x 150# for the front. These are the “stock” set up according to bean. I’m not happy with the front springs as they need to be compressed too much in order to set the ride height lower so I’m going to move to an 8” spring in the front. I happen to a set of 8” springs but they are 140# (left over from one of my Elan rebuilds. These springs were too short for my S1).

So the question is, do I go to 250# front?

I would go with what you have first, doubt you would be able to notice much difference between 150 and 140 but the shorter spring will hopefully give you the ride height you are after (could always put a helper spring in with the 140 if 8" turns out to be slightly short...) and with the adjustable dampers you will probably notice the changes in damping as you play with the range of adjustment.

250lb springs are pretty serious tbh and really are more suited to a bit of intended track use etc than mostly road miles - especially in a relatively standard car. (Yes, I have 250lbs springs fitted to mine on both the front and rear, it's far from standard/original and I have not experienced any handling issues so far that makes me think that I will be changing anything - it used to be a track only racer and the fronts where somewhat heavier than 250 when it was used on track.)

Again, as I said in a previous post, it's all really down to personal preference and intended use. A good place to start is whatever the original rates where and adjust from there to suit whatever you are doing with your car.

Slightly related.... if you look at the more modern mid engined cars (Elise/Exige for example) and the spring rates that they run then you may notice that unlike the Europas they actually run heavier spring rates on the rear relative to the front! - if it wasn't all confusing enough already!!

[Clifton]

Yes, I have 250lbs springs fitted to mine on both the front and rear, it's far from standard/original and I have not experienced any handling issues so far that makes me think that I will be changing anything - it used to be a track only racer and the fronts where somewhat heavier than 250 when it was used on track.)

Slightly related.... if you look at the more modern mid engined cars (Elise/Exige for example) and the spring rates that they run then you may notice that unlike the Europas they actually run heavier spring rates on the rear relative to the front! - if it wasn't all confusing enough already!!

 Just throwing this out there. If your car had good balance with it's previous race rate set up and the front was softened, it should now oversteer.  Fun until you don't plan on it.


Elise have a different motion ratios. If the spring pickup point moves in or the lower control arm pickup moves out, the spring rate will need to be higher for the same wheel rate.

[EuropaTC]

Elise have a different motion ratios. If the spring pickup point moves in or the lower control arm pickup moves out, the spring rate will need to be higher for the same wheel rate.

A good point and not forgetting that it's not just the pick-up locations but also the angle of operation that will modify the effective spring rate.  If it's at a significant angle like the front then it reduces the rate, unlike the rear springs which are almost vertical and thus carry their rated weights. When you apply the factor for the front spring angle & motion ratio it knocks the 250lb down to more like 160-ish from memory.  For the rear, if you have 160lbs it pretty much stays at 160lbs due to the different angle/motion ratio.

I'm sure most folks know this but it's worth mentioning for anyone new to the topic and reading the thread;  it's not reliable to compare springs from different cars, you need to look at the wheel rates/frequencies as a whole package which takes in suspension geometry, weight distribution, etc. 

Brian

PS - if you want to lower the car then I'd think you'll have to increase rates. Lowering will reduce suspension movement (unless you move the mounting points    ) so less movement with relatively low OEM spring rates is more likely to have it bottoming out. FWIW mine is 250/160 with the dampers about half way, it's hard but no harder than the more modern Elise.

[JR73]

 Just throwing this out there. If your car had good balance with it's previous race rate set up and the front was softened, it should now oversteer.  Fun until you don't plan on it.


Elise have a different motion ratios. If the spring pickup point moves in or the lower control arm pickup moves out, the spring rate will need to be higher for the same wheel rate.

Yes my car was very balanced on track. However, it's no longer running on racing slicks and being driven very much at the limit - I'm never going to be pushing THAT hard on the public road with all of the associated bumps, pot holes, speed restrictions and hazards etc to get it close to the limit (even if it's 'limits' are now reduced from its on track days). All that I meant was that from some 'spirited' driving that I have done since having it on the road I haven't experienced anything that gives me cause for concern. Also, the rear suspension on my car is nothing like the original.

I wasn't suggesting that anyone uses the spring rates from an Elise or any other car - exactly as Brian has stated, there are so many different elements that have to be considered if you are changing spring rates that really must relate directly to your own vehicle - Engine swaps, non original chassis and suspension, wheel and tyre changes etc etc all contribute towards differences between our cars and whilst they may all look similar from the outside and are called 'Europas' they don't necessarily operate in the same way underneath with the various modifications that people have applied. If your car is as it left the factory then, fair enough, you can compare notes with somebody else with the same car.

From what I've read, Certified wants to lower the front ride height to remove the federal spec stance - this would be possible to do using the standard rate springs from the British spec cars (Dakazmans chart seems to show these?), its the length of spring that he wants to get right - he doesn't HAVE to go to the 250lb front springs but if he did it would be wise to change the rears out to what is recommended relative to the uprated fronts (his car being very much to original spec).