Captive nut in suspension mounting bracket

[dmccormick]

Answered my own question - couldn't get it hot enough to braze.

Am thinking more about the welder. Now I've read more it seems you need an arc welder if you want to weld outside and weld thick things and a MIG welder for thin metals like car panels.

My immediate need is for this captive nut and to weld a nut onto a broken bolt to get it out. I also have a garden roller where the frame has broken that I'd quite like to mend.

For these jobs it's sounding like an arc welder. The MIG forum says that the £50 buzz boxes are pretty useless and would put off a beginner DIY'er. I could face dropping up to £200 for something, but I don't fancy doing that twice.

Does it make sense to get a "buzz box" now and then a MIG later if I start to do some more jobs that need it ?

 

[JulianP]

That job is easily withing the capabilities of a DIY type MIG, one rated at about 160amp would suffice and use 0.8mm wire.

Don't buy a buzz box MMA welder, if you want to go down the MMA welder route then buy an inverter machine. I managed to buy a Wolf 200 amp MMA inverter welder for a lot less than £200 which will run off a 13amp supply although the fuses don't last long at 200 amps!

But I think you're barmy, just chuck a nut and bolt in it and be done. Don't worry about struggling to get it apart in years, if you can't then just grind the bolt head off!

 

[dmccormick]

I know it is barmy for just this job, but as mentioned I've often fancied having a go at welding and being able to make things so this is really an excuse to take the plunge.

A garage quoted me £300 to do the suspension arms(100 quid each and 50 extra each if they had trouble with the bolts), so even if I spend a bit on a welder I've still saved money and got the welder to use for future projects.

 

[JulianP]

Well you just have to decide what sort of things you anticipate welding and then buy a machine.

Hobby style MIG's are perhaps more suited to thinner material - say up to about 4 or 5 mm thick. Stick (MMA) machines will deal with stuff up to any thickness (believe it or not) as you can make multiple runs, but not suited to thinner sheet metal.

Actually a MIG is not easy on car body steel as you'll end up with holes, you have to develop a pulse technique with stuff that thin. Or better still get a TIG machine

If you just want to have a play at minimal cost then buy a little inverter style MMA welder. Welding rods are dirt cheap and you've no gas to bsugger around with.

 

[AlanE]

Hire one for the day and have a play first before buying one.

 

[Mursal]

Just run a drill through the captive nut and use it as a spacer. Then just use a nut and bolt. A cheap socket set will help with holding the nut, or even the vice-grips. As you tighten it will take less and less to hold the nut.

Cut the head off with a grinder the next time, but it just might come loose. Grease or Waxoil on the threads will stop corrosion. But, it will be over 30 years old by then, probably never out before?

Edit:
After running the new bolt down on the threads of the nut a few times, can you damage the nut slightly so you have to tap it into the hole in the suspension? You may not have to drill the threads out, if you can stop it turning, which wont be as hard as you think.
Threads will be metric either fine or course, just take the nut with you to any good hardware supplier. Don't tell them what its for, just ask for a high tensile steel bolt

 

[dmccormick]

Not sure if it's clear on the photo, but there's no space to hold a nut in place with either a spanner or socket or mole grips:

IN this photo:

the red circle is the end of the bolt. The track arm is in the way of getting anything to this, especially as it will be in the wheel well pointing downwards with the wheel arch further restricting access.

That is why it's such a pain - you have to put the track arms in place before you bolt it back into the car.

 

[JulianP]

You've only just got to jam the nut with a screwdriver while you tighten the bolt. It's easy as friction does 95% of the work for you here.

 

[mfarrow]

Forgive my ignorance but can't you just flip the nut-bolt 'assembly' and have the bolt coming up from underneath? Just hold it up with some blu-tak or something whilst you get everything in place, then spin the nut on and tighten up.

If things start slipping, just put some mole grips on the thread when tightening up. Cut off any excess thread at the end if you need to. Job's done.

 

[dmccormick]

The bolts have to be done up to 75Nm. I am guessing that trying to hold the nut with a screwdriver whilst doing the bolt up is not going to work. This is based on the fact that in undoing the bolt in the first place, it broke the captive nut loose rather than turn the thread. Although that was obviously rusted up.

I think the idea with the bolt the other way up and using the mole grips to hold the thread might work, although could then be an issue to undo if needed in future and I'd be back to grinding the bolt head off.

Have got some metal epoxy glue that reckons to be "nearly" as strong as a weld. Might just try that and worst case just be back to grinding bolt head off again.

 

[mfarrow]

if you lock two bolts together on the exposed thread, that will give you some additional purchase to undo/tighten the nut you need loosened.

I think there's a good chance you'll end up snapping the nut off again in a year's time, if you have to do undo it again.

 

[dmccormick]

Its, not pretty:

but this is better:

Thanks for all advice. I spent less than it would have cost for the garage to do the work and now I have a MIG welder to play with