Series 3 Wishbone Pivot Bar

[niduncan]

Would anybody happen to know what the pivot bar in the top wishbone is made of, e.g. are they stainless or mild steel? It's been years since I last had them out and cannot remember. I need to make a couple of new ones as mine are worn.

[Longboarder]

Mine are able to rust so not stainless but what grade of steel they are I haven't a clue. Something with about the same properties as 10.9 bolts would be about right. They are a critical component!

 

Nigel

[cb750]

I replaced mine with 10.9 material (actually 16mm bolts) when I modified the pivot system.

[niduncan]

Would any of these be suitable do you think?

 

Silver Steel: http://www.ebay.co.uk/itm/271375266482?_trksid=p2060353.m1438.l2649&var=570253633433&ssPageName=STRK%3AMEBIDX%3AIT

 

Stainless Steel 316: http://www.ebay.co.uk/itm/272196950657?_trksid=p2060353.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT

 

Bright Steel EN24T: http://www.ebay.co.uk/itm/1-2-dia-Bright-817M40T-EN24T-/222045732717?var=&hash=item33b2f4ff6d:m:mKboHdpfs7XJIEHEr6CdtuQ

[Grim]

The first is a tool steel and is too brittle and unmachinable.

 

The 316 might be too soft if annealed bar, or ok if cold worked. It doesn't say but i suspect not.

 

The en24t should be fine, i assume it is supplied in a heat treated condition.

[rthomas69]

As above EN24T is probably your best bet & shouldn't need heat treating ( 'T' condition has a tensile strength of 850MPa & hardness of up to 30HRc). It's a reasonable quality medium strength engineering steel (will be as tough as the original spindle if not better)

.

For reference a 10.9 bolt is about 830MPa & 35HRc so slightly harder but it's the tensile strength that is more important.

 

Rich

Edited April 8, 2016 by rthomas69

[niduncan]

Thank's for the advice, I shall order some and try and get someone local to thread the ends.

[fry61]

Would of thought this pivot bar is subject to wear & shear -- not tensile stresses.

[rthomas69]

True but the biggest measure of material strength is UTS (ultimate tensile strength).

I was just trying show the relationship between a 10.9 bolt & EN24T.

The pivot bar is basically a bolted joint therefore under tension.

[fry61]

Corrosion seems to be the biggest problem shown in the second O.P picture, a grease nipple added to the wishbone tube which carries this bar would solve that.

[niduncan]

The picture of the pivot bar was taken many years ago when I had to replace the bearings in the wishbone, the bar cleaned up OK and has been used since, I did the grease nipple mod then. The bar has now worn where it goes through the mounting points hence I would like to replace them before the play becomes an MOT issue.

 

Thanks for the help.

[fry61]

Pump in more grease on your replacement, will keep the water out.