I've been working away on my brass windshield for my 11 T. It's a nice original Metzgar Automatic that hasn't been apart for at least 100 years! It needs to get safety glass put in but I can't get the removable brass channel off because the steel screws holding it on are rusted in place. They are a flat countersunk,slot, 8-32 machine screw. I've been soaking it with penetrating oil over the last few weeks and tried tapping on the screw hoping to break loose the rust. No luck. Does anybody have a sure fired method of getting the screws out??
Have you tried a impact screwdriver? I know you said you tapped with a hammer but that is not quite a good as a impact driver. You can get a cheap driver at Harbor Freight. I normally drill them out being very careful to drill the center of the screw and start with smaller bit. be sure to use cutting oil and good grade of drill bits. Do not force anything so as not to break the bit off in the process. You can always tap the threads if needed. With luck when you get close to the diameter of the screw you can use the tap again they break very easy and then you are up the creek. If you are not familiar with using taps either get someone that is or take it to a machine shop. Some people will tell you to use a easy out but they really break easy and once again you are up the creek. No matter what you try do it with ease and do not force anything. The impact driver usually works for me. Lots of good luck. Just remember if you feel you do not have the talent for doing the job do not do it get help.
Set a 1/4 or 5/16 nut onto the head of the screw and then mig weld them together in the centre. Probably use the 5/16 nut. Set the mig to the high end of the heat. You want to put as much heat in the screw as you reasonably can. I then use ordinary candle wax as a lubricant as it cools (just below the "smoking point "). Let it cool. It should then turn out easily. The logic is that the heat tries to expand the screw and what it is in is still relatively cold. So the net effect is the screw shrinks and the rust is broken. The wax "wicks in" nicely when it is hot
I have used this on machine screws with success
I have used the suggestion Les offered, but I used a TIG welder. Either way, the problem bolt came out easily after welding the nut on.
Won't the screw expand with heat?
Yes the screw will expand with heat but you wait till is cools and shrinks back to the original size before trying to remove then screw. The movement from hot to cold will help to loosen the screw.
For what it is worth I have used all of the above methods. If the screw has a fairly undamaged screw slot the impact screwdriver works great especially after liberal application of 50/50 acetone ATF mixture or sometimes some heat and wax. If you have a good oxy/acetylene set up you can heat the screw very quickly and sometimes it will back out very easily. Welding a nut to the screw has the same effect.
I have tried an impact screwdriver without success. I'm nervous about using heat as the steel screw head is countersunk into the brass windshield frame which of course I don't want to damage.
Les do you think mig welding a nut to the head would be ok and not damage the brass? I've often used heat before for steel to steel applications and had great success.
The thing to remember is you're dealing with dissimilar metals that heat and cool at different rates. I would imagine welding the nut onto the end of the screw is going to cause the brass to heat much faster then the steel and will not only absorb more heat but will also expand at a greater rate. The screw which will lag behind will also expand but not enough to stay tight in the brass threads. Being able to get that much better grip by putting a wrench on the welded nut and applying more force while utilizing the leverage of a wrench ought to make it extremely simple to remove the screw.
Do the screws go through the wall of the channel and get held in place with some form of steel insert?
I've explained what I have done on my own stuff
I will further elaborate for Mike's benefit. The point of electric welding is that a LOT of heat is put into the screw in short time. The whole screw will approach red hot in a few seconds and the piece it is threaded into will be much cooler at that time. As others have mentioned this breaks the rust but as I have stated the screw will in fact be smaller once everything cools. And yes do NOT attempt to remove the screw until it all cools down. I hope this helps
With the Rands windshield the screws that hold the hinges to the windshield frame can be removed and the mounting blocks with the brass channel mounted to them can be slid out of the windshield frame. If all goes well the brass channel may not need to be removed from the mounts. I don't know if the same applies to the Metzgar windshield.
I have an original Rands and the mounting blocks are steel. I don't know if the same can be said for your Mezger or for all Rands. As Art said, if removing the blocks is an option, that would be best so as to avoid risking damage to the frame in the process.
Well unfortunately the automatic doesn't have removable blocks like the rand. Thanks for the suggestion Art and Walter. I'm going to try Les's method of welding a nut to the head. I'll let you know how that goes.
Art. Looking forward to seeing you and Gail at Bakersfield in April. Can hardly wait!
With a screw that small, the amount of weld time, & heat generated by same, will be minimal and should do nothing to hurt the brass, so long as your aim with the mig welder is good.
Can you please post pictures as you work on your Metzger? I have one I bought almost complete, just needs the glass dividers replaced. I let someone take it to restore, they wer going to put it on their car and trade me for their original Rands. After a year went by I got tired of waiting, bought. Repop and the Metzger is sitting on the side, now disassembled. I really want to get it completed but don't have any 'before or during dissassembly' pictures.
I'm thinking that welding a washer to the screw head first then welding a nut to the washer would minimize the heat build up and be easier to get at with the welder. Also a copper spacer placed between the washer and the brass channel might help dissipate the heat faster.
Ah, my mistake. This is the style with the patented Mezger latch so your channel screw is in the heavy brass casting at the top? If it is a flathead screw and you don't feel it's rusted (or even if it is, it won't make much difference) sometimes you can carefully cut away the head with a small carbide burr and doing so will relieve a lot of the pressure. You can then remove the part and have enough screw shank to hold onto to extract with pliers. If that doesn't work, you can still carefully weld a nut and at least if you miss and arc to something else, you won't damage the piece you're trying to remove. Given the weight of that casting, I don't think the heat will cause any problems, I just hate to think what can happen if you miss.
If I understand you correctly it is the screw holding the brass end caps to the uprite???
Everyone is telling you the correct processes here. I would not want to damage the brass divider-glass drip-channel if it has this.
I would drill the screw head off first 1/4" drill bit and careful pressure! You will see the head twist off before it starts drilling into the brass end cap. Light pressure and a careful eye here. Remove all of the parts and then tackle the metal insert in a vise away from the windshield assy. Welding around the brass is risky. I would have someone good with a tig torch weld on the nut if you are leaning this way!!! Should find somebody really good for 20-30.00 to do this for you. That's a lot better than ruining that windshield frame assy.
What that does is cause the screw to expand. It is TIGHT in the hole! When it cools down to ambient temperature it will shrink some. half thousandths or so. Using candle wax while it is about 120 degrees or so will allow that receding shrinkage to pull in the wax. This usually does work great! I wait an hour or two before trying to reverse turn the old screw. If that does not work then countersink the remaining shaft of the screw as the nut will have broken off. Then unsize drill out the screw. I have left spiraled Bits to do this with. But the good quality drill bit should work fine. You are not alone most of the old windshields I have had to do this to. If I READ your thread wrong than I apologize for the comments.
Joe in Mo.
Sorry for the delay in posting. Flu for a few days and then I had some T's and another old car in a movie shoot.
Today I went to see my good friend Chico who has a mig welder. I don't have one yet... He has removed stuck screws using the method Les recommended. It worked exactly like Les said. Why would I doubt him anyways?? The brass hardly heated up. the whole job took about 10 minutes.
Here are the pictures showing the whole project.
The windshield that was giving me grief
Here's the problem screws
And here is how we removed them
Thanks everyone for all the help and suggestions.
I'm glad it worked out. I'd hate to give a friend bad advice!!
I have done this on a couple of bolts, I agree works great. I had to braze the ones I did.