Area Representative Tin Man Posted April 24, 2002 Area Representative Share Posted April 24, 2002 I am upgrading to wide track front suspension with 250lb springs on adjustable platforms. I have searched the archives & helper springs from DT are recommended. Can anyone advise how they fit & work. Is there a size & poundage I need to specify? Thank you Link to comment Share on other sites More sharing options...
ECR Posted April 25, 2002 Share Posted April 25, 2002 Demon Tweeks put me in touch with the technical director of the company who make them. I kept up with him on the phone for about 3 minutes but thereon it was a lost cause. They are a technical piece of kit and not just something to stop your springs rattling. In the end I decided that it was better to replace the damper spring caps with purpose designed ones and use standard springs Ex Chairman Roger Link to comment Share on other sites More sharing options...
Peter Carmichael Posted April 25, 2002 Share Posted April 25, 2002 Helper springs not *tender springs*. Sounds like you got put onto Eibach, Roger. Helper springs just compress flat and stop the springs rattling. Tender springs give you a variable (or a dual) rate. For 250lb/in main springs you want 40lb/in x 2 inch helpers. These are available in 60mm diameter, which will work with the green springs from caterham which are 2.25 inch. You will need a joiner piece and IME, you will have to file one side of it down a few mm to be compatible with the spring platform. All of this should be mounted at the body end of the damper. Remove the lock ring on the adjustable platforms and you will have room to fit the whole spring stack. The platform will not move accidentally because it will now never go slack. Link to comment Share on other sites More sharing options...
ECR Posted April 25, 2002 Share Posted April 25, 2002 Thanks for the correction. I asked initialy for helper springs but eibach quickly moved me on to tender springs which is where I started to glaze over... Ex Chairman Roger Link to comment Share on other sites More sharing options...
Tony Martyr Posted April 25, 2002 Share Posted April 25, 2002 I have faced the same problem with 250 ib green springs but have decided to do without them for the first couple of track days. If I jack the wheels off the ground the clearance between spring and platform is about 20mm. I would have to almost leave the ground (cadwell?) before the springs should move I hope. I thought Peter that the helper springs needed more than I had spare and was concerned about taking the locking ring off. Link to comment Share on other sites More sharing options...
julians Posted April 25, 2002 Share Posted April 25, 2002 If you have adjustable platforms can you not just raise the spring seat to take up any slack caused by having too short a spring. Theres probably a good reason why not, but that seems to be the simple answer. Hmmm, just thought about it and I guess there may not be enough adjustment available in the seats, but I guess you could have another groove for the circlip (and hence the adjustable spring seat) cut somewhere higher up the damper body, come to think of it dont the bilstein dampers have two grooves at different heights for just this sort of situation (mine do, but thats narrow track). Edited by - julians on 25 Apr 2002 17:43:52 Link to comment Share on other sites More sharing options...
Peter Carmichael Posted April 25, 2002 Share Posted April 25, 2002 Classic schoolboy error, Julian. When you drop the car off the jack so that it is carrying its own weight, it has the same load on the springs regardless of the spring rate. Stiffer springs move less form unloaded to loaded, so if you go above a certain stiffness the springs will not compress far enough from the "just touching the platforms" position to set a reasonable ride height. You either have to have a way of allowing *safe slack* (helper springs, lock wire etc.) or you need a shorter open length on the damper (remove spacer). Removing spacers isn't too clever as it disables the bumpstops. Link to comment Share on other sites More sharing options...
julians Posted April 25, 2002 Share Posted April 25, 2002 Ah, I see, so its not necesarily that the new springs are shorter than the old springs, but the new (stiffer) springs will have raised the 'settled' height of the car ,hence needing the platforms opening out (to lower the car) and a soft helper spring taking up the new space/slack created . I knew there must have been a reason why you couldnt just do it that way. Link to comment Share on other sites More sharing options...
jonhill Posted April 25, 2002 Share Posted April 25, 2002 I put the green, 6.75" long, 250s from Caterham on my wide track car, and adjusted the spring seat so that it just held the spring. The ride height seem perfectly fine, and the spring can't get loose on drops. Obviously if I wanted to go any lower, things could get slack, but I think the height is about right. If you want to go lower, could you not just get shorter springs to allow a shorter open length damper when "just touching"? DT have 2.25" dia 250lb springs from 4" to 14", so surely the right rate length combination could be found without needing extra helpers? Or have I missed the pointquestion.gifconfused.gif My 250s are ~5.5" compressed which according to my calculations is about the same as the std 7.5" 150s (1.25" * (250/150)). Not sure of the significance of this (if any) but maybe it's no coincidence, which is why Caterham sell these particular length springs? Jon Edited by - jonhill on 25 Apr 2002 21:30:27 Edited by - jonhill on 25 Apr 2002 21:38:43 Link to comment Share on other sites More sharing options...
jonhill Posted April 25, 2002 Share Posted April 25, 2002 OK, been thinking about it more, and I see that shorter springs won't make any difference - as soon as you have the spring seat just touching when unloaded, the ride height will be the same regardless of spring length once the car is on its wheels (for the same rate spring). I think smile.gif Jon Link to comment Share on other sites More sharing options...
Area Representative Tin Man Posted April 27, 2002 Author Area Representative Share Posted April 27, 2002 Many thanks for the replies. Peter do DT supply the joiner pieces? Can you tell me what IME stands for? As you can see I am a technical ludite, though I did build my Seven. I will probably try the springs & see what ride height I get. Thank you Link to comment Share on other sites More sharing options...
FH Posted April 27, 2002 Share Posted April 27, 2002 and IME In My Experience FH teeth.gif Link to comment Share on other sites More sharing options...
don_g Posted April 28, 2002 Share Posted April 28, 2002 Easy job - I've done it on the rear springs (Leda) only recently. If you've been 'flat floored' note carefully the position of the spring platforms so that you can refit correctly and not upset the corner weights. Bought the assistor springs from DT a couple of years ago... £ only. Same dia as the springs, so no engineering necessary at all. Airborne at Cadwell is about the only place my suspension could come unseated and, maybe, cause problems when recompressing on landing so there really was no ungency to fit. Link to comment Share on other sites More sharing options...
Area Representative Tin Man Posted April 28, 2002 Author Area Representative Share Posted April 28, 2002 Thank you FH. blush.gif Link to comment Share on other sites More sharing options...
Area Representative Tin Man Posted May 11, 2002 Author Area Representative Share Posted May 11, 2002 The springs have bee fitted. 80mm ground level to sump on 14" 185/60. The springs are slighty loose, but not enough to come free from the seat. The car has been transformed! Link to comment Share on other sites More sharing options...
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