Help! Overtightened and threaded headset top cap on my Super

OhPinchy

So in a moment of pure idiocy I was trying to lower my stem on my Cannondale Supersix Evo, loosened the stem, loosened the top cap (not sure now if that was even necessary?) and then took off the stem, took out some spacers, put the stem back on and put the spacers above the stem. Thing is, I forgot to add the last, thin spacer. So as I tightened the top cap on the headset, there was very little resistance. I was actually using a torque wrench for the bolts on the stem (6Nm) but didn't see any torque setting listed for the top cap so thought it would be find to tighten by hand until it felt right.

Problem is, it never felt right as it didn't feel like it was tightening at all, probably as the missing spacer meant there was too much slack to be taken up. Even though it didn't feel like I was pushing that hard, in one move, the allen wrench completely threaded the hole on the top cap so now it's round and not hex shaped so the allen key can't loosen it. The headset is rocking forward a few millimetres so I can't ride the bike at the moment. There's some pics of it in this folder: http://sdrv.ms/14hrWQM

I reckon I need to first find a way to remove the top cap, get a new top cap that's compatible and then fit it correctly. Has anyone encountered something like this before and have good ideas for how to remove the threaded top cap?

Is it a Cannondale-specific replacement top cap I need or are there others compatible, and any online stores that stock them?

Lastly, once I get the top cap off and get a replacement, what's the correct procedure for installing it?

Thanks for any pointers on how to clean up my mess and get this beaut of a bike back on the road!

freezing77

Deleted

monkimark

Did you tighten up the stem pinch bolts before the top cap?

OhPinchy

I'm trying to call exactly (it was yesterday, been out of coverage since then), but I think I may have tightened the stem pinch bolts first, not 100% sure.

jgsi

Good grief, bit of a bloodbath that is.

OK that has scuppered that top cap and bung... so order a replacement

http://qwertycycles.co.uk/collections/s ... edge-kp017

and if you want to drop the stem then you are going to have to bite bullet and drop the forks completely and do a clean cut on the carbon steerer, leaving 5mm above the stem for good measure.. or if you want to leave more stem above.. then use 1x10mm spacers not 2 x 5mm

When the bung has gripped the carbon steerer properly that will eradicate the headset play.

OhPinchy

Thanks JGSI. Yep, it sure ain't pretty but hopefully it's redeemable. Any thoughts on how the top cap can be removed given the threads are stripped?

I bought it in another country and there's not many shops nearby interested in servicing bikes not bought there, but there is one good place I know I can try - good to know what's involved (and that it's doable) before I bring it to them though.

agent nomad

First things first

You need to remove the cap head bolt that holds the top cap in place.

I would do this by drilling the head of the bolt out.

This needs to be done in stages with several sizes of drills and these need to be good quality HSS drill bits and a slowish speed hand drill.

Will post further details from work need to go and start a 12 hour night shift so will try and explain in detail latter.

jgsi

OhPinchy wrote:

Thanks JGSI. Yep, it sure ain't pretty but hopefully it's redeemable. Any thoughts on how the top cap can be removed given the threads are stripped?

I bought it in another country and there's not many shops nearby interested in servicing bikes not bought there, but there is one good place I know I can try - good to know what's involved (and that it's doable) before I bring it to them though.

Hopefully it is not on so tight.... use any method apart from violence...

you could sacrifice the spacers and try turning with wide mole grips... is the smaller bung allen down below still in good order?

jermas

Undo the stem pinch bolts before trying anything. This might loosen everything up allowing you to undo the top cap more easily. You could try turning the handlebars/stem to unscrew the top cap.
Drilling might work but stainless steel is a pig to drill.

agent nomad

Looking at the photos the hexagon in the cap head has been well and trully rounded so this makes me belive that it could be an alluminum cap head so drilling will be easier.

So the bolt size is 6mm the size you would drill to tap a 6mm female thread would be 5mm so, the size of the allen key is 5mm across the flats now the cap head has beem rounded off it will be larger than 5mm, I will try and get to the workshop and measure across the corners but lets say 6mm for round numbers.

If you drill into the head with a 6mm drill this should just remove a little material and center the drill do not drill down into the head just remove material in the hole to the depth it is now, change the drill size to 3mm and using the newly formed center at the bottom of the hole in the cap head drill down around 5 to 6mm this is enough now increase the drill size 0.5mm at a time until you get to 6mm at this piont the head of the cap head should fall off the shank of the bolt you may need to drill to 6.5mm, once the head is free and out the cap should pull free and then with mole grips remove the stud from the star washer or fork bung.

Rebuild with a new 6mm cap head avoiding the previous mistake.

PAul.

OhPinchy

Thanks folks. I generally manage to do most work on my bike quite well but I've clearly butchered this job so I'll try take it to a shop and see if they're confident they can get the top cap off and replace it with the necessary new part, might be the surest way to get it done. I'll ask them to show me the right procedure for next time as I'll likely have to move the spacers around a couple of times before I get the positioning perfect.

Bar Shaker

Your stem bolts must have been still tight as that much torque would have locked the stearer into the headtube so it no longer rotated and may have even cracked the frame around it. You have been lucky.

Drilling the top off the bolt need not be too precision an operation as the parts are scrap now anyway. To drill stainless, the drill speed needs to be extremely slow. The cutting faces on the drill tip must slowly scrape away material without getting hot. If you don't fancy drilling it, you could cut two slots in the bolt head sidewalls and insert a man size flat bladed screwdriver to loosen it.

Before drilling, definitely loosen the stem bolts. The whole assembly may go loose enough that an allen key will still get the top cap bolt out.

New top cap, new bolt, new fork bung and you are sorted.

blackhands

You could use a screw extractor:

http://www.ebay.co.uk/sch/i.html?_trksi ... &_from=R40

You need to drill a suitable sized hole on the bolt head (the rounded off hex hole may be deep enough) and screw the extractor in (its got a left hand thread) and just keep turning it until it bites - at which point it should unscrew the bolt from the bung.

When you fit a new bolt don't forget to have the stem bolts loosened off and then just tighten up the top cap bolt enough to get the headset free but with no play, then tighten up the stem bolts, which will make the whole assembly secure.

ricky1980

1) use a slightly larger allen key - go to hareware store and try to buy a 5.5mm - ebay has one for £2.5
2) if that 5.5 is too small then aldehyde the 5.5mm into the bolt and leave it set for 24hours then unscrew it
3) last resort drill it out with a 10mm HSS drill bit, you will need to get some drilling oil to prevent overheating etc

bare in mind drilling it out will only remove the top cap, the bung will still be tightly lodged in the stem. not entirely sure how you gonna get that out with any ease. also supersix stem is carbon i assume, is it cracked or is there any creeping noises?

keef66

For anyone in a similar position, for a rounded hex socket in an alloy bolt, hammering in a slightly larger torx bit is often quite successful.