Which retaining compound do you use for gluing?

I’m not getting long lasting results with Loctite 638 no matter how much I use. I think that the 638 is too thick e.g. for gluing press-fit shafts to the can or even gluing gears or pulleys to the shaft. Therefore I wonder if I get better results with thinner compounds like 603 or 648.

Loctite retaining compounds

  • 620 (up to 230°C | up to 0,2mm gap)

  • 648 (up to 175°C | up to 0,15mm gap)

  • 603 (up to 150°C | up to 0,1mm gap)

  • 638 (up to 150°C | up to 0,25mm gap)

Also I wonder if it makes a big difference if I sand the parts a bit before gluing? Of course I clean/degrease everything before gluing but that’s it.

Which retaining compound worked for you and lasts? Or what am I doing wrong?

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I use LT 680

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I have used 648 on three dual motor setups over the past two years and if has not failed me yet. and I you only that, no grubscrews, no keyways I solely rely on the loctite.
I do however key both surfaces with something like 60-100 grit paper then degreses with acetone. And for some reason I have always left it drying for like a week before ridging it. if you look at the strength charts it takes a shitload of time for it to achieve it’s full strength.

idk you might be more of a madman than me when it comes to riding, and I have it sitting on street boards all using belts so that might contribute a bit. That being said I am riding in the middle of the road so I obviously have to keep up with traffic.

I would assume something more liquidy would be suitable for the shaft to can situation as that is normally a press fit. this is something I would love to hear what other do as my motors rattles like crazy because of those stupid grubscrews and they can’t seem to holt it laterally.

Here is a video showcasing it, thought for weeks it was something in my enclosure rattling. So I bet some of you guys have the same issue. because I have it on 5 different freerchobby motors and they are all from three different batches and two different vendors.

(video quality is junk because i just uploaded it.)

this is what i use and never had problem.

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Had good experience with 648 as well for motor gears without scrub or keyway (besides the first one…which came lose after 3km. Did glue it back and was on the road two hours later. So far so good)


Interesting, never heard of but the more research the more compounds you find :sweat_smile:

This is some interesting heat strength chart from the 680 data sheet


I didn’t think about that before but at 80°C the strength decreases to 60% which is the case eg. with hot motors.

Here a better chart for comparison between compounds

That sounds promising :grin: My gears shift sideways with 638. The glued motor axles of some cheap motors shift sideways as well and this with belt drive :flushed:

Gonna try that

I think 603 is the thinnest, 648 comes next.

That’s actually the most recommended, also by @mutantbass thanks for that.


I actually had to remove one of my pulleys because of misalignment and it was really really difficult. granted, I only had a butane lighter and not a proper blow torch but even after 10 minutes of heating it up, it wouldn’t budge. in the end, i had to dremel the pulley and use a gear remover to get it out.

part of the reason i am not upgrading to gear drive is that no fucking way am i doing that again to get my 2 motors out. lol



According to the chart the 638 doesn’t look too bad in the strength department, might have something to do with the compound being too thick as well as the lack of scratches/crevices to hold on to.

And for an open motor pulley I would say you don’t need high temp stuff as that is generally weaker overall and the the circulating air would cool it down a fair bit more than what’s inside the motor.

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Me, too but with the blow torch (1900°C) it’s really easy to remove a glued gear/pulley within 30-60 seconds, did that many times already. The small one is nice for removing thread locked screws.

True that’s why I chose it but I guess it’s too thick for minimal gaps or it’s the lack of sanding.


well,i guess i need to start looking at some gear drives. fuck


I have used both a heat gun and a butane torch on steroids to get it off both took me a solid 2 minutes before i could get it off, so im cringing the full two minutes of heating the damn pulley but so far I haven’t ruined a motor by removing the a pulley.

I normally clam either the motor or preferably the motor mount in a vise, make a shield using some aluminum foil and I use a flat screwdriver to get some leverage and try to pry off the pulley once it get’s hot enough. And looking at Rich’es charts it makes perfect sense as the loctite compound gets weaker and weaker with heat.

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Everything I own is held together with spit and rage :grinning:


I’m heating the shaft and not the pulley/gear itself until the retaining compound starts smoking/smelling, then remove it with a flat screwdriver.

Can you send me some spitting compound? How much?


How much, it takes a lot of beer to make hi quality spit :grinning:


Does the bond get stronger with whisky or rum instead of beer? I need high-strength.

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Nope, totally negates any binding, actually makes grease at high enough quantities :grinning:

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White sticky glue from @Brenternet :tongue:

Sticks like a champ.


Jeeeeesus :sweat_smile:

From where do you know, first hand experience?


Still got some areas" retained" from last time.

Would Recommend 10/10


so you havent taken a no.2 for a while?

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