What's best to repair clutch/crankcase covers?

[vifferman]

My right-hand crankcase cover (over the clutch basket) is weeping oil, from a hairline crack. What's best to repair it - argon weld on the inside, or epoxy?

[Panther]

Stop being so tight and buy a new one, that way your leak wont cause you to crash; remember bike bits come first, food on the table comes second.

[Firefight]

My right-hand crankcase cover (over the clutch basket) is weeping oil, from a hairline crack. What's best to repair it - argon weld on the inside, or epoxy?

if its ali, get it to me, my mate is the shit for ali welding, he did one for Renagade Master looked better than new when done, and of course its free.


F/F

[The Pastor]

if its ali, get it to me, my mate is the shit for ali welding, he did one for Renagade Master looked better than new when done, and of course its free.


F/F

Yes, he did a very good job, awesome in fact.

[Ocean1]

My right-hand crankcase cover (over the clutch basket) is weeping oil, from a hairline crack. What's best to repair it - argon weld on the inside, or epoxy?

Epoxy will work of you degrease it properly and rough up the surface, ain't "proper" though.

Best way is to make a service plate to screw it to (to prevent distortion) and TIG weld it.

Wait... check it's not a high magnesium alloy first... If you're welding the case of (to take a random example) an XL350 and it starts to spit and fart and sorta "sparkle" drop the welder and run away. Don't bother with the fire extinguisher... and above all don't fling it into a bucket of water. Just wait until you can see again and then sweep up the mess before the boss sees it.

Just how much is a new one dude?

[Conquiztador]

is a quick fix as long as U get rid of the oil and dirt first (said that I have some old dirt bikes that got a araldite "quick fix" a few years ago and have not had a problem since...)

[vifferman]

Epoxy will work of you degrease it properly and rough up the surface, ain't "proper" though.
I'm thinking that's the way I'll go, as I won't need to repaint the cover then.


Best way is to make a service plate to screw it to (to prevent distortion) and TIG weld it.

Wait... check it's not a high magnesium alloy first...
Years ago (back when me 'n' Moses were just boys, I had an MT250. The cases proudly announced "MAGNESIUM" on the sides. I went on a 100 miler ride (one of Roger White's, at Atiamuri), and part of it was logging roads with fist-sized rocks on it. Another part was a stream crossing, and I remember thinking, "Meh! No problems - nowhere the water can get in!" I enjoyed it so much, I went across twice, and then again on the way back after lunch.
As you do.
Inspecting the bike at home, I noticed a gaping crack in the case over the points. :shit: Obviously, one or more rocks had been flicked up by the front wheel and hit it.
Amazingly, back in them steam-powered days, I actually found someone in Rotorua that could weld it for me, and he did a good job (I don't think it caught on fire and he had to hide it from the boss. He may have even been the boss!)
[A potentially worse problem was the gas can in my backpack, that was old and rusty and weak, which started dribbling petrol down my back after about 35 miles or so, when there wasn't enough room yet in the tank to transfer it. Oops....)


Just how much is a new one dude?
I haven't bothered pricing one here, but Arizona Motorsports has them listed at US$180.

[Ocean1]

I'm thinking that's the way I'll go, as I won't need to repaint the cover then.

OK, check the clearance between the cover and the clutch basket with a couple of dabs of plasticine. If there's 2-3mm or more I suggest you add a couple of strips of 25mm fibreglass tape or cloth to the repair. Rough up the inside of the cover around the crack, apply a little epoxy (Araldite high strength is OK) and work it into the crack. Smear epoxy around the crack and lay the tape over it, work the tape into the epoxy (just tamp it down with a stiff brush or similar) until it's all wetted out, apply more epoxy if needed but be careful not to disturb the tape too much. Chuck it into the oven at 90 deg C for an hour or so (while the Mrs is out of course).

PS: is it the sort of thing a wrecker is likely to have/get?

[Wired1]

Are these things any good?

http://www.trademe.co.nz/Trade-Me-Motors/Motorbikes/Parts-accessories/Other/auction-138948984.htm

I have a half inch hole (12cm) in my left hand crank case around the chain area of course. There is a cast knob that gets knocked off too easily on these (XT550/600 etc) and it doesn't seem to have any purpose. Another set of cases I have already have had this repair so it must be common.

Anyway I was going to take it along to my local alloy welder guy then I saw these and wondered if they were any good, or are they crap?

[Paul in NZ]

Yes - they are fantastic but require a little practise...

[Ocean1]

Are these things any good?

http://www.trademe.co.nz/Trade-Me-Motors/Motorbikes/Parts-accessories/Other/auction-138948984.htm

I have a half inch hole (12cm) in my left hand crank case around the chain area of course. There is a cast knob that gets knocked off too easily on these (XT550/600 etc) and it doesn't seem to have any purpose. Another set of cases I have already have had this repair so it must be common.

Anyway I was going to take it along to my local alloy welder guy then I saw these and wondered if they were any good, or are they crap?

They work well in some situations but it's more accurate to call them alloy brazing rods, the technique in using them is more like brazing also. They have a high silicon content and a few additives to reduce the melting point to a bit below that of most alloys and to make them flow. Like any gas welding job you need to get the whole item quite hot, which will destroy the temper, making the part less strong, (depending on the alloy).

Personally I'd get a C/case TIGed but if you want to have a go with those rods go for it. You might struggle to build up enough weld material to completely fill a big hole, if so make a wee plug to weld in place.

Clean the weld area bloody well, especially the edges of the weld prep, (file, clean one). Use oxy/acetylene, turn oxy off and cover the case with the black sooty smoke from the acetylene only flame. Readjust the flame and heat the case evenly until the soot starts to disappear, that's when you're almost at the right temp, time to start the weld proper.

I like to screw the case to a steel benchtop or similar to prevent distortion, up to you.

[pete376403]

Repco have some 2 part epoxy ("Steel putty") made by Pratleys of South Africa. I used some to repair a gearbox sprocket cover of a FZR1000. Sets hard in about 2 hours and can be filed, drilled, tapped, etc. Metallic grey in colour, about $15.
Usual provisios apply - clean and roughen the surface first.

[HenryDorsetCase]

Repco have some 2 part epoxy ("Steel putty") made by Pratleys of South Africa. I used some to repair a gearbox sprocket cover of a FZR1000. Sets hard in about 2 hours and can be filed, drilled, tapped, etc. Metallic grey in colour, about $15.
Usual provisios apply - clean and roughen the surface first.


a mate used that on an engine cover on an RGV250: then he painted it and it looked mint.

FWIW a new alternator cover from the LBS for my Hornet was ~$225. a new one might not be as dear as you think.

How did it get a hairline crack in it?

[MaxB]

They work well in some situations but it's more accurate to call them alloy brazing rods, the technique in using them is more like brazing also. They have a high silicon content and a few additives to reduce the melting point to a bit below that of most alloys and to make them flow. Like any gas welding job you need to get the whole item quite hot, which will destroy the temper, making the part less strong, (depending on the alloy).

Personally I'd get a C/case TIGed but if you want to have a go with those rods go for it. You might struggle to build up enough weld material to completely fill a big hole, if so make a wee plug to weld in place.

Clean the weld area bloody well, especially the edges of the weld prep, (file, clean one). Use oxy/acetylene, turn oxy off and cover the case with the black sooty smoke from the acetylene only flame. Readjust the flame and heat the case evenly until the soot starts to disappear, that's when you're almost at the right temp, time to start the weld proper.

I like to screw the case to a steel benchtop or similar to prevent distortion, up to you.

+1 for TIG if the part is load bearing. By far and away the best repair method for alloy.

I have not had that much success with the low temp alloy kits. It seems to lower the strength by too much for my peace of mind.

For a 12mm hole, as long as it is in a medium to low temp area eg just to keep a bit of oil splash out, then I use JB Weld. It is a fibre-filled 2 stage high strength epoxy.

For your repair I would make up an alloy plug that fits as closely as possible to the hole. Then working from the inside of the case I would fill around the hole until there were no gaps. You can make an epoxy bead around the inside seam to act as a top hat but check there is enough clearance first.
Then you can work some JB weld into the outside of the cracks.

It can be drilled or machined but beware, this stuff sets like concrete and often has better mechanical properties than the surrounding alloy.

[Wired1]

Awesome thanks, I'll give the epoxy stuff a go. I'll let you know how it goes.

[vifferman]

JUst a followup - I used the JB Weld, it worked brilliantly, the crankacse cover is fixed.
I was so impressed, I've looked around for other things to fix. Last weekend, I repaired the glovebox lid on the Fart - both hinges were broken. Even though it's some softish plastic (PP?), the JB Weld worked brilliant;y, and the glovebox lid is actually stronger than new now.
One hinge I just glued up, the other (which was completely snapped off) I glued, wired together with 10A fusewire, then reinforced on one side with fine aluminium mesh (insect screen).
THis stuff rocks! :niceone: