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Cracked steering arm

I was washing the front axle and chassis on my ulster special today while the engine was out and discovered a crack line on my steering arm! Nothing new to most on here. I replaced the arm with a 'good' one and a strenghtening plate I made up. I don't know if anyone supplies them but I can if anyone wants one.
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Location: Ireland

Re: Cracked steering arm

Are you still able to get the split pin in?

Re: Cracked steering arm

Ian Bancroft used to supply a steering arm truss very similar to yours. My concern was also whether there was enough thread left to secure the ball end properly.

Re: Cracked steering arm

Yes it's all back together now. No problems. Although I can see where you are coming from. I would machine some material off the back of the nut if needed.

Location: Ireland

Re: Cracked steering arm

I used 2mm plate. Plenty of thread left.

Location: Ireland

Re: Cracked steering arm

Be warned, these type of braces do not completely stop cracks propagating, there have been a number of people who have produced them in the past and on paper they certainly seem like a good idea. I fitted one to my special around 1987, at the time I also polished and crack tested the arm, some 20 years later I removed the arm during a rebuild of the front end and re tested it. I was horrified to discover a crack developing on the inside of the radius, so fitted one of David Cochranes arms to all of my cars. I can also report that when I rolled the special four times at high speed during a racing incident, the new arm although having gone though some serious stress being quite badly bent was still intact and uncracked. They are not expensive from A7C and I know what option I want to trust my life to from now on!

Location: NZ

Re: Cracked steering arm

We tend to think that cracked steering arms are a result of old age or perhaps damage over the years. But Arthur Waite told me that when his 1928 AGP Super Sports chassis arrived in Melbourne from Longbridge, the steering arms were highly polished, presumably to enable an eye to be kept on the arms. He added that this was standard procedure on Austin Twelves from new. Re the diagonal bracing idea - our Bob Booth (unfortunately now deceased) produced some many years ago. They may not have prevented cracking, but even if the arm broke, it all still held together with his design. Cheers, Bill

Location: Euroa, Victoria

Re: Cracked steering arm

Arms also crack at the shoulder tight radius/step, but the usual place is usally more advanced!
The shoulder must seat all around and definitely not primarily on the centreline, and the nut tight to pretension.
Prewar particularly, polishing was the stock way of forestalling fatigue, so key engine and other parts of racing cars likely to have been treated. Now recoginised as much inferior to shot peening etc.
I have seen the likes of the bracket fitted before new arms available. Would certainly help in the event of a failure. But many may not notice until bracket also failed!

Location: Auckland, NZ

Re: Cracked steering arm

anyone checking there steering arms for cracks.

Should also check around the the eye that the ball fits into.

I've had a couple in the past that haven't just cracked, but have then been brassed back together.


Around 15 years ago, I had saved up all the different cracked arms. Some 32 in total. That I had crack tested. To do an article for the club.

Stoopidly I lent them out to another club member around the country on the request that they were doing a talk on this matter at there local club meet.

They never came back, I heard they were sold back out into the public.

" you know who you are "

Never again.

Tony.

Location: Huncote on the pig

Re: Cracked steering arm

I was out early this morning and had a look at the arm on an axle that came with the last unfinished project I bought. It looks new. A slightly heavier casting and it's much heavier where the ball fits in. Also when I fitted it to my car I noticed it saith at a lower angle.

Location: Ireland

Re: Cracked steering arm

A7 Components offer different arms for standard and sports or special cars, so choose the right one for your application. If you bought a 'kit of parts' you get what the seller chose, and you don't know without looking carefully whether it is an old one possibly modified or a good new type item, probably the latter in your case.

Location: just north of Cambridge

Re: Cracked steering arm

The obvious difference between the original arm and the A7Components arms is the radius of the bend where the arm turns through 90 degrees. The original arm radius is much tighter.
See: http://www.a7c.co.uk/steering-arms.php

Re: Cracked steering arm

Big seven arms sometimes get fitted as well, though not the best idea unless you alter the drag link too.

Location: NZ

Re: Cracked steering arm

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The one fitted now is definitely a new one. Looks like it is designed for a sports axle too

Location: Ireland