Sir_Name 

A few years ago I picked up a ‘74/‘75ish Klein. When I got the bike two of the three top tube cable guides had been broken free from the top tube and were strung freely along the brake cable housing. I’ve tried a few different adhesives over the years to try to get these bonded back in place with no lasting success (hobby glue and cement, some Gorilla product, silicone caulk/adhesive). Curious what the collective here recommends. Given the quality and relative rarity of the bike I want to get this right. I’m thinking that something with a bit of give when cured could be useful to provide some damping and isolation from road vibration. That there are pockets in the paint to seat the guides is helpful and may provide a bit of additional purchase.







I’ll of course need to clean off the last adhesive before applying the next.

I’ll give a two part epoxy a go depending on feedback here.

'02 nrs

an epoxy as long as the surfaces are bondable-clean.also are you applying pressure after the adhesive? if not try a zip tie to keep the guides in place till dry.

bark_eater 

That looks fussy. I would be tempted to try West System G Flex Epoxy here. If you are careful with the prep you could leave the paint ridges in place and get a pretty much invisible repair. I would read the various instructions that covers bonding aluminum with Epoxy. The big thing is to get the surfaces free of oxidation. I've done this with an acid etch, but I think that gluing up immediately after prep work can be effective. I would scrape off the old adhesive down to bare metal, cross hatch both surfaces with an exacto blade, I think an acetone wash would be a good idea, but I'm going on 20 year old recollections, best to read the data sheets. The other way to go would be one of the Loctite products. I recall they had an adhesive designed to replace silver soldering for some gunsmithing operations. I might skip the cross hatching as these are less gap filling than epoxy. I'd start with the Brownells gunsmithing supply website and work back towards the hardware store for availability. If your just going to try and "giterdone" rear view mirror adhesive is impressive stuff and clear.
PS. There it is:

https://www.amazon.com/Loctite-13542.../dp/B000132VEE

https://www.brownells.com/gunsmith-t...-prod6139.aspx

Sir_Name 

Thanks, I’ve been (carefully) using some quick-grip clamps to apply pressure while curing. I believe one of the best products so far was a two-part crafts-grade epoxy, but it’s been a few years since that attempt. Surfaces were cleaned prior to application, prep is key I’m sure. A higher quality epoxy might be the ticket.

Sir_Name 

Thanks, it is fussy... Each of those seem promising and better suited than the cheap hobby epoxy and other products I’ve used so far. I’ve used west system epoxy in the past fabricating a fiberglass body for single-seater race car in college. Great stuff. When I first started the search about five years ago (sheesh...time flys...) I made a basic test setup for the various products I was trying. Probably worth another shot here. And yes, using a product that cures clear is high on the priority list. I figure success here will be 80% prep work, 20% product selection.

unworthy1

Yes to using a high grade name-brand epoxy, yes to proper surface prep (clean with denatured alcohol or acetone) and roughen surfaces. Yes to careful measuring and mixing and I always opt for SLOW-cure and give it plenty of time with no movement. That said you do not need to clamp epoxy tightly, just enough pressure to keep the piece(s) in place. You might even get away with taping to hold..

jackbombay

I would use a dremmel and tiny grinding wheel to make sure I had bare metal on both sides, I would probably go with JB Weld myself to stick them back on there.

repechage

What is interesting is the failure shown appears a bit different either side.
the stronger bond most likely was to the aluminum.
I wonder what those guides are made of.

He is around, I would ask Gary Klein. Could not hurt.
Or

Check Rockwestcomposites
they have some stout adhesives.

repechage

epoxy likes "room" temp at a minimum.
there are various types with different flex tolerance.
The G series from West System might work

rccardr 

Good prep, Shoe Goo.
Done.

dedhed

https://www.jensentools.com/permabon...gram/p/121-544

scarlson 

Vitus used Redux 203, an epoxy, to bond their 979 frames (patent US4479662A). This cross-references to Araldite 2011, which is readily available today.

J-B Weld is about 1/3 the tensile strength, but may be more flexible. Loctite "Magic Steel" has higher stated tensile than J-B, but I haven't used it.

jackbombay

JB really has no appreciable flex to it. I know there are much stronger adhesives out there, but they generally have to be special ordered and can be quite expensive. I've used JB enough to know that it would stick those housing guides on without issue, they would never come off unless the bike was dropped against a wall directly on the housing guide.

"Better" is the enemy of production, JB weld is "good enough" which is perfectly acceptable for this, IMO.

jackbombay

Just to throw a bit of math at it, JB has a tensile strength of 6200 PSI, those housing guides have about .5" by .25" of surface for adhesive, or .125 SI, at 6200 PSI you get 775 pounds of tensile strength holding the cable housing guide in place.

Kabuki12

I have used JB weld on a few projects and the stuff is amazing . On this application it may not be as clean as you would want . Whatever you use I would try to get to bare surface before bonding.

jdawginsc 

Interesting. I have to file that one, since my last shoe-goo repair on a pair of Adidas Sambas was a No-goo...

acm

If you're OK with an uglier but more reliable fix, I would clean up the surfaces with a dremel grinder or some emery cloth and aluminum braze it on. You don't need any expensive equipment since the brazing rod melts at around 700F. You can probably get the mapp torch setup and the rods for less than $35. I don't think that low a temperature should have any effect on the thinner parts of the tubing (Those cable guides were probably brazed on at a much higher temp) but someone more knowledgeable feel free to correct me.

nlerner

Plastic zip ties are really cheap.

John Nolan 

G-Flex in a syringe is probably your best choice, but it's still pretty pricey. Good prep is key.

I'd look at a clamp if I were you.

sced

Gel super glue is amazing stuff. You could also just go with stainless clips.

Sir_Name 

Thanks, folks. I have a West Marine nearby with the G/Flex syringe in stock. I’ll grab that over the weekend. Araldite 2011 also sounds promising, will track that down. Shoe Goo too, at least for a pair of hiking boots but worth a test here.
Huh, that actually worked!

francophile 

I got a chuckle out of the Shoe Goo. That stuff saved many a pair of Airwalks, Vision Street Wear and Vans in my younger days.

This thread reminds me, I still need to repair this. This thread covers alloy bonding ... is there anything similar to be used for finer/thinner steel bonding repairs like the one I just linked in the previous sentence?

AeroIronBiker

JB weld can work wonders if it is bonded to clean surfaces

base2 

Op: You mention silicone caulk/adhesive.

Nothing sticks to silicone & silicone has a way of working itself into the pores or anything it comes into contact with.

I fear you have impregnated your project with a parting agent that may never be removed. Before doing any bonding, I would use new fresh abrasives, single pass, one direction, all the way down to bare metal. The idea is to remove all potential contamination with out redepositing it so that the new adhesive can bond to a bare, fresh, clean, & uncontaminated surface.

Bad Lag

Precisely!

Remove all visible traces of any/all prior adhesives. This will likely require a file or sand paper and a deft hand.

The problem is, he used silicone caulk. Silicone is notoriously difficult to remove from surfaces to allow subsequent bonding with anything, even epoxies (like JB Weld). Our composites bonding shop will not allow silicone adhesive in the door much less allow you to use it there.

Personally, I would lightly file or sand my way down to bare metal, then clean like crazy (acetone comes to mind but mask off the surrounding paint). Do both sides of the interface to be bonded - tube and guide. Then use a clear epoxy (not JB Weld, which is grey). Whatever you use, clean off the squeeze out to keep the bonds looking nice.