Striped my headlight thread at bottom need help

[redcoupe86]

Im installing the H4 conversion and the bolt welded to the bottom of the bucket has stripped threads due to them getting rusty.

Need some help on what to do. I went out and bought a new bolt to fit the screw but I have to have a way for it to be fixed and stationary while I turn the srcrew so it can pull the headlight tight.

The only thing I could think of was to JB weld the new nut to the back of the old nut and hope it holds. Because if it doesn't then I'll never get the damn thing out.

Any other suggestions.

[Early_S_Man]

I think I would prefer to MIG-weld a nut on the backside of that tab after drilling out the old threads so a new screw can pass through easily. The new nut needs to be very precisely aligned with the hole -- secure with a new bolt and washer out front with anti-sieze on the threads -- to hold the nut in place for welding. Just tack one corner on one side, then let everything cool back down. Tack it down on an opposite corner, and let it cool again. Four tack-welds with good penetration of the nut and tab should hold the nut securely.

I would carefully grind the back of that tab until bare, shiny steel is exposed all across the backside!

A stainless steel countersunk Phillips screw with anti-sieze compound applied should be troublefree in the future.

A Helicoil could also work.

[DarrylD]

Here's how I solved that same problem using a SAE #8 - 32 TPI rivet nut. Works slick, no welding required, I can live with a non-metric machine screw that stays put:



Eastwoods sells a nice set:

Pro Rivet Nut/ThreadSetting Tool Kit SAE

http://www.eastwoodco.com/jump.jsp?itemID=6090&itemType=PRODUCT

[K-Jetronic]

..the easiest for the moment would be to take some stainless steel wire and bend it through the opening/nut several times. This way your screw will have some friction inside the nut again (hope it makes sense).

[redcoupe86]

Originally posted by K-Jetronic
..the easiest for the moment would be to take some stainless steel wire and bend it through the opening/nut several times. This way your screw will have some friction inside the nut again (hope it makes sense).

are you saying loop some wire through the stripped nut so the screw has somthing new to "bite" to?

[K-Jetronic]

Yep, that's it. Not really "Porsche worthy" but works fine. Perhaps it's even better to use some copper wire.

[Howard M]

Isn't there enough "meat" left in the nut to simply drill and tap a new thread, possibly a close English gauge?

[redcoupe86]

Originally posted by Howard M
Isn't there enough "meat" left in the nut to simply drill and tap a new thread, possibly a close English gauge?

I would, but I need to use this screw for the H4 Euro upgrade to secure the trim ring:

[IMG]http://www.**********.com/cs_products/m_1777.jpg[/IMG]

it is a 5mm - .8. Im thinking of Helicoiling the thing, but the problem is geting the drill square with the tang. Don't know if this is possible, or if they even make a 'coil that size.

[Howard M]

I just checked my H4's. My trim ring screw (chrome trim ring, not painted) is a simple dome head phillips with a cone base. I don't think you have to match your special screw head, or thread.

[redcoupe86]

Well, if you have chrome, no. But I have a trim ring that goes over the chrome. It is painted to match the Guards Red of the car.

That trim ring lips around the top of the chrome headlight piece and has a hole at the bottom that secures it to the headlight. That hole aligns with the bolt shown above. Without that special bolt you can't attach the trim ring.

[Howard M]

Ahh, I get it now. I never knew that the painted ring goes OVER the chrome ring. Maybe some solder wire in the threads will provide the little grip you need. Good luck. It's an easy thing to try.

[Gunter]

Originally posted by DarrylD
Here's how I solved that same problem using a SAE #8 - 32 TPI rivet nut. Works slick, no welding required, I can live with a non-metric machine screw that stays put:



Eastwoods sells a nice set:

Pro Rivet Nut/ThreadSetting Tool Kit SAE

http://www.eastwoodco.com/jump.jsp?itemID=6090&itemType=PRODUCT

I like it.
The tab that holds the head lamp assembly is a weak spot.
If you want to keep the metric screw that holds both lamp ring and trim ring, try to get a rivet nut with enough "Meat" to allow you to tap the metric thread over the SAE thread.
Other than that, some precise welding is required.

It has to be solid; people have lost the whole assembly while driving!
I made an extra wire loop to hold the lamp on the inside.
Should the bottom fastener ever come loose, that loop prevents the lamp from falling right out.

[donporfi]

You can use a metric rivet nut like the one DarryId is suggesting. Check Mcmaster they sell these rivnuts in metric sizes.
Or you can use the u-nuts, spring nuts check in Mcmaster to see what I am talking about and probably you can find these nuts in a Pepboys.

[jdbunda]

I had this problem with my car, the screw threads in the welded nut on the tab had partially stripped. I suspect they were weak already due to rust, but were holding my H5 trim rings ok. I suppose my hamhanded attempts to mount my new H4s made the least of a deteriorating situation. Anyway, it's a good thing I had read other threads on H4s, because I had installed tie-wrap tethers on them, which saved me when one of them popped out - that is when I discovered the mounting screw would not hold.

I buzzed off the stripped nut with a dremel cutting wheel, leaving just the flat tab, and slid on an M5 speed nut from a motorcycle shop (they use these on plastic bodywork/fairings). I like the speed nut for this application - it can't turn on the tab (I have seen rivnuts spin loose), easily replaced, easy to thread.

[RSBob]

I can beat that with a non-Porschesque solution after that last helicoil failed. I used 1/2 of those cheap plastic recievers used to secure a screw in drywall (don't know their name - but you typically drill in an oversized hole for these things, and tap them in with a hammer and then screw into it) in the stripped bolt hole on the bottom and secured with a dab of superglue, then scewed in the bolt. It bit nicely into the soft plastic piece. I was skeptical this would work but it and has kept the headlight in place for many miles and hard bumps with no issues. Total cost $0 with no trip anywhere, besides it's easily reversable.

[donporfi]

I think this is jdbunda´s solution

[Ian Comerford]

I used an electric soldering iron and some soft solder to fix a nut to the back of the tab. 10 mins and a lasting solution

Ian

[jdbunda]

donporfi is correct, these are what I am talking about and at $0.85 or so, not much more expensive than the plastic drywall anchor. FWIW, I am pretty sure you can get metric speed nuts at the Porsche dealer if you insist on factory-approved hardware, my Carrera tail is mounted with them. When I googled "M5 speed nut" I found them offered on Amazon for a motorcycle application, and stopped searching at that point.

I like the drywall anchor idea - my only quibble is it might even be more susceptible to spinning loose (like a rivnut). At that point, you would likely end up having to drill the screw to get your headlight off. I really think the speed nut should have been the factory solution to begin with, because they are so easily replaced and will not spin. Oh, and they also will not strip, and they start easily, even if the angle is not spot on.

[wwest]

Originally Posted by Early_S_Man

I think I would prefer to MIG-weld a nut on the backside of that tab after drilling out the old threads so a new screw can pass through easily. The new nut needs to be very precisely aligned with the hole -- secure with a new bolt and washer out front with anti-sieze on the threads -- to hold the nut in place for welding. Just tack one corner on one side, then let everything cool back down. Tack it down on an opposite corner, and let it cool again. Four tack-welds with good penetration of the nut and tab should hold the nut securely.

I would carefully grind the back of that tab until bare, shiny steel is exposed all across the backside!

A stainless steel countersunk Phillips screw with anti-sieze compound applied should be troublefree in the future.

A Helicoil could also work.

Propane torch and regular solder will work just as well, weld?

[Cooper77]

Originally Posted by Gunter

people have lost the whole assembly while driving!

So true... didn't see this thread, answers my question as well....

And then my H4 lamp overtook me at the stop sign...

C