[Spridgets] Handbrake rods

Mark Haynes 220caribou at gmail.com
Wed Dec 14 08:21:38 MST 2016


Daniel-Assuming a yield strength of 35ksi (typical for 304SS,18-8SS), The
approximate yield point of load application is around 1100 lbs/in of
thread. I'm referencing some work that I just did on #10-32 threads which
are a bit smaller than M6. Assuming that you have a 10" lever arm on the
handbrake handle (guessing here), that would require ~110 lbs of upward
force applied to the handle. This assumes no drag and no additional
leverages (which there are of both). Cold rolled steel ( your average steel
for such things) has a yield strength of 45-65 ksi, which means the cold
rolled will yield with ~130lbs of upward force, therefore, if you increase
your engaged, threaded length of SS rod by 30+% over the stock CR steel,
you should be fine.

Mark Haynes
>
It only goes one way-Pay It Forward

>
> Hi list,
>
> The last will be first etc.  I don't have anything to sell and if I  did I
> think the shipping might be excessive.  I think the list/my response  gave
> a
> couple of listers the impression I did when I commented on a previous  post
> about a 1275 and box being the best parts etc.
>
> So, onto a brand new question and probably never asked before on the  list.
>  I run 8" drums on the rear of my Sprite to balance out the big discs  on
> the front and so I can perform 'parking brake turns' when the mood takes
> me...  Consequently I also originally had modified handbrake rods to work
> with
> the 8" drums.  When the holes in the clevis ends was worn more than I
> liked and made the cotter pins sloppy I replaced them with new rods.  The
> new
> rods are for 'unisex' by which I mean they are designed to work with steel
> wheel or wire wheel axle casings being adjustable in length.  The
> adjustment
> is at the drum end by way of the rod being threaded (metric M6 I  think
> ...) and a threaded clevis fork.  Having recently swapped my  handbrake
> (photo
> attached and yes I realise I need to paint the inside of the  holes black)
> I
> decided to adjust the rods.  One rod wasn't adjust that well  and when I
> put the rod in the vice and put a wrench on the nut I sheared the  rod.  OK
> new rods on order + an extra long clevis end and an M6 die so I  may be
> able
> to salvage the old rod by threading past the break.
>
> However, it occurred to me that if the rod hadn't rusted the nut wouldn't
> have jammed and the rod sheared.  So, I'm pondering making a pair of
> replacement rods in stainless steel.  Since this stainless steel isn't to
> the ARP
> grade of stainless and it is loaded in tension is it likely to be strong
> enough?  Probably I'll make a stainless rod anyway and find out.
>  However, I
> figure the standard steel rod wasn't that great a quality of steel  and
> yanking on the handbrake and loading the rod in tension ought to not break
> even stainless bar, or will it.
>
> Thanks
>
>
> Daniel
>
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