Graham Sewell Posted January 7, 2003 Share Posted January 7, 2003 I know this has been done to death in the past, but I could not find details in a search of the archives.... I wish to raise my car slightly to stop the tyres attacking my clamshells on bump corners. On the rear, it is easy to calculate how many turns I need by dividing the 5mm I need by the pitch of the thread on the AVO's (2mm I think) as the dampers are vertical (or nearly). However, for the front damper, what is the multiplier as the dampers are inclined dramatically? I am asking so that I can at least get the car in the ball park on the first iteration. Also do you need a C-spanner to adjust these, or can the platform be twisted by hand once the weight is off the wheels? Cheers, Graham Low tech luddite - xflow and proud! Link to comment Share on other sites More sharing options...
Jaseb Posted January 7, 2003 Share Posted January 7, 2003 For the height measurement, I'd find yourself a reference point if poss (vertically up to the edge of the clamshell maybe) and measure from the centre of the wheel to it, failing that trigonometry from yer school days would be my guess. On regular cars in my days at Spax I used to measure vertically from the wheel arch to the centre of the wheel so would try to mimic that. Or better still get it put on some corner weight scales and tinker with the whole balance of the car front and rear. As for turning the collar, C-spanners are probably best (and easiest) as the springs are a fair rate on the front and I think you may struggle and by the time you get everything ready (car in the air etc) for the price of a spanner it'll be worth not struggling - Spax in Bicester used to sell these for peanuts FWIW. Plus with C-spanners you can do it with the weight on the wheels I would have thought. Edited by - jaseb on 7 Jan 2003 11:46:26 Link to comment Share on other sites More sharing options...
stevefoster Posted January 7, 2003 Share Posted January 7, 2003 Depending on the damper type you may need another large spanner to hold the body of the damper to stop it twisting. Bilsteins are like this. They have a flat in the body for this. /Steve My racing pics, 7 DIY, race prep. Updated often here Photo's of the year here Hants (North) and Berkshire Area club site here Edited by - stevefoster on 7 Jan 2003 13:20:29 Link to comment Share on other sites More sharing options...
Graham Sewell Posted January 13, 2003 Author Share Posted January 13, 2003 There is very little weight on the front springs once the wheels are in the air - so the platforms can be adjusted by hand without tools. However, once the fronts are set to the correct height, do you set the 15mm rake when the fuel tank is empty/full/notionally half-full? From simple calculations based on a tank of fuel weighing 30kg, and spring rates of 130lb/in (60kg/in) this would account for a difference of 1/4" (6.25mm) - so it becomes an interesting question.... Low tech luddite - xflow and proud! Link to comment Share on other sites More sharing options...
Simon Dart Posted January 15, 2003 Share Posted January 15, 2003 Graham, If you can't get hold of the correct C-spanner use beefy (4 x 5mm wide minimum) tie-wraps to take up the spring tension, just jack the car up on the opposite diagonal to load the spring, tighten the tie-wraps and then jack the corner up. This works fine for non-adjustable platforms too. Be careful though! Simon Link to comment Share on other sites More sharing options...
Area Representative Richard Price Posted January 15, 2003 Area Representative Share Posted January 15, 2003 Graham, I've just found a spreadsheet I did a few months ago with the answer to one of your original questions. The "multiplier" for the front ride height changes from 0.73 at full bump, to 0.64 at full droop. That is for each 1mm of suspension movement, the damper will move between 0.73 and 0.64mm. (These figures were calculated for my 2002 standard track RoadSport) Edited by - richard price on 15 Jan 2003 21:22:18 Link to comment Share on other sites More sharing options...
Graham Sewell Posted January 16, 2003 Author Share Posted January 16, 2003 Richard, Thanks for the info, from an initial thought I had it the other way around, namely that movin the spring 1mm would change ride height by 0.7mm. But I have now worked through the trig with a couple of basic example and you are correct and I have messed up my front/rear rake angle... That will be put right this weekend. For those interested in my calculations - using the old maths triangle of 3/4/5 where the triangle is 3 high, 4 wide and a hypotenuse of 5 (spring component), reducing the spring by 1 to a value of 4 will reduce height to 0. Alternatively, with some algebra it can be approximated that (for small changes - thereby ignoring 2nd order equations) the change of spring length is the change in height multiplied by the height of the triangle over the overall damper length (with is approximately 0.7 @ 45 degrees). Low tech luddite - xflow and proud! Link to comment Share on other sites More sharing options...
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