Servicing my M4’s today, I lapsed in to a daydream and managed to shear of one of the top cap bolts.

Yes I am an utter knob. 😯

But that’s not the whole reason for this post. I can’t get the other side off, as one of the bolts is rounded off (not my fault this time). The bikes was bought second hand and I decided to tinker with it by putting some lighter/better forks on.

Should have just left well alone as it was good as it was.

So STW do you have any tips to getting a rounded top cap bolt out. All suggestions welcomed and feel free to berate me at your will.

cut a slot and use a screwdriver would be the first option, will probably make a mess of the aluminium though.

You could drill it out, but being a steel bolt in aluminium the odds of getting it right are slim to none as the drill will try and squirm off into the aluminium.

Could consider this – try superglueing an allen key into the rounded bolt head carefully, it’s gven me enough grip to remove a bolt like that before. If not, you could try cutting a slot in the one that has a head on it as suggested, ignoring the fact that your top cap will be damaged – remove that bolt. Then file/ cut away the alu of the top cap around the sheared bolt, or rotate it loose, or both. You’re probably gonna ruin the top cap anyway but that and a couple of bolts won’t cost too much. That should leave the sheared bolt in place with the top protruding clear of the lever body so you can grip it with a molegrip and unscrew it?

Oh and edit to add, you prat ) but I wouldn’t say that if I didn’t know just how it feels…

I thought, based on the title it was a poll?

if you’ve got some torx or spline bits you can normally hammer the next size up in and get the bolt loose. Worked for me when I rounded off 3 of the 6 bolts holding the driveshafts on my campervan 🙂

I did mine by cutting a slot with a hacksaw and then using a screwdriver – very easy but you do catch the top cap
If it is in place/not leaking why not just take off the one on the underside?

It’s the older mono’s, with only one entry point. I’ve thought about the slot thing but first thought there may be a better option.

Good shout with the superglue I’ll give that a go, THe way this spattering sessions gone I might end up glue myself to the handlebars. 😕

i think the torx idea’s good too – that should work.

seen araldite (twin tube)glue do amazing stuff – but has to be left to set.

could you pliers/molegrips the rounded bolt out (tradition was to file down both sides to give edges but that was motorbike land and you’re dealing with much smaller parts – but hopefully much less torque as well)

Torx every time and a liberal spray of plus gas or penatrating oil

If you are careful a slot can be cut without marking the black. You can always add some tape on the cap to protect it

+ 1 for torx

If that fails slot it and hope for the best with a screwdriver

Or, it’s a long shot, but try calling Hope and ask for advise?

They might be able to get it out for you?

I’ve never, ever done that to a Hope M4 topcap bolt, oh no, not me honest… 😳

You could just drill the head off, remove the cap, and use pliers or molegrips to remove the remaining stub. Don’t think i’ve come across one that the thread was seized on, usually just a combination of the head binding on the cap, and small hex key/soft bolt head.

Try using the ball end of the allen key. Also try a different set of allen keys…I have a blue Park Multi-tool and it always slips on my top caps, but I have an older clamshell type Park multitool and its a perfect fit.

The replacements I got from wiggle a while back have a deeper socket and the top isn’t domed, they still round easily though!

You could also try gently clamping the top cap onto the reservoir with some mole grips (with cardboard or similar in the jaws) to remove some of the friction under the bolt head.

You could also try gently clamping the top cap onto the reservoir with some mole grips (with cardboard or similar in the jaws) to remove some of the friction under the bolt head.

Good call, this worked well for one of mine a while back.