Lotus Elan

springs and shocks

PostPost by: ecamiel » Tue Apr 06, 2010 12:16 pm

What spring rates do people use for racing?
What shocks? What sway bars and sway bar attachment?
I've been running 220 front, 160 rear, 1 in bar and 3/8 rear bar with 7 in rims
Here are specs for stock Koni fronts

Eric
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PostPost by: cabc26b » Fri Apr 16, 2010 12:58 pm

Eric ,

Your spring rates are within 10% of what I recall running on my s2 - my S1 is about 10 lbs lighter in the rear and I think the same on the front. I ran a 1inch solid mount front roll bar on the s2 and and have a 7/8's bushed bar on the s1. I have never run a rear bar on an elan. ran 6" rims on the s2 will run 5" on the s1.

George
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PostPost by: vintrace » Thu Sep 02, 2010 4:23 pm

Hi, Your spring rates will vary quite a bit depending on your tyre choice..the stickier the tyres the more spring you are going to need.... a rear bar is fine providing your front bar is adjustable so you have a way to ballance the car..
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PostPost by: rgh0 » Fri Sep 03, 2010 12:06 pm

I run at the soft end of race springs because I like a soft car that easy to drive if its wet and because i have to run relatively low grip road tyres in my historic class ( Yoko A048 or Dunlop DZ3G are typicsal current choice of available options) compared to full race slicks

I run 150lb fronts and 110 lb rear with 7/8 inch front bar and no rear bar. I space down the rear rubber springs by about 20 mm which when combine with lower spring heights means they come into play after about 30mm of rear suspension movement.

The hard end of springs is around 250 lb fronts and 150 lb rears and a 1 inch front bar. But you need to like a hard car, be running sticky slicks and be changing spring rates ( or dont mind going off the track) in the wet if your up that end of the spring rates.

Historic racing is not 10/10ths serious in my mind and we are all amateurs so I like to keep it a little softer and easier to both drive and stay out of trouble.

cheers
Rohan
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PostPost by: vintrace » Fri Sep 03, 2010 4:10 pm

Hi Rohan, when you say rubber springs are you talking about the bump rubbers..?
I agree with vintage tires soft springs are better... I think you will find for sticky slicks your 250/150 is a bit on the low side... but I don't see many Lotus cars anymore with a lot of tire, not like the old Modsport days.
My only problem with a soft car is as you say easy to drive till you get it on the limit then it will bite you... though it sounds like you have that taken care of with your extra rubber springs. Always interesting to get another take on this stuff.
Cheers, Tony
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PostPost by: rgh0 » Sat Sep 04, 2010 12:34 am

Hi Tony

Yes I guess I was not talking about a mod sports elan with 10 inch wide wheels and sticky slicks I would assume with those you would go stiffer again. As you start increasing the track width and rebuilding the chassis for increased stiffness anything goes. I was really talking more about a typical current historic racing elan with limited modifications to wheel width ( say 6 inch ) or track.

The rear rubber springs on the shock struts are just that "springs" they are not bump rubbers and should not be treated as such. They formed a key part of the orginal Lotus suspension design. The provide a progressive rate rear spring system that is important to keeping the Elans rear end under control when cornering hard, you can probably replace their function to some degree with a rear roll bar but. When they come into play they provide an additional rising rate spring that starts about 50 lb/in and increases to about 150 lb in adding to the spring rate of the outer rear wheel in a corner in a similalr way to a roll bar. Unfotunately the orginals are no longer available, (though I have found a guy who can make an exact copy if i give him the design which i will do one day when i get time). The replacements most of the unsual suspects sell are usually more like bump rubbers than the orginal rubber springs unfortunately in terms of their spring rates.


A harder suspended car is certainly more forgiving on the absolute limt as it will tend to slide with more stability and i would be a little faster if I made my car a little harder but i dont think i would enjoy the racing so much as conditions varied and I am out to have fun as my first priority :wink:
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PostPost by: batfish » Sun Sep 05, 2010 3:49 pm

Interesting thread about spring rates. My old Appendix K Elan I think I finally ran on 250 fronts and 170 rears on slippery Dunlop historic race tyres. I seemed to like it but it was difficult to push on in the wet allowing for the fact that I am only of an average standard weekend race driver. When I bought the bits from TTR for my new car he sold me 325 fronts and 180 rears which to me sounds incredably stiff and will be a real handfull in the wet. Once the car is finished I will see how it drives but I may well have to go softer on the springs.

regards

Andy
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