Lotus Elan

Elan springs rear-front - different lengths & wire diameter

PostPost by: garyeanderson » Mon Mar 19, 2012 11:53 am

So I was rounding up the rear springs, I found 11 that came with the various Elans bought over the years. Why I seem to have an odd number of everything is only fitting and goes with my character. Anyway I was figuring just taking the least rusty springs and giving them a cleaning and quick sand blast and paint. I am only going to be using 2 of the 11 so I figured a piece of cake. Then I notice that a couple look short and then I notice that the wire seems heavier on a couple. The parts manual lists only one part so I am wondering what is going on. I have only owned one Plus 2 and it left whole with out me doing anything around the rear suspension. I have bought a pair of rear uprights but they were springless as I wouldn?t have wanted them anyway. So the two outboard springs are 15.875 tall and have a wire diameter of .475 inch, the inner most are about 15 inches long and the wire diameter of the other 9 is .404 or so. Anyone ever come across this abnormality before:?
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Last edited by Guest on Tue Apr 17, 2012 11:15 am, edited 1 time in total.
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PostPost by: prloz » Tue Mar 20, 2012 3:34 am

Hi Gary,
The late Elan workshop manual gives the following specs. for the rear springs.
Number of coils 8.7
Wire diameter 0.40 in.
Length - free 14.71 in.
Length - fitted 8.0 in.
Rate 67.5 lbs.in
Looks like you have a pair of rogue springs in there.
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Peter.
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PostPost by: garyeanderson » Tue Mar 20, 2012 10:00 am

Hi Peter

I read the workshop manual but the dimensions do not agree with what I measured. The shortest was 15 inch (5 of them, and is probably what the workshop manual is referring to) and and then the next were 15 1/2 (4 of those) and then the two outboard are 15 7/8 with the large diameter coil wire. I was just pointing out that there are differences in the rear springs and don't get too alarmed if it does not match the spec listed. The two I will use are going into an early S2 so I'll just use the 2 best looking ones of the shortest 5 for it. It's nice to have a choice.

Gary
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PostPost by: rgh0 » Tue Mar 20, 2012 10:21 am

Hi Gary

Assuming all your various Elan rear springs are original then it looks like Lotus varied the spring detail spec over the years without admitting it or documenting it in the manual - why does that not surprise me.

Your are one the few people with a large enough collection to actually identify it.

Sounds like a whole new area of previously unknown Lotus variation to explore.

cheers
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PostPost by: garyeanderson » Tue Mar 20, 2012 10:36 am

Hi Rohan

A sad but true statement. I only find this stuff out when I collect all of the stuff and start to look at whats in the pile. I have replaced a lot of rear springs with the 2 1/2 inch coils over the years and thats how I ended up with all of these stock springs. Rear Rotors used to be cheap too so there is a stack of dozen (probably more, "make that 19" at the moment but I will use 4 so thats 15) or so of them. Those Lucas starters that seem to multiply fall into the same category except I really don't like the way the pinion slams into the flywheel in 4 spots. My guess about the springs are the S3 and S4 were a bit heavier and Lotus needed to adjust, I can't say for sure as I didn't label any of these parts as I "assumed" they were all the same. The "running changes happened, and when and which cars is anyones guess.

Gary
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PostPost by: cabc26b » Tue Mar 20, 2012 12:34 pm

Gary,

I pulled out of storage 2 pair off circa 63/64 cars -

Both pairs the same

15" with 7/16" dia on the Wire.


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George
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PostPost by: garyeanderson » Wed Mar 21, 2012 5:54 am

Mark sent me this photo pf 2 pair of rear springs. One pair of them from an S2 and the other pair bought new as eplacements sometime around 1968. The pair on the left are 16 inch and 15 inch on the right.
The running undocumented change of Lotus Elans continues...

Gary
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PostPost by: Galwaylotus » Wed Mar 21, 2012 10:16 am

It would be interesting to see how the spring rates vary.
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PostPost by: garyeanderson » Wed Mar 21, 2012 11:01 am

My Guess is the rate is the same as quoted in the work shop manual as the wire diameter is the same (except for the 2 outer springs in the first picture). If I had a press here I would check a couple out to see (just for grins) but I don't. If I end up going back to straighten some more control arms soon, I'll bring the scale, a tape measure, and a few springs to check. I may be surprised! :o

Gary
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PostPost by: Galwaylotus » Wed Mar 21, 2012 11:52 am

If you do, please let us know the results! Thanks, Gary.
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PostPost by: frearther » Wed Mar 21, 2012 8:28 pm

And there's always the question of aftermarket springs. Might there be any of those in the collection?

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PostPost by: garyeanderson » Thu Mar 22, 2012 10:59 am

frearther wrote:And there's always the question of aftermarket springs. Might there be any of those in the collection?

Art


The large diameter wire springs that are 16 inches tall may be an after market springs but I clearly don't know. All of them are from Elans that I bought that were well used up and most left for dead. Why they would buy "new" springs of any type and not spend the money on where it was needed probably didn't happen. I did some searching and there seem to be a few topics covering spring length. I am not going to get carried away with this topic as I normally just buy new small diameter kits and springs. I happened to round them all up to select the best two for 26/4020 and noticed there was a difference. The original springs from 4020 are in the photo but I do not know (or care) which they are. From what I have read the rates do not change although the lengths do. Lengths can "sag" but I don't think that is what we are looking at in the first photo as 4 are the same and the other 5 are the same. the two on the end are a question. Now if we start to talk about front springs there seems to be even more of a difference in "free" length, see photo below.
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PostPost by: PanoGuy » Thu Mar 22, 2012 8:51 pm

Gary,
On those rear springs, the pair on the left are not really correctly wound. They will cause the car to ride too high since only the "active" coils count in the spring rate, not those that are bunched together at the top and bottom. I have a pair like that on my 71 Sprint and need to replace or cut them, or just get to like the high ride height. I was hoping they would sag down to the correct height, but I've been waiting for 20 years now.
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PostPost by: garyeanderson » Thu Mar 22, 2012 8:57 pm

PanoGuy wrote:Gary,
On those rear springs, the pair on the left are not really correctly wound. They will cause the car to ride too high since only the "active" coils count in the spring rate, not those that are bunched together at the top and bottom. I have a pair like that on my 71 Sprint and need to replace or cut them, or just get to like the high ride height. I was hoping they would sag down to the correct height, but I've been waiting for 20 years now.
Doug


Hi Doug

They are not my springs, I own the rusty ones in the first photo. :) I don't think Mark is planning on using them, they were just a picture of what he had that he sent me to show the springs, I don't know if they were bought from Lotus or not, I may have to read his email again...

Gary
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PostPost by: PanoGuy » Sat Mar 24, 2012 3:33 am

Gary,
Right, I should have been more specific in my post. It's just that I put a pair like that in my car not knowing that they were not wound correctly to give proper ride height and spring rates. I didn't know the difference between active and passive (or what is the term for it?) coils. They were purchased from a reputable vendor, with whom I still do business, but I still have to do the whole job over again. And the whole process took some many repeats that I wore out my spring compressors and my patience.
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