[W126 Coupe] Broken bolt

[Vedat Iplikci]

David and all concerned,

Following the correspondance about the broken bolt, I see that the general 
tendency is closer to removing the wheel hub somehow. IMHO this is much more 
complicated than using an extractor and will require the same procedure 
anyway, once the hub is removed.

Instead, simply (may not be that simple) remove the darn thing with a 
correct size bolt extractor. All that is needed is to use the correct 
drilling procedure and then use the gadget with care and attention. If the 
broken surface is more or less perpendicular with respect to the axis of the 
bolt, just drill a correct size (will be designated in the manual of the 
extractor) hole to the dead center of the bolt and remove the remains using 
the extractor.

Frequently, the broken bolt's surface will be an uneven surface, making it 
very hard to for the drill bit to start making an entry point in the metal. 
If that is the case, a pair of experienced hands will find a way as follows, 
using low drill speeds:

If the surface is even but angled and is close to the hub's surface, start 
the drilling at the center of the bolt's diameter, but perpendicular to the 
angled surface, rather than following the bolt's axis. You can start with a 
smaller diameter bit than the manual advises if you can't reach the bolt 
center. As soon as the bit starts plunging into the metal (about 1mm after 
the entry point reaches the diameter of the bit) slowly move the drill to 
align it with the bolt's axis and finish the hole. If you started with a 
smaller diameter bit, now you can go to the correct spec bit.

If the surface is uneven and is not too deep, you can use a larger diameter 
bit (maybe even larger than the bolt's hole) and use the sides of the bolt 
hole as a guide to hold the drill bit steady until you can make an entry 
point in the metal.

If the surface is too deep, then take a same diameter but shorter length 
bolt as the broken one, drill a hole in the dead center at a machining shop. 
Then screw the bolt with the hole to catch as much as possible threads, and 
then drill through the pre-drilled bolt. It will keep the bit steady while 
you drill through the broken bolt.

Hope this will help...

Vedat Iplikci
1987 560 SEC Euro

----- Original Message ----- 
From: "Dick Spellman" <spell.yy at verizon.net>
To: "Mercedes Coupes Mailing Lists" <mbcoupes at mbcoupes.com>
Sent: Tuesday, September 04, 2007 7:43 PM
Subject: Re: [W126 Coupe] Broken bolt



> Hi David:

>

> I sure do not want to tell you how to get that rotor off with wheel and 

> caliper attached as I have never had to do this kind of repair.

>

> I'd ask your local mechanic if he can drill that stud out from the front 

> of the wheel or if he has a recommendation on pulling the hub and all with 

> wheel attached which now that I have thought about it is NOT LIKELY. 

> You've got the wheel decorative center cap, then the bearing cap, then the 

> outer bearing lock with /side mounted/ locking screw.  Perhaps there is a 

> way to raise the car up, remove the gravel shield and spin the hub to 

> where you can access that stud from the back with everything still 

> attached.

>

> Really best to go hat in hand to a mechanic that's been there done that 

> unless someone on the list has had the pleasure of fixing this kind of 

> thing.

>

> Dick

>

> David King wrote:

>>   Dick,

>>   As luck would have it the brakes were due for changing several days 

>> before

>> yesterdays ago.  Can you pull the front hubs off without removing the 

>> front

>> caliper first?

>>   Dave

>>   David A. King, PE&LS

>>   A2 Maps & Surveys

>>   627 Norwich Road

>>   Oakdale, CT 06370

>>   Ph. (860) 889-5905

>>   Fax (860) 889-5942

>>   http://www.A2Maps.com

>>   ----- Original Message ----- 

>>   From: "Dick Spellman" <spell.yy at verizon.net>

>>   To: "Mercedes Coupes Mailing Lists" <mbcoupes at mbcoupes.com>

>>   Sent: Friday, August 31, 2007 4:51 PM

>>   Subject: Re: [W126 Coupe] Broken bolt

>>

>>

>>   > So David, seeing as how it's a front rotor, when are the rotors 

>> (brakes)

>>   > due to be replaced?  If soon, just order them up with pads and 

>> senders

>>   > and leave the old bolt. If the rotors are fairly new, you can do the

>>   > repair on the vehicle only if the break is right up near the rotor or

>>   > remove the troubled rotor set it on a bench and drill the stud out 

>> from

>>   > the back side followed by judicious use of the extractor.  Then 

>> repack

>>   > the outer wheel bearing, check the inner seal and replace the rotor.

>>   >

>>   > Good luck and your welcome!

>>   >

>>   > Dick

>>   >

>>   > David King wrote:

>>   > > Mr. Spellman,

>>   > > Thanks for the info.

>>   > > It was a front left side bolt. It sheared near the head and left 

>> sharp

>> point

>>   > > offset to one side.

>>   > > Dave

>>   > >

>>   > > David A. King, PE&LS

>>   > > A2 Maps & Surveys

>>   > > 627 Norwich Road

>>   > > Oakdale, CT 06370

>>   > > Ph. (860) 889-5905

>>   > > Fax (860) 889-5942

>>   > > http://www.A2Maps.com

>>   > > ----- Original Message ----- 

>>   > > From: "Dick Spellman" <spell.yy at verizon.net>

>>   > > To: "Mercedes Coupes Mailing Lists" <mbcoupes at mbcoupes.com>

>>   > > Sent: Friday, August 31, 2007 2:50 PM

>>   > > Subject: Re: [W126 Coupe] Broken bolt

>>   > >

>>   > >

>>   > >

>>   > >> David:

>>   > >>

>>   > >> You need to run down to a Sears store and pick up a bolt extractor

>> kit

>>   > >> of a diameter less than the wheel bolt so as to not damage the

>> threads.

>>   > >> The kits have a drill bit followed by an extractor that will 

>> permit

>> the

>>   > >> bolt fragments removal if done right.

>>   > >>

>>   > >> Or reassemble the wheel with just 4 bolts and torqued to factory 

>> spec

>> of

>>   > >> 80 ft lbs only.  Run it up to a local garage and ask they remove 

>> the

>>   > >> damaged lug bolt.

>>   > >>

>>   > >> All the wheel bolts should be inspected if this happened from 

>> being

>> on

>>   > >> there way too tight by some mechanic that used say an air tool

>> without

>>   > >> regard for the torque.  Replace any that use the long stem with 

>> the

>> new

>>   > >> MB bolt version available at the local MB dealer.  These extension

>> bolts

>>   > >> on the 15 hole wheels have been done away with because they do 

>> snap

>> and

>>   > >> represent a safety issue too.  So, if that's what you've got, get 

>> the

>>   > >> updated bolt from MB.

>>   > >>

>>   > >> Was this the front rotor or the rear wheel hub where the bolt

>> cracked?

>>   > >>

>>   > >> Dick

>>   > >>

>>   > >> David King wrote:

>>   > >>

>>   > >>> I need some help with a broken wheel bolt on a 1990 560 SEC.  The

>> last

>>   > >>> 1/2 inch fractured at a nasty angle and I'm not sure what to do? 

>> Any

>>   > >>> ideas.

>>   > >>> Dave

>>   > >>> David A. King, PE&LS

>>   > >>> A2 Maps & Surveys

>>   > >>> 627 Norwich Road

>>   > >>> Oakdale, CT 06370

>>   > >>> Ph. (860) 889-5905

>>   > >>> Fax (860) 889-5942

>>   > >>> http://www.A2Maps.com

>>   >

>>

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