I’m overhauling the engine on my 1980 Yamaha SR250. It seems that every single screw is so firmly in place that I either start to strip the head or else break off the head altogether :eek: .
I’ve already had to drill a few out – not a fun process. Does anyone have any tips? I’m using the appropriately sized screwdrivers and such. Is this a common problem for mechanics?
Have you tried a squirt of WD-40 to free the screws?
Alternatively, there are products for freeing damaged screws - e.g. http://www.globalair.com/discussions/ac_tool/article.asp?msgID=17
Maybe somebody put some of that nut lock stuff on when they installed the screws?
I haven’t tried a squirt of WD-40, though it is hard to see how any could possibly get between the bolt and casing (they are bolts, not screws…I’m clearly no mechanic). I have an extractor, but extracting the screws is time-consuming and a little risky (the extractor could snap or I could accidently drill the casing).
I might try some of the friction-increasing compounds, but even when I extract the screws the torque needed to turn them seems beyond what a screw-driver with some diamonds on the end can pull off.
Thanks for the advice. Keep it comin’!
Sorry, but what is a screw driver with some diamonds on the end? That and I want to know what part of the engine are you taking apart using a screwdriver, not wrenches or sockets.
I’ve worked on a number of bikes myself. What you MUST purchase is a Hammer Driver.
They make childsplay out of those screws.
I’ll look for more information on the net and post a link.
It’s a metaphor. Think about it.
Liquid Wrench is made for just this purpose, although I’m not sure how it’s different than WD-40 as mentioned above.
A screwdriver with diamonds on the end is a reference to the first link, which talks about friction-increasing chemicals. But as a metaphor, its possibilities are limitless.
The part of the engine I’m taking apart, at present, is the clutch. The tops of the bolts are rounded with a philip’s head slot. So a socket/wrench ain’t gonna cut it.
Enipla: I just bought a hammer driver. It worked great on a few, and stripped others, but I was probably gonna have to drill those anyway. Thanks for the advice.
One of the guys here at work clued me into Posidrive screws. Some screws which look like Phillips actually have Posidrive slots; a Phillips screwdriver will usually work, but there are enough subtle differences between the two that you can get a lot better “grip” if you use a Posidrive screwdriver. Which are hard to find; I believe that Snap-on has them.
The clue on the screw head is the presence of little radiating lines between the slots, making the whole thing look kind of like a starburst.
Thanks for the tip, but they are definitely just plain old phillips head bolts.
If the screws protrude from the surface, you might try grinding a slot for a flat screwdriver into the head by using a Dremel tool. Alternatively, put flat edges on the head so pliers or vise grips can grasp it.
No good if the screws are recessed or sit flush, obviously.
When encountering frozen bolts and screws, a torch should help. My favorite is an air/acetylene unit commonly called a plumber’s torch. The flame produced is fine and pointed so you can apply heat to the fastener only and not cook everything. Fastener size will determine length of time for heating: 1/4-20 would need perhaps 30 seconds to a minute, while a 1/2-13 bolt could require a few minutes. Try to loosen the fastener immediately after you’ve finished torching. Good luck.
i’ve ripped apart a bike or two in my day and i say without hesitation that an impact driver is what you need.
all those squirts and sprays might make you feel better but the driver is the key.
there is a huge range in price. i once had a $45 set that grew feet on me. the $5.99 set i got from the auto zone bargin bin has served me just as well for the last 5-years.
good luck on the ride
+1 for the torch
Ex-bike wrench here. The problem is that the aluminum corrodes around the screw threads and siezes the screw. An impact driver may work, but what worked best for me was to get a good screwdriver bit (the cheap ones are either too soft or too brittle), place it on the screw and hit it with a hammer. This breaks the screw free from the corrosion and sort of helps mate the head to the bit. After that, use a 1/4" socket to turn the screwdriver bit, pressing down on the top of the head to help keep the screw from camming out.
Beyond that, a torch may also help. The heat causes the screw to expand breaking it free from the corrosion.
We’ve had this question asked here before. At that time, an aircraft mechanic said that he had success with soaking the screw with penetrating oil, then letting the screw sit for a day or two. Personally, I’ve never had much luck with penetrating oil, but I also didn’t have the time to wait a day or two on a screw (and I doubt that my customers would have wanted to wait that long either.)
Might be a bit late for you on this job Zhao Daoli, but I can recommend the ScrewGrab paste from DarrenS’ link. Though I haven’t used that actual brand, I have something very similar called Griptite; tiny sharp diamonds suspended in a light grease. Smear some on your screwdriver tips when faced with a stubborn fastener and the little diamonds dig into the contact faces of the bit and the screw, and locks solid as long as you maintain the torque. Works for spanners and sockets and allen bolts and all sorts - great stuff. The downside is that every time you use it you take a few little chunks out of your tool faces, so it’s not good to use all the time.
Electrolytic corrosion between Al alloy castings and steel bolts is a right git. The furry salts produced can expand when wetted with water or oil and hold the bolt in even tighter. A sharp blow with a big hammer (+ impact wrench if available) is best for breaking this fuzzy seal.
If the bolt shears off, you can always drill it out and helicoil it. That would cure any future electrolytic corrosion problems for that particular bolt.
Also, IR shocked. Do you not use Pozidrive screws as the crosshead standard in the US? I thought Phillips screws had been obsolete for years. How about Torx head bolts? They’re really effective.
It’s a 25 year old Japanese bike.
I have a '78 Yam 650 that has phillip screws in the engine case. Funny my '75 Yam DTC 250 B used allen heads.