How to stop bolts from loosening

[Yellow Saddle]

Here is a pic of the fitting. I have added a split washer between each bolt and stainless rack arm.

Seat post clamp with rack bolts

• BurningLegs
• 17 Oct 2017

Is this the best side to fit the washer? Is it worth adding another one the other side of the rack arm, to sandwich it with washers?

Time will tell. My money is on it coming loose again. The rack stays move up and down and I suspect the bolt will ratchet out. But keep us posted, it should be interesting. Movement is not the same as vibration.

 

[Randy Butternubs]

The pritt-stick style of threadlocker mentioned earlier is good if you work in the house as its harder to splash blue liquid all over the carpet. I find the liquid kind is sometimes reluctant to show itself but then decides to make a break for it. Maybe I'm just incompetent.

I've heard* that wavy washers, spring washers and such are totally worthless and that it's a wonder why they continue to be specced/are available for purchase.

*peerless credibility

 

[Ian H]

Just a plain washer under the head will stop most bolts from loosening. Such has been my experience.

 

[slowmotion]

I would shy away from a Loctite "thread locker". They tend to do what it says on the bottle, and you may never get the fastener undone. Go for a "low strength retainer". Whatever you use, clean the threads with IPA before applying it.

 

[Ajax Bay]

you may never get the fastener undone

Scaremongering rubbish. Has this ever happened to you? What threadlocker did you use?

 

[Profpointy]

Scaremongering rubbish. Has this ever happened to you? What threadlocker did you use?

It-s not rubbish. The higher strenght ones are designed to never come undone. Some only come undone with heat. The low-strength ones are ok though, but other grades not so much

 

[Ajax Bay]

@Profpointy would you "shy away from a Loctite "thread locker"." then, which is what @slowmotion is advocating, scaring the OP with "may never get the fastener undone"?

 

[Profpointy]

@Profpointy would you "shy away from a Loctite "thread locker"." then, which is what @slowmotion is advocating, scaring the OP with "may never get the fastener undone"?

That's not what I said, is it?

Edit: in an earlier post I recommended threadlocker and explained the grades

 

[Ajax Bay]

There are many grades of threadlocker. "low strength" is what you want here. Loctite, a leading brand, have data sheets to guide you through their myriad set of products, each with a code number and various attributes such as chemical or heat resistance, but conveniently also say "low strenght", "medium strenght" etc on the bottle. The higher strenghts aren't intended to be undone ever, so don't just think higher strenght is better !

I note you would not shy away from Loctite products. We agree that 'high strength' threadlocker is not required.

 

[MichaelW2]

I thought star washers were primarily for electrical connectivity eg for earth wires

I believe they are used for the same purpose, to prevent the fixing bolt coming lose with time.

 

[mmmmartin]

This is an interesting "bike shop test" - take it to your LBS and see what they say. Sometimes in a strange town I wander in to a bike shop and ask for an M5 bolt. (I should get out more but I spend a lot of time in the shed.)

 

[slowmotion]

Scaremongering rubbish. Has this ever happened to you? What threadlocker did you use?

Here's the spanner. Go to it pal.

 

[Ajax Bay]

Here's the spanner. Go to it pal.

Great if you felt able to answer my question: "Scaremongering rubbish. Has this ever happened to you? What threadlocker did you use, for what bolt/thread function?"
And if that was the threadlocker you used, why?
(I agree that high strength is not appropriate for cycle use, but you painted all threadlocker as 'to be avoided'.)

 

[BurningLegs]

Time will tell. My money is on it coming loose again. The rack stays move up and down and I suspect the bolt will ratchet out. But keep us posted, it should be interesting. Movement is not the same as vibration.

Well I commuted today, albeit just 12.5 miles total but the rack has stayed tight. I won’t be satisfied until it stays tight with a heavyish load and a good few weeks of commuting but it hasn’t failed immediately which is good

 

[BurningLegs]

Well I’ve now done a week of commuting, including two “heavy days” (laptop, shoes and other bits and bobs carried) and the rack has stayed nice and tight.

Thanks for all the input here guys. Initial signs are good that the split washers alone may do the trick for less then £1 spend! If it comes loose again within a couple of weeks I will get some loctite, but if I need to tighten it every now and then I can live with that.