loose engine mount bolt

[FJRFolly]

Hi all,

Last year I put some frame sliders on, when I re-installed the lower engine mount bolts with the sliders in place I used some red thread locker. Last weekend while getting everything ready for the season, I went to check the torque on them and found the left side to be very loose! I have since put more thread locker on (medium strength blue, 'cause that's what I had and according to their spec's it should be strong enough). After riding it and rechecking the torque (35 lb ft) several times I have found it loose each time. :angry2: What gives? Anyone had this happen? My plan is to remove the bolt clean the hole with some alcohol and brass gun brush and reinstall the bolt with some red loctite. By the way; forgive my ignorance but will I get any negative interaction between the gun brush metal and the engine block metal? Is the block steel or aluminum?

 

[FJRBluesman]

Never had an issue, although I never rechecked the torque either after installing my sliders on my Gen1. I used blue loc-tite.

Is your torque wrench correct?

 

[adaniel]

Are the sliders Delrin?

Mine took a few re-torques to fully compress after some long rides.

 

[jet mechanic]

+1 on what adaniel said.

Rechecking the tq's a couple of weeks after install, had to re-tighten the right side once, left side twice.

 

[odot]

Drill a couple holes in specific places. Retorgue it. Safety wire the bolt.

 

[dsmack]

A couple of possibilities come to mind...

As mentioned, if the sliders are Delrin (without a steel inner sleeve), the material will compress over time and be difficult to torque and have hold spec.

If you were able to remove the bolts without the application of heat after using red Loctite, then the holes/bolts weren't clean enough at initial installation. A good cleaning as you mention will help, but I don't think you need to go to the extreme of using a bore brush! Alcohol (the generally available kinds) are not a particularly good solvent, so I'd suggest you might want to get a can of BrakeClean or PB Power Blaster to use instead, followed by a good blow-dry with compressed air. LocTite Blue is strong enough for this application...

Each time you apply your torque wrench to check the bolts, you are breaking the bond of the LocTite, which is kind of a self defeating thing, don't you think? The safety wire approach is bulletproof, but a pain in the butt to accomplish.

Steel Inserts in sliders, clean bolts/holes, Blue LocTite, torque to spec, mark head of bolt with dot of paint so you can visually check for movement without breaking LocTite bond... should be end of problem! :yahoo: Sorry for the Loooooonnng post!

Have fun!

Don

 

[FJRFolly]

...What about replacing the standard washer with a lock washer or using a tooth washer with the standard washer? Do you think that would affect the torque setting enough to be bothered with? Should I be concerned with the dissimilar metals? I guess I really don't want to safety wire it, but it backs off more than just a quarter of a turn.

 

[painman]

And remember to torque the left side first....PM. <><

 

[madmike2]

I don't think the conversation is centered on the bolt loosening because it is backing out (and thread lock compound should prevent that). Instead, it is because the Delrin will compress without a steel sleeve to prevent the compression.

 

[terrebandit]

Are you sure its not stripped? I find that unlikely as it would take a lot to over torque that. I bought the OES ones that have the metal insert.

 

[just roy]

my first question is is the bolt stainless if it is the locktite wont work without locktite primer. locktite needs contact with carbon to set. some types of stainless bolts in aluminum will not cause the chemical process that locks the bolt. the other thing to look at is what others have said. is the bolt turning or is it just compressing the delrin or is it stripped.

 

[FJRFolly]

Thanks to everyone, I think I have this solved. The male and female threads are fine but were very dirty, hence the loctite wouldn't work. After a good cleaning and some new loctite and a tooth washer I don't think that sucker will move. I just wouldn't have expected a bolt like that to move in the first place. My wife and I were talking and we seem to remember my commenting on the bolt being loose when I put the slider on originally. Odd...

 

[vabrzn]

I would stick with the blue loctite in aluminum threads. The red is so hard it can strip the threads when you take the bolt out.

 

[BwanaDik]

Also a strong possibility that the bolt was overtorqued at some time in the past and has exceeded it's plactic limit. Never get it tight again but the torque wrench will tell you otherwise. Might not be a bad idea to replace the bolts. Cheap insurance

 

[Nikk]

I'm running into this same problem. I have the Motovation sliders with metal collar inserts. This is only a left side issue.

• torque to speck.

ride ~200 miles.

retorque required.

I am asking Motovation to send me a replacement bolt.

Meanwhile, I removed the slider inspected the hole threads, as best I could, and torqued in my stock bolt, no loctite. Being nervous about the engine threads I went to 47 Nm rather than 50 Nm. The stock bolt started in smoothly and went to torque.

Could that be part of my problem, could 3 Nm make the difference?

Does anyone know if the engine threads are an insert or a threaded block?

Also, the Motovation installed without any washer, could this play a part?

-Nik

 

[SkooterG]

3 NM will not make a difference. Threaded aluminum block.

 

[Geezer]

Maybe it will help if you loosen the right side, then torque the left first and re-torque the right.

 

[wfooshee]

And locking the bolt with Loctite doesn't help if the slider compresses, you'll still lose tension on the bolt, even though it hasn't moved.

If the bolt's backing out, then Loctite it, but don't look to that to fix a problem with the Delrin