AkumaNoZeta Posted April 14, 2009 Share Posted April 14, 2009 I started reading Chassis Engineering by Herb Adams today and besides the fact that the book seems to be a little dated he said that urathane bushings had a short life expectacy which I guess would make sense for the time he's in but are they better now since every bushing kit seems to use them? Or are polyurathane and urathane bushing different? He also said that having spherical bearings and heim joints only increase ride harshness the same amount as adding 5 PSI of air into tires and the only real complaint about them was the road noise. Now is this true? I've always thought that the harshness of having a completely solid suspension was supposed to be back-breaking like when James May was driving that Aston Martin race car around Europe in the quest for the ultimate driving road. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted April 14, 2009 Share Posted April 14, 2009 I started reading Chassis Engineering by Herb Adams today and besides the fact that the book seems to be a little dated he said that urathane bushings had a short life expectacy which I guess would make sense for the time he's in but are they better now since every bushing kit seems to use them? Or are polyurathane and urathane bushing different? He also said that having spherical bearings and heim joints only increase ride harshness the same amount as adding 5 PSI of air into tires and the only real complaint about them was the road noise. Now is this true? I've always thought that the harshness of having a completely solid suspension was supposed to be back-breaking like when James May was driving that Aston Martin race car around Europe in the quest for the ultimate driving road. About the bushings, I'm sure polyurethane and urethane are the same thing and they may have gotten better since Chassis Engineering was written, but I have other reasons for not wanting to use them. The big one is stiction. Spherical bearings have much less stiction and if the suspension can move more freely it will actually feel like there is less spring rate in the car over bumps. You'll feel every pebble in the road, but the suspension will react to them all as well. I drove my car with sphericals on the front LCAs and TC rods and camber plates for tens of thousands of miles with many many passengers and never heard a complaint even when I took my 70+ year old dad for a ride. What made that Aston Martin stiff was the stiff springs and shocks, not the heims joints in my opinion. Quote Link to comment Share on other sites More sharing options...
AkumaNoZeta Posted April 14, 2009 Author Share Posted April 14, 2009 Wow. So all these years of hearing "steel on steel = ungodly awful ride" was wrong? This opens up a whole new realm of supsension options for me. Thank you, I was thinking I would have to stick with bushings to keep a daily-able ride. Quote Link to comment Share on other sites More sharing options...
johnc Posted April 14, 2009 Share Posted April 14, 2009 The three main contributors to ride harshness are: 1. Tire construction - low sidewall height and/or stiff sidewalls. 2. Tire pressures. 3. Shock compression damping. Spherical bearings will transmit more noise into the cabin but in the S30's case, most of the suspension cabin noise comes from the rear. The more expensive spherical bearings have Kevlar/Teflon linings which reduce noise transmission a small amount. Quote Link to comment Share on other sites More sharing options...
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