Alex Wong1697456877 Posted September 21, 2007 Share Posted September 21, 2007 I've bought this Eibach ERS supension I've done as much research into what it is and where it came from - have even found the guy who built them who's since left Eibach. I've done some sums as well...... Fronts:- eye to eye 37cm, body 20cm, adj thread 10.5cm. Rears:- eye to eye 46Cm, adj thread 16cm. SPRINGS:- Length ID Rate(N/mm) Tender Main 40 60 40 140 60 90 140 60 100 40 60 20 160 60 90 180 60 90 180 60 100 200 60 100 1 N/mm 5.71 Lbs/Inch 20 N/mm 114.2 Lbs/Inch 40 N/mm 228.4 Lbs/Inch 90 N/mm 513.9 Lbs/Inch 100 N/mm 571 Lbs/Inch Ci Initial rate Cm Main spring/ Final rate Ct Tender Spring Rate Ci = Cm x Ct ------- Cm + Ct Possible Combinations --------------------- Ct 40 Ct 40 Cm 100 Cm 90 Ci 29 Ci 28 Ci Lbs/inch 163 Ci Lbs/inch 158 Ct Lbs/Inch 571 Ct Lbs/Inch 514 Ct 20 Ct 20 Cm 100 Cm 90 Ci 17 Ci 16 Ci Lbs/inch 95 Ci Lbs/inch 93 Ct Lbs/Inch 571 Ct Lbs/Inch 514 The possible combinations seem to show a very low initial rate and an extremely high final rate, but I actually cannot decide if this is ok or not. I think it'ss be a case of try it and see. The Tender springs are ok and I can always get softer main springs if needed. I've read some of the mammoth posts on dual rate springs on BC but still can't get my head around this. I can turn into a corner and get say 163 lb/inch at the front and 95lb/inch at the back which gives me a certain handling characteristic. (Would in reality be a bit more as the car's weight will be compressing the springs). Although the're not variable rate tender springs, the rate then rises a bit but will suddenly become 571/514 lb/inch when the tender springs go coil bound - and one one will go coil bound before the other. I guess it's like hitting the bump stops but won't the handling suddenly change at this point? Edited by - Alex Wong on 21 Sep 2007 13:07:45 Link to comment Share on other sites More sharing options...
Jason Plato Posted September 21, 2007 Share Posted September 21, 2007 I not sure understand the layout of the figures ? what are the options of tender and main springs ? Am i correct in thinking that the tenders are either 114 or 228lb/" in which case they will be compressed and coil bound with the static corner weights of the car being inexcess of these spring values vs length ? and that leaves you with 513 and 571 lb front and rear springs being a doctor - do you get a discount with the dentist given those spring rates 😬 its a fair way off the "normal" 275 / 200lb/" spring rates for a Vx 🤔 Dave Taffia rear gunner Edited by - Dave J on 21 Sep 2007 13:30:23 Link to comment Share on other sites More sharing options...
Jason Plato Posted September 21, 2007 Share Posted September 21, 2007 also are the dampers valved for those spring rates ? The dampers maybe very hard Taffia rear gunner Link to comment Share on other sites More sharing options...
Alex Wong1697456877 Posted September 21, 2007 Author Share Posted September 21, 2007 >>Am i correct in thinking that the tenders are either 114 or 228lb/" Yes, but it's not that simple. If you have a 114lb tender and 571lb main spring, the initial rate is 163lb/inch Seeing as I used to run 150lb at the front, I'm sure the tender will not be coilbound at rest >>513 and 571 lb front and rear springs Yes - but that's only on steady load in corners when the tenders are coilbound. As it starts to bounce around the rate will fluctuate between 163 and 513 lbs. Just what happens when that's going on is beyond me. Dampers may well be very hard - will have to try and see, but as I said, the initial rates are lower than what we normally run so maybe not? I do know that these were purpose built for a widetrack 7. There are 9 clicks of adjustment on each shock. Edited by - Alex Wong on 21 Sep 2007 13:37:15 Link to comment Share on other sites More sharing options...
Alex Wong1697456877 Posted September 21, 2007 Author Share Posted September 21, 2007 Am I right in saying that the angle of the front shock means that the lb/inch does not directly traslate into mass of car and shock compression? The car may weigh say 500lb at the front, but will not deflect two 250lb springs by half an inch each? >>being a doctor - do you get a discount with the dentist given those spring rates 😬 The whole idea is to have those rates to allow flat cornering, but the tendersprings make it comfortable when it bounces. It also tries to stop the tyre bouncing off the road. Maybe I'll be grateful for my ample natural gluteal 🙆🏻 dampening if it's that bad! Edited by - Alex Wong on 21 Sep 2007 13:44:33 Edited by - Alex Wong on 21 Sep 2007 15:52:39 Link to comment Share on other sites More sharing options...
Tom_C Posted September 21, 2007 Share Posted September 21, 2007 I think maybe Stressed Dave is the man you need here, but I know he's away this weekend. When I see him on Monday I'll point him at yuor thread if he hasn't already seen it. Cheers Tom FH54WLX see here - UPDATED again Link to comment Share on other sites More sharing options...
Jason Plato Posted September 21, 2007 Share Posted September 21, 2007 yes - your 150lb springs are Ok but they are 7" long The tender springs are only 40mm long at 114lb / " The combined rate is 163lb at the chassis. I would consider if these springs are actually designed as adding and functioning as springs or if they are simply there to prevent the main springs falling off the platforms as you crest the mountain at Cadwell. Taffia rear gunner Link to comment Share on other sites More sharing options...
Jason Plato Posted September 21, 2007 Share Posted September 21, 2007 third option (and my favourite *wink*0 sling them on and see how it rides Taffia rear gunner Link to comment Share on other sites More sharing options...
Alex Wong1697456877 Posted September 21, 2007 Author Share Posted September 21, 2007 These are definitely tender springs and not helper springs. Helper springs tend to be about 40lb. I understand what you're saying, but don't have the knowledge to work out if they will be coilbound at rest. My gut feeling is that they won't be. sling them on and see how it rides Yup - that's the plan, but I'd like to try and understand just what on earth goes on between the initial and final rate, and the theory behind the dual rate spring. There is a huge post by PC and alot from Neil Anderson on this that I read and half absorbed here. Edited by - Alex Wong on 21 Sep 2007 14:07:05 Link to comment Share on other sites More sharing options...
tiddy1 Posted September 21, 2007 Share Posted September 21, 2007 The dampers can only be valved for one rate so they will always be a compromise with dual rate springs Simon Link to comment Share on other sites More sharing options...
Jason Plato Posted September 21, 2007 Share Posted September 21, 2007 on the thread you link to Arnies helper springs were much stiffer than the main spring - on your dampers the "tender" springs are much softer. This is odd. Taffia rear gunner Link to comment Share on other sites More sharing options...
Alex Wong1697456877 Posted September 21, 2007 Author Share Posted September 21, 2007 Hmmmmmm I think by definition, the softer spring is the tender spring? The only difference is the tender springs are flat/square section so they can close properly and fully. Edited by - Alex Wong on 21 Sep 2007 15:48:12 Link to comment Share on other sites More sharing options...
Jason Plato Posted September 21, 2007 Share Posted September 21, 2007 but the tender is supposed to be much stiffer rate per inch so that the spring compresses and the rate is then transfered in a manner to the main spring that doesnt upset the chassis. In Arnies case the tender was a lot stiffer and only had 8 mm to compress before it went coil bound, of course it was also compressing the main spring at the same time. I'm sure that Stressed Dave and Neil can provide a far info than me - I dont relay have a clue about this but I dont think its a helper and I do think the main springs are far too stiff gotta go now 😶🌫️ Taffia rear gunner Link to comment Share on other sites More sharing options...
Alex Wong1697456877 Posted September 21, 2007 Author Share Posted September 21, 2007 Cheers Dave Have given myself quite a headache trying to decide whether to go for it or not. Could do with a pie and a pint whilst I think about this........ Edited by - Alex Wong on 21 Sep 2007 16:02:07 Link to comment Share on other sites More sharing options...
Alex Wong1697456877 Posted September 21, 2007 Author Share Posted September 21, 2007 Arnies logic does make some sense but seems to be more focused on reducing roll than maintaining the contact patch. Will play with the spreadsheet some more. Link to comment Share on other sites More sharing options...
LesG Posted September 21, 2007 Share Posted September 21, 2007 Wow! Where's the Nurofen? Link to comment Share on other sites More sharing options...
Andy Best Posted September 22, 2007 Share Posted September 22, 2007 Alex I have the ERS setup on my k-series I hope these figures help however, the springs are nothing like I have Front has no tender spring the main spring is 200-60-40 Rear has tender spring 30-60-30 main spring 300-60-35 This suggests my rears are set up to provide a Ci of 16 the car certainly handles OK and I still have my teeth 😬 These were designed by Eibach for the seven back in early 2000. I recently needed then rebuilding and found the european Eibach specalist in Barnsley, Russ at Mick Gardner Racing 01226 240099. He seemed knowledgable I don't know if he can help but I would give him a ring, he works long hours but races most weekends. BTW you got a bargin, the dampers without the springs cost £180 plus vat each. If you need to change the springs they are the cheap part of the set up Link to comment Share on other sites More sharing options...
Alex Wong1697456877 Posted September 22, 2007 Author Share Posted September 22, 2007 Hmmmm Dan White (ex of Eibach) reckoned these were a one off set built for PTP and cost to the tune of 7500 UKP. Either way, it's a bargain. They're certainly VERY light. Do you run the rears upside doen to get to the damping adjuster? Your springs look more like what I would expect on a Seven. Do you have any reference numbers on your shocks? Mine are : CATERHAM FRONT FO5 800-149-001/2 14-02. CATERHAM REAR RO5 800-150-001/2 14-02. Edited by - Alex Wong on 22 Sep 2007 13:18:28 Link to comment Share on other sites More sharing options...
Andy Best Posted September 22, 2007 Share Posted September 22, 2007 Mine are 800-188 and 800-189 so yours are slightly different. Duncan Fraser was the contact at Eibach. Like you say they are very light I think the ones you have differ from mine in that they have smaller spring lengths. So we still both have unique setups! The rears were an 🙆🏻 to fit as they are a little bigger diameter than the standard items fit the adjuster at the bottom and remove the rivets for the ally turrets in the boot otherwise you will never get them to fit. When fitted the turrets can be riveted back but with use you will get a small bump that is made by the top of the damper. Andy Link to comment Share on other sites More sharing options...
Alex Wong1697456877 Posted September 22, 2007 Author Share Posted September 22, 2007 Thanks Andy - good tip about the rears - will remember that when I fit them (plan to start after the club's Rockingham day.) Do yours use the through the (de dion) tube or the under the tube mounting? My understanding of the ERS system is to allow higher spring rates to be used to promote flat cornering whilst maintaining good tyre contact over bumps, so I'll give the seemingly absurd 500lb springs a go at the front, but I'm tempted to try something softer maybe 300lbish main at the back, but anything at this stage is just a stab in the dark! Thanks for your spring rates - at least I know what to try if all the ones I've got are not suitable. Link to comment Share on other sites More sharing options...
Alex Wong1697456877 Posted September 22, 2007 Author Share Posted September 22, 2007 Neithe Dan Frazer nor Dan White work at Eibach anymore but I have tracked Dan White down. Will try Russ as well for any advice he may have. Link to comment Share on other sites More sharing options...
Alex Wong1697456877 Posted September 23, 2007 Author Share Posted September 23, 2007 Why is a10 inch 300lb spring different from two 5 inch 300lb springs on top of each other? 5 inch 300 lb springs on top of each other is basically a 150lb spring, but one 10 inch 300lb spring is a 300lb spring. Is a 10 inch 300lb spring twice as stiff per unit length than a 5 inch 300lb spring? 🤔 🤔 🤔 Edited by - Alex Wong on 23 Sep 2007 11:14:41 Link to comment Share on other sites More sharing options...
Rob Walker Posted September 23, 2007 Share Posted September 23, 2007 Alex. No, springs are rated as lbs per inch of compression. So it will take 300lbs of load to compress either spring by one inch. Helper springs are normaly 14lbs /in and are designed so that they always apply preloading to the top caps and platforms to stop the whole lot falling apart when the suspension becomes unloaded. Rob. Link to comment Share on other sites More sharing options...
Alex Wong1697456877 Posted September 24, 2007 Author Share Posted September 24, 2007 But if Ci=CtxCm/(Ct+Cm), 2 300 lb springs on top of each other = 150lb/inch, so in theory a 10 inch 300lb spring is the same per unit length poundage as a 600lb 5 inch spring? 🤔 Link to comment Share on other sites More sharing options...
Rob Walker Posted September 24, 2007 Share Posted September 24, 2007 No Alex if the spring rate is 300lbs thats means the spring will compress 1" along the entire length of the spring. A 5" X 300lb spring will compress to 4" with 300lbs applied and a 10" or 2 X 5" X 300lbs spring will compress to 9" with 300lbs applied. A 10" 300lbs spring will compress to 8" with 600 lbs applied and a 5" 600lbs spring will compress to 4" when 600lbs is applied. Now if you start adding different spring rates together then it gets more complicated as the softer spring will take most of the deformation. Edited by - Rob Walker on 24 Sep 2007 11:36:07 Link to comment Share on other sites More sharing options...
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