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PostPosted: Wed Jul 11, 2018 7:30 pm 
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Joined: Wed Dec 09, 2009 8:34 pm
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Location: sydney
That picture of that wheel and disc is insane


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PostPosted: Thu Jul 12, 2018 11:41 pm 
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Joined: Wed Jul 27, 2005 4:45 pm
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Location: Zombie-free unfluoridated town in QLD
Some datsun 1200 guys used Mazda s5 alloy hubs, the 4 spots calipers as well on
some American Nascar alloy hat discs. Much cheaper from racejunk.com.
If you can machine or sleeve your stub axles to take the Mazda hubs and bearings
its a big savings but dont forget to angle grind the mazda logo off the calipers :cheers


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PostPosted: Tue Jul 24, 2018 2:29 pm 
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Location: CRACE, ACT
I managed to find a photo of Greg Carr's strut, with somewhat higher resolution. What it shows is remarkable. The high tensile bolts used to fix the steering arm to the strut were fitted with Nyloc nuts.
Here's my assessment of what happened .. brakes get really hot, so does the strut (shock absorbers can get hot, too) ... heat gets transferred to the steering arm ... hot enough for the nylon to soften ... nut comes loose under extreme vibration and falls off ... bolt slides out as far as it could go and fouls the bolts that attach the rotor to the hub ... the wheel can no longer rotate ... as the say, the rest is history.
This problem could have been avoided by using a Crimp Lock Nut, ConeLock type nut or locking tab to hold the nut in place regardless of temperature.
But for want of the "right" 50 cent component the race was lost.
"Things work best when it matters least, and ...

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Things work best when it matters the least, and ...


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PostPosted: Tue Jul 24, 2018 2:50 pm 
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Location: Melbourne, Australia
Interesting. Nylon's glass transition temperature (Tg) is only 47degC. Melt point is around 200degC.
I would assume the Tg temperature would be fairly easy to reach considering the proximity to the heat source.
This might be enough to soften it up compounded with vibration and as you say... the rest is history.
Definitely a good refresher. Thanks Alan.

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PostPosted: Wed Oct 31, 2018 11:48 am 
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Location: CRACE, ACT
Interesting retrospective: Carefully check out the two photos and spot the difference in the ways the steering arms were attached on two Ford Escorts used in competition.

If you didn't spot the important difference, here it is (I missed it too):

In the steering / suspension photo, the bolts that hold the steering arm to the McPherson strut are secured by castellated nuts and split pins: they are not going to work loose.

Greg Carr's 1980 Southern Cross International Rally, Ford factory-backed Escort suffered this obvious failure because the steering arm bolts had Nyloc nuts which loosened with heat and vibration: OUCH! Remarkably it appears that lock wire has been installed on the heads of the bolts that attach the brake rotor to the hub, but no similar method was used to secure the steering arm nuts, and the wrong nuts were used in the first place!


Attachments:
[ attachment ]
Escort Rack.jpg [ 24.43 KiB | Viewed 1753 times ]
[ attachment ]
RS1800 Greg CARR strut [Simon Brown].jpg [ 99.57 KiB | Viewed 1753 times ]

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