Broken steering arm

[Ian Williams]

For the record today whilst looking for a replacement I pulled out four more, two were cracked in the same place as the first, and two were fine, well one was fine, the other although un-cracked had a poor thread.

[Steve Bryant]

While on this subject of replacing cracked steering arms perhaps we could be reminded of the cherished suppliers who currently sell them please ?
Thanks,
Stephen

[Ruairidh Dunford]

David Cochrane sells new ones.

Tony Betts sells crack tested second hand ones.

There will be others as well.

[Bob Culver]

For fatigue cracks of long standing in any component,  a brown colouration from the fretting of the surfaces is common.
As with cranks, it is apparent from the large number cracked that the condition must often exist for a large part of total life (which is not the case with revolving bending fatigue tests of plain rods at constant load)
Fatigue is reckoned to be much increased in corrosive conditions. It is prudent to keep the arms, stub axles etc greased.
In simple bending the cracks generally seem to run near straight between the ends.
It would be interesting to see how extensive was fatigue part of crack in arms failed in normal use. In crankshafts crack extends a huge way through.
The original arm in my car failed at about 60,000 and that with a last owner careful not to tug on the wheel. Like many older cars it had been in a crash. However a few overloads sometimes extends fatigue life!
The shank failures are a concern as new arms the same. It is essential the arm seats properly and not seat primarily on the vertical centre line. As with big end bolts keeping tight protects flange from fatigue.
If a crack can be established as definitely only 3/32 or so deep it is not going to fail tomorrow or even next year, but by eye depth is uncertain. But if someone fights the car in and out of a tight park every day life may be short....
Older motorist were taught not to haul on the steering wheel but many owners of moderns have become especially used to turning the wheel with car stationary. (It is remarkable that the modest proportioned components of moderns seem to stand this repeated action. Many owners must chirp the wide tyres almost every day.)
As before, if Seven wedged in a tight park, best to get out and pull the wheels by hand.
 
Where dependent on magnet the poles should span the crack.
 
Google currently produces some interesting pics of fatigue cracks in RR Trent turbine blades.
The advert dependent newspapers, which adopt the role of drama queen about asbestos pipes in schools etc, accept the glib played down reports from the airlines without speculation.

[Geoff Halstead]

JonE,
Details please as the only results I get on eBay are for the white powder stuff.

Geoff - Minds a blank.

[JonE]

https://www.ebay.co.uk/itm/Flawtek-Weld-...1040603133?

I'd like to know what the magnet is for Ruaridh? Does one need it or will the kit 'do'?

[Ruairidh Dunford]

The kit you have is a dye kit Jon. Mine is different and relies on a magnet drawing tiny iron filings, which are spayed on, into the crack - which stand out against the special white paint.

[JonE]

this WAS the cheapest thing I could find - for the benefit of others, is the dye thing worth buying for this application? Be honest...!

[Chris KC]

this WAS the cheapest thing I could find - for the benefit of others, is the dye thing worth buying for this application? Be honest...!

Jon, there's more than one way to detect a crack, none is infallible and different methods are more or less likely to pick up different flaws. A certain amount of skill is needed in both using and 'reading' them. If you want to be 'certain' use all the methods available and you'll be nearly there. Dye penetrant kits are affordable and ought to pick up a serious crack in my opinion.

[Tony Betts]

this WAS the cheapest thing I could find - for the benefit of others, is the dye thing worth buying for this application? Be honest...!

hi jonE, needless to say ive crack tested alot of parts.

ive used both the dye penatrant, and the magnetic test.

my opinion only, im sure as always others will disagree. but i found the dye penatrant fine, until it came down to smaller cracks. were as the magnetic picks up alot more.

i visited kiddy engineering in the next village, many years ago. and he used a simular but more professional system. i felt if it was good enough for him. its good enough for me.

chris KC is spot on as well, it takes a little bit of getting used to what you are looking at (skill). especially on machined serfaces.

i find the worst thing to test is a crank, often you can leave a crank for 24 hour after testing. without the magnet on, and the crack then shows up.

its also worthwile buying a de-magifier as well, for obvious reasons.

i used to stock the test kits, but there was very little demand. probably because people didnt know how to use them. or couldnt be bothered to learn.

the companies adress is on the tin, but you have to buy a box of 10 at a time. and often a tin wouldnt work.

i could do with some more black magnetic myself, so if anyone wants a tin, let me know.

tony.