Lotus Elan

Spring calculator, ride high, sping rate/harshness...

PostPost by: Davidb » Tue May 24, 2016 5:44 pm

Mario, Dave Bean in the USA does 12 inch 115lb springs for the Elan. I have a pair but my car is not on the road yet. For rear springs I went with these:
https://www.amazon.co.uk/QA1-12HT095-Sp ... entries*=0

They come in various rates-I actually have the 80lb but may go to the 95lb

I included the UK amazon listing but they are available on US amazon, at Summit Racing, ebay, etc.

This is the manufacturer's web site:
http://www.qa1.net/suspension/springs/2 ... el-springs
'65 S2 4844
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PostPost by: UAB807F » Wed May 25, 2016 7:56 am

mariodschy wrote:Now i've checked what springs are available, the closest are:

front 1,9"ID 100lbs free length 12"
rear 2,25"ID 90lbs free length 12"

I wouldn't go any lower, but in the other direction for front are only 125lbs available and this is to much.
Perfect would be 110 (not available) but better a bit softer and keeping my teeth...



Hi Mario,

Avo list 110lbs in 1.9" and 12" length on their website if that's what you really want.

http://www.avouk.com/MotorsportFrameset-84.htm

I can't post directly to the page but go through competition springs/1.9" and you get there.

I can't comment on your other point because when I did my calcs for the Europa suspension I measured the suspension components & operating angles then used road test weights & distributions to do calcs for wheel rates rather than individual pre-loading.

Out of curiosity I adapted the spreadsheet for the Elan to see what Pat had given me and using your numbers get this...

OEM 1.18:1.34
100/90 1.36:1.55
110/90 1.43/1.55
150/125 1.67/1.82
175/140 1.8/1.93 (mine)

This doesn't include the contribution from the standard roll bar, which becomes a less significant % contributor as spring rates increase.

I'm not going to claim these numbers are exactly correct because there are several assumptions or inexact measurements (weights/operating angles, etc), but they do serve as a comparison for the magnitude of any change.

Brian
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PostPost by: mariodschy » Wed May 25, 2016 11:41 am

UAB807F wrote:http://www.avouk.com/MotorsportFrameset-84.htm


OEM 1.18:1.34
100/90 1.36:1.55
110/90 1.43/1.55
150/125 1.67/1.82
175/140 1.8/1.93 (mine)

Brian


Thanks David and Brian.
@ Brian: Very usefull homepage and good prices :)
When i look at the list above, compared with the feeling that i have with 150/125 (1.67/1.82) springs, i'll get safer to be correct when i order the availabel

front 1,9"ID 100lbs free length 12"
rear 2,25"ID 90lbs free length 12"

I think as a non raceing driver i will not notice any difference between 110lbs and 100lbs front springs, so i'll order them and let you know the results, for sure...

Other question, what about dust covers?
I still have no dust covers fitted but this would be the chance to upgrade the dampers with it.
Does it make sense and where did i get covers who fit under the 2,25" and 1,9" springs?

Mario
- 1972 Lotus Elan Sprint LHD/DHC
- 1962 Austin Healey Sprite MK II - Sold 09.05.2016

Sorry for my bad survival English ;-)
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PostPost by: mariodschy » Fri Jul 08, 2016 7:30 am

After testing a lot with springs, tires and tire pressure i've found the (for me) perfect configuration for "fast road", here is the result:

In conjunction with adjustable spax krypo gas damper and also adjustable ride hight platform on the rear the following springs are used:

front 1,9"ID 100lbs free length 12"; ride high 6" (platform full up)
rear 2,25"ID 90lbs free length 12"; ride high 6,5" (platform 60% up)

Tire pressure front 1,7 bar (fulda ecocontrol, 155/80 R13)
Tire pressure rear 1,9 bar (fulda ecocontrol, 155/80 R13)

Hope this helps some others to save a lot of time...

Thanks all for your support.
Mario
- 1972 Lotus Elan Sprint LHD/DHC
- 1962 Austin Healey Sprite MK II - Sold 09.05.2016

Sorry for my bad survival English ;-)
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PostPost by: vstibbard » Sun Jul 10, 2016 5:36 am

I just finished an Elan for fast road/Track use and used 150lbs fronts, with heavier antiroll bar from TTR and its fabulous, I'd suggest either you have coil bind occurring, or a very hard bump stop, they've supplied incorrect spring rate, or the shocks have an issue with their valving, I have experienced this in past with a batch of valves for Koni's, the material was wrong and they broke up, locking the shock.

V
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PostPost by: john.p.clegg » Sun Jul 10, 2016 5:45 pm

Digressing just slightly,is there a laymans way of testing springs,ie.if a 10 stone man was to stand on a spring and it compresses 1 inch does that make it rated at 140 lbs ?

John :wink:
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PostPost by: rgh0 » Mon Jul 11, 2016 11:37 am

yes what you say is correct

the easiest way to test a spring I find is put it on my bathroom scales and push down on it to compress it a measured distance and then read the load on the scale.

You will generally need a wooden board on the bathroom scale to spread the load as they don't like the point load from the spring

I you have a press its easy to set up to do it in the press


cheers
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PostPost by: prezoom » Mon Jul 11, 2016 3:29 pm

Years ago, I modified a corner weight jacker into a spring checker, to be used in a hydraulic press. One thing I learned after checking an untold number of springs, was not to trust the measurement when depressing the spring only one inch. I now check at one inch, again at two inches as well as at three inches. Dividing the later two measurements by two or three to get, what I believe is a more accurate number. The resulting number never seems to match the one inch number, but is fairly close. But, when looking for 10 to 20 pound differences when changing spring rate, it seems to be the most accurate. The main thing is to be very accurate with the depression measurement. Being off by the slightest amount, will give you skewed results. Never trust the number that is marked on the spring, unless you did the marking. Some companies springs vary considerably when comparing two springs with the same marking.
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PostPost by: john.p.clegg » Tue Jul 12, 2016 4:09 pm

Well I did it,took the springs out of my Plus2 (1.5" low at the front ) and rigged up the bathroom scales in the lathe and with 1" of compression the reading was 88lbs and with 2" compression 198lbs.....

20160712_163349_resized.jpg and


Where have I gone wrong??

1/4" aluminium plate behind scales ( in front of face-plate ) and 1" mdf in front to spread the load.

Surely the front springs should read 140lbs for the first inch and 280lbs for the second inch??

..or is this why it was a little low at the front

John :wink:

EDIT Just found the Bible and the front springs should be 110lbs/in ( don't know who posted 140...)
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PostPost by: rgh0 » Wed Jul 13, 2016 1:27 pm

Sounds like you have standard Elan springs not plus 2 springs fitted which is why it is low at front !

cheers
Rohan
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PostPost by: john.p.clegg » Wed Jul 13, 2016 3:50 pm

Just phoned Christopher Neil up as one set are marked FS007 Plus2 F and I remember buying them years ago,anyway the guy on the spares counter confirmed that they are their springs and are the standard springs for the Plus2 but didn't know the poundage ( or any specs for that matter )

You could be right 110 for the Plus2 fronts,FS007 measure approx 91...Elan??

Can anyone confirm? If so I have a new set and a few good used sets going spare.

Ordered a pair of 1.9/14/120 made to measure.....5 weeks for delivery..I'll let you know.

John :wink:
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PostPost by: rgh0 » Thu Jul 14, 2016 12:15 pm

so what are the key spring dimensions

i.e.
wire diameter
coil outside diameter
number of free coils
free length

based on the the desgin spring rate can be calculated and whther it is really an Elan not Plus 2 spring detemrined.

cheers
Rohan
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PostPost by: john.p.clegg » Thu Jul 14, 2016 1:18 pm

Rohan et Al

From the book..



Plus2 standard front suspension specs

No of coils 15.6
Wire diameter .343" ( 8.71mm )
Rate 110 Lbs.in ( 1.267Kg/m )
Length
free 14.19" ( 36.04cm )
fitted 8.6" ( 21.8cm )

Note:- longer springs,which increase the front ride height to suit all market requirements are available
Part No 50C 010A...and must be fitted in pairs

Specs

Length
free 14.59" ( 37.04cm )
fitted 9.0" ( 22.86cm )

My front springs approx specs

No of coils 16
Wire diameter 0.344 ( 8.7mm ) 11/32"
Coil O.D. 2.625 ( 68mm )
Rate X
Length
free 14" ( 35.56cm )
fitted 10.875" ( 27.62cm ) No Load..


John :wink:

P.S.
Rear suspension
Number of coils 9.7
Wire diameter .434" ( 11.02mm )
Length
free 16.0" ( 40.6cm )
fitted 8.6" ( 21.8cm )
Rate 93lbs ( 1.071Kg/m )

Edited for coil O.D.
Last edited by john.p.clegg on Thu Jul 14, 2016 1:29 pm, edited 1 time in total.
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PostPost by: rgh0 » Thu Jul 14, 2016 1:22 pm

I also need the actual spring coil OD to calculate the actual spring rate.

cheers
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PostPost by: john.p.clegg » Thu Jul 14, 2016 1:52 pm

P.S.
Can someone post the specs for the Elan springs front and rear...

Thanks
John :wink:
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