S3 rear suspension ride height.

[davidj]

Good evening,

Over the past couple of years I have been restoring an S3 Elan. I have used a new spyder chassis with new wishbones and springs dampers all round and all new rubber. Basically, new everything using standard components. All the suspension mounting bolts were left loose. When the body was bolted onto the chassis, I was concerned it was high at the rear. The distance from the lower edge of the sill behind the front wheels to the ground is 6", while in front of the rear is 8"! I have ignored the problem until now as I believed (hoped) that once more weight was added to the car it would settle. However, the doors. glass, seats bonnet, engine, transmission etc are now all fitted and it is still the same at the rear.

The rear springs have a blue line painted on them and a possibility occurred to me that the supplier, Kelvedon, had supplied +2 springs by mistake. There does appear to be more coils compared to some pictures I have seen, However, Kelvedon said their springs are manufactured by the original Lotus supplier and the blue line signifies baby elan springs. They also said it will settle with use.

So, I am sure there are lots of owners on this site who have rebuilt elans. Have you had similar problems and will it settle 2" with use?

Thanks in advance for any help./suggestions.

Cheers, David

[bitsobrits]

If a spring settles 2" with use, then it's a garbage spring. And it's ridiculous for them to suggest that. Do all new car settle 2" after being used a bit? No they do not. Looks to me as if they have supplied you with the wrong springs, but I don't have any standard springs to compare with yours, as my two Elans both have reduced diameter units.

Properly made springs will not settle to any appreciable degree, maybe a few percent, and typically only if they have ground flattened ends (i.e. the thinner flat section on the ends can yield a bit under initial loads). The spring rate, i.e. the amount of force it takes to compress the spring a defined amount (typically lbs/inch in the U.S.) is constant. So a spring rated at 80lbs/inch will compress 2" under a 160lbs load. Over and over and over.

Given the compliance of the total 'system' of the rear suspension with various rubber bushings and shock mounts, and all the friction points, etc a car may settle a bit during the first 100 miles or so. But it's going to be like 1/2", not 2" and none of the settling is due to the spring.

What is the spring rate of the springs they supplied? I believe the specs for the original springs are in the manual, or perhaps someone here can post a photo of a standard spring?

Edit: Manual indicates the stock rear spring is 14.71" free length (uncompressed, not mounted) with 8.7 coils. Looks to me like your spring has about 10 coils.

[UAB807F]

Hi David,

One thing I remember Pat Thomas telling me when I bought their spring/dampers conversion with an adjustable spring platform was to set the height so that the rear wishbone was roughly horizontal.

I think measuring from either the chassis or setting the arms horizontal is more accurate than going from body measurements if only because the body might not be settled down on the chassis. Unlikely I know, but measuring from a steel chassis is definitely repeatable between yours and other cars.

Having said that, I checked the sill height on my S3 which does have the arms horizontal and that's roughly 6" front & rear.

I'd agree with the previous poster though, a spring settling 2" is either unlikely or just plain wrong.

Brian

[nmauduit]

One thing I remember Pat Thomas telling me when I bought their spring/dampers conversion with an adjustable spring platform was to set the height so that the rear wishbone was roughly horizontal.

I think it is also described this way in the shop manual (together with floor height front and rear) : horizontal suspension arms can be seen as the optimum point, as where response will be symetrical up or down when subject to a variation around that point (linear response around that point, which is not exactly the case further away since the arms are moving in a circle from the chassis attachment point).

[512BB]

40 years ago I had this problem with rear springs bought from Spyder and Vic Moore. The car, a Sprint, sat far to high at the back. VM said they would settle...........ridiculous. I could not get the rear of the car anywhere near low enough to fit the donuts, and if I could have, the donuts would have been shot before leaving the garage. And that was when you could buy quality donuts.

I sent them back for their customary 25% restocking fee and bought the correct springs elsewhere, probably CN, but can't remember. Still on the car to this day. I suggest you do the same, only next time, ask your prefered supplier detailed questions about the spec of the springs before buying.

Good luck,

Leslie

[2tmike]

Since dropping the car to the ground have you pushed it forwards and backwards a few metres ? It will have landed with the suspension on full droop and the wheels need to recover their running position .....otherwise I agree with previous posts, there is zero chance of springs settling 2"

[davidj]

Thanks very much for your pearls of wisdom.

Before I go back to Kelvedon, how many coils do the standard springs have and/or does anyone have any pictures of a standard set of springs? Below is a picture of mine before I fitted them and you will see they have 10 coils. Unfortunately I did not measure the length.

Is there anything else which will influence the ride height? I assume the Spyder chassis is true and the mounting points are in the correct position. Could I have assembled something wrong? The rear suspension does seem quite obvious how it goes together but I could have made a mistake. The lower wishbones are way off horizontal.

Thanks again.

[nmauduit]

Is there anything else which will influence the ride height? I assume the Spyder chassis is true and the mounting points are in the correct position. Could I have assembled something wrong? The rear suspension does seem quite obvious how it goes together but I could have made a mistake. The lower wishbones are way off horizontal.

springs are not primarily defined by number of coils, but rather by stiffness (expresserd in in/lb in the UK) and free length (in inches)

the manual would tell what the stock springs look like, see for exemple
https://lotuselan.net/forums/viewtopic.php?f=42&t=24824&start=
but equivalent springs could be made with sligtly different parameters

[USA64]

I have the same problem on my S4. After complete disassembly and reassembly on the original springs the tail sat high. I replaced the springs with another set of original springs but the result was the same. The strut inserts are new Spax but I have been assured it could not be them (by Ray at RD). The painter of the body Dave Hoffman, looked it over and couldn't find the cause. My plan is to ignore it and hope it goes away when, if ever, I get it done and drive it. I'm just saying it may not be your springs.

[661]

Horizontal rear arms is about right. The ride height will vary with tyre depth (amongst other things).
If you don't have an adjustable rear platform and you have the car to it's kerb weight then an 8" gap at the rear is never going to be anywhere near right, even with tractor tyres on!
I've just taken off a Pat Thomas fast road set up and the springs are really stiff ( but the right length). I've replaced it with the TTR set up, much softer. But, with a rear adjustable platform I can set the height where I want it . ( horizontal A frames and a bit of rake)

[NickWilmshurst]

Hello David,

I had exactly the same problem as you after a total rebuild. I scratched my head for a few years before seeking advice from Sue Miller who told me that, some years ago, all you could get were federal springs which have a higher ride height. I bought some new ones from her, installed, and, Bob's your uncle, problem solved!

Good luck

Nick

[davidj]

Thanks again for all your advice.

The Lotus Elan manual gives the following figures.

Length - free 14.71 in.
Length - fitted 8.0 in.

The free length corresponds with the old springs. I presume the fitted length is when the car is sat on the tires? If so, my car springs are hopelessly wrong at approx 11in.

The consensus is that the springs are incorrect so I will contact Kelvedon on Monday.

Cheers all.

[nmauduit]

[quote="davidj"I presume the fitted length is when the car is sat on the tires? If so, my car springs are hopelessly wrong at approx 11in.
[/quote]
the fitted length is the car ready to go (I check that with a half a fuel tank and a driver in my 2 seater)

11" sounds like a lot... you may want to get an idea of spring stifness by weighting the trunk and checking the height variation (note, there is a leverage effect so you won't directly deduce the actual stifness, but you would get an idea of ride height fully loaded)

[davidj]

Update. I removed both the new springs from my car (which is not an easy task) and compared with the originals. As you can see the new ones provided by Kelvedon are much longer which explains why the car was sitting so high at the back. The original are 14.7" long while the new ones are 16.2". The spring rate is the same for both springs

Why a established Lotus parts dealer ships springs which are too long is a mystery. Maybe they are for a +2 or as Nick has suggested above, federal springs. Very frustrating.

Cheers.

[alanr]

Hi,
Whilst the new spring is obviously quite a bit longer as seen on the photo, unsure if it just an illusion or my eyes but to me the wire thickness looks thinner on the new spring?...That could explain why perhaps the spring is longer to achieve the same in/lb?
Have you measured the wire thickness to prove or disprove my thoughts?

Alan.