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DMc

Can I use stainless steel...

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DMc

...in the wishbone ends? 

 

Ive always avoided mixing carbon steel and stainless, but I’ve noticed a few people  using stainless rod ends in the wishbones. 

 

Is this generally acceptable? What’s the Worst case? 
 

am I right I thinking that stainless  is more brittle that carbon and, possibly less forgiving if they were to take an impact? 
 



 

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CosKev

Can't say I've seen stainless rod ends

 

I know stainless bolts are a no no on suspension mounts due to them not being high tensile

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corsechris

 Ampep Silverline are a stainless rod end. I used some on the wishbones of a Marcos some years back with no issues. This was a car that snapped a Triumph upright due to lateral G loads (and the fact they were a crap design upright!).

 

Like all alloys, there can be a huge variation in material properties depending on the recipe used. As long as it’s a decent brand and spec you are using is appropriate to the use, no worries.

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Robin (Red Spider) - Yorkshire AO

Stainless bolts can snap. We don't fit them to the bus seats at work as they can "snap like carrots" They can also "pick up a thread" where the nut can get locked onto the bolt and the only way to get round it is to shear the bolt. This tends to happen when stainless and steel nuts and bolts get mixed up. 

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Snags

As corsechris says both metals stated are alloys and the percentage of constituents makes for very different performance. I know that some stainless steel mixes do suffer from fatigue if subject to movement and is a major reason for not using them for high load situations, but mixes can be available to alter this as we used to fit them for gantries in sewage farm works.

Again with carbon steel the higher strength mixes makes them stronger in tension but not so good on shear loading.

Basically you really have to refer to the manufacturer for clarification, especially in high risk situations like this.

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Snags

You can also get a battery type condition happening between differing materials when an electrolite is introduced (water especially salt saturated), causing one or both materials to erode quickly. In boats they fit sacrificial anodes to help control the effect.

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DMc

Thanks lads. 

I have a few stainless rod ends in my store and thought about using them on the rear wishbones. 
they have a higher load rating than the aurora ones I’m using so In theory they’re  stronger, but with a potential reaction with carbon and being more ‘brittle’ I’ll stick with the carbon type. 
 

 

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AndrewBClarke

I had a similar quandary when changing mine. After speaking with those who know,  the suggestion was good quality stainless steel rod ends were better. All in the quality though. Poor stainless ones are potentially more likely to snap than poor quality heat treated steel alloy versions. 
 

What made my decision easy was a discussion with the chap at ABC bearings where he simply said what he would and would not have on his own car. 
 

NBS stainless were therefore purchased with the right size bearing for a Westfield without needing a spacer. 
 

Not cheap but I believe in doing the job properly once. 
 

Hope this helps. 

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Lyonspride
On 11/01/2020 at 21:09, Snags said:

You can also get a battery type condition happening between differing materials when an electrolite is introduced (water especially salt saturated), causing one or both materials to erode quickly. In boats they fit sacrificial anodes to help control the effect.


This was the first thing to mind, known as "galvanic corrosion".

012-Bi-Metallic_Corrosion_of_Commonly_En

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Snags
1 hour ago, Lyonspride said:


This was the first thing to mind, known as "galvanic corrosion".

012-Bi-Metallic_Corrosion_of_Commonly_En

That's the first time I've seen it presented so easily.

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corsechris

It’s a factor for sure, but no worse than carbon steel with aluminium. Yes, typically there will be a layer of zinc in the way with say bolts in uprights for example, but that often gets damaged, negating the benefit.

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AdamR

It made me think "lashings of copper grease" 😁

 

I think something else to factor in is that those 7/16" rod ends are waaaayy over specced. You could get away with a good quality M8 or even M6, so I think stainless will be fine personally.

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dhutch

I worked in the marine industry and there was a mix of powder coated marine grade Ali and 316/A4 stainless and they where very careful to provide isolation gaskets, glass filled nylon top had washers etc.

Howeverthere was always times when it was unavoidable either because the load was too high was the nylon washers, or one part was threaded into another, and then they reverted to liquid isolation paste (can't recall the brand sorry) and or lashings of polyurethane sealant. 

 

The fastening where all 'high tensile' stainless aka A4-80 which are about on par with an 8.8 steel bolt, if obviously not a 12.9. So the right stainless bolts shouldn't 'snap like carrots' but certainly the wrong ones can have a lot less strength than an 8.8 which has become almost the lowest standard within engineering applications.

Goto a timber yard and they will supply you mild steel coach bolts and the like which will again fail at remarkably low loads, if usually a ductile than carrot failure. 

 

For ball joints I would be looking at the load ratings, if available, and comparing one with the other. But certainly caution is important in this area. 

 

Daniel

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DMc

Thank Daniel.

 

Rose joints seem have a 'static & radial load' rating in lbs rather than a 'grade' like bolts have, this is whats confusing me.

 

The stainless ones i have have a much higher load rating than the non stainless ones.

 

My main concern was corrosion or fatigue between the stainless rose joint and carbon wishbone threads. plus Id much rather a rose joint bent rather than snapped under failure 

 

the chart that @Lyonspride posted above shows a warning of galvanic corrosion 

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Dave Eastwood (Gadgetman) - Club Secretary

I wouldn’t screw a stainless component into a threaded mild steel component like a wishbone, though. Stainless with a stainless nut is one thing, but the stainless item into steel, especially with the exposure a wishbone gets can cause the threads on the wishbone to pick up and rip out, when trying to adjust the Rose joint. (Worst case scenario)

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