1/4 Elliptic Spring Clamps - Are those Whitworth Threads on those 1/4 Screws

[Jim_Gruber]

I managed to unscrew the nuts on the Mini U Bolts without breaking them - Yeah a small victory as at $19.95 each to replace they aren't cheap.

After 2 days in Evaporust, the nut holding the spring stack together came right off. And that nut is not a standard size. Bigger that 1/2" smaller than 9/16 and not a 14 mm i.e. Must be Whitworth
I was able to loosen both without breaking the bolt.

Now on to the spring clamps. I succeeded in getting all 4 to come off without stripping the heads. Those threads are not 1/4 x 28 as far as I can tell. WTH Sells Whitworth Hardware. And does anyone know the correct size. Yes I could replace with a 1/4" Screw and a bolt but if I can find a Whitworth Screw... All the better.

 

[Trevor Jessie]

I do not know what size they are, but if they are whitworth you can use britishfasteners.com

 

[Trevor Jessie]

Also, note that there are some fasteners out there with oddball distances across the flats but common threads.

 

[Jim_Gruber]

I'll try British Fasteners. I can always replace with a 1/4" screw/bolt if needed with a nut. Of course with wider tires need to worry about clearances. Will try to maintain stock appearances. They have all sorts of interesting things at their site, including Drain Plugs for the Diff. Anyone know by chance the size of a BE Differential Plug. They actually have a plug with a Hex Head on it in of course 42 different sizes and thread pitches.

This car is so much nicer an experience that the '59 I took apart and sold to a guy in Detroit. Things actually unscrew after almost 60 years, without breaking bolts, without ripping threads off of screws. I found one other Whitworth on the nut for the Generator Bracket. Bolt does not fit anything else in my toolbox other than an adjustable wrench.

 

[Jim_Gruber]

British Fastener has the Screws, 3" long, as well as a die so I can cut to 2 1/4" long and clean up the ends, also a nut I can weld onto the one bracket that is buggered up. Here on Friday or Saturday. Yeah. I love it when a plan comes together. Springs will get sanded and primered tonight. Then on to Rear End Degreasing and disassembly. BTW, Whitworth Threads are 1/4 x 26 TPI. Not 1/4 x20 or 1/4 x 28. Learn something new daily.

 

[Sarastro]

Those are actually BSF, not Whitworth. Whitworth (AKA BSW) has a much coarser thread. BSF have the same head sizes, but are one size smaller than Whitworth for the same bolt diameter. Thread profiles of both are 55 degrees.

For thread dimensions:

https://www.engineersedge.com/hardware/whitworth-screw-threads-chart.htm

Head sizes:

https://www.baconsdozen.co.uk/tools/conversion charts.htm

I'm a little surprised there are still BSF bolts in a Bugeye. I thought they were history by then.

 

[Jim_Gruber]

I'll look at the package again. And she what it says in the invoice. They do screw right into the spring clamps. 1/26 tpi

 

[Jim_Gruber]

Steve,

You are indeed correct. Invoice reads 1/4' x 26 BSF Thread - Not Whitworth. Available from https://britishfasteners.com
Screws come 3" long. I ordered a Die as well so I can cut the Screws to length with a Dremel Cutoff wheel and then make sure threads are good to go so they can be removed at some time in the future. In addition 1/4 x 26 thin flat nut which I will use as a locknut. These are thin and will work just fine for the application.
Locktite Blue will finish off the job.