Revin Kevin Posted June 23, 2003 Share Posted June 23, 2003 HI ALL, Has anyone ever measured dump steer on their seven ( someone must of ). What were the results like , did you decide to live with the results or modify. CHEERS in anticipation CHRIS Link to comment Share on other sites More sharing options...
DohNut Posted June 24, 2003 Share Posted June 24, 2003 Mine was done at Whitings some time ago. The rack was raised about 5mm which aparently helped. But i need to get it checked again as I have changed the front ride height. I would like to think that a fairly new car with a new rack running at standard ride height should be OK as it is. - but maybe I am expecting too much Nick Link to comment Share on other sites More sharing options...
Revin Kevin Posted June 25, 2003 Author Share Posted June 25, 2003 Nick Thanks for your reply, did you feel a significant difference afterwards? I'm suprised on how few replies, as I understand bump steer can have a significant effect on straight line stability/driver confidence in his car and a small difference like 5MM in rack height , I've been led to believe can have significant effects. When caterham supply racks they also supply shims to alter the rack height, I assume to allow for production tolerances. How are people with new cars, built as kits knowing how many shims to use and I can't see caterham measuring each car as it's not a difficult job to measure bump steer just a fiddly time consuming task and you need the required equipment as an amateur. COME ON ALL YOU TECHSPERTS OUT THERE GIVE US A CLUE. CHEERS CHRIS Link to comment Share on other sites More sharing options...
Paul Richards. Posted June 25, 2003 Share Posted June 25, 2003 Measuring bump steer is something I've kept meaning to do. As you say it's a bit fiddly, but will cost nothing. I seem to recall that suspension guru Alain Staniforth set up a lot of Sevens and virtually all needed some adjustment to eliminate/minimise bump steer. Need to take spring off shocker and move the wheel up and down through normal range of travel and watch for steering movement. You can make a hinged board with pins on it as described in some of the suspension set up books, but you can get a good indication by removing wheel and clamping a long piece of wood or metal to disc and watching end of said long piece - this exaggerates movement. Paul R. C7PPR K series that starts when hot!! Link to comment Share on other sites More sharing options...
DohNut Posted June 25, 2003 Share Posted June 25, 2003 Kevin previous owner did it so I cant comment on before and after i'm affraid. Nick Link to comment Share on other sites More sharing options...
JonP Posted June 26, 2003 Share Posted June 26, 2003 Hi, Just investigating the same subject! I think it is never possible to illiminate all bump steer but generally it seems the rack is set too low, giving you the option of shimming it upwards. Both cars I have adjusted need 5 to 8mm under the rack, I would start with 6 and see how it feels. You will need longer bolts (available from Caterham) otherwise your nylocs will not nyloc! From reading some US web sites it seems some bump out is OK (and may actually improve turn in) but bump in should be avoided at all costs. This translates into a rack set too low is OK but too high is a no no. Search Google for Bump Steer and you will see what I mean! Best regards JonP No longer Sevenless....! Link to comment Share on other sites More sharing options...
Jason Plato Posted June 26, 2003 Share Posted June 26, 2003 Yes it is worth doing if you are not happy with the steering feel / performance . I checked mine and raised the rack by 4mm . This did improve the situation . But then I changed all my suspension settings and droped the ride heights etc etc , and I havent redone it yet . Although it does *feel* Ok Dave Link to comment Share on other sites More sharing options...
Revin Kevin Posted June 27, 2003 Author Share Posted June 27, 2003 Thanks all for your relies, DAVE what method did you use to check your bumpsteer, long metal bars strapped to the wheels or a more accurate method. CHEERS CHRIS Link to comment Share on other sites More sharing options...
Jason Plato Posted June 28, 2003 Share Posted June 28, 2003 I followed the instructions in Allan Stainiforths book - Competition Car suspension . This shows you how to graph the movement on the static suspension . dave Link to comment Share on other sites More sharing options...
Revin Kevin Posted June 29, 2003 Author Share Posted June 29, 2003 Dave, Thanks again, I'll have a read, CHEERS CHRIS Link to comment Share on other sites More sharing options...
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