Lotus Elan

Softer Ride Rear Suspension

PostPost by: William2 » Fri Nov 09, 2018 6:23 pm

I currently have 12" 100Lbs 2.25" rear springs fitted to my S4 Elan and I find the ride comfort is far too hard compared to the original standard Elan springs. I have adjustable spring perches which are currently adjusted to about half way up the threaded portion to obtain the correct ride height for road use. Having trawled the internet I found a company called Faulkner who can do a spring with a 100 or 80Lbs rating and a length of 12 or 14". Would a longer spring help to give a softer ride or would it be worth trying an 80Lbs rating? The reason I have the narrower springs is that I have Minilite wheels. Any comments would be much appreciated.
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PostPost by: rgh0 » Fri Nov 09, 2018 7:58 pm

For a softer ride you will need to use the 80 lb/inch springs and with a 14 inch length the spring seats will be a little lower than currently. I.e. At normal ride height a loaded 14 inch free length 80 lbs/ inch spring length of around 9 inches versus the current springs 8 inches

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PostPost by: Frogelan » Sat Nov 10, 2018 6:06 am

Rohan's reply sounds about right. I have looked at rates / lengths and in detail on the Forum but it is not very easy to put together and overall vision. Your rear spring rates are the same as the period 26R rate.

I have ordered some TTR front (1.9") and rear (2.25") tour / rally springs in order to have a base line to start from. Unfortunately TTR do not wish to share the details of the ratings, but I will post them when I get these.
1965 Lotus Elan S2 26/4022 (originally Dutchess Lotus East, PA and NJ Area, USA)
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PostPost by: William2 » Sat Nov 10, 2018 9:34 am

Thanks for your help Rohan. I assume then that a 12" 80lbs rear spring would compress too much to give the correct ride height. Would I be correct in saying that fitting 14" springs is quite usual?
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PostPost by: rgh0 » Sat Nov 10, 2018 10:11 am

Weight on the rear springs is roughly 400 lbs of static load. Thus a 80 lb spring needs to compress 5 inches and a 12 inch spring will be 7 inches long under normal ride height static load and a 14 inch spring will be 9 inches long.

Note the free length of the original Lotus 67.5 lb/in rear springs was 14.7 inches with a fitted length of 8 inches

You need to check that your spring platforms will go down far enough to use a 14 inch 80 lb/in spring of 9 inches fitted length or go up far enough to use a 12 inch 80 lb/in spring of 7 inches fitted length.

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PostPost by: William2 » Sat Nov 10, 2018 5:49 pm

Thanks for that information Rohan. I should be ok to fit 14" springs as the previous owner has fitted the threaded perch sleeves as low as possible on the Chapman struts. With the 12" springs currently fitted the perches are fixed at about 2 1/4" up from the bottom to give standard ride height.
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PostPost by: fatboyoz » Sat Nov 10, 2018 7:59 pm

Hi William,
I also run Minilites on my S4. I have fitted 2.25" springs, adjustable perches, and 80 lb x 14" springs. The correct ride height is obtainable and the ride is very comfortable whilst still allowing a fully loaded boot, for extended trips away, without any bottoming out.
Cheers,
Colin.


quote="William2"]I currently have 12" 100Lbs 2.25" rear springs fitted to my S4 Elan and I find the ride comfort is far too hard compared to the original standard Elan springs. I have adjustable spring perches which are currently adjusted to about half way up the threaded portion to obtain the correct ride height for road use. Having trawled the internet I found a company called Faulkner who can do a spring with a 100 or 80Lbs rating and a length of 12 or 14". Would a longer spring help to give a softer ride or would it be worth trying an 80Lbs rating? The reason I have the narrower springs is that I have Minilite wheels. Any comments would be much appreciated.[/quote]
'68 S4 DHC
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PostPost by: William2 » Mon Nov 12, 2018 4:50 pm

Thanks Colin that's gratifying to know that the 14" spring is the way to go. Regards, William.
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PostPost by: William2 » Wed Nov 14, 2018 5:29 pm

Having removed both rear strut assemblies I thought I would change the dampers for a pair of Tony Thompson adjustable limited drop ones as my old dampers seemed quite stiff and probably very old (date stamped 1989!!) before trying softer/longer springs.It was straight forward fitting them in conjunction with my current 12" 100lbs 2.25" springs. I set the adjuster at the minimum fully anti clockwise setting and took the car out for a spin. The ride seems to be significantly better i.e. softer than with the old dampers and the clonking noise I had from the rear end is more or less gone. Ultimately 14" 80lbs springs would be even better as has been suggested but for now I may stick with this set up. I would be interested for advice on whether it is ok to have the dampers on the minimum setting all the time or should I just experiment? I have adjusted the spring perches to give a ride height of about 6 1/4" from the bottom of the sill to ground.
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