A frame or Panhard

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Re: A frame or Panhard

Postby Big Daddy » Fri Jan 20, 2017 12:39 am

Countryboy wrote:The road wheel is transmitting load/impacts to the lower fulcrum pin . The telescopic damper and I'm guessing uprated coil Spring are more effectively resisting those loads/impacts . In the end somethings got to give...

Insufficient spring or damper force often results in suspension travelling to full bump (metal to rubber) or jounce (metal to metal if rubber stop fails). Both transmit much greater loads and hence component stress than springs or dampers, especially the hard shock impact suffered by jounce contact.

Wheel kerbing is another common high stress impact, which could have instigated these wishbone pan cracks.

Countryboy wrote:I wonder if these cracks would happen suddenly or if you were really lucky your MOT tester might spot them :whistle:

Probably not under all the road grime, especially as crack initiation to failure would take much less than a year (when we had MOTs)... :roll:

Seems we've returned again to the wheels falling off... :mrgreen:
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Re: A frame or Panhard

Postby Dave Clark » Fri Jan 20, 2017 6:39 am

All this is making me nervous about ever taking my car out again.
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Re: A frame or Panhard

Postby Hurtzberg » Fri Jan 20, 2017 10:02 am

I'll do you a deal Dave, I'll swap that modified car of yours for my safe unmolested original.
Andrew

1957 A35
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Re: A frame or Panhard

Postby gazza82 » Fri Jan 20, 2017 10:39 am

Wondering if wheel spacers might contribute to failing wheel nut seats. Many have larger holes that the stud, especially the universal ones, so that would mean no solid base to bolt down to. Over-tightening and the use of impact drivers to put wheels back may now be a factor?

I've only use spacers on one car and that was our old Midget. It had 5" Cosmic alloys which for some reason caused the tyres to slightly foul on something behind .. memory isn't what it was .. and so I fitted slim spacers on the front to add clearance. Those wheels had steel nut seat inserts. I remember one dropping out! :shock:

For those of you not familiar with Cosmics (these aren't mine, just a pic I found on t'interweb)..
Cosmics.JPG
Cosmics.JPG (65.19 KiB) Viewed 121 times

I spent a lot of weekends polishing these with AutoSolvol!!
"If you're driving on the edge ... you're leaving too much room!"

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Cars: "Project 757" '58 A35 2-door 948cc (in storage) - plus the "family fleet" - Alfa MiTo, Peugeot 206, Renault Clio plus Fiat Punto. (Ex 1998 Alfa Romeo 156 2.0 TS)
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Re: A frame or Panhard

Postby Big Daddy » Fri Jan 20, 2017 11:20 am

gazza82 wrote:Wondering if wheel spacers might contribute to failing wheel nut seats. Many have larger holes that the stud, especially the universal ones, so that would mean no solid base to bolt down to.

Spacers and wheel nut seats are critical to those nuts staying torqued.

We use spacers on the racers. Best sort physically attach to the hub. Rigid loose spacers are satisfactory but far from ideal. All starts going wrong if you attempt to fit two spacers under one wheel, which prompts the wheel nuts to loosen. Don't really understand why but probably related to degraded friction drive between wheel and hub faces (nuts merely provide clamp load).

Same cone angles between seat and wheel nut, and consistent stud PCD between hub and wheel are also critical. Never bodge it :!:
Last edited by Big Daddy on Fri Jan 20, 2017 11:56 am, edited 1 time in total.
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Re: A frame or Panhard

Postby Big Daddy » Fri Jan 20, 2017 11:24 am

Dave Clark wrote:All this is making me nervous about ever taking my car out again.

Ever looked at FMEA :?: Failure Modes Effects and Analysis: all the ways things can go wrong and consequences of those failures, catastrophic or otherwise. Focuses the mind... :thumbs:
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