I am useing PC- Metal epoxy putty on my mounts

peppers · May 24, 2011

I know some of the people of these forums believe this to be a bad idea but it works fine for me.

Previously I have used it to correct the angle of the back mount to better fit my frame, I have used it in place of a large frame adapter and to fix an engine with half the front mount broken off after it fell off a table.

This stuff cures into a pretty strong resin and it works well. I would not trust it to stay stuck to the metal of the bike frame or engine so I paint over it with a thick coat of a regular epoxy of the highest strength I can find to ensure it stays in place. I do not believe it will crack or crumble any time soon and it has held on after many rides on my earleyer bike.

I thought this might be something for people to reconsider, so far so good but if I ever have any problems I will post in this thread.

biknut · May 24, 2011

If it works it works, but most epoxy's, including JB Weld, don't like heat.

turtle tedd · May 25, 2011

It will not work for long...

peppers · May 25, 2011

I think it will be fine the mounts do not get that hot, I choose to dismiss negative comments as naysayery unless its from people with personal experience. Not that I do not appreciate everybody thoughts cuz I do.

I will know soon enough, I plan on reporting back in about a month.

biknut · May 25, 2011

How about some pictures?

peppers · May 25, 2011

sure but give me a few days to clean it up so it look nicer

biknut · May 25, 2011

I'm mostly interested in the mounting technique when using it, and how I can adapt it to different frame shapes.

After it cures can you work it with a file or grinder?

peppers · May 25, 2011

I have filed it down after its cured in the past and it dose not seem to effect its strength.

For the large frame the method I used was I dry fitted the engine to the back bar and marked where I wanted to put it. I put electrical tape over the front bar so the stuff dose not stick very well too it so the engine can be removed. I then mixed up a good amount of the stuff and placed it over the front mount and put the back mount in place on the bike and losely bolted it down making sure it was on there straight. I pushed the front mount down so the material would take the shape of the bar and then worked the substance into the mount with my fingers and shaped it, (before it cures its the consistency of a thick clay and can retain its shape under some weight). Since it dose harden fairly quick you gotta do this quickly.

For the older bike with the back bar needing a different angle, I simply bolted the engine down and worked the stuff into the gap with my fingers.

BarelyAWake · May 25, 2011

I s'pose it should be mentioned that if it's just a matter of improper angles, often the engine mounts themselves can be filed (or sanded) to conform, aluminum works easy & s'long as ya don't get too radical, drastically changing the angle of the mounting bolts for example (should be as close to 90° as possible) or removing more than roughly 1/4" frm the mounts (less is better ofc lol) - this can result in a perfect fit w/o any filler material.

The rear mount's spacer block has tons of potential for customization...

kerf · May 25, 2011

Modern adhesives are amazing and used in their proper place can be quite functional. The fact however is that adhesives are far inferior to a properly welded or bolted joint. I offer the following stats:

J.B. Weld / Tensile Strength 3960 PSI

6011 Welding Electrode / Tensile Strength 60,000 PSI

As you can see, J.B. Weld is weld in name only and I would never use this joining method where a failure could become catastrophic.

Please keep in mind that kerf is just a crazy old man.

biknut · May 25, 2011

kerf said:
Modern adhesives are amazing and used in their proper place can be quite functional. The fact however is that adhesives are far inferior to a properly welded or bolted joint. I offer the following stats:

J.B. Weld / Tensile Strength 3960 PSI

6011 Welding Electrode / Tensile Strength 60,000 PSI

As you can see, J.B. Weld is weld in name only and I would never use this joining method where a failure could become catastrophic.

Please keep in mind that kerf is just a crazy old man.

When building a MB being a little crazy helps, me thinks.

peppers · May 25, 2011

Would that be the strength of the joint formed or the raw material?

Because in the manner I am using it its more as a bracket made out of the stuff that the engine sits on rather than a way of joining two peace

s together. People have safely made such hardware out of plastics and resins in the past such as a hockey puck. Generally a good hit with a hammer will usually separate a joint made with this stuff if what you stuck it too is smooth but it separates in one peace

.

kerf · May 25, 2011

peppers said:
Would that be the strength of the joint formed or the raw material?

Because in the manner I am using it its more as a bracket made out of the stuff that the engine sits on rather than a way of joining two s together. People have safely made such hardware out of plastics and resins in the past such as a hockey puck. Generally a good hit with a hammer will usually separate a joint made with this stuff if what you stuck it too is smooth but it separates in one .

Not being at all critical of your plan just keep an eye toward what happens if there's a failure. By "catastrophic", I'm not talking about a failure that leaves you walking or calling for a ride, rather one that has you sailing down the road face first. All cut and broke up kinda puts a damper on the joy.

peppers · May 26, 2011

I can appreciate that but all I'm saying is adhesives are measured by whats called Lap Shear Tensile Strength, this is a measurement of its ability to stay stuck to a different substance. But I am not using it as an adhesive I am using it as a mold-able resin. I personally believe that as a hardened resin its less brittle than the low quality aluminum the crank case is made of.

peppers · May 30, 2011

It had been holding up fine on the bike but I decided to do some heat tests on the epoxy.

I put two of the rear mounts together using epoxy putty and I then took a lighter and held it under the flame. I found after holding it under direct flame for a few minutes that it dose lose adhesion at this temperature but a large chunk dose not seem to become brittle or weaken by this.

I then took a smaller peace

and found that it was possible to set it on fire, the burnt peace

became brittle after I let it burn much as a peace

of wood would. I am beginning to think that perhaps I am a stupid jackass although I am not convinced.

kerf · May 30, 2011

peppers said:
it had been holding up fine on the bike but I decided to so some heat tests on the epoxy.

I put two of the rear mounts together using epoxy putty and I then took a lighter and held it under the flame. I found after holding it under direct flame for a few minutes that it dose lose adhesion at this temperature but the large chunck dose not seem to have become brittle or weakened.

I then took a smaller and found that it was possible to set it on fire, the burt become brittle after the fire burn itself off much as a of wood would. I am beginning to that that perhaps I am a stupid jackass although I am not convinced.

I don't feel that your mounts would be exposed to extreme heat and I certainly hope they would never be exposed to open flame. I would give it a try and keep an eye on the epoxy for signs of deterioration. I know that the stuff has been used to repair cracked engine blocks and I wouldn't think your application would be any hotter. The heat may soften the material over time but you should be able to see any play in the mounts. Just watch it closely so as to avoid all that catastrophic stuff.

biknut · May 30, 2011

peppers said:
It had been holding up fine on the bike but I decided to do some heat tests on the epoxy.

I put two of the rear mounts together using epoxy putty and I then took a lighter and held it under the flame. I found after holding it under direct flame for a few minutes that it dose lose adhesion at this temperature but a large chunk dose not seem to become brittle or weaken by this.

I then took a smaller and found that it was possible to set it on fire, the burnt became brittle after I let it burn much as a of wood would. I am beginning to think that perhaps I am a stupid jackass although I am not convinced.

I became convinced I'm a stupid jackass a long time ago, and just moved on from there.

peppers · May 30, 2011

good advice

DaveC · May 31, 2011

A better product is Permatex Epoxy Putty. It's can be found at WallyWorld with the adhesives in the hardware section. It's a 2 part stick where you cut off what you need and knead it until it's one solid color. It doesn't run so that's a plus. I used it to correct the angle where the back clamp goes around the seat post. I built up a wedge to correct the angle useing a piece of plastic bag to prevent sticking to the clamp, removed the plastic and had a molded adapter that's still on the bike. I'll have to knock it off when my Morini motor gets here but I might not even bother

Oh, yeah, I've seen 1 pound sticks of epoxy putty at Lowe's in the plumbing section.

peppers · Jun 10, 2011

I used a product called quick steel on my last one cuz its cheaper and has a higher temperature rating, you find it in the automotive section of walmart, its a little thinner making it harder to work with but it seems to cure adequately strong.

needs a little cleaning up but you get the idea of what it looks like, dose not look ugly if done right.

This time I positioned the engine by sliding an extra mounting bracket underneath the engine and siting the engine on top of it and then filling the gap with the epoxy putty.

I am useing PC- Metal epoxy putty on my mounts

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