Jammed idler nuts

[FrankfromCrete]

During a routine inspection/service on my 2012 JCB 8085 I noticed that a few of the bolts holding the bottom wheel idler looked loose as I could slightly turn the washer by hand, no problem I thought just tighten them up a bit .... wrong ....with only a normal amount of pressure on my ratchet 3 out of 4 bolts sheared, on inspection the bolts were half corroded through, after about 45 mins of struggling I managed to get the last bolt out which remained intact, the problem I have is I can not remove the nuts on the inside of the undercarriage frame they just won't come out, based on the one I managed to remove with the bolt intact they have sheared at the base of the nut the nuts seem to be slightly tapered like a car wheel nut I guess to center them they show no welding or any other form of fixing in place, I have managed to get a ring spanner on them and hitting with a lump hammer does nothing, tried getting a sharp chisel between the frame and the nut to wedge off again hard blows of the lump hammer have no effect, what should be removing and replacing 4 nuts and bolts has turned into a nightmare... any help please ?

[Muz]

Can you provide a pic so we can offer best advice ?.. would be good to see location and access etc

[FrankfromCrete]

Photos

Can you provide a pic so we can offer best advice ?.. would be good to see location and access etc

IMG_0228.jpg
Once the idler had been removed looking up under the undercarriage with about a 150mm gap between the metal track and the main frame, this is the nut left in place it looks like it should just lift off but it is solid, the one that came off with the bolt intact was just loose like any nut with the bolt removed, its really got me puzzled what is holding this nut in place, I can see no weld or any form of fastening.

IMG_0229_LI.jpg

This is before I started work, you can see a slight gap between the washer and the roller which is what I first noticed, there are 5 rollers each side and at least 3 on each side have this problem it took me about 1 hr to remove one roller as the bolt that did eventually come apart was rusted solid.

[v8druid]

not a splined Rivnut are they ..... I'd be getting the thin disc to 'em and slicing the buggers off flush

[Muz]

So these are nuts welded to the frame, or captive as we call them .. they will be a fairly basic metric if I know JCB. I just did a set of bottom rollers on a Kubota 8 tonner and got all the 3 " bolts out no problem, they are all metric fines and quite deeply threaded so dirt ingress was minimal.

Of course a lot depends on where the machine has been used, operating in tidal conditions for example is very agressive on metal work and will seize anything solid in a heartbeat.

In your case from what I can see, you would be quicker burning off the bolt heads to get the rollers off (you call them idlers but I suspect you mean the bottom rollers ?) then heating the studs and captive nuts, the nuts dont look very thick and should yield easily using heat, theres not much will resist a bit of cherry red heat believe me !

If youve already destroyed a few, and the rest look like trouble you might want to consider just burning off the captive nuts too, and changing the roller fixing system to some high quality bolts and nuts. The base frame looks a good half inch thick, so would give enough support enough ok. You can see a tiny cut in the frame to allow expansion from rust on the bolt, you could also try an extensive soak with penetrating fluid here, if you want another go at getting the bolts out, or do not have access to heat. Ive been using this stuff with a fair degree of result so far


http://www.innotecworld.com/products...p?productid=84

Good luck and keep us posted