John E Posted June 19, 2001 Share Posted June 19, 2001 Took the 7 to work yesterday and on the return home decided to take a diversion over Saddleworth Moor. Whilst overtaking at speed I ran across some undulations in the road surface. Not pot holes just a few ups and downs. The car seemed to want to launch itself into the scenery and whilst to some the local sheep may have seemed attractive I was rather more concerned about staying on the road. On flat roads the car is excellent and runs very true but unfortunately not all public roads are like race tracks. Any one got a comment. About the seemingly bouncyness as apposed to the sheep. Link to comment Share on other sites More sharing options...
Jonathan Ratty Posted June 19, 2001 Share Posted June 19, 2001 In my car, I'd attribute this to the live axle. Jonathan Link to comment Share on other sites More sharing options...
Simos Posted June 19, 2001 Share Posted June 19, 2001 Or hard springs and shocks. If you have adjustable shocks turn them down to a soft setting to let the wheels work a bit, you're doing rather more low flying than driving by the sounds of things, you need to get the wheels in contact with the road more. Link to comment Share on other sites More sharing options...
PJ Catteeuw Posted June 19, 2001 Share Posted June 19, 2001 Correct me if I'm wrong, but doesn't a harder suspension push the wheels back on the ground faster. It just feels like your car is bouncing more, b/c the force acts quiker. If you soften your suspension, it will take longer to put the wheel back on the ground. Link to comment Share on other sites More sharing options...
John E Posted June 19, 2001 Author Share Posted June 19, 2001 Thats what I thought. The car seems to react as though the shockers are knacked but they aint. Link to comment Share on other sites More sharing options...
Mike Bees Posted June 19, 2001 Share Posted June 19, 2001 If the harder the suspension the more likely the wheels are to leave the ground in the first place. If you're not running rock hard springs then it sounds like underdamping. If your dampers are AOK then I'd surmise that you've just found a piece of road which at a certain speed your spring/damper combination doesn't cope with at all well - no big surprise that it exists, relatively unusual to actually find it though! Mike Link to comment Share on other sites More sharing options...
John E Posted June 19, 2001 Author Share Posted June 19, 2001 Mike, can I e mail you? Link to comment Share on other sites More sharing options...
Peter Carmichael Posted June 19, 2001 Share Posted June 19, 2001 All suspensions have a resonant frequency. You probably just hit it by finding a bit of road with a regular undulation and then driving up to the speed at which the resonance started kicking in. Hard suspension might have a ride frequency of ~1.4hz, soft of ~1.1hz. If your car is outside this range then it is probably hideously compromised as a road car. At 60mph you are talking about an undulation every 20 metres or so. Link to comment Share on other sites More sharing options...
Dartmoor7 Posted June 19, 2001 Share Posted June 19, 2001 Is this a case of 16" wheels? Link to comment Share on other sites More sharing options...
Simos Posted June 19, 2001 Share Posted June 19, 2001 I havn't calculated the resonant frequency of my suspension but I do know that if I drive the backroads with the shocks set to a track (hard) setting I'm in danger of losing my fillings. Setting them back to a soft setting changes the car significantly and I can see the wheels moving more let alone feel it in the lower dorsal handling sensor. I've never changed the springs on the fly although when i changed to adjustable shocks I added stiffer springs and there's no doubt it made the car more of an A road rather than a C road car if you know what I mean (Peter yes I know that's no where near quantitive enough for you teeth.gif) I can only speak as i find. Link to comment Share on other sites More sharing options...
Red SLR Posted June 19, 2001 Share Posted June 19, 2001 John, I have a similar problem but not as pronounced. I think the problem is the springs are not too hard, it is the car is too light! It can easily be thrown upwards by the re-coil. Ask Gordon about this as he had the same problem and made some adjustmets and the problem is now sorted. Simon. X777CAT Link to comment Share on other sites More sharing options...
Red SLR Posted June 19, 2001 Share Posted June 19, 2001 Just to add on the streach of road you were going along I have managed to get all 4 wheels off the road. X777CAT Link to comment Share on other sites More sharing options...
Dartmoor7 Posted June 20, 2001 Share Posted June 20, 2001 There are quite a few roads here in Devon on which I can go faster in my 164 than in my 7. This is the reason that I am one of the few Seveners who wish their car was fitted with the '96 suspension. Link to comment Share on other sites More sharing options...
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