chasing /repairing a captive nut

[steveo3002]

ive slightly buggered the thread in a captive nut on the polo , its in a poo place where the rear beam fits on

from what i can see its not too bad , but i cant screw the bolt in by hand and it soon nips up on a spanner

any suggestions to sort it ...run a tap up it ? thread chaser?

I'm really buggered if i ruin it ...gona be major hassle to cut it out

[cobblers]

Yeah, just run a tap up it and it should be fine.

[goldenwonder]

Carefully run a tap through it, making sure you use oil/cutting fluid on it just to be safe.
Should be ok as long as the thread isn't completely buggered.

[retrowagen1234]

Christ, 16 odd polos and i cant picture the rear beam mounts allready.. Its only 4months since i was last there!!!

Is it possible to get to the other side of em? I.e run the bolt thru as well as it will go, Then put a nylock nut the other side to pull it in and prevent it from pulling out. It depends in what way you mullered the thread, If its just a bit wonky a tap will work. If you stripped it all out then your not likely to be able to get the bolt up to torque very easy.. Hence the put a nut the other side...

if you cant get to the other side it might be possilbe to nip a small bit of metal out with a dremmel to access the captive nut...

[optima21]

I'd be tempted to run a tap up it, bit depends why the thread is damaged as its pretty high torque, so you wont want to strip it later.

the nuts cant be accessed from behind, so its not easy to replace them

[task]

If it's properly fubared then you could always replace it with a rivnut. But try the above suggestions of a tap, should work fine

[purplevanman]

If a tap is not available you can grind a step or two in a spare bolt, difficult to explain :/
Use a grinding disc and grind a step that forms a over vertical edge in the thread on the leading side?

hehe google fu is good

[mrj]

^^ i was just about to post the same; that really works well !

[BenzBoy]

Sept 24, 2010 20:00:59 GMT purplevanman said:

If a tap is not available you can grind a step or two in a spare bolt, difficult to explain :/
Use a grinding disc and grind a step that forms a over vertical edge in the thread on the leading side?

hehe google fu is good

I've not seen that before - what does it do, act as a tap? Or thread in easier and stay there as the fastener?

[purplevanman]

It works like a tap, the ground area gives the chewed bits somewhere to go instead of jamming the bolt up, have to use with care though, in a bit then back out, use a bit of grease. Idea is to use a new bolt but I have used the ground bolt on more than one occasion

[steveo3002]

Sept 24, 2010 19:35:04 GMT optima21 said:

I'd be tempted to run a tap up it, bit depends why the thread is damaged as its pretty high torque, so you wont want to strip it later.

the nuts cant be accessed from behind, so its not easy to replace them

had trouble getting the bracket holes lined up when refitting the beam after a new tank , i think its just mullered the first thread as i didnt really force it in at all , the bolt still looks okay and the threads are visible with a torch

looks like it will be proper ball bag if i cant repair it

[retrowagen1234]

Sept 24, 2010 21:01:44 GMT steveo3002 said:

Sept 24, 2010 19:35:04 GMT optima21 said:

I'd be tempted to run a tap up it, bit depends why the thread is damaged as its pretty high torque, so you wont want to strip it later.

the nuts cant be accessed from behind, so its not easy to replace them

had trouble getting the bracket holes lined up when refitting the beam after a new tank , I think its just mullered the first thread as I didnt really force it in at all , the bolt still looks okay and the threads are visible with a torch

looks like it will be proper ball bag if I cant repair it

huh? you took the beam out to do the tank? Why? and not to mention the brackets you undid are the ones that line the beam up. So your likely gonna need the beam aligning unless you marked it all before hand.
To remove the beam you should have taken the pivot bolts out, It prevents any of these issues..


Having changed the tank on all but a couple of my polos , I'm 100% certain the beam does not need to be touched...

It takes me all of 20 mins to do one now, In the dark on my gravel drive.. ;D ;D practice makes perfect I guess

[steveo3002]

really wouldnt come out with the beam in place , hayner suggests the same

although it was a poop pattern part tank so maybe that didnt help

[Deleted]

You should be able to drill and tap one size bigger if you've got enough space to get a tap in there? Or weld the hole up, re-drill and re-tap. All is never lost

[retrowagen1234]

Sept 24, 2010 21:09:26 GMT steveo3002 said:

really wouldnt come out with the beam in place , hayner suggests the same

although it was a poop pattern part tank so maybe that didnt help

they are all pattern dude..

But you realy realy don't need to take the beam out, And haynes are curse word, I got half way thru removing my rear pads today on the carlton to take the discs off, Only to realise i was reading a missprinted description of how to do the fronts.


The best way ive found, Is

*pop the rear seat up ,
*take the cover plate off and disconnect the wiring for sender and breather

* jack car up in centre of beam

*put axle stands on rear of sills and lower car (support on beam for time being)

*open filler flap and remove rubber boot, then pry the breather pipes off neck

*working under the car, undo the 13?mm bolts holding the lip of the tank

*drop rear of exhaust (unclip rubber hangers)

*get a suitable container (assuming tank has some fuel in) and disconnect the pipes and drain

*then unbolt retaining strap while supporting EMPTY tank with other arm (it aint heavy )

*once unbolted remove jack from beam

*unclip handrake cable hanger and drop it out of way

*Once this is done, you need to pull the neck end down first so the tank is flat to the floor.

*then push the nearside of tank upwards and slide the neck out between the sill and beam mount..


Tank out...

Refitting is reverse of removal... as haynes would say...

I realise you've allready done it, But thats how i do it and its allways worked time and time again on gsf/hadrians tanks...

and it might help for future reference....

[retrowagen1234]

btw the reason for supporting the car on the axle stands on sills is that if you support on the beam the extra compression of it will prevent the tank from coming out (beam will be too close)

[steveo3002]

well thanks for the write up...the neck on my tank is wider than the gap between the end of the sill and beam bracket ..cant see a way round it tbh

shouldve only added 10 mins to the job if i hadnt loused it up lol

[retrowagen1234]

Sept 24, 2010 21:26:07 GMT steveo3002 said:

well thanks for the write up...the neck on my tank is wider than the gap between the end of the sill and beam bracket ..cant see a way round it tbh

shouldve only added 10 mins to the job if I hadnt loused it up lol

tbf the first time I did it I thought the same, It aint gonna go thru like lol..

But thats where the dropping the tank then tilting it up bit works.. It gets it a such an angle that gives you JUST enough space.

I realise none of this helps you now so ill stop explaining it


As for the captive nut...fill it with weld? Get a diamond drill bit and then tap it out?

[RobinJI]

If you've just crossed the first few threads then just run a tap though it as others have said.

[optima21]

the tanks come out on some polos easier than others, the filler pipe can get jammed between the inner wheel arch and the bracket that mounts the rear beam. On my polos I've cut the bottom of the wheel arch/sill off and rewelded them, and flattened the filler pipe so its now oval to gain clearance. The annoying thing is that VW could have done this from the factory (and aftermarket suppliers of fuel tanks) so there wouldnt be any clearance issues. I'm guessing that when the cars are made, the tanks are fitted before the rear axles