Brompton luggage block fail

[superDove]

Hi all,

My first Brompton has a jubilee clip holding the luggage block on after one of the bolts failed.

I bought another Brompton and yesterday after only a couple of months riding it one of the bolts has sheared. I've left it with my LBS as my new self-enforced rule is to never touch my bike unless I'm in a zen like state of abundant patience.

Weight in the bag is about 4 Kgs. I've only checked the bolts once after I'd originally went over the bike when I got it.

What do i need to do to stop this happening? I don't have a torque wrench so could get one I suppose.

Brompton luggage block | Flickr - Photo Sharing!

Ps I've posted before but didn't get a reply about changing my avatar name. Facebook stupidly took over when I joined up and didn't give me the option of changing it. I'm not happy having my full name on here for security reasons, I'm probably being thick but can someone show me how to change it please?

 

[jerrysimon]

As I understand the bolts keep the block hanging firmly on the little welded lug where the block edges/cut out enable all the weight to be taken on the lug not the bolts. If the bolt(s) become lose then there is a danger that the block with rattle around and the weight is taken on the bolts which will then tend to fail in shear.

I check mine on a regular basis and use a little thread lock to prevent them from vibrating lose. I also notice that for the newer blocks the bolts now include a ragged washer as well.

PS looking at that picture it appears the top one has become loose as you can see the marking where the block has been rubbing/moving on the bottom half.

(Off to check my bolts are tight )

Just checked nice and tight phew.

Regards

Jerry

 

[flecc]

In the Member's editing facilities there is no way of changing the membership name, probably because it's tied to any threads posted and the search facility. Many have re-entered the forum using a new name and email address and that's an easy way to do what you wish. Alternatively, perhaps admin could change your member name, so try contacting the lead administrator Russell Scott on this private message link to ask if this is possible.
.

 

[GaRRy]

In the Member's editing facilities there is no way of changing the membership name, probably because it's tied to any threads posted and the search facility. Many have re-entered the forum using a new name and email address and that's an easy way to do what you wish. Alternatively, perhaps admin could change your member name, so try contacting the lead administrator Russell Scott on this private message link to ask if this is possible.
.

Based on other forums I frequent that use this bulletin software (vbulletin) Admin should be able to do this.

 

[superDove]

Thanks Jerry, will try some thread lock and try and get into the habit of checking them every time I clean the bike. I am using the ragged washers.

The mechanic at the LBS reckons that the bit left in the headtube is going to be jammed against the threads so I'm guessing will have to be rethreaded and a bigger bolt used. There's not much metal either side of that lug though so hoping this won't happen again with regular checks.

James

 

[superDove]

Have PM'd Russell. Thanks flecc, thanks GaRRy.

James

 

[shemozzle999]

Hi James,

As the LBS will have to drill out the stub, why not suggest they use a left hand fluted drill bit and see if it will unscrew the broken stub while drilling in the reverse direction.

Left Handed Drill Bits - YouTube

http://www.ebay.co.uk/itm/New-Dormer-HSS-Metal-Drill-Bit-Left-Hand-Drill-Bit-3mm-x-approx-60mm-Long-/370612399907

 

[jerrysimon]

Interesting

Jerry

 

[jerrysimon]

This shows it in practice, assuming you can find one small enough.

[video=youtube_share;FYvaPbX1sT4]http://youtu.be/FYvaPbX1sT4[/video]

I note the use of a center drill first. Youtube always makes it look so easy lol

PS looks like great care needs to be taken NOT to snap the drill bit in the bolt!

Jerry

 

[Scimitar]

PS looks like great care needs to be taken NOT to snap the drill bit in the bolt!

Indeed. That way lies a World of Pain, sometimes only alleviated by a trip to the spark-eroder.

 

[jerrysimon]

spark-eroder

Interesting you learn something every day. Had to Google it

Jerry

 

[MikeyBikey]

Hi James, Ouch that looks nasty! :-(
The torque wrench setting is not in the Brompton manual, no torque setting for the Luggage Block bolts!
Brompton website does: Linked YouTube vid says tighten 4mm Allen bolts to 4nm.
Anybody think of a workaround with a U-bolt & bracket?
Are there stud extractors in that small a size? Sorry, wish I had a fix, Mikey

 

[Quark]

It should come out with the reverse drill bit but worse case it will have to be drilled oversize and a either a thread insert kit used or tapped to the next size up. Maybe higher tensile strength bolts could be used with thread lock?

 

[Deleted member 4366]

It should come out with the reverse drill bit but worIsye case it will have to be drilled oversize and a either a thread insert kit used or tapped to the next size up. Maybe higher tensile strength bolts could be used with thread lock?

You shouldn't use higher tensile bolts. They'll snap at the thread after a while due to metal fatigue, which is probably what's happened here. Instead, you should use normal low-tensile mild steel bolts because mild steel doesn't suffer from metal fatigue.

 

[jazper53]

You could use a tapered spiraled left hand drill bit, and use a standard tapping bar rather than a drill, after you have drilled a pilot hole great care is required not to snap, avoid carbon tool bit.

 

[superDove]

So yeah, worst case scenario is here.

The mechanic phoned last night to say the extractor broke inside the bolt. I'm taking it as a sign I should have taken the opportunity to man up and had a go myself.

Any suggestions?

All I've got is to use the remaining bolt and also make hole through luggage block and jubilee clip it to head tube.

cheers

James

ps no reply from admin. May have to cancel membership and rejoin.

 

[jazper53]

So yeah, worst case scenario is here.

The mechanic phoned last night to say the extractor broke inside the bolt. I'm taking it as a sign I should have taken the opportunity to man up and had a go myself.

Any suggestions?

All I've got is to use the remaining bolt and also make hole through luggage block and jubilee clip it to head tube.

cheers

James

ps no reply from admin. May have to cancel membership and rejoin.

Maybe you could create a slot for a flat head and use a manual impact driver kit make sure the slot is a tight fit

 

[superDove]

use a manual impact driver kit

Stuff that works when you hit it. My kind of technology!

Thanks will speak to the mechanic and see what we can do!

cheers

James

 

[jazper53]

Stuff that works when you hit it. My kind of technology!

Thanks will speak to the mechanic and see what we can do!

cheers

James

Another if not last resort idea, is to drill a hole left of center deep enough to give a punch good purchase and good size hammer and try to get it moving in a anti-clock wise direction if you can apply some heat to bolt area, can also be beneficial during this procedure

 

[Old_Dave]

Another Brompton sheared bolt thread (no pun intended) that's going from bad to worse