screw removal

[CanAm76]

Started the job of replacing the left leg fork seal this weekend. All was going fine until I tried to remove the small buttonhead cap screw that holds the bracket for mounting the brake line to the back side of the fork slider. Before I go and purchase an "easy out" type screw remover can anyone tell me if a particular brand of screw remover is better at removing these small screws than others. There appears to be several designs to choose from. Thanks. Ed

[RFW]

Started the job of replacing the left leg fork seal this weekend. All was going fine until I tried to remove the small buttonhead cap screw that holds the bracket for mounting the brake line to the back side of the fork slider. Before I go and purchase an "easy out" type screw remover can anyone tell me if a particular brand of screw remover is better at removing these small screws than others. There appears to be several designs to choose from. Thanks. Ed

So what happened to it? Did the head break off?

 

I am unaware of any one type being better than any other. One trick that has worked for me is to first heat things up to 150-200°C before attempting to remove the remains of the screw. The reason it wouldn't come out is corrosion, and heating it like this will fracture the hardened corrosion that is jamming the screw. Often this makes a screw that won't come out at all, almost finger loose.

 

Easyouts are often not very successful with small screws, because the small screw dictates an even smaller easyout. You may have to drill it out and helicoil it (or maybe tap it with the next larger screw size).

 

Bob.

[CanAm76]

I tried heating it with a hair dryer first. Got it so it felt fairly warm, but would still not break loose. Do I dare go at it with a propane torch...carefully?

[nrp]

Yes - heat with a propane torch - and not gently.

 

Was this one of those button head hex key screws that breaks the head off between the hex key bottom and the thread OD? Those screws should be outlawed.

[CanAm76]

It isn't boken yet. But buttonhead cap screws have less depth to the allen shape which makes it hard to get a good purchase on the screw. I assume they use these for "cosmetic" purposes. Bad choice. The screw was somewhat buggered from the previous owners or mechanics working on it. I'm also thinking if worse comes to worse, maybe cutting a straight slot across the screw head with the trusty dremel is a possible path to a good conclusion. That type of screw will not be going back in.

[nrp]

You can save yourself a lot of work if you don't have to drill it out etc - and that will be darn difficult!

 

Use a very small punch and a light hammer to carefully drive the head sidewise ever so slightly as you are torquing on the screw head itself (maybe with 2 people?). At least this will tend to break up any corrosion under the head while it also will tend to loosen the threads.

 

Be sure there is no oil or grease around. Degrease the hex key and socket with solvent and dry. Use a new unplated hex key. Sand blast the key and internal hex surfaces if you can.

 

You've got only one clear shot. Make the best of it.

[johnt650]

An impact wrench may be useful, this was always a great tool for corroded screws on my Japanese bikes.

[RFW]

It isn't boken yet. But buttonhead cap screws have less depth to the allen shape which makes it hard to get a good purchase on the screw. I assume they use these for "cosmetic" purposes. Bad choice. The screw was somewhat buggered from the previous owners or mechanics working on it. I'm also thinking if worse comes to worse, maybe cutting a straight slot across the screw head with the trusty dremel is a possible path to a good conclusion. That type of screw will not be going back in.

 

It will come out. As I mentioned earlier, heat well over 100°C (preferably more like 150°C). In fahrenheit, that is about 300°F.

 

A hear drier is useless. Hit it hard and fast with a torch; it is the thermal shock you are after.

 

While still hot, insert a drift punch right to the bottom of the allen recess (or the stub of an allen wrench), and give it a good sharp whack. This will help to break the threads loose.

 

Then while still as hot as practical, insert the allen wrench and start wiggling back and forth. Usually what happens is there is at first a very small free movement, and as you work it left and right, it begins to free.

 

Bob.

[Eckhard Grohe]

Get one of those paint stripper guns. That warms pretty well without the high localized flame temp of a torch.

 

Good luck...

[RFW]

Get one of those paint stripper guns. That warms pretty well without the high localized flame temp of a torch.

Actually, it is the highly localized heat that is most beneficial in this instance. The usual problem with stuck screws is corrosion that locks it in place. By locally heating the screw, the sharp thermal gradient helps to crack the corrosion (which is relatively brittle).

 

All this is reminiscent of my first car, which was a Mini. Typical of most British cars of the era everything rusted. In many cases, pre-rusted from the factory! The only way to adjust the brakes was to blast the adjuster bolt with a torch, then work it back and forth until it freed up. Fond memories!

 

Bob.