Thread: Filling and Retapping in alloy

Hi All,

I am restoring a 1966 Suzuki A100 motorcycle. The old guy that gave it to me was a bit of a bush mechanic. Where there was a stripped bolt etc, he would just use a larger one(Steering Bracket). He has also used self tappers(Carbi Cover) where the original screws would no longer fit. I aslo need to weld a lug on the Fly wheel cover(Fly wheel cover) as it had broken off. Can this be done.

Is it possible to fill these holes and retap them. Or is there another way of doing it. Can sanyone recommend someone in the brisbane area to do this.

CHeers

Michael

You could use thread inserts.

http://www.emhart.com/brands/heli-coil

Would Heli-Coils be ok for use on the steering head. I thought they might pull out with the stress from the handle bars etc.

Cheers

Michael.

I am no engineer, but I do know that mechanics use them routinely in engines for stripped threads for cylinder heads etc.

When my son-in-law was in the Air Force, it seemed to be used there a fair bit too on aircraft engines and the like.

If ib doubt, ask the helicoil people.

Carbi Cover That looks like it would heli-coil just fine.
Steer Bracket Thats a bit more of a worry as the clamp appears to have been drilled out. If you helicoil the steering head the bolts will be undersize in those holes. The holes may already be over size on what you need for a heli=coil anyway. There doesn't seem to be much metal around the bottom right hole. Could you bolt right through it and put nuts on the back?
Fly Wheel Cover Could you add a little "hook" that bolts to the cover plate before you fit it to the flywheel cover. Slide it in from the right so it hooks onto the flywheel cover?

Hi,

Yes i had thought about using longer bolts on the steering clamp and putting a nut on the back. I would like to keep it as original as possible but. I may not have a choice in this case.

Would it be possible to TIG/MIG the holes up and re-tap them.

I was thinking of using a "Hook" type of arrangement for the cover plate. It shouldn't be too hard to do.

Cheers

Michael.

G'day Michael,

Where there is sufficient parent metal left, using Heli-coils will not only restore the original thread size but will significantly increase the strength of that fastener. These are routinely used in high stress applications, eg lifting or mounting points on industrial machinery.

Where metal is lacking it can be TIG welded but the alloys used by the Japs in their 70's and 80's motorcycle parts used to contain a very high proportion of zinc; making welding them an absolute pig. As yours is an earlier model it may be better quality alloy but judging purely by the photos I doubt it.

Another "welding" method for these types of alloys is more a form of soldering; there are CIGWELD alloys you can buy that melt at a lower temperature than the parent metals and can be used to join or build up damaged parts. They're not too expensive and you can even buy them in the Big Green Shed, but I will admit to never having used them. Twenty odd years these were specifically marketed for the motorcycle and car restoring fraternities.

This product (Aluminum welding - Aluminum Repair - Aluminum Brazing - AluminumRepair.com) was recommended in another forum. Might be something to look at if you want to refill the holes (http://aluminumrepair.com/video/ThreadRepair.html). I haven't used it myself but the videos look impressive.

Christian

There are other types of thread insert apart from helicoils as well. Some require a larger hole than the same sized helicoil, so that might be an option to enable you to use the original sized bolt. A specialised nut and bolt store would be the place to start. The problem you might have is the cost of buying the kits for the different size threads you want to repair. Sometimes, if you only have a couple each of different sizes, its cheaper to take the job to someone who does these sort of repairs.

Also do a web search on "thread inserts" or "thread repair"
ie Thread Repairs

Recoil Thread Repair


Inserts in alloy are supposed to be a stronger thread than one tapped directly into the alloy. In some application inserts are installed by the manufacturer of the parts first off.

bollie7

Back when I was doing National Service in 1970 I bought a K2 Honda 750 from a fellow out at Chermside mower centre, his name was John Farnham (not the singer). After many many rides the chain needed replacing, could not afford a new one so I took three links out. Big Mistake. The chain broke an went through the gear box, busted a hole the size of a box of red head matches. Farnham knew a bloke who was getting into alloy welding. I gave him the motor and a week later it was done. You could not tell where he had repaired the break in each side of the split crankcase it was that a good of a job. So it can be done, welding that is. Dont ask me the name of the bloke, its long gone.

DD

I had a 1983 Rm250 that had a cracked headstock that I had welded and heat treated, it went for years without further problems.

I am currently an aircraft/helicopter engineer and we use helicoils on all the transmission mounting stud holes. So they must be pretty good. I have never seen one fail when installed correctly.

Originally Posted by Muzza 260

I had a 1983 Rm250

Sorry for the OT

They were the good old days When I was 15, I had a RM125X (81) that was only 12 months old when I bought it. It ran for years before it got stolen, I then upgraded to a new RM500E what a power house that was.
About 5 years ago my nephew brought a RM125 (Z) up for me to fix up for him. I rebuilt everything except the motor as it was running good and he didn't have the extra money as he had already laid out $1200 on this fix. I had the rear shock rebuilt in QLD, the head stock, swing arm, wheel bearings etc, the frame sand blasted new seat guards tyres etc. He had it for 6 months and the piston let go so sold it to my mate for $500. I rebuilt the motor for the mate which cost him another $1300 to fix. He rode it 3 times then offered it to me for $800 as he was tight for cash. So I ended up with a fully rebuilt bike that I know inside and out. I still have it in the shed and wont ever sell it, it is sort of a sentimental thing to me.

Dave

They were good days, I bought a CR125M Honda when they came out, my brother purchased a TM125 Suzuki, he still has it to this day. Forerunner to the RM series. Mentioned to him he should get it back out and fix it up, dust off the cobwebs and race it in the vintage scrambles.

DD

Sorry if we are hijacking this thread, but I always wanted a RM500 but settled for a YZ490 that would shake itself to pieces every ride. What a buzz.

"Upgraded" to a 93 Husky WR250 which I still have and scare myself silly on every time I ride it. Had to weld the swingarm on this thing as well. Been pretty happy with that repair too.