Suspension: Broken Subframe Bolt

[JamesG1980]

ouch. i feel your pain with this as i had not one but both front subframe bolts rust in and refuse to come out when i had to drop the subframe on mine . many hours spent sorting that out and not something i'd ever want to repeat.

when you say "re tap the hole" do you mean run the correct sized tap up the hole to clean the threads or are you talking about cutting a whole new thread?

if you've drilled into the threads at some point then running the original thread size tap up there isnt going to fix it as there will be no material there. and you cant retap an already tapped hole

drilling the threads out and tapping to another size isnt going to work as the volvo subframe bolts are only 1 size.

I would say your only option now is to get it drilled out and tapped to have an appropriately sized helical insert fitted..

this is the state of the end of one of the bolts after it came out (eventually).

[AidXC90]

Originally Posted by luggsey

Have you tried running a new bolt up there to see if it snags the edge of the bolt that's left and drives it out?
Not much to lose now?

Hi luggsey,

I don't want to touch it anymore. That bolt is so stuck in there that I'm pretty sure I'll wreck something else if I try something like that. Plus with the hole's threads damaged I doubt anything will be able to get further into or out of the hole as it is.

Thanks for the idea, though. It's all part of learning what to do in future.

[AidXC90]

Originally Posted by JamesG1980

ouch. i feel your pain with this as i had not one but both front subframe bolts rust in and refuse to come out when i had to drop the subframe on mine . many hours spent sorting that out and not something i'd ever want to repeat.

when you say "re tap the hole" do you mean run the correct sized tap up the hole to clean the threads or are you talking about cutting a whole new thread?

if you've drilled into the threads at some point then running the original thread size tap up there isnt going to fix it as there will be no material there. and you cant retap an already tapped hole

drilling the threads out and tapping to another size isnt going to work as the volvo subframe bolts are only 1 size.

I would say your only option now is to get it drilled out and tapped to have an appropriately sized helical insert fitted..

this is the state of the end of one of the bolts after it came out (eventually).

Hi James and thanks for your picture. It certainly looks worse than what I managed to get out of the hole on mine, although I suspect the rest of mine probably looks like yours does, too. Hoe did you manage to get yours out without breaking them?

I decided to call in the services of a mobile thread repairer rather than taking it to Volvo if I can avoid it. I haven't got a quote yet but I'm pretty sure it won't be as much as Volvo would charge to dismantle the whole front end again and then do the same as what the mobile guy has to do, then reassemble everything again. And yes, he will be oversizing the hole and heli-coiling it to get back to the original size for the Volvo bolt. At least that's what he said he'd be able to do, and does do on Range Rovers.

So there might still be hope...

Of course I'll keep the forum updated.

[JamesG1980]

both mine snapped off and had to be drilled out just like you are doing. i have a borescope that i used to look at the very top of the bolt so i could see if i was centre or not (i was slightly off) when i got through with a small diameter drill bit, then worked accordingly from there. eventually when the hole got big enough the bolt collapsed in on itself slightly and dropped out when i pulled the drill bit out. i expect the heat and vibration from the drilling helped as well.

good call getting someone in to finish off for you. i think a helicoil is definitely the way to go with this.

[XJSDriver]

Having read this troubling thread I am thinking I should do some preventative maintenance and remove my subframe bolts and grease them, also perhaps do same with the hub bolts which also have a tendency to seize.

[AidXC90]

Originally Posted by XJSDriver

Having read this troubling thread I am thinking I should do some preventative maintenance and remove my subframe bolts and grease them, also perhaps do same with the hub bolts which also have a tendency to seize.

Probably not a bad idea, XJSDriver. If it's elective maintenance as in your case and you're not pressed for time, I suggest using up at least a can or more of penetrant fluid over a week or so both at the head end of the bolts and especially on the other end, particularly with the front bolts (I don't even know if the end of the rear bolts is accessible). Then proceed with utmost caution on the subframe bolts.

If I'd known what to expect I would've applied a bit of clockwise torque first to try and break any rust then anti-clock and so on until the bolt was well and truly loose. But mine felt like it was coming loose from the start, albeit with a lot of effort, so I just kept at it with the breaker bar and I broke the bolt. I had almost no experience with this sort of thing until now, so I'm paying the price.

The first pic shows the troublesome end of the bolt. Not a very clear picture, I'm afraid, but access to that area is very limited especially with something like a phone (although it's a great place for moisture to collect). I was lying on my back and holding the phone into the opening in the chassis with my right hand. You can see the end of the sleeve that the bolt runs through protruding above the surrounding metal and how rusted it was inside. I think that's where the trouble starts. You can reach this area with your fingers, but not much else, so I was able to hold the tip of the Plusgas straw onto the tip of the bolt and flood that little recess around the bolt with fluid. If only I'd done that before I'd started to remove the bolt. If you have access to a proper blowtorch, you may be able to direct it's flame onto the end of the sleeve as well. I guess that can't hurt although I don't know what effect a proper flame would have on a piece of metal that's not a solid lump of thick casting? The other pic shows the accessible end of the bolt once the subframe is removed and after I'd drilled and removed what I was able to of the bolt.

Anyway, I'm just hoping these ideas and pictures will help others to avoid the stress and cost that I've incurred and am still incurring.
I think that once the hole is helicoiled - hopefully today - and the new bolt inserted, I may try to find some sort of plastic cap to fill with grease and push over the sleeve's end to ensure this doesn't ever happen again. Once bitten, twice shy etc. etc.

Good luck and let us know your experiences, please. I hope they are all pleasant ones.

[Bob Meadows]

Recommended for such conditions: ~
Bob

[AidXC90]

Well, the mobile thread repair guy came around yesterday. He seems to really know his stuff and easily managed to drill and ream out the remainder of the bolt and screwed a tap throught the hole's threads to clean them out, hoping that's all he'd have to do.
He then tested the fit of one of the old bolts into the cleaned hole and although it went in easily enough it was clearly a bit loose, so he decided to insert a coil - what he called a 3D coil.
So he tapped the hole to 16mm and inserted a coil which brought it back to 14mm thread diameter. Trying an old bolt again it fits perfectly; nice and snug with no looseness at all. So I'm happy again as I can use new bolts from Volvo with no issues. He said my situation was nothing unusual or bad compared to what he's seen and even congratulated me on getting as far as I had - made his job a little easier after all
The guy I used is based in Essex but he was able to travel to me here in Kent. Not sure what his travel limits are but I recommend him. I have no affiliation with him but I'm happy to recommend his services in advance as this kind of service is usually needed in an emergency so it's good to have his details to hand before you panic.
The company is Threadworx (thread repair specialists), Basildon, Essex. Contact: Clint 07713 902 011.

[luggsey]

Did you see what tools and bits he used for the job?
I know it caused you grief but it's really interesting!
Last bolt I snapped off was on the bearing retainer cover on my Landy.
That was a weld on nut job but was bloody hard.

[Clan]

Originally Posted by AidXC90

Well, the mobile thread repair guy came around yesterday. He seems to really know his stuff and easily managed to drill and ream out the remainder of the bolt and screwed a tap throught the hole's threads to clean them out, hoping that's all he'd have to do.
He then tested the fit of one of the old bolts into the cleaned hole and although it went in easily enough it was clearly a bit loose, so he decided to insert a coil - what he called a 3D coil.
So he tapped the hole to 16mm and inserted a coil which brought it back to 14mm thread diameter. Trying an old bolt again it fits perfectly; nice and snug with no looseness at all. So I'm happy again as I can use new bolts from Volvo with no issues. He said my situation was nothing unusual or bad compared to what he's seen and even congratulated me on getting as far as I had - made his job a little easier after all
The guy I used is based in Essex but he was able to travel to me here in Kent. Not sure what his travel limits are but I recommend him. I have no affiliation with him but I'm happy to recommend his services in advance as this kind of service is usually needed in an emergency so it's good to have his details to hand before you panic.
The company is Threadworx (thread repair specialists), Basildon, Essex. Contact: Clint 07713 902 011.

a good result !! He makes his bread and butter on citroen vans no doubt , just about all of them have the nut break loose in the chassis box section , a far worse job .