Snapped wheel bolts

[219]

In changing over a set of wheels on my W126 in order to replace worn tyres ( I have two sets of MB 15 hole alloys ) I have had the well known problem of wheel bolts that hadn't been out for a while snapping - a total of four bolts out of the twenty , two on each offside wheel !

When I first discovered them to be tight , and being aware of the possibility of them snapping , I spent a while trying to ease them out gently , tried to spray penetrating oil in , with little hope of it reaching the threads , and left them for a couple of weeks in the forlorn hope that they might free up . There were quite a few stubborn bolts , the wheels not having been off in about a year , but all apart from these four came out .

These are the long bolts with the thin extended section which have been known to break in the past and I know there are modified bolts available to replace them .

Because of the way the snapped bolts are recessed into the wheel , there seems no option other than to drill them out - only they seem to be made of such hard metal that I have spent most of yesterday drilling away and made little headway , whilst blunting countless drill bits .

These bolts are so tight that I doubt an 'easy out' would help , Applying heat or welding something onto the stub of the bolt would be impossible without damaging the wheel .

I was hoping to drill the bolt out until the tapered seat came away , allowing me to remove the wheel , then with application of heat to the hub , remove the remains of the bolt , or just get a hub from another car since I plan to replace the discs anyway .

Has anyone else been through this , and how did you get them out ?

 

[Doodle]

Had this on my old 202 - the garage got one of those "thread doctor" guys who came and drilled it. Cost was very reasonable considering the ballache that would have otherwise been required.

 

[trapperjohn]

Total PITA when it happens. CNC machine shop might have better than standard drills for you to use. I got hold of some "milling" bits and they helped.

 

[Alex]

Sheared bolts are a proper pain. Get a set of cobalt or carbide drill bits and take your time.

 

[spike60]

Does just the head snap off, leaving the the seat holding the wheel on? In our line of work we have quite good success welding nuts onto snapped in bolts, often the heat does as much good as the fact you also have something to turn it with. Fluted easi out sockets are good as long as they've got something to go over.

 

[Doodle]

Pretty much. Not sure there would be enough space to get a welding torch down there though.

 

[219]

Does just the head snap off, leaving the the seat holding the wheel on? In our line of work we have quite good success welding nuts onto snapped in bolts, often the heat does as much good as the fact you also have something to turn it with. Fluted easi out sockets are good as long as they've got something to go over.

These bolts are a real pain , and a known problem which others have reported on before ,

Basically , they have the usual threaded section ending with a tapered seat which holds the wheel on , then there is a thinner extended stem before it widens out to the hexagonal head - I will post a photo of one later on .

The thin stem is where they always break , and this is recessed an inch or more down the bolt hole in the alloy wheel ; said bolt hole is only just wide enough to get a 17mm socket into , so no chance of welding anything on without damaging the wheel , due to the low melting point of most alloys , I don't fancy trying to apply heat to them either .

It will be a different matter once I get the wheel off , after which welding on a nut or whatever will be a good option .

 

[Doodle]

To be honest, I'd just replace the lot with the new short bolts. Perhaps not quite so pretty but they won't break.

 

[jaymanek]

You need some special drill bits and/or oxy acetelene kit after which the wheels will need a refurb.

We once had to cut the wheel off...

I have replaced all bolts on my cars that have the extended shank.

 

[219]

Yes , I intend to replace all the bolts with the newer type which don't break .

Cutting the wheel will be an absolute last resort .

 

[hotrodder]

I know this style of wheel bolts makes things even more of a PITA but i wouldn't have thought they'd be harder than the usual grade 10.9 used for wheel bolts? More important than 'colbalt' or other 'fancy' drills is decent quality i.e. Dormer, Presto, Sherwood, Guhring. HSS-Co (there's two flavours, M35 is 5% Co, M42 is 8%) are harder than plain ol' HSS, the upside is that they can be run at slightly higher speeds without softening, the downside is that they're more brittle i.e. easier to snap. Having said that cheap colbalt drills are often junk compared to quality HSS... too brittle, often poorly ground so they don't cut properly etc.

HSS-Co can be handy when using a hand drill as they don't have the range of speeds- rpm is related to diameter as cutting speeds are figured in metres/min or surface feet/min. Larger drill and/or harder material = slower speeds, too fast and the tool rubs instead of cutting, overheats and softens. The other problem with having to using a hand drill is feed. Hard materials/larger drills need leaning on to get them to cut rather than rub, easy enough when drilling something in a drill press or lathe, trickier when working freehand and trying to keep the hole straight. A DIY variable speed drill (rather than something with a gearbox) doesn't help either as you lose all the torque when you slow the rpm and then it stalls/overheats when you lean on it. Some cutting compound/coolant, while a ball ache with a hand drill, will help some too

FWIW with HSS tooling mild steel is typically machined at around 90ft/min give or take. Tool steels and some alloy steels as low as 30 - 35ft/min. For a 10mm drill bit that equates to around 900rpm for mild steel and 300-350 for the tougher flavours. 13-14mm drill and it's more like 600 and 200rpm respectively. Colbalt can be run around 10% faster or, at the same speed, will hold it's edge for longer

It is possible to attack this sort of job with a welder but it ain't easy and a MIG won't cut the mustard. Using a bit of thin wall tube down the bolt hole to protect the wheel you build up a pad of weld on the remains of the bolt until you're past flush and can weld a nut on. Again, not easy as you're working blind for most of the job.

 

[JcMercZ]

There are penetrating oils (not wd40)available(not sure of the correct name or brand off the top of my head). Try and get it in as far up the bolt as possible. Then try bashing the bolt with a hammer and maybe a ratchet extension or sumthing similar to get the oil down further, while also freeing the bolt from rust or from being seized. Also see if you can get sum heat on the bolt, even warming the head might help. This may need to be repeated a few times, but be carful not to overheat and set the oil on fire. Also can try a chissel centre punch,if you have the room to hammer the bolt in the right direction.
Failing that i would get the drill out.
Oh.. also note the penetrating fluid(i think) dries out/evaporates/becomes less effective over a long period of time making it less effective at doing its job(if that makes sense!).
Hope this helps

 

[Druk]

Anything further on this Derek? And how much of the snapped shank is sticking out from the shoulder?

 

[brucemillar]

Derek

Plus Gas is possibly the best penetrating option. Used to be sold in Halfords. An air hammer/chisel will help vibrate any rust off. Or if you have a big hammer drill try that with a socket. Failing that I think heat may be your best option.

I now always put a smear of copper-slip on my bolt threads when re-fitting. Good luck.