Repair / Helicoil captive nut. Help!?

PobodY

PobodY

Moderators
Staff member
I'm beginning to think there should be a PobodY's "What have I broken today" thread... it always seems to be suspension related too!

Those of you that I saw at the NW meet last year may be aware that I had a captive nut with stripped thread on one of my wishbones, and that I couldn't torque it up. It has lasted quite a while like that without any issues.

However, today I found out what happens when it doesn't hold any more and you stomp on the brake pedal (admittedly I may have been on full boost before hand). - The short version is that the wishbone slides sideways and the wheel mashes into the chassis with quite a bit of noise... and damage. :roll:

Yes, that has worn off the front of the side skirt and taken the paint off the body panel... it also coated my tyre with melted plastic.

Don't worry - I worked out how to put it back: Put it into reverse, back up a bit, then hit the brakes to slam it back into place! :twisted:

Here's the culprit:

You can see the one good bolt is holding well...but, the bracket it actually bent now (you can see it in the photo).
This is what it looked like after I tried to straighten it out again:


Before you all start having a go at me, I did take Andy C's advice and try to find someone to helicoil it for me. However, they didn't have a M12 helicoil to do the job, and it seems like a waste to buy the tools for the sake of one captive nut!

I then tried some JB weld to fabricate a new captive nut (essentially just a wad stuck over the hole with a thread cut in it), but that didn't work and just pulled off the body when I tried to torque it up... but at least the bolt doesn't just fall on the floor, and maybe it'll give me a little resistance against the twsity wishbone.

So, is there anyone in the Deeside/Chester area that can help me? Got a M12 helicoil kit I could borrow, or maybe a M14 thread tapping kit and a suitable M14 bolt? Even a garage who can definitely fix it without my having to take a mortgage out.
I don't really want to get into cutting panels to replace the captive nut.

I got all the way to Norfolk and back through the Peak District (we took the scenic route because the R loves those roads) without any issues, so I'm reasonably confident it'll hold for a bit longer yet.
 
A

ashills

Active Member
mate uve been lucky i wouldnt drive it to hard but its up to u ? cant remember if floor is twin skinned where that is but could you put a bolt through and a nut in the footwell and maybe a small plate?
 
PobodY

PobodY

Moderators
Staff member
Yeah - sometimes I push my luck...
I was thinking about it, and have come to the conclusion that it was slamming on the anchors with a bit of steering on (right before a roundabout) that was the final straw. Hard braking in a straight line hadn't caused any problems... although it might now.

I did have a quick look at the floor pan, but couldn't work out where they'd come out - it looks like it's right on the firewall.
I'd prefer not to have to start cutting and welding - it's just end up like the Fast and the Furious and the whole floor will fall out! That's why I was trying to chase-up Andy's suggestion and get it helicoiled; then I can just put the original bolt back in!
 
vss irvine

vss irvine

Well-Known Member
i think your only option is to open the floor up george, theres a good chance the original will be damaged more now and you wont have anything to secure the helicoil too.

the floor is double skinned, but iirc you open up a hole above the nut, and that will give you access to the culprit, on the plus side you should be able to sort it yourself, use a drill bit up through the nut to the floor pan, this will give you the exact area you need to open.

i would just pull the carpet back from the dash, as its not that far from the bulkhead.

as above, youve been lucky!
 
J

jambo_gtir

Member
i wouldn't cut corners when it comes down to vital parts of the cars mechanics. If that wishbone pops out at 70+ on the motorway or something you will kill yourself. IMO re-tapping it to M14 would be the best/easiest option. Be carefull though mate, really isn't worth crashing it and injuring yourself. I messed around with my suspension once on my previous car and 2 days later i rolled it....
 
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Paul20

Paul20

Member
i had the same problem mate, but it looked as though it was double skinned so i got away with with tapping and helicoiling it. i have definately got a full m12 helicoil/tapping kit you can borrow if you like and i can probably get hold of an m14 too.
 
PobodY

PobodY

Moderators
Staff member
Thanks for that info Sam! I didn't like the idea of drilling though the floor pan, and it's just as I thought; right on the edge of the firewall (so not even a nice flat bit to bolt down on). Even the same bushes by the look of it, so it's right on the money!:thumbsup:

I'm pretty sure that the captive nut is still there, but the thread is stripped; it looks like the previous owner of mine had just tried to tap a bigger bolt (the good one says 9 on the top, but the new one says 10 - it looks like an M12 but I would guess the thread pitch is different and that's what did the damage). - All your links are dead though; can you tell me what size helicoil kit you used (and which bolts I should buy if the one I've got isn't suitable)?

Paul, if you do have a kit I could borrow; how can I get my hands on it? Are you likely to come to any of the NW meets soon? - I should be there if the wheels haven't fallen off (again :doh:). Failing that, do you trust the postal service?
I could always just fork-out the £30 odd and buy my own kit in case there's more threads to repair... :roll:

Jambo, I'm pretty sure it won't be coming loose on the motorway. As I said, it made it all the way across the country last weekend with lots of high speed driving (but not quite as aggressive braking with the wife next to me). It's definitely slamming them on that causes it to do that, and it will keep rolling with the wishbone out... it just won't do it any good.
- I know these bloody wishbones like the back of my hands now.

Don't worry, I've been taking it easy since. I even turned the boost controller off to stop me speeding. :evil:

EDIT: I read closer; looks like you used an M8? I'm pretty sure that I've gone past that because it's a 18mm head (which is consistent with an M12) on the loose one, and a 17mm head (which I assume is the original one because it's the same as the other side) on the good side. Looky:

I know it looks like they are the same, or that the old one is slightly bigger, but it isn't.

I also think that I can still see thread on the captive nut... albeit shredded and hanging off.
 
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Paul20

Paul20

Member
i can pop it in the post if you like mate, saves you spending 30quid or whatever. the numbers on the bolt head is just the strength of the bolt, not the size. i have the helicoil kit at homewith me now including a couple of different helicoil lengths and i have some suitable m12 bolts too with the correct pitch. if you pm me your address i will get them in the post for you fella. let me know
 
J

jambo_gtir

Member
Paul20 said:
i can pop it in the post if you like mate, saves you spending 30quid or whatever. the numbers on the bolt head is just the strength of the bolt, not the size. i have the helicoil kit at homewith me now including a couple of different helicoil lengths and i have some suitable m12 bolts too with the correct pitch. if you pm me your address i will get them in the post for you fella. let me know
Click to expand...
What a nice bloke lol.
 
Paul20

Paul20

Member
just a nice guy. ha. seems like its a common problem with these cars so if anyone else wants to borrow the bits to do it, feel free
 
PobodY

PobodY

Moderators
Staff member
Well, after all my claims that it would hold together for a bit longer yet... It seems that I've lost that loose bolt and the wishbone is slipping out more often now.
I've started to spam the breakers threads to see if I can get my hands on an un-bent bracket and a replacement bolt... although it might be safest if I just bought a new one.

I've got the action of fixing it down pat now... stop *kathunk....scrape*... back up a little, stomp the brake... *klunk*... engage 1st and start off again - I think I'll stay off the main roads until it's fixed though.
 
Paul20

Paul20

Member
you should be able to just bend the bracket back to shape. as for the missing bolt, i have put a couple of m12 bolts in the helicoil kit i have just posted to you so one of them should do the job. good luck
 
PobodY

PobodY

Moderators
Staff member
This is what it looked like when I took it off:


Luckily I still have the old wishbone with the original bush on it:

With a suitable application of brute force, and a fair degree of ignorance, I bent it back into shape. :twisted:
 
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