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Lotus Europa Race Car Collection
Mecky:
Hi Brian,
--- Quote from: EuropaTC on Tuesday,November 26, 2013, 03:42:26 AM ---Stefan, the standard springs (TC) are stronger at the front, 116lbs/ins & 75lbs at the rear, but of course there's more suspension leverage at the front so the effective rate drops.
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That surprises me.
--- Quote from: EuropaTC on Tuesday,November 26, 2013, 03:42:26 AM ---ps - Stefan, did you stay with 2.25" spring diameters for both front & rear ? I find the smaller 1.9" springs a real nuisance to compress but the slightly larger ones fit my tools much better and would prefer to use them all round if possible.
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Yes, 2,25 all around.
Best regards
Stefan
EuropaTC:
Thanks Stefan, although it's one of those silly things I feel happier working with slightly larger diameter springs providing there's no significant trade-off in performance. I've also looked at the pro-tech site and SJS, their UK supplier and they look well made units.
The OEM spring rates always puzzled me as the first impression seemed to be the wrong way about. But I used some formula from Alan Staniforth's book on suspension (dated now but from the era of these cars) and weighing what I could then making some assumptions for what I couldn't, I found that the spring pre-loads after allowing for suspension leverages came in at 427F, 417R. Of course that can be well out with the guesswork, but it did slow me down a bit as the maths indicate it balances well.
I've read a lot of Jay Mitchell's postings and there's no doubt he is good at the game. Personally I like the way he goes about it. But regarding his choice of spring rates you've got to remember that he's specifically aiming at autocross and using the OEM suspension layouts. I suspect once you change the physical suspension design/dimensions as you've done, all bets are off as to what previous recommendations will work and the best way forwards is practical experience (and lap times ;) )
I'm currently going through the knowledgebase and sifting out various combinations that have been discussed. If there's any interest I'll post the results here when I think I've got it all down.
Brian
HealeyBN7:
Brian,
I am very interested in spring rates, so please do post what you learn.
In my Zetec S2 I started with Dave Bean's recommendation of front 2"x10x110 with 2" x 13.5 x 115 on the rears. All are on adjustable AVOs. The front setup far too light and would not keep the car off the bump stops.
Replaced the fronts with 2"x 10 x160... With this set I was unable to lower the front to a non Federal height, so I ordered 2" x 9 x 160, but as you can imagine the same spring force with a lower height softened the front too much and I would bottom on road imperfections. With a passenger it was frequent.
This led me to my current setup which is still not ideal. I cut the 2"x 10 x160 to 8" effectively raising the spring rate by 20% to 192. it is better. I fell that I can go even higher. Perhaps to 220 without any drawbacks. With no changes to my rear setup you can see that I am radically out of balance 192 front/115 rear.
I have a new larger front sway bar to install and I would like to get my springs sorted this winter, so I'll be watching this thread with interest!
Thanks. Great thread.
Dean
Bainford:
--- Quote from: EuropaTC on Thursday,November 28, 2013, 12:43:11 AM ---
I'm currently going through the knowledgebase and sifting out various combinations that have been discussed. If there's any interest I'll post the results here when I think I've got it all down.
Brian
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I'm very interested in hearing what you've learned regarding spring rates. My car is still wearing its original springs and dampers so thoughts of replacing these are on my mind. I haven't looked too deep into this yet but it's quite high on my 'must do' list of Europa improvements. Cheers
EuropaTC:
I'll be happy to post up what I find as long as you guys remember I really don't know enough about this aspect of our cars, this will just be data for interpretation & background. I'll try to collate it for the weekend.
One thing that does stick out though is a phrase from one of Jay Mitchell's posts - "getting recommendations is easy, getting ones that work less so" (or something like that). There's a whole range from the standard 100/116 of the S2/TC to 750lbs/ins for a track car. I can't even imagine what that's like on the roads !
Brian
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