front axle big 7 radius arm bolt removal heat

[Dennis Nicholas]

Hi all
1938/39 Back axle now back on Nippy 

Next challenge front axle 
It is a big 7 one and I am trying to get the radius arms off to make it more manageable as need to get king pins out to add spacers to take up vertical movement and to clean up and paint all bits (after shot blasting in cabinet so bits must fit in).
The radius arms have a fork that goes above and below the axle with a bolt right through.  The bolt head is round and has a small cut out that fits around a small peg to stop the bolt turning.....goodness knows why not just an ordinary hex head bolt or why it is "waisted" in the middle.  The bolt is 1/2inch 16 BSF and one has bad teeth so really needs renewing.  However I have been unable so far to shift it.  I have used a hot air gun to heat the axle and fork end and at least the radius arms now swivel, tightly and slightly, on the bolt (note that means the pegs are U/S).  The bolts are therefore seized in the axle.  
I have an induction heater tool and can wrap one of the elements round the axle where the bolt goes through but have no experiance as to just how hot you can make the axle before doing irreparable damage.  I believe the tool would actually heat it to well over red hot fairly quickly (30 to 60 seconds?) 5/16 studs red in 10 seconds!
So question....how HOT should I go.  Hammer and drift on bolt...axle clamped in vice near bolt tried so far.
Can't shift the "cross tube leavers" in the stub axle either so will probably just leave them in and remove cross shaft ball end tapers.

Dennis

[Stuart Giles]

I have had this problem when replacing the front axle on my special with a Big 7 axle which had been sitting in a breaker's yard for a long time.... I needed to get the axle to dull red heat with an Oxy Acetylene torch before I could knock the radius arm bolts out with a big copper mallet. But if you know someone with a hydraulic press, you might be able to get them pressed out with a lot less heat input. I had to put the torch on the kingpin eyes too before the king pins would come out, didn't need to get them anywhere near red heat though.

[Dennis Nicholas]

Thanks Stuart
Did you use hex head 1/2 inch bolts to replace the original round head and peg type?  I am still mystified why round head and peg was used originally.
I will persist with the induction heating after a tentative try yesterday when I got it too hot to touch but no where near dull red. (about 15 seconds worth of heating)
I have a 20 ton hydraulic press but the problem is my holding the weight and lining it all up and operating the pump all on my own! Elderly muscle power very much deteriorated.  Will call for reinforcements if next heating and hammer in vice are not successful.

Dennis

[Stuart Giles]

Hi Dennis,
Yes I did use 1/2" hex head bolts when I put it back together; the original bolts looked a bit grim when I did get them out.

For my setup I did need reduce the head height on the new bolts before installing them as the flattened spring meant that the spring eyes came quite close to top of the bolt heads.

Good luck with it.

[Dennis Nicholas]

1/2 inch bolts out.  In the end I had to take it over to a machine shop where the elderly man drilled them out.....he said it was quite a struggle.  Interestingly the bolts did not have a waist cut in them in the middle.  I have some new 1/2 inch BSF bolts and had to cut the thread a little further up.  Next stage will be to see if I have to turn down under the head to get that part sitting in the recess in the top of the radius arm. I may just fill the recess with a washer. Why on earth was that turned head with a little peg used???
There is plenty of room between spring eye and top of head of bolt using the original type BIG 7 spring shackles.  
I await with bated breath to see how easily the shackle bushes go in and how free the pins are......because of course the interior of the bush has a course thread as does the pin so no reaming here.

Dennis