Fitting roll bar to B275

[TrevGood]

I'm in the process of fitting a David Thomas roll bar to my B275. It requires to be fixed by both of the mudguard studs and two bolts into the threaded holes on the back of the axles. Does anyone know what size and thread type these holes are? Mine are full of paint where a previous owner has lavished attention and I don't want to use the wrong taps.

 

[Exfarmer]

Think they would be Whitworth, but may be UNC. Certain sizes are the same but be careful. Also beware of using bolts too long which may break the casting

 

[TrevGood]

Many thanks....yes, pity the holes are so short.....might even construct a welded up clamp instead which will connect around axle. Methinks the thread is un, but cannot see whether course or fine due to paint and 60 years of ****!

 

[Gapples]

If I had to take a guess I'd say they'll be 5/8 unc, if a bit smaller perhaps 1/2 unc.
Very unlikely to be unf....

 

[startinghandle]

From 1976

 

[startinghandle]

From 1976 to 1980 I worked at main
IH dealer in Newtown and in the same town was David Thomas making safety frames although he did also have outside factories all over the country making frames
I remember the handbrake lever depending on what type needed altering but never was any bolts or studs screwed into axle casting
Are you sure you have correct frame?

 

[Exfarmer]

Looking further, it is critical to ensure you are using the correct bolt, as although Whitworth and UNC use the same TPI the pitches are marginally different resulting in poorer grip

 

[startinghandle]

Looking further, it is critical to ensure you are using the correct bolt, as although Whitworth and UNC use the same TPI the pitches are marginally different resulting in poorer grip

All the frames I fitted to 275 and 276
And 414 and 434 tractors and I fitted a lot did not have any bolts screwing into casting

 

[Exfarmer]

All the frames I fitted to 275 and 276
And 414 and 434 tractors and I fitted a lot did not have any bolts screwing into casting

I know nothing of the IH fitting, just going off the DB tractors we had fitted, though some of these used a large U bolt going round the axle

 

[startinghandle]

I know nothing of the IH fitting, just going off the DB tractors we had fitted, though some of these used a large U bolt going round the axle

That is correct for fitting frame to DB
But not IH also David Thomas did not
Make frame for DB

 

[Exfarmer]

That is correct for fitting frame to DB
But not IH also David Thomas did not
Make frame for DB

I am going back 50 years but I thought they made after market roll bars for DBs
may well be wrong as it is such a long time ago.
i was though trying to guide the OP towards the correct bolts, without your knowledge