Removing X-brace bolts covering midpipe

[Axiolus]

So I'm having some real trouble changing my midpipe to the N55 version, and I'm looking for advice. My problem is that the Torx bolts holding the cross brace in place just will not come out. I've sheared two bits off already just trying to loosen them with a breaker bar. I don't own any air tools, so I'm going to try heating them tomorrow and see if that helps. Anyone have any trouble with theirs? What did you do to get them off?

[houtan]

You spray them with pb blaster?

[drunkenup]

Don't remember if a long bar or air gun was used, but it took a proper quality snap on torx bit, courtesy of a shop by me. Which says a lot, since my cheaper bits started to round out the bolts. If you're running out of tools at this point, it might be cheaper to run to a shop and toss a couple bucks there. Anti-seize the shit out of them going back in

[Axiolus]

Yeah I'm letting them sit in some penetrating oil overnight, and I'll grab a new bit tomorrow. Hopefully that'll do it. If not, I'll try some heat and maybe take it to a shop.

[The Wind Breezes]

Try an impact gun and some penetrating oil, they will knock stuff like this loose easily when you can't make it move with a breaker bar.

[MightyMouseTech]

A lot less likely to round them off/break them if you use a good impact gun compared to hand tools. Be very careful if you do heat them up, remember, the carpet is right above them.

[vtl]

These are only specified for 24Nm.

I never have issues removing them unless a bonehead mechanic has worked on the the car for some exhaust work and rattled them on.

Carefully spot weld a nut to the rounded bolt (grind it first as its galvanized) and use a breaker bar to remove

[Dackelone]

Originally Posted by vtl

These are only specified for 24Nm.

Nope.

On my 135i that rear cross x-brace was indeed hard to break loose those e-torx bolts. I'd say they were torqued quite high around ~100 ft/lbs or so. I used a LONG breaker bar, which didn't budge them so I used a 600 ft/lbs 1/2 inch air gun. That did the trick.

You really need a high quality reverse torx socket(e-torx) like from SnapOn or Mac or the like. El cheap sockets won't cut it. I wouldn't use a torch. Just spray down the bolt heads and maybe use a big punch and hammer to "wake them up" before wrenching on them. IF your car has been driven in winter/salt... spray down the bolts over a day or so.

Also be prepared for the front downpipe studs to snap off. They were a real pain on my car. You WILL need an acetylene torch to get those broken bolts off. Make sure you have new dp gaskets and a rear mid pipe gasket donut, and new bolts/nuts for this job. I think I spent about $40 in spare hardware/parts when I replaced my mid pipes.

Good Luck,
Dackel



PS: This thread might help you out...

DIY installing N55 mid pipes on a N54...
http://www.1addicts.com/forums/showthread.php?t=797160

[vtl]

They're only M8 torx bolts (18mm in length), no way in hell they'd be 100Nm

Attached is the official ISTA documentation

Torque spec ID is 33 32 11AZ

33 32 11AZ Trailing link to body - 24 Nm

[houtan]

i think it's the size of the head of the bolt that makes them so hard to take off. The head is like a big washer, so even at 24NM, they are hard to take off, because there is a lot of bite from the head. They felt like they were torqued to 100ftlbs when i removed them.

[The Wind Breezes]

Originally Posted by houtan

even at 24NM, they are hard to take off,

Yeah, that's not how it works. 24NM is 24NM and it's not very much torque. The reasons these are "hard to take off" is mostly because they're under the car and they get seized with corrosive shit from the road. So even though the bolt may have been torqued to spec it could require hugely more torque to undo since not only do you have to break torque you also have to break through all the frozen shit holding it on there.

[Axiolus]

Well I finally managed to get them off, but I had to have a shop do it. I don't own any impact tools, and it took them two hours to finally get them out. I'm thinking it might have had to do with the fact that the bad cat in the pipe I was replacing was putting out way more heat than normal. Making it awfully difficult to get those bolts out again. I had them put anti seize compound on them so it doesn't happen again.