Steering knuckle joint failure and ABS
#1
12-27-2007, 04:53 AM
Steering knuckle joint failure and ABS
Incident[/b]: This happened to me recently on a state highway in Karnataka (India). I own and Drive a Sonata S20 (Hyundai) mfd Dec 2004. The Odometer reading was about 23650KM (14750miles)at the time of the incident.
After negotiating a right turn that was rather sharp, at a speed about/under 60kmph (38mph)I found that I could not correct the course of the car to straight. Applied brakes but the car continued to slide towards right and went off the road.
Inspection[/b]: The left front wheel knuckle joint had cut at the point of joining the tie-rod of steering (figure2 and 3), while the transmission part was perfectly OK. Apparently what has happened is that after the sharp right turn, the cast-iron joint (amazingly small for a 1.4 metric ton vehicle!) has sheared and the wheel now turned the max. inside the wheel well. While the right wheel responds to the steering correction to point straight the left wheel is pointing completely right as much as it can within the wheel well (the wheel well is quite generous I have not measured upto what degrees turn it would allow a ‘free’ wheel, but would not be amazed if it is over 45°). This is evident in Fig 1
Since the vehicle is front-wheel drive and does not have any sensors to detect the breakage of the cast-iron knuckle steering joint, the transmission continues to rotate both the wheel. The ABS and EBD (that typically work on the rotational speed of the wheel using a proximity sensor) also do not help here, on the contrary, they do not allow the errant wheel to be locked in this case; The 4th figure (the GIF file)
Epilogue: [/b]Of course I and my co-passenger were lucky to escape and surprisingly there was no major damage! I wrote to the manufacturer: Hyundai but have *received no reply from them*[/b]. The service personnel at the Hyundai authorised showroom maintain that the cast iron parts can only break due to an impact, there has never been a case reported like this etc… maybe because most Sonata cars do not make sharp turns(?) Anyway, it would be an interesting statistics how many of these “cast iron” spares have been sold, for this might mean at least that many breakages or “accidents” as they put it! However, I would advice against lock-to-lock turns in a Hyundai... And of course, they do not have a proper ordering process, I believe,the service folks delayed repair of the car and said that they recieved wrong part (that for the new model Sonata Embera).
Anyway, I feel that the manufacturer (Hyundai) does not bother... We do not have a habit of suing companies over this in India, unfortunately!
[IMG]local://upfiles/4887/E1D8C0DBA3B9434C887E5BF6793AC08D.jpg[/IMG]
[IMG]local://upfiles/4887/E392150871D34A9A93B2605013C8262B.jpg[/IMG]
[IMG]local://upfiles/4887/D1E5196F4479427EB2037735A0CD660D.jpg[/IMG]
[IMG]local://upfiles/4887/D060762142BA4E69B6A2F4E5DA760412.gif[/IMG]
After negotiating a right turn that was rather sharp, at a speed about/under 60kmph (38mph)I found that I could not correct the course of the car to straight. Applied brakes but the car continued to slide towards right and went off the road.
Inspection[/b]: The left front wheel knuckle joint had cut at the point of joining the tie-rod of steering (figure2 and 3), while the transmission part was perfectly OK. Apparently what has happened is that after the sharp right turn, the cast-iron joint (amazingly small for a 1.4 metric ton vehicle!) has sheared and the wheel now turned the max. inside the wheel well. While the right wheel responds to the steering correction to point straight the left wheel is pointing completely right as much as it can within the wheel well (the wheel well is quite generous I have not measured upto what degrees turn it would allow a ‘free’ wheel, but would not be amazed if it is over 45°). This is evident in Fig 1
Since the vehicle is front-wheel drive and does not have any sensors to detect the breakage of the cast-iron knuckle steering joint, the transmission continues to rotate both the wheel. The ABS and EBD (that typically work on the rotational speed of the wheel using a proximity sensor) also do not help here, on the contrary, they do not allow the errant wheel to be locked in this case; The 4th figure (the GIF file)
Epilogue: [/b]Of course I and my co-passenger were lucky to escape and surprisingly there was no major damage! I wrote to the manufacturer: Hyundai but have *received no reply from them*[/b]. The service personnel at the Hyundai authorised showroom maintain that the cast iron parts can only break due to an impact, there has never been a case reported like this etc… maybe because most Sonata cars do not make sharp turns(?) Anyway, it would be an interesting statistics how many of these “cast iron” spares have been sold, for this might mean at least that many breakages or “accidents” as they put it! However, I would advice against lock-to-lock turns in a Hyundai... And of course, they do not have a proper ordering process, I believe,the service folks delayed repair of the car and said that they recieved wrong part (that for the new model Sonata Embera).
Anyway, I feel that the manufacturer (Hyundai) does not bother... We do not have a habit of suing companies over this in India, unfortunately!
[IMG]local://upfiles/4887/E1D8C0DBA3B9434C887E5BF6793AC08D.jpg[/IMG]
[IMG]local://upfiles/4887/E392150871D34A9A93B2605013C8262B.jpg[/IMG]
[IMG]local://upfiles/4887/D1E5196F4479427EB2037735A0CD660D.jpg[/IMG]
[IMG]local://upfiles/4887/D060762142BA4E69B6A2F4E5DA760412.gif[/IMG]
#2
12-27-2007, 09:56 AM
RE: Steering knuckle joint failure and ABS
it's unfortunate that that happened to you. i've been working on them and i've never seen something like that happened before. guess that was one of the bad apples.
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