Axle bolts to differential ... can't get bit in them - PeachParts Mercedes-Benz Forum

BodhiBenz1987 · #1 10-16-2010, 10:59 PM

This is tied to my subframe job, but I thought I'd start a new thread because it's sort of a separate issue. I think it's come up before, but not having much luck in search. The bolts that hold the axle shafts to the differential are caked in oil and dirt, and I can't seem to get a 12-point bit in them (they might be stripped/corroded, but I can't even tell!). Firstly, what size bit should fit in it? I can't even tell. Beyond that, have others had this problem, and how have you dealt with it? I'm dropping the subframe out anyway, so should I just leave the axles attached to the diff until the whole unit is out and try to clean them? If they're stripped, what should I do?
... Or should I just leave the axles attached to the diff and put it all on the new subframe. I have no reason to believe the axles are bad. However, I'm going to have to deal with it at some point, I'm guessing. I do have a full set of replacement bolts, which have the other kind of head (a torx socket goes over them).
Hope this isn't repeating a former thread ... I did search but to be honest I'm a bit out of it right now ... not a great day ...

compress ignite · #2 10-16-2010, 11:23 PM

1.Take a break
2.The Stupid Inset Allen heads have to be almost Surgically clean to insert the
"Allen" Wrench (Successfully) into them.
[They're not 12 pointers]
3.With Safety Glasses on to protect your eyes,force the tiny plastic wand piece of a can of Brake Cleaner into the Allen Head to blow out and clean it of any debris.
4.Knocking the Allen Wrench into the Head with a suitable Hammer insures Total contact.

Sorry, I can't help with the Allen Wrench Size.

vstech · #3 10-16-2010, 11:26 PM

well, before even attempting to put a wrench on them, I'd totally clean the snot out of the bolt heads, grease and grime are prime fodder for stripping a bolt out.
after you see clean metal on the heads, you'll have a better idea of what wrench to use.

BodhiBenz1987 · #4 10-16-2010, 11:45 PM

Thanks guys ... would it make more sense to drop everything down with the subframe first, then clean the living daylights out of each bolt? Access would be a bit easier and I can't think of a reason that wouldn't work.
I could have sworn they were 12-point ... good thing I didn't try to force anything in there!

Hopefully I'll get some sleep now and make some progress tomorrow.

69shovlhed · #5 10-17-2010, 10:04 AM

seems to me they could indeed be 12 point. clean em out w/ a pick and brake clean. then gently hammer the bit into the hole. it should be real tight. if its not tight you prob'ly got the wrong size bit. DON'T use an allen if its 12 point. those type bolts really suck, but the krauts love em for some reason.

biopete · #6 10-17-2010, 10:20 AM

Do you think they love them because they stick on the screw gun better during assembly of the car? Or maybe because they strip less? I asked a guy at a car plant why they were all using those 12 pt torx screws and he said they strip less. My experience is its my cheap torx bit that strips usually.

Re axle bolts , Never done it on an 87 300D but i've never had too much trouble getting em off. Just rotate axle to get one where you can get at it., clean it real good and then unscrew. it can be a pain to unscreew if the axle is wanting to turn with the wrench though. I remember having someone hold the while while i unscrewed it.

Good luck.

Diesel911 · #7 10-17-2010, 12:29 PM

Make sure the ends of the Allen Wrench or the 12 point are flat. See post #20 for pics in the below thread.
They often have too much of a tapered beveled area that reduces the area that they can make contact with.
http://www.peachparts.com/shopforum/showthread.php?t=260567&page=2

BodhiBenz1987 · #8 10-17-2010, 02:53 PM

Quote:

Originally Posted by Diesel911

Make sure the ends of the Allen Wrench or the 12 point are flat. See post #20 for pics in the below thread.
They often have too much of a tapered beveled area that reduces the area that they can make contact with.
http://www.peachparts.com/shopforum/showthread.php?t=260567&page=2

Didn't think of that ... my 12-point bits have flat ends but some of my allens are beveled ... that will be helpful to keep in mind on a LOT of bolts in the future. Thanks. Why are some made with a taper? Easier to get in the hole?

okto · #9 10-17-2010, 07:37 PM

W124 axles were originally secured with 10mm XZN (aka 12-point, triple square) bolts. Yours might have been changed to Allen. My guess on why German car manufacturers use these are massive torque handling and the fact that Torx was patented until the early 90s.

As for beveled bit tips, that shouldn't make any difference. The percentage of bolt socket depth not engaged because of the bevel is insignificant. If you're camming the driver out of a Torx bolt, you either have a crummy Torx bit that's made to loose specs, crud in the bolt socket, or the bit isn't seated at the bottom of the bolt socket.

Diesel911 · #10 10-17-2010, 09:21 PM

Quote:

Originally Posted by BodhiBenz1987

Didn't think of that ... my 12-point bits have flat ends but some of my allens are beveled ... that will be helpful to keep in mind on a LOT of bolts in the future. Thanks. Why are some made with a taper? Easier to get in the hole?

Yes, they have that bevel so that the go into the Hole easier. However, the various companies have their own idea as to how much bevel to put on.
On some of them you would lose almost 1/2 0f the gripping area inside of the head and if you added a little dirt to that they are more prone to strip out the head than a tool with no bevel.
If you notice most "L" shaped Allen Wrenches almost always have flat ends on them (no bevel).
For some reason when they make Allen Sockets they put a bevel on them.
I would rather have a little bit of trouble getting an Allen Socket into the hole than to strip out the head of an Allen Bolt.
But, you will decide what is best for you.

vstech · #11 10-17-2010, 11:28 PM

be SURE you get a close look at the bolt head after it's totally clean, and verify if it's tripple square, torx or allen.
autozone used to stock a 4 pack of bits in tripple square, but they and advanced just changed their layout and no longer carry the packs.
orilies should still have them, but I don't know. snap on trucks will have the bit, but it'll cost a ton.

Tpawlik · #12 10-18-2010, 07:19 AM

When I replaced the half shafts in my car, the original axles had the 10 mm Tri Square (12 Point) bolts. The new half shafts came with an Allen head bolt.
At first I could not find the 10 mm Tri Square, but as vstech said I found a set at Autozone. If you don't want to buy a set that you may never use again.
PM me and I can mail the 10 MM to you.

odie · #13 10-18-2010, 10:26 AM

my bolts were 12-pt. they were damn tight and i was afraid of stripping them. I actually almost stripped a couple....

best way i found was to use a good clean 12-pt bit and impact wrench. Just make sure the bit is fully seated and straight and hit it with a few good wacks of the impact wrench and they break free easy.

The problem is that they have thread locker on them and a regular ratchet or breaker bar ends up pulling the bit too the side. Once you strip out the bolt head you are screwed.

My new axles came with new 6-pt allen bolts...much better.

wrench56 · #14 10-23-2010, 10:35 PM

I bought sockets to pull my rear half shafts off the differential from my local Carquest. It was a 4 pack of double star sockets. The only problem was, you need a good quality 1/2 in drive 1/2(?)in socket to use them. After God knows how long being installed on my S350D, only an impact would break them loose. Straight line torque is way more efficient than pulling on a bolt with a ratchet and a very long extension. Anyhow the socket set wasn't 20 bucks if I recall.
Wayne

BodhiBenz1987 · #15 11-07-2010, 07:25 PM

Well, after putting this on the shelf for two weeks due to vacation followed by being sick, I'm back at it. The current status is: Driveshaft off, exhaust off, springs out, shocks and swaybar detached, ABS sensor out, drain hose out. I just need to get the parking brake cable off ... and to be honest, have no idea how to do so. I'm assuming it involves the bracket up underneath the driveshaft, but the FSM is very vague and I don't want to break anything. Guess I'll try to find a more detailed section of the FSM, but if anyone has a quick description of how to remove the cable, please share ... it's the last thing keeping me from lowering the frame.