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Possibly been discussed before but a quick search revealed nothing. I was trying to update my MB outboard Disc wheel studs to fit SIP rims and the obvious happened.. I broke a wheel stud. None of them will budge and it's probably a no hoper but an engineer told me he could bore them all out and re tap if I supplied the appropriate reverse thread tap. Anyone ever done this before? It's a shame to bin an otherwise great front brake set up just because of the wheel studs.

I'm not very sure about the hub studs on your scooter,but if there the same as standard hub studs,the heads on the studs are difficult to get a spanner on them.I've got some standard ones out by gripping them in a vice.I first soaked them in WD40 for a couple of days.

Sod your luck.

You can only try & accurately drill out the remnants so the original LH thread remains in the alloy hub.

It is possible but takes patience & accuracy.

Drill a dead centre pilot hole & gradually increase the drill size until a thin walled tube remains & then you can usually collapse that inwards to be tempted out. Loads of penetrating oil helps, as will heat. WD40 is not a true penetrating oil. It is moisture dispersant.

Despite what you’ve been told, you cannot ‘re-tap’ back to the original size without welding the hole or heli-coiling.

Yes they are the same as standard, the MB disc just used a modded standard hub.



They aren't budging at all with heat, wd40, vice, locking 2 nuts to push it out whilst using a ground down 12mm socket on the head to help it along ( how I snapped it) thought about getting someone to weld a length of bar to it to add some leverage. But I need all 4 of them out really so the drilling then re tapping or even helicoil seemed a good idea if I could get hold of the left hand thread tap or helicoil kit?

Did a rear hub couple of years ago. 3 came out no problem but typically one was not for budging no mater how i tried. I finally thought sod it and cut the stud off level with the hub lug then drilled it out with a slightly larger drill each time and as said previously once thin enough i was able to tap the remaining thread inwards with a dot punch. Good luck.

Thanks for the advice, I'll try and get on a mates pillar drill and have a go. Fingers crossed.

another good way is to drill out so far, then weld a bolt onto the side where the socket fits, should come out easy, providing you have a welder of course.

i had a broken stud in an head set removed once using a spark eroder and never damaged headset or threads so if you know a friendly tool maker

Post by bike grim » Wed Aug 03, 2016 8:08 pm

or even helicoil seemed a good idea if I could get hold of the left hand thread tap or helicoil kit?

Helicoil thread inserts are very common in certain industries such as Aerospace & Motorsport where alloy castings will have them fitted from the outset.

‘Our’ more common metric threads tend to be all RH such as M8 x 0.5, M6 x 1.0, M7 x 1.0, M8 x 1.25 & the M14 x 1.25 spark plug threads. Even I have Helicoiling equipment for those sizes.

The more universal kit sizes are often much more obtainable (& cheaper!) than the more unusual M10 x 1.0 LH hub hole size.


If all else fails, Beedspeed appear to do an oversize hub stud that utilises a Whitworth thread.

https://www.beedspeed.com/lambretta-stud-oversize-p-8195.html?osCsid=1556si5anv42c3orrjom4ouhg1

holty wrote:another good way is to drill out so far, then weld a bolt onto the side where the socket fits, should come out easy, providing you have a welder of course.

Thats good advice.

The only time I tried this technique, the stud was so hard, it didn't take the weld: the metal of the stud just seemed incompatible with the weld rod (wrong melting point).

Having said that, I would try it again in your circumstances.

Great news, a fellow club member has come to the rescue and removed all of the old studs by welding a flat bar to the bolt heads and turning them out ! Result. Thanks for all the help and suggestions

Result... Well done that man

Great stuff, I no longer feel responsible.

Right or wrong I always copper grease hub studs in to prevent them seizing.

corrado wrote:Great stuff, I no longer feel responsible.

Hahaha