Destroyed screw removal. Vintage SC. Tips?

[cantforgetthe80s 31]

Found a nice vintage Super Champ and the gearbox has an original Thorp ball diff installed - so I need to get the gearbox apart. 

Problem is the two inset black screws that hold the rear bumper in place are completly destroyed/ stripped at the head.   

I can't cut the aluminum case with a dremel wheel because the wheel will heat up and shatter.  (From prior experience!)

So those screws have to come out to take it apart.  I was thinking carbide bits and just drill all the way through them,  but after testing titanium bits on a sample screw it didn't seem to do much damage.  

My other thought was to try a carpenter's trick and create a slot on what's left of the screw and use a flathead to unwork it,  but I can't figure what would cut into this screw effectively in such a tight channel.  

For reference in the photos,  it's the two screws that inset into the rear bumper beneath the "FS" plate.  

Any thoughts would be appreciated. These things are literally bullet proof..

.Thanks!

 

[DTSCB 96]

Hammer the largest square or torq bit you can in the screw and try that.

maybe try an easy out?

Lastly, just break/cut/mangle the head of the screw off?

Since this is metal to metal, you can try a penetrating oil spray a couple times over a couple days.

[cantforgetthe80s 31]

Thanks. The torque bit I'll give it a shot, but these screws are harder than kryptonite lol. 

So the head on one is already completely off. But the screw is threaded into the metal frame and inset in the hole unfortunately so it has to get either drilled or screwed out as far as I can tell..

[BattleTrak 61]

Try heating up the the area with the threads with a mini torch or a soldering iron/gun.  This will expand the metal to loosen its grip and soften up any threadlocker.

[acprc 1443]

Torx bits. Get a set of them and use the one that fits (maybe with a gentle hammer). Never fails me when I have issues with stuck or stripped screws.

 

[Snappy1 966]

I reckon the top screw would come out just with vice grips, the lower one might benefit  from cutting a flat blade screwdriver slot in the head, if that makes sense .

Be careful with the rear bumper, they break very easily .....

[Howards 456]

^ this. The top one can be grabbed and turned with screw removal pliers. The lower one can have a slot cut in to its face with a Dremel cutting disc or small multi-tool blade.

[BattleTrak 61]

OP is referring to the two recessed screws in the bumper you can’t see.. 

I would try heat with the torx bits.  Then maybe extractors or left-hand drill bits.  If you have to resort to destruction with a Dremel tool cut-off wheel..get the fiberglass reinforced ones.

[Kol__ 3377]

These things are always a pain in the A. Along the lines of what the chaps have already said...

If it were me, I'd be buying a very small set of stud extractors and a set of very small tungsten carbide drill bits. Drill out the centre of the screws and use the appropriately sized stud extractor. Penetrating oil/fluid for 24hrs may also help.

[cantforgetthe80s 31]

Thanks all very much. 

Fortunately these are in re-re status. 

Because complete destruction of the gearbox was ultimately the only solution.  A total of 5 different strategically placed screws with broken or stripped heads and 30 year old lock tite on the threads made alternative methods virtually impossible. Whatever they are making military tanks out of, they should reconsider using the brutal combo of material for these black Tamiya screws and ancient locktight. 

Good news is the Thorp diff is pristine and in tact. 

Although I see some rust in those internal screws also,  so looking like a second project will be undertaken soon to refurb it ....

 

[Kol__ 3377]

23 minutes ago, cantforgetthe80s said:

Because complete destruction of the gearbox was ultimately the only solution

So you broke apart the gearbox casings to get the gears out?😱

Good news on the Thorp being in good nick mate.

[Willy iine 18805]

I would wrap tape around a bit enough to to fill the hole somewhat, and easy out the screw or drill the screw head off.  Unless there is thread lock on the threads, you can probably pick turn it out since the bumper is off.   

[cantforgetthe80s 31]

4 hours ago, Willy iine said:

I would wrap tape around a bit enough to to fill the hole somewhat, and easy out the screw or drill the screw head off.  Unless there is thread lock on the threads, you can probably pick turn it out since the bumper is off.   

I had one with the screw head off. Then used a small left handed carbide drill bit. Nothing. Tried boiling it,  used WD40. In another one tried drilling all the way through the screw but it took out too much of the aluminum with it. Torx bit couldn't grip the stripped out head on another.  It caught for a moment then spun. The flathead screws holding the bumper mounting bracket were glued in as well. Salvaged two A arms. The bracket and one half of the gear case.  Had to crack the bumper in half to work the worst - those two inset screws - out.