Topic: Speedo cable fastening screw removal.

[Polak_Phil]

Hi,

I have bought a CB750 recently and i want to remove the forks cause they are leaking and look damaged. First i need to remove the wheel and the person before me has stripped the screw that holds the speedo cable to the wheel really bad. My efforts to make slots in it using a hammer and an old flat head screwdriver have further degraded the screw.

The screw is a button head philips head 5X16 and it's unfortunately counter sunk into the speedo device that attaches to the wheel.

Can someone please recommend a way to remove this screw. I am tempted to try and drill it out but am worried about stuffing the thread and the speedo device.

Once i remove it can i replace it from something at a hardware store? I am in Australia so we don't have any old honda parts stockists.

I am a total amateur and this is my first bike and mechanical adventure so please dumb it down as much as possible.

For reference, this is the part below.

http://www.bikebandit.com/1981-honda-cb750k/o/m2003#sch22597

Part number 19

[martin99]

G'Day (in my best Aussie accent)

You should be able to remove the wheel without removing the cable at the speedo drive, undo it at the back of the clock instead and thread the cable through. At least then you can carry on with the fork removal, while you ponder what to do with that screw.

FYI, the screws on our bikes are JIS (Japanese Industry Standard) and not Phillips, which is usually why they get buggered up in the first place - owners using the wrong screwdrivers. You'd do well to get a set of JIS screwdrivers to prevent this scenario in the future.

If the head of that screw is too knackered, you may well have to drill it out. At least it will be easier on the bench or with a pillar drill if you have access to one.

[BobbyR]

There are reverse twist which provide the heat, vibration and torque you need to remove a stuck screw.

I did go to the hardware store and found small hex head metric the looks fine.

[Polak_Phil]

Awesome, good to hear.

Will undo the other side and drill it out and replace with hex.

Thanks a lot.

[madmtnmotors]

Left hand drill bits (reverse twist that BobbyR mentioned) are the ticket here. Most of the time they will "grab" and twist the screw out at the same time. Just be sure to use the drill in reverse with left hand bits!

Here's an excerpt from my build thread:

Of course the speedo retention screw has the philips wallered out...





If ANYBODY tries to steal my left-hand drill bits their going to have a fight on their hands!

[Polak_Phil]

Awesome! Can't wait to give it a try.

Thanks a lot madmtnmotors.

[ekpent]

Those screw heads were made out of butter !! When I had that problem last I secured the front wheel best I could and worked on it with a small variety of little punches and chisels. Got a good dimple on the edge of the head for grip and was able to loosen it enough with some tapping of the hammer and chisel to get it out in one piece.

[JeffM]

Funny enough, I had this exact same problem the other day. Tried a couple of different things, but the way I got the screw out was to hit the housing with my propane torch for a while and then take a solid flat head screwdriver and a hammer and tap the edge of the screw in a counter-clockwise motion until the screw loosened up and backed out.

[Jerry Rxman Griffin aka MuthaF'er]

I won't touch one without my impact driver. Been there, done that, it sucks.

[Polak_Phil]

Oh boy did i cock this up lol.

I used a left handed drill bit that was too big and drilled too far into the head and when i tried the easy out it simply sheered off the head completely, after drilling the next hole crocked and breaking my left hand bit i ened up drilling the hole out bigger and tapping it and putting in a bigger hex bolt.

Live and learn. 

[70CB750]

The drive gear is not that hard to come by - they sell on ebay for under 20 bucks in US.

[Airborne 82nd]

I won't touch one without my impact driver. Been there, done that, it sucks.

Same here plus put a wedge behind it I don't like the way it hangs out and hitting it with out a wooden wedge

[hondamad]

I removed the speedo drive unit and wedged in a vice with a stubby phillips and used a vice grip to move. Fitted an alan key tapered screw , no problems after that.

[madmtnmotors]

Oh boy did i cock this up lol.

I used a left handed drill bit that was too big and drilled too far into the head and when i tried the easy out it simply sheered off the head completely, after drilling the next hole crocked and breaking my left hand bit i ened up drilling the hole out bigger and tapping it and putting in a bigger hex bolt.

Live and learn. 

Broken bolts will try your patience. The trick is to start with a small bit and work your way up from there. I usually start with a bit that is a smaller diameter than the bolt itself. This will usually allow drilling all the way through the bolt and out the bottom (bottom of the bolt, not the part it's threaded into). Most of the time it's the point where the bit "breaks through" the bottom of the bolt that the bolt lets go and spins right out. If it doesn't, then I keep stepping up in size of the bit until I'm close to getting into the threads. Usually have to go ahead and drill the head off the fastener at this point. Then I go to work on the remains of the bolt with the Dremel tool and diamond stones.

I've never had much luck with "easy outs". My success rate with the left hand bits alone is about 70%. The Dremel with diamond stones get about another 20% to 25% (after drilling to the limit) with the remainder usually getting drilled a little oversize for a helicoil repair. If you continue to work on old machines you will encounter more broken bolts... just the nature of the beast. After I had a few successful extractions under my belt it began to bother me less and less when encountering a broken bolt. It's still no fun (that would just be wrong) but it is less aggravating than it used to be.