I repaired my first stripped bolt (with a Tap and Die)!

[Emission]

I've been using hand tools for decades, and each time I come across a stripped thread I just twist harder and "force" it in.

Well, this time when I came across a stripped threads on my Porsche it was pretty bad. The dealer (or someone the PO took the car too) had used an air tool to put the bolt back in the pan that covers the steering rack. Of course, it was cross-threaded. Normally no big deal to just crank it down with a bit of bad thread, but this bolt also holds one end of the sway bar - it had to be tight and strong.

I did some research on the process, and went to Sears and purchased a "Tap and Die" set.

I bought a new M10x25 bolt in stainless at the local hardware store, and set to work.

Wow! This was pretty easy. Taking my time, I was able to "tap" the "stripped" threads and clean them up again. The trick was working slowly, back and forth just a little bit further each time. Perfect.

The new bolt, and a new lock washer, went it smoothly and took the torque just fine. Success!

I know there are guys out there who have never tried a tap and die... I feel stupid for not trying one years ago!

(The crescent wrench was used for something else - fixing my horn. You turn the die with a special tool in the kit.)

[pwd72s]

Bravo!

[Porsche_monkey]

No problem doing what you did on a 'cover', I wouldn't do that with a suspension bolt though...

[911 Rod]

Originally posted by PBH
No problem doing what you did on a 'cover', I wouldn't do that with a suspension bolt though...

Does this bolt not also hold the sway bar bracket?
This is why it's such a b***h to get in.

[Porsche_monkey]

I believe Rod is correct, but I don't think this would cause a catastrophic failure if it were to let go.

[Emission]

Originally posted by PBH
I believe Rod is correct, but I don't think this would cause a catastrophic failure if it were to let go.

No, it just rattles like crazy as you load and unload the front sway (when it was "stripped" it wouldn't go in all the way and it made tons of noise). Worst case, the sway comes loose on one side.

I'm not worried about this repair. It took all the torque I wanted to give it (to crush the lock washer).

[randywebb]

student machinist's texts will give a how to in detail for this

be sure to lube the cutters & then I spray more lube to get all the chips out

[klaucke]

For the record, you just used the tap. The die is used for cutting/cleaning threads on a stud. Great job though, and good choice buying a Craftsman set, they are of good quality. Cheap taps and dies cut away too much metal and do not leave you with proper thread engagement.

For taps used very frequently, it is worth it to buy a very good quality one (I like Vermont American taps), and even a good racheting holder. And always, always use plenty of oil, go slowly, and clean the chips often. Broken taps are a horrible experience to remove.

[Blanco]

Cross threaded is better than locktite.

I remember hearing that once.

[randywebb]

yes, the taps are made of very hard, tough alloy - you don't ever want to have one broken off down deep somewhere in teh inards of your 911...

[Emission]

Yeah, I dropped about $175 on the Craftsman set (I didn't want a cheap Harbor Freight set for this job). The "old guy" at Sears was stressing the lube oil and cleaning and oiling the tool before I put it away - rightfully so. It looks like a nice set that I should have for a long, long, time.

[Emission]

Originally posted by randywebb
yes, the taps are made of very hard, tough alloy - you don't ever want to have one broken off down deep somewhere in teh inards of your 911...

Are you always supposed to do the tap and die stuff by hand? I'd think putting it in an electric drill would do more damage. Right?

[Nine9six]

Originally posted by randywebb
yes, the taps are made of very hard, tough alloy - you don't ever want to have one broken off down deep somewhere in teh inards of your 911...

Yeah...Its called tool steel. Very high carbon content, so its extremely hard, yet brittle after being heat treated. Breaking a tap off inside a hole requires a carbide drill bit and plenty of patients.

BTW,
I seriously doubt threads were tapped in a hole that had been stripped. If the hole was stripped, the term implies that the threads were already pulled out of the hole.
If you say you cleaned up some threads in a hole that was cross threaded; that I can understand.

Also, a thread chaser is a better tool to use in a cross threaded tapped hole. It will straighten out the the crossed threads without cutting and changing the PD on your existing threads like a tap will do, when attempting to chase threads with one.

A tap will weaken the existing threads by cutting additional metal off the already formed threads as soon as it encounters pressure from the cross threaded area. Be careful when retorquing, as you may find yourself installing your first heli coil, or time cert.

[Nine9six]

Originally posted by Emission
Are you always supposed to do the tap and die stuff by hand? I'd think putting it in an electric drill would do more damage. Right?

Yep, hand tapping...Thats the correct method.
Although, many a machinist, myself included, have been seen power tapping a hole on a lathe. Of course years of experience with different materials, feel, and a certain number of broken taps, go into the training of this not so recommended practice.

[ruf-porsche]

Originally posted by 911 Rod
Does this bolt not also hold the sway bar bracket?
This is why it's such a b***h to get in.

Most DIYER cross thread this bolt when they remove the pan if they only jack up one side of the car because the sway bar is preloaded. If they jack up both side of the car, there will be no preload on the sway bar and the bolt would go into the hole easily.

[randywebb]

Unless you know how to runa Bridgeport or a lather, hand tap.

I'd never, ever use an electric drill... tho I bet there are people who can do that.

[Emission]

Originally posted by Nine9six

If you say you cleaned up some threads in a hole that was cross threaded; that I can understand.

I think that is what I did.

The bolt was pretty messed-up, with rounded threads. The hole (on the vehicle - whatever they call the "hole") was filled with decade-old anti-sieze and Loc-tite. It was a mess.

[PorscheGuy79]

oooohhhhh...just the thought of pulling out the tap and die set makes me cringe...

[jbrinkley]

oooohhhhh...just the thought of pulling out the tap and die set makes me cringe...

my rack and pinion suddenly and inexplicably has a few 3/8 bolts on it.........did I say that?

[billyboy]

Stainless bolts shouldn't be used in place of steel in high stress applications except for highly corrosive environments. They are not as strong as grade 5 or grade 8.

M10x25 bolt in stainless at the local hardware store