Tony Posted September 5, 2007 Report Share Posted September 5, 2007 The cause for "Heel and Toe" has been argued between the tyre manufacturers and car manufacturers for years and both have offered convincing reasons. wim was requested to write a report for an arbitrator in the states to aid in a dispute between 350z owners and Nissan. I concluded these observations.... 1> Complaint:- The initial detection of heel and toe wear is vibration below 30mph and high level of harmonics over 50mph. 2> Tyre design:- Although all designs are susceptible to heel and toe the vast majority of complaints where with directional tread pattens. 3> Car:- All forms of drive are susceptible but FWD cars had the highest complaints with heel and toe wear on the rear. Summary The tyre tread is without structure and subject to compression between the road and inner constructive casing. In essence the tread is "pinched". The directional tyres tread design of lateral fingers needs to resist a "pull" on contact, and "push" off during release with the road. The "pinch" pattern of wear cannot be uniform along the longer fingers of tread, explaining a reason for the heel and toe by tread design alone. Observations that FWD cars have heel and toe wear on the rear belays the "pinch" theory since the rear tyres are meir passengers. It has been suggested by some engineers that a coil and damper disparity is allowing the rear tyres to pulsate on the road as the car brakes and the nose submarines. This is a reasonable argument since historically the complaint on FWD cars only appears after the car has done 40k miles or so. wim says: I feel both reasons are correct only adding confusion to the complaint. A frustrating combination of tread design, suspension ratios and type of drive has left a difficult legassey to resolve..... Incidentally, Nissan did indeed change the suspension on the early 350z and the problem disappeared Heel and Toe> Quote Link to comment Share on other sites More sharing options...
jon Posted September 5, 2007 Report Share Posted September 5, 2007 An interesting post. I'm not sure I understand this correctly so let me ask a few basic questions just to make sure I do. 1) Why is this different from the usual camber / toe wear? 2) Is the slightly patchy wear shown in the image a feature of heel and toe or just a one off. Regarding the issue with the 350z, suspension realignment plus a new treadblock pattern from bridgestone solved the problem, it wasn't just a geometry fix. Quote Link to comment Share on other sites More sharing options...
Tony Posted September 5, 2007 Author Report Share Posted September 5, 2007 An interesting post. I'm not sure I understand this correctly so let me ask a few basic questions just to make sure I do. 1) Why is this different from the usual camber / toe wear? 2) Is the slightly patchy wear shown in the image a feature of heel and toe or just a one off. Regarding the issue with the 350z, suspension realignment plus a new treadblock pattern from bridgestone solved the problem, it wasn't just a geometry fix. Geometric wear is uniform over the entire circumference.. The patchy wear in the image is "heel and toe" and not a on off. The 350z had a "stand alone" Geometry set-up. Most times the manufacture modifies a proven past chassis for future models. This was not the case with the Z. The Geometry positions have been revised several times to assist the chassis and control the handling/tyre wear tracking problems. The heel and toe issue was stopped after the damper ratios were adjusted... But i have no written evidence this was Nissan's solution to the problem. And i do agree with you jon this was not a Geometry problem. Quote Link to comment Share on other sites More sharing options...
jon Posted September 5, 2007 Report Share Posted September 5, 2007 The patchy wear is certainly very interesting (and confusing!) You'd think something as round as a tyre would wear evenly even if the forces came in pulses... Do you know how they revised the Z over the years geometrically? Quote Link to comment Share on other sites More sharing options...
Tony Posted September 5, 2007 Author Report Share Posted September 5, 2007 The patchy wear is certainly very interesting (and confusing!) You'd think something as round as a tyre would wear evenly even if the forces came in pulses... Do you know how they revised the Z over the years geometrically? The main change is the front toe. It progessively moved from +.4mm to the current +1.1mm per side. Nissan where quite adamant that + 1.1mm per side was printed on each invoice. Quote Link to comment Share on other sites More sharing options...
jon Posted September 6, 2007 Report Share Posted September 6, 2007 Over doubled the toe, that I didn't expect to cure that sort of wear. I have a lot to learn still. Quote Link to comment Share on other sites More sharing options...
Tony Posted September 6, 2007 Author Report Share Posted September 6, 2007 Over doubled the toe, that I didn't expect to cure that sort of wear. I have a lot to learn still. On the Z the heel and toe wear stopped when they changed the suspension... But they still had issues with front toe wear, so over time the toe positions have been move more and more positive. Quote Link to comment Share on other sites More sharing options...
jon Posted September 6, 2007 Report Share Posted September 6, 2007 Ah I'm with you, so the heel and toe wear was separate from the tyre feathering issue they experienced with the early models? Quote Link to comment Share on other sites More sharing options...
Tony Posted September 6, 2007 Author Report Share Posted September 6, 2007 Ah I'm with you, so the heel and toe wear was separate from the tyre feathering issue they experienced with the early models? Yep Quote Link to comment Share on other sites More sharing options...
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