1949 Dennis F1 Fire Truck Restoration

You can also put a nut over the broken bolt and weld up into the nut, if that makes sense.

Hey Loadstar, that sounds like a neat trick too! I'll give them both a go! Never stop learning, ay!

Bugly, that's nice work you're doing there. Clever thinking, re the filters. Never even thought about the wire and oven trick for shrinking spring size, I'd have been cutting and reshaping the spring.
Just goes to show, you're just not a pretty face ..

Re the broken studs. Yes, the guys have nailed the technique for broken bolt/stud removal. Not helped by the apparently small diameter.
If there's enough "meat" in the surrounding metal, I'd be drilling and retapping to the next largest fastener diameter.

I don't know that any HT Whitworth bolts are still available. You could try a specialist fastener supplier. I'd suggest using the next largest Whitworth bolt diameter and using stainless bolts.
By staying with Whitworth threads, you're ensuring conformity and eliminating any future stuff-ups by mixing thread types.
Stainless fasteners aren't HT, but they will resist any future corrosion, particularly if you purchase grade 316 or 318 stainless, rather than 304.

Cheers - Ron.

Bugly, Whitworth and National Coarse have same thread pitches except 1/2 inch, thread angles are different, if stud binds run a NC tap through, as One Track says you would lose originality re stud head size, Cheers David.

Bugly
The next thing you will have to worry about is the fuel pump. There is a good chance the diaphragm will be stuffed, so you will advisedly have to replace it. The old rubber doesn't take kindly to modern fuels.

They are stll available as spares for Gardener diesels, which use a similar pump.

Hey, thanks everybody for your hints, tricks and advice ... truly appreciated! I said in the earlier post that the side plate bolts were Whitworth threaded. This was only a wild guess, as AF and Metric spanners and sockets don't fit, but Whitworth does. And the grey matter up top reminded me that old English vehicles used Whitworth bolts. So I assumed Dennis was the same.

But googling tonight, I got conflicting stories ... some said that Whitworth was a fairly course thread, and vehicles post WWII changed to BSF, which was a finer thread. So maybe Dennis has BSF bolts.



This is one of the side cover bolts (one that didn't shear off!) and my 1/4W-3/16BS ring spanner fits it beautifully. Don't worry about the yellow bit, it's just a paper clip to hold it parallel to the rulers. The bolt has what looks like 6 threads in a quarter of an inch, making 24 tpi. So ... would this be more likely to be 3/16BSF than 1/4W? Or are both 3/16BSF and 1/4W near to the same? I'm guessing that BSF are readily available, whereas Whitworth will probably be quite scarce. And if 3/16BSF and 1/4W are near the same, perhaps running a 3/16BSF tap down the hole might let me use high-grade S/S bolts of the same size without enlarging the hole/bolt size. Am I on the right track here?

I'm not too fussed about the authenticity of the bolt type, as there will be quite a bit on the truck which will not be quite ridgy-didge original. Like the air cleaner, but that will be revealed in another post. Still working on it!

Hello Bugly, Chinese Whitworth bolts available in Bunnings. BSF will be rarer as will taps & dies. They do have common spanner sizes. Regards David.

Me again, Re-reading your post, 1/4 whit and 1/4 BSF same diameter bolt, just different thread pitch. David.

Hi Bugly
1/4 whit is 20TPI and 1/4 B.S.F is 26TPI (TPI threads per inch) 3/16 B.S.F 32TPI 3/16 Whit 24TPI
3/16BSF OD .1875" and 1/4W OD .250"
Whitworth bolts are not 'quite scarce' the whole of Australia was built using Whitworth bolts even up to the 1980s I was installing new machinery that had Whitworth bolts and if you want to repair it you had to use Whitworth bolts
Spanners-you can

Bugly, I'd have to say you've got a 1/4" BSF bolt there, with 26 TPI. BSF bolts are hard to source, except at a few specialist shops, and then at exorbitant cost.

A crowd in S.A. deal in them. Here's the link to them ..

www.classicfasteners.com.au/fastpack.htm

If you aren't concerned about uniformity, then metric would be the way to go. Drill and tap to say, 8mm x 1mm pitch, and install 8mm metric bolts.

Whitworth were common on British stuff up until WW2, then BSF became popular as HT was more suited to the BSF thread (fine threads are generally used for HT).

Most run-of-the-mill Australian products that didn't require HT bolts, used Whitworth right up until metrics started to rule in the late 1980's .. but as David says, the mild steel Chinese bolts from Bunnings (that are still sold in imperial sizes! : ) are still all Whitworth thread.