Author Topic: Disaster! My front xlinks disk mount came loose! (Read 4019 times)

junkster · « **on:** February 19, 2005, 10:11:52 pm »

[smiley=upset.gif] [smiley=diaper.gif] [smiley=diaper.gif] [smiley=disbelief.gif] I just stopped to check the tired pressure and noticed. Lucky I had installed a brace that held it in place. I had been going down a hill on a very busy road not 5 mins before. [smiley=turtle.gif] [smiley=diaper.gif]

Just when it was working so well. Have been on 3 long rides and it has been faultless. Can't understand it as it is bonded in exactly the same way using JBWeld directly onto a roughed up surface on the leg. Well almost. I had used JBWeld 20min bond whereas before I used standard JBWeld that took a lot longer to set. However, I left it for a day anyway so kinda ruled that out. The mount virtually just slid off so don't reckon the bonding agent is to blame here.

There are a few other possibly causes:

[smiley=bomb.gif]It has been very cold of late and perhaps with the constant expanding and contracting of the alloy leg, mount and JBweld in between, the bond has weakened. Kinda ruled this out as JBweld has been tried and tested, (Will - you swear by this stuff don't ya?), and surely the xlinks alloy to carbon bond using epoxy that a lot of you have used would have far more of an issue being totally different materials.

[smiley=bomb.gif]I painted it yesterday and to remove excess paint I used paint thinner.
Perhaps some excess thinner managed to get in between the bond and reacted with it. I wonder if this is the real culprit. [smiley=blankstare.gif]

[smiley=bomb.gif]The adapter still had some JBweld from the first bond to my Elite fork alloy legs on it, though I had sanded this and then roughed it up, plus redrilled the holes so the Jbweld could ouze through just like before.

[smiley=bomb.gif]The alloy leg wasn't roughed up enough or there was some residue of oil of something. I was very thorough though - had cleaned it with soapy water wiped and left it to dry, and the area was sufficiently roughed up (as much as in the first bond)

Dilemma [smiley=worry.gif] Do I rebond? Any ideas would be greatly appreciated.

cheers Dan [smiley=beer.gif]

kiwi · « **Reply #1 on:** February 20, 2005, 02:33:22 pm »

paint thinner,soapy water,20 minute bond,all spell less than ideal bond strength to me dan......I would read jb weld(the full strength version) to see how you should prepare your surfaces,and follow that to the letter.If you are concerned about bonding times i think a warm oven can help there,again refer to instructions.One warning tho if you do try the oven it can sometimes make your epoxy a little runny at first so make sure you have some "protection"....for yourself AND the oven in case of leakage!!!!My experience has been with a product called araldite.....

will · « **Reply #2 on:** February 20, 2005, 11:49:12 pm »

Dan,

Not a disaster, just a healthy indicator of what doesn't work. Always good to know!

Great advice from Kiwi. Past experiences with marine resins & hardeners taught me a few lessons about the narrow application windows; Too much hardener and it gets brittle, not enough and you end up with a gooey mess. Cure time is also more important than you might think. (Unfortunately, I think we're both Friday night fixers & Saturday riders.)

Justa coupla trix that helped me out:
1. Embed the tab at least 1 cm deep in the epoxy.
2. Build a cofferdam type mold for the epoxy using aluminum foil tape.
3. Make sure there are irregulaties in the surface of the brake tab for the epoxy to sink its teeth into. I drilled little holes in the tab.
4. Make sure your metal surfaces are way above the dew point and do your work in a warm, dry place.
5. Wait at least 24 hrs for it to cure.

If yours doesn't work, I'm gonna get nervous...

junkster · « **Reply #3 on:** February 21, 2005, 12:29:54 am »

Hi Kiwi/Will,
cheers. Could be all those reasons. Will attempt a rebond - Had drilled holes in the previous incarnation - that had been rock solid - I think it is more likely the intervention of the paint thinner, or a dogy mix of JBWeld. Will look into it, and taking both your comments onboard I'll re-bond.

Will - not sure what you mean by this:
Build a cofferdam type mold for the epoxy using aluminum foil tape. Brain can't cope smiley=disbelief.gif]

Here was the original mount before I bonded it to the first leg. (as you can see, the drill holes are there)

cheers,

DAN [smiley=beer.gif]

Old Proflexer · « **Reply #4 on:** February 21, 2005, 01:41:11 am »

I'm not an expert on bonding agents so I probably shouldn't even be posting here but - I should imagine any good metal bonding, high strength, longer bonding time, epoxy resin compound would work just fine.

If the adapter unit is centered propery, very little if any stress is ever applied to that joint - unless, as Kiwi would say, you need the brake to keep from rolling backwards on a hill.

(I've just never figured out why he would want to stop on a hill

)

OP

will · « **Reply #5 on:** February 21, 2005, 01:55:19 am »

Dan'l

When you set your adapter onto the fork leg with the epoxy, it should get gooey enough that excess material will follow gravity out of the joint.

If you lay the fork "face down" so the adapter lays on top of the leg in a bed of epoxy that may be the best way to set it.

By using foil tape you can build a semi-rigid barrier around the adapter to keep the JB Weld from dripping out and around the fork leg.

That should look good and help "Keep the medicine where the pain is."

Make sure you get epoxy to ooze up through those little holes so it can really grab onto it!

TTFN
Will

junkster · « **Reply #6 on:** February 21, 2005, 09:04:47 am »

Hi guys,
ok just finished re-bonding it again. I decided to remove all the paint, and following all the advice given I went a little OTT with the JBweld.

The mount itself before bonding (took ages to remove the old paint) This is the best you can do with old scooter parts and a lack of welding tools and any technical expertise [smiley=turtle.gif] [smiley=diaper.gif]:

http://idriders.com/proflex/galleries/junkster/2nd_attempt_stripped_disc_adapter_1.jpg
http://idriders.com/proflex/galleries/junkster/2nd_attempt_stripped_disc_adapter_2.jpg

Positioning:

http://idriders.com/proflex/galleries/junkster/2nd_attempt_before_bonding_disc_adapter_1.jpg

http://idriders.com/proflex/galleries/junkster/2nd_attempt_before_bonding_disc_adapter_2.jpg

The bonding (this stuff started to set hard within 5 mins of mixing, (used a minute amount more hardener in the mix). As it ouzed through the holes in the mount I tried my best to mould it into shape, covering as much of the mount in JBweld as possible. Looks a bit of a mess - will set to it with a file and spray paint it afterwards):

http://idriders.com/proflex/galleries/junkster/2nd_attempt_bonded_disc_adapter_1.jpg

http://idriders.com/proflex/galleries/junkster/2nd_attempt_bonded_disc_adapter_2.jpg

Will let it cure for 24hrs, then file it down, and test it. The more I think about it the more I think the reason it failed was that I did it outside in cold, damp weather, coupled with the use of paint thinner when I cleared up the excess paint.

Thank you all for your prompt inputs - will update. Fingers crossed![smiley=worry.gif]

cheers,

Dan [smiley=beer.gif]

will · « **Reply #7 on:** February 21, 2005, 11:54:47 am »

Y'kno, dat ain't so bad.
I'll bet she looks good after a little dress up. AND, I bet she don't come off!

Ride 'em cowboy!

kiwi · « **Reply #8 on:** February 21, 2005, 05:48:43 pm »

Quote

I've just never figured out why he would want to stop on a hill

I never like stopping on a hill OP but quite often(i love trying tough uphill sections cos of the dig in) I find myself stopped in the middle of a steep bit with the front brake clamped on as i try a quick dismount or sliding back down the hill [smiley=redface.gif],hence my disc brake mount will encircle the fork leg......i wouldnt be paranoid if people didnt pick on me al the time.....

junkster · « **Reply #9 on:** February 21, 2005, 07:02:03 pm »

Yeah, agreed with Kiwi here. Have the top alloy brace/clamp to install after I tidy up and may put one on the bottom, since they weight hardly anything.

cheers guys,

Dan [smiley=beer.gif]

junkster · « **Reply #10 on:** February 22, 2005, 07:18:39 pm »

Hi guys,
Will - what type of paint did you use on yer disc mount? Did you use a metal primer first? It looks thicker than standard spray paint - kinda like it. [smiley=nod.gif]

I am very cautious after the possible cause of the failure of the bond was paint or paint thinner reacting with the JBWeld. [smiley=diaper.gif]
Needs spray painting as looks a mess without it, and was hoping to get a can of silver/metallic spray paint, thus matching the polished silver look of the legs.

cheers,

Dan [smiley=beer.gif]

will · « **Reply #11 on:** February 23, 2005, 05:10:59 am »

Actually... I just used spray primer. The plan was to dress it up with better matching paint, but it looked okay.

Mostly I just couldn't wait to go riding! [smiley=nod.gif]

It would be nearly impossible to match the pearlescent white on my crosslink forks, so it will remain imperfect.

I'll bet there's a good aluminum spray that will make yours look factory fresh.

junkster · « **Reply #12 on:** February 23, 2005, 05:26:36 am »

Hi guys,
Cheers Will. Ok, almost finished. Needs tidying up a bit, (run out of JBweld so might just bung some plastic padding product on to make it look more even). Then will sand and paint it.

Looks a little messy at the mo:

http://idriders.com/proflex/galleries/junkster/2nd_attempt_bonded_disc_adapter_with_brace.jpg

It is dead centered:

http://idriders.com/proflex/galleries/junkster/close_up_2nd_attempt_new_long_girvins_adapter_centering_1.jpg

cheers for all the input - much appreciated,

Dan [smiley=beer.gif]

junkster · « **Reply #13 on:** February 24, 2005, 06:44:35 am »

painted:

http://idriders.com/proflex/galleries/junkster/2nd_attempt_bonded_disc_adapter_with_brace_painted.jpg

ToNYC · « **Reply #14 on:** February 24, 2005, 12:52:18 pm »

Junkster,

I agree - those 'possible causes' sure ain't JBweld-friendly . In my case, I used an industrial-grade aluminum-filled epoxy from Mcmaster-carr.com. It comes w/ a hardener and a resin w/ a 25-minute work time. I also made sure I 'roughened' the leg a bit w/ sandpaper and cleaned it w/ alcohol before bonding and let the whole thing cure for two days ( waiting was a pain). I'm attachng my 'how-to' pictorial guide for those w/ future projects. Anyhoo, good-luck!

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Author Topic: Disaster! My front xlinks disk mount came loose! (Read 4019 times)

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