Cracked hinge clamp plate

[doginabag]

If you are on the London Brompton facebook page you may have already seen this, but thought it would be worth sharing here just in case.

Yesterday I noticed a crack had formed in one of the hinge clamp plates. Not a major problem as I spotted it, I f I hadn't and it failed without riding it could have been nasty.
I will be heading down to Brompton Junction today to pick up some replacements, but it seems that they are now only available in black anodised (unless you go for expensive aftermarket options) so spotting a crack will become harder. Something to bear in mind when servicing/looking over you bikes.

 

[doginabag]

I have just returned from Bromtom Junction with replacements, I got two to replace them both but they kindly only charged for the one due to the failure, the mechanic had never seen it happen before.
Fortunately they had some silver plates in stock, they only advertise the new black ones on their site and my concern was that these a similar issue in the future may go unnoticed.

Checking the new against the old with a set of vernier calipers they both dimensionally the same, so the plate itself isn't worn.

On the Brompton website it says that they should be periodically checked for wear. However a data sheet that came with the replacement suggests otherwise, they should be replaced every 2 years / 5000 miles, though it is only a recommendation.
Interestingly (or maybe not) only one of the replacements came with the data sheet. Unless stated in the manual when purchased, I certainly never noticed it, not everyone would be aware.

Both now replaced and imminent death averted.

 

[Kell]

After my crank snapped, I found out the same as you - that 5,000 miles is when Brompton recommend replacing all the aluminium parts.

Cranks, clamps, pedals and bars...

Even in that thread I posted, however, I don't recall anyone else mentioning the two year thing.

Mine looked fine, but I replaced them anyway.

They're inexpensive enough to make it worth doing. Now that i know anyway.

 

[12boy]

Must be a casting flaw...I have Al stuff that is 50 years old and hasn't cracked. Still, if possible, within reasonable weight limits, I prefer steel especially for frames, forks and sprockets and carbon stuff is too iffy for me. Supposedly Al handle bars should be replaced too, but I've never had one fail.

 

[doginabag]

I can see why aluminium is used. Being a softer metal than the steel frame it will wear and deform over time from continued tightening and can be easily replaced while the flanges of the steel hinge will be unaffected.

If the hinge plate were steel both the plate and the hinge would wear down over time and replacing the plate may not work as the mating profile would have changed.

I suspect that it may have been defective. A quick back of a fag packet calculation suggests that the section that cracked should have been able to resist around 2.3 tonnes, I am not sure what that equates to in over-tightening of the bolt, but I dare say it is more than I could manage.

 

[FolderBeholder]

Brompton makes a fairly big deal (in the owners manuals I received) regarding inspection and care of the aluminum componentry. Aircraft....(all aluminum) have very fastidious inspection/replacement schedules....why shouldnt our Bromptons ?

 

[LCpl Boiled Egg]

I've experienced it before and I find it surprising the mechanic hadn't come across it to be honest.

 

[ukoldschool]

I had the same recently on a NOV magnetic clamp...