jbcollier Posted February 28 Author Posted February 28 Just for your information, the spring fitted was a RedLine Components 75532H. Faulkner confirmed that they make the springs for Redline and the nominal spec is 14" long and a 100 lb rate. I'll chime in again once I have the new 80 lb springs on and the roads have cleared.
EdWills Posted March 1 Posted March 1 Also John, when they've filled in some of the potholes. I used to drive up to Edmonton using a rental car as I didn't want my personal vehicle being damaged by the roads to and from Calgary and Edmonton. Calgary is now suffering from poor maintenance on our major ring road, and vehicle repairs for many motorists are becoming the norm due to bad paving and snow plough damage. It's what you get living in a northern climate with freeze/thaw conditions, but the city sure takes its sweet time to fill in the holes in the spring when the weather improves. W.
EdWills Posted March 2 Posted March 2 John. This from the Calgary Herald March 2/2025. Most appropriate
jbcollier Posted March 2 Author Posted March 2 Edmonton is a dumb place to build a city. Gorgeous, sure, but bed rock is 80 to a 100 feet down. Above that are multitudinous layers of clay, coal, gravel, and other crap. In freeze/thaw cycles, the land heaves like a wallowing water buffalo. Roads don't stand a chance.
EdWills Posted March 2 Posted March 2 Getting back to the original question regarding springs for a Lotus Seven, there is a very good article on the web at: http://7-dna.com regarding the springs and dampers on the writer's car called 'Eugene'. He mentions the original spring rates that Lotus chose for the fronts and rears. David Kaplan of DSK advised in one of his publications on springs and dampers for a Seven that the springs manufactured for Lotus Seven Series 2 and 3s were not very reliable and would lose tension. Even Lotus in a letter to me admitted that the springs on my car were probably sagging badly (which they were) due to a less than optimal oil pan clearance. The Eugene owner has done some great research into this subject, and is worth a look at his site. W. 1
pethier Posted March 3 Posted March 3 9 hours ago, EdWills said: http://7-dna.com Color combinations make my eyes hurt.
MV8 Posted March 3 Posted March 3 (edited) 16 hours ago, EdWills said: Getting back to the original question regarding springs for a Lotus Seven, there is a very good article on the web at: http://7-dna.com regarding the springs and dampers on the writer's car called 'Eugene'. He mentions the original spring rates that Lotus chose for the fronts and rears. David Kaplan of DSK advised in one of his publications on springs and dampers for a Seven that the springs manufactured for Lotus Seven Series 2 and 3s were not very reliable and would lose tension. Even Lotus in a letter to me admitted that the springs on my car were probably sagging badly (which they were) due to a less than optimal oil pan clearance. The Eugene owner has done some great research into this subject, and is worth a look at his site. W. Didn't see an article there, but (as I'm sure Ed knows) the smaller the spring diameter, the less reliable and stable they are. 1.9/1-7/8" is about as small (and light) as they get for suspension. I'd have converted to a 2.5 id (more common, reliable, greater variety) with new seats but still gone to a lower rate. Edited March 3 by MV8
EdWills Posted March 3 Posted March 3 Hi MV8. My apologies. 'Iamscotticus' advised me that the web site I quoted leads to a forum not the page I originally saw and bookmarked on my computer.. When I google searched for 'Lotus Seven springs and dampers', a site popped up titled 'Eugene' and the web location was simply the address www.7-dna.com. I am not sure how best to locate the pages I found, but the web site owner provided some helpful information on his car. Great advice again MV8, thank you. W.
EdWills Posted March 3 Posted March 3 (edited) 13 hours ago, pethier said: Color combinations make my eyes hurt. Apologies. Please see my reply to MV8 above. W Edited March 3 by EdWills error
EdWills Posted March 3 Posted March 3 Try 'Lotus Seven Eugene', then on the opening page click on 'modifications'. The car owner provides info on the work he did on the new car after a bad crash to the first one. I should have done my homework before just placing a web address on this forum. Duh! W
pethier Posted March 3 Posted March 3 28 minutes ago, EdWills said: Apologies. Please see my reply to MV8 above. W Not your fault. You didn't design that mess.
EdWills Posted March 3 Posted March 3 Hi Pethier - thank you. Yes I found it a tad difficult to find what I was looking for on the site once I found it again. The main point of the article I found was that the writer advised that the spring rates on original Lotus Seven Series 2 and 3s, was 105 lbs. for the front springs and 75 lbs. for the rears. As MV8 notes, this is about as small and light as you can get. Bearing in mind however that the Seven - as originally designed and built - was much lighter (1000 lbs plus or minus?) than the current Caterham cars of course. When Lotus built the one-off Seven S show car, the weight was increased quite dramatically, and the twin-cam cars were just as heavy. DSK advised that for a Lotus Seven twin-cam, spring rates should have been increased by 10% on the front from original, although they quoted that the front springs on a standard Seven were about 85 lbs. Mick Lincoln of the original Redline Components, advised that the rates were 105 lbs F, 75 lbs. rear. I have a chart sent to me by a gentleman who was originally on this forum, listing sizes and spring rates for the Seven Series 1 and 2 (plus the Lotus 11 Series 1 and 2). It seems that rates varied quite a bit during the years of manufacture of these cars and the way the cars were used. W. 1
JohnCh Posted March 3 Posted March 3 @EdWills were you trying to link to this page? https://www.7-dna.com/eugene/suspension.html
jbcollier Posted March 3 Author Posted March 3 https://www.7-dna.com/eugene/home.html Seems a bit more biased to track days than regular roads.
EdWills Posted March 3 Posted March 3 (edited) Hi Both. Yes, that was what I was attempting to add (the correct web address that is!) - thank you. I guess the only part that appealed to me was the author's information on shocks and springs, and some of his calculations. Agreed it is more for track than road, and he did go heavier on his springs as suggested by Caterham and Redline for racing purposes. I should have specified his information only on the road spring poundages, as it agreed with others who had measured them. Cheers, W. Edited March 3 by EdWills
jbcollier Posted July 25 Author Posted July 25 Well, it almost worked! The 80 lb spring is softer but requires significant preload due to its "short" 14" length. Once it is wound up, you are pretty much back where you started. I would need 80 lb 16" springs. I put the 100 lb springs back in as I'm driving down to the Calgary car meet with my good, albeit quite substantial, friend. I have a set of 75 lb, 16" springs I'll try next.
IamScotticus Posted July 26 Posted July 26 (edited) anyone know the Bilstein damper part numbers for live axle Cat & Lotus? Searching for them on the UK site doesn't reveal anything. I suspect they're no longer in the 7 game? https://www.bilstein-shocks.co.uk/collections/caterham https://www.bilstein-shocks.co.uk/search?q=CATERHAM+SEVEN (CF)+Year+ maybe here https://performance.bilstein.com/en/caterham-suspensions-exclusively-made-by-bilstein/ Much better https://web1.carparts-cat.com/default.aspx?14=4&52=1&1230=9997&1231=&10=55F6D647E7E6438C9026676892784A73018004&12=102&30=1490&1250=0&31=4250&330=1704&1260=1 Bingo! https://web1.carparts-cat.com/default.aspx?34=0,1000100121&240=0&32=127267&230=29&1271=48&1272=0fc7c03c-00b7-429c-aa7e-9da827f97145&10=55F6D647E7E6438C9026676892784A73018004&14=4&12=130 6/1986-12/1991 1.6 Crossflow: Fronts: Rears: Aw, poo. Oh, well, the rears are eyelet top bush (DeDion) The very early DeDions had stem types Edited July 26 by IamScotticus
pethier Posted July 28 Posted July 28 "Don't ask me to explain why, but stacking two springs gives you a reduced rating." Back over half-century ago when I started autocrossing, I was befriended by John Proshek, who drove an Elan. As I recall, John explained the spring thing to me like this. 1. A coil spring is a torsion bar, wound in a helix. 2. The dynamics of a torsion bar are intuitively simple. 3. Pick up a garden hose with your hands two feet apart. 4. Twist the hose. 5. Note how much the hose resists your twisting it. 6. Move one hand so that your hands are one foot apart. 7. Note how much the hose resists your twisting it. To apply this exercise to the stacking of coil springs: If you stack two springs, it is the same as making a torsion bar longer. 1
IamScotticus Posted July 28 Posted July 28 This makes sense, especially if there is slip between the springs.
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now